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linux/crypto/asymmetric_keys/pkcs7_verify.c

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PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/* Verify the signature on a PKCS#7 message.
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) "PKCS7: "fmt
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/asn1.h>
#include <crypto/hash.h>
crypto: KEYS: convert public key and digsig asym to the akcipher api This patch converts the module verification code to the new akcipher API. Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David Howells <dhowells@redhat.com>
2016-02-03 02:08:53 +08:00
#include <crypto/public_key.h>
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
#include "pkcs7_parser.h"
/*
* Digest the relevant parts of the PKCS#7 data
*/
static int pkcs7_digest(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
struct public_key_signature *sig = sinfo->sig;
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
struct crypto_shash *tfm;
struct shash_desc *desc;
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
size_t desc_size;
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
int ret;
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
if (!sinfo->sig->hash_algo)
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
return -ENOPKG;
/* Allocate the hashing algorithm we're going to need and find out how
* big the hash operational data will be.
*/
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
tfm = crypto_alloc_shash(sinfo->sig->hash_algo, 0, 0);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (IS_ERR(tfm))
return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sig->digest_size = crypto_shash_digestsize(tfm);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
ret = -ENOMEM;
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
if (!sig->digest)
goto error_no_desc;
desc = kzalloc(desc_size, GFP_KERNEL);
if (!desc)
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
goto error_no_desc;
desc->tfm = tfm;
desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
/* Digest the message [RFC2315 9.3] */
pkcs7: use crypto_shash_digest() Use crypto_shash_digest() instead of crypto_shash_init() followed by crypto_shash_finup(). (For simplicity only; they are equivalent.) Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
2017-12-08 23:13:28 +08:00
ret = crypto_shash_digest(desc, pkcs7->data, pkcs7->data_len,
sig->digest);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (ret < 0)
goto error;
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
pr_devel("MsgDigest = [%*ph]\n", 8, sig->digest);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/* However, if there are authenticated attributes, there must be a
* message digest attribute amongst them which corresponds to the
* digest we just calculated.
*/
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
if (sinfo->authattrs) {
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
u8 tag;
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
if (!sinfo->msgdigest) {
pr_warn("Sig %u: No messageDigest\n", sinfo->index);
ret = -EKEYREJECTED;
goto error;
}
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
if (sinfo->msgdigest_len != sig->digest_size) {
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
pr_debug("Sig %u: Invalid digest size (%u)\n",
sinfo->index, sinfo->msgdigest_len);
ret = -EBADMSG;
goto error;
}
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
if (memcmp(sig->digest, sinfo->msgdigest,
sinfo->msgdigest_len) != 0) {
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
pr_debug("Sig %u: Message digest doesn't match\n",
sinfo->index);
ret = -EKEYREJECTED;
goto error;
}
/* We then calculate anew, using the authenticated attributes
* as the contents of the digest instead. Note that we need to
* convert the attributes from a CONT.0 into a SET before we
* hash it.
*/
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
memset(sig->digest, 0, sig->digest_size);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
ret = crypto_shash_init(desc);
if (ret < 0)
goto error;
tag = ASN1_CONS_BIT | ASN1_SET;
ret = crypto_shash_update(desc, &tag, 1);
if (ret < 0)
goto error;
ret = crypto_shash_finup(desc, sinfo->authattrs,
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sinfo->authattrs_len, sig->digest);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (ret < 0)
goto error;
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
pr_devel("AADigest = [%*ph]\n", 8, sig->digest);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
error:
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
kfree(desc);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
error_no_desc:
crypto_free_shash(tfm);
kleave(" = %d", ret);
return ret;
}
/*
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
* Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7
* uses the issuer's name and the issuing certificate serial number for
* matching purposes. These must match the certificate issuer's name (not
* subject's name) and the certificate serial number [RFC 2315 6.7].
*/
static int pkcs7_find_key(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
struct x509_certificate *x509;
unsigned certix = 1;
KEYS: Overhaul key identification when searching for asymmetric keys Make use of the new match string preparsing to overhaul key identification when searching for asymmetric keys. The following changes are made: (1) Use the previously created asymmetric_key_id struct to hold the following key IDs derived from the X.509 certificate or PKCS#7 message: id: serial number + issuer skid: subjKeyId + subject authority: authKeyId + issuer (2) Replace the hex fingerprint attached to key->type_data[1] with an asymmetric_key_ids struct containing the id and the skid (if present). (3) Make the asymmetric_type match data preparse select one of two searches: (a) An iterative search for the key ID given if prefixed with "id:". The prefix is expected to be followed by a hex string giving the ID to search for. The criterion key ID is checked against all key IDs recorded on the key. (b) A direct search if the key ID is not prefixed with "id:". This will look for an exact match on the key description. (4) Make x509_request_asymmetric_key() take a key ID. This is then converted into "id:<hex>" and passed into keyring_search() where match preparsing will turn it back into a binary ID. (5) X.509 certificate verification then takes the authority key ID and looks up a key that matches it to find the public key for the certificate signature. (6) PKCS#7 certificate verification then takes the id key ID and looks up a key that matches it to find the public key for the signed information block signature. Additional changes: (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the cert to be rejected with -EBADMSG. (2) The 'fingerprint' ID is gone. This was primarily intended to convey PGP public key fingerprints. If PGP is supported in future, this should generate a key ID that carries the fingerprint. (3) Th ca_keyid= kernel command line option is now converted to a key ID and used to match the authority key ID. Possibly this should only match the actual authKeyId part and not the issuer as well. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:13 +08:00
kenter("%u", sinfo->index);
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
/* I'm _assuming_ that the generator of the PKCS#7 message will
* encode the fields from the X.509 cert in the same way in the
* PKCS#7 message - but I can't be 100% sure of that. It's
* possible this will need element-by-element comparison.
*/
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
if (!asymmetric_key_id_same(x509->id, sinfo->sig->auth_ids[0]))
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
continue;
pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
sinfo->index, certix);
X.509: fix comparisons of ->pkey_algo ->pkey_algo used to be an enum, but was changed to a string by commit 4e8ae72a75aa ("X.509: Make algo identifiers text instead of enum"). But two comparisons were not updated. Fix them to use strcmp(). This bug broke signature verification in certain configurations, depending on whether the string constants were deduplicated or not. Fixes: 4e8ae72a75aa ("X.509: Make algo identifiers text instead of enum") Cc: <stable@vger.kernel.org> # v4.6+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
2017-12-08 23:13:29 +08:00
if (strcmp(x509->pub->pkey_algo, sinfo->sig->pkey_algo) != 0) {
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
sinfo->index);
continue;
}
sinfo->signer = x509;
return 0;
}
KEYS: Overhaul key identification when searching for asymmetric keys Make use of the new match string preparsing to overhaul key identification when searching for asymmetric keys. The following changes are made: (1) Use the previously created asymmetric_key_id struct to hold the following key IDs derived from the X.509 certificate or PKCS#7 message: id: serial number + issuer skid: subjKeyId + subject authority: authKeyId + issuer (2) Replace the hex fingerprint attached to key->type_data[1] with an asymmetric_key_ids struct containing the id and the skid (if present). (3) Make the asymmetric_type match data preparse select one of two searches: (a) An iterative search for the key ID given if prefixed with "id:". The prefix is expected to be followed by a hex string giving the ID to search for. The criterion key ID is checked against all key IDs recorded on the key. (b) A direct search if the key ID is not prefixed with "id:". This will look for an exact match on the key description. (4) Make x509_request_asymmetric_key() take a key ID. This is then converted into "id:<hex>" and passed into keyring_search() where match preparsing will turn it back into a binary ID. (5) X.509 certificate verification then takes the authority key ID and looks up a key that matches it to find the public key for the certificate signature. (6) PKCS#7 certificate verification then takes the id key ID and looks up a key that matches it to find the public key for the signed information block signature. Additional changes: (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the cert to be rejected with -EBADMSG. (2) The 'fingerprint' ID is gone. This was primarily intended to convey PGP public key fingerprints. If PGP is supported in future, this should generate a key ID that carries the fingerprint. (3) Th ca_keyid= kernel command line option is now converted to a key ID and used to match the authority key ID. Possibly this should only match the actual authKeyId part and not the issuer as well. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:13 +08:00
PKCS#7: Handle PKCS#7 messages that contain no X.509 certs The X.509 certificate list in a PKCS#7 message is optional. To save space, we can omit the inclusion of any X.509 certificates if we are sure that we can look the relevant public key up by the serial number and issuer given in a signed info block. This also supports use of a signed info block for which we can't find a matching X.509 cert in the certificate list, though it be populated. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:17 +08:00
/* The relevant X.509 cert isn't found here, but it might be found in
* the trust keyring.
*/
pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
sinfo->index,
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sinfo->sig->auth_ids[0]->len, sinfo->sig->auth_ids[0]->data);
PKCS#7: Handle PKCS#7 messages that contain no X.509 certs The X.509 certificate list in a PKCS#7 message is optional. To save space, we can omit the inclusion of any X.509 certificates if we are sure that we can look the relevant public key up by the serial number and issuer given in a signed info block. This also supports use of a signed info block for which we can't find a matching X.509 cert in the certificate list, though it be populated. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:17 +08:00
return 0;
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/*
* Verify the internal certificate chain as best we can.
*/
static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
struct public_key_signature *sig;
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
struct x509_certificate *x509 = sinfo->signer, *p;
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
struct asymmetric_key_id *auth;
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
int ret;
kenter("");
for (p = pkcs7->certs; p; p = p->next)
p->seen = false;
for (;;) {
KEYS: Overhaul key identification when searching for asymmetric keys Make use of the new match string preparsing to overhaul key identification when searching for asymmetric keys. The following changes are made: (1) Use the previously created asymmetric_key_id struct to hold the following key IDs derived from the X.509 certificate or PKCS#7 message: id: serial number + issuer skid: subjKeyId + subject authority: authKeyId + issuer (2) Replace the hex fingerprint attached to key->type_data[1] with an asymmetric_key_ids struct containing the id and the skid (if present). (3) Make the asymmetric_type match data preparse select one of two searches: (a) An iterative search for the key ID given if prefixed with "id:". The prefix is expected to be followed by a hex string giving the ID to search for. The criterion key ID is checked against all key IDs recorded on the key. (b) A direct search if the key ID is not prefixed with "id:". This will look for an exact match on the key description. (4) Make x509_request_asymmetric_key() take a key ID. This is then converted into "id:<hex>" and passed into keyring_search() where match preparsing will turn it back into a binary ID. (5) X.509 certificate verification then takes the authority key ID and looks up a key that matches it to find the public key for the certificate signature. (6) PKCS#7 certificate verification then takes the id key ID and looks up a key that matches it to find the public key for the signed information block signature. Additional changes: (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the cert to be rejected with -EBADMSG. (2) The 'fingerprint' ID is gone. This was primarily intended to convey PGP public key fingerprints. If PGP is supported in future, this should generate a key ID that carries the fingerprint. (3) Th ca_keyid= kernel command line option is now converted to a key ID and used to match the authority key ID. Possibly this should only match the actual authKeyId part and not the issuer as well. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:13 +08:00
pr_debug("verify %s: %*phN\n",
x509->subject,
x509->raw_serial_size, x509->raw_serial);
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
x509->seen = true;
PKCS#7: Handle blacklisted certificates PKCS#7: Handle certificates that are blacklisted when verifying the chain of trust on the signatures on a PKCS#7 message. Signed-off-by: David Howells <dhowells@redhat.com>
2017-04-03 23:07:25 +08:00
if (x509->blacklisted) {
/* If this cert is blacklisted, then mark everything
* that depends on this as blacklisted too.
*/
sinfo->blacklisted = true;
for (p = sinfo->signer; p != x509; p = p->signer)
p->blacklisted = true;
pr_debug("- blacklisted\n");
return 0;
}
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
if (x509->unsupported_key)
goto unsupported_crypto_in_x509;
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
PKCS#7: X.509 certificate issuer and subject are mandatory fields in the ASN.1 X.509 certificate issuer and subject fields are mandatory fields in the ASN.1 and so their existence needn't be tested for. They are guaranteed to end up with an empty string if the name material has nothing we can use (see x509_fabricate_name()). Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-07-31 21:46:44 +08:00
pr_debug("- issuer %s\n", x509->issuer);
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sig = x509->sig;
if (sig->auth_ids[0])
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
pr_debug("- authkeyid.id %*phN\n",
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sig->auth_ids[0]->len, sig->auth_ids[0]->data);
if (sig->auth_ids[1])
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
pr_debug("- authkeyid.skid %*phN\n",
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
sig->auth_ids[1]->len, sig->auth_ids[1]->data);
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
if (x509->self_signed) {
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/* If there's no authority certificate specified, then
* the certificate must be self-signed and is the root
* of the chain. Likewise if the cert is its own
* authority.
*/
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
if (x509->unsupported_sig)
goto unsupported_crypto_in_x509;
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
x509->signer = x509;
pr_debug("- self-signed\n");
return 0;
}
/* Look through the X.509 certificates in the PKCS#7 message's
* list to see if the next one is there.
*/
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
auth = sig->auth_ids[0];
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
if (auth) {
pr_debug("- want %*phN\n", auth->len, auth->data);
for (p = pkcs7->certs; p; p = p->next) {
pr_debug("- cmp [%u] %*phN\n",
p->index, p->id->len, p->id->data);
if (asymmetric_key_id_same(p->id, auth))
goto found_issuer_check_skid;
}
PKCS#7: Fix panic when referring to the empty AKID when DEBUG defined This fix resolves the following kernel panic if an empty or missing AuthorityKeyIdentifier is encountered and DEBUG is defined in pkcs7_verify.c. [ 459.041989] PKEY: <==public_key_verify_signature() = 0 [ 459.041993] PKCS7: Verified signature 1 [ 459.041995] PKCS7: ==> pkcs7_verify_sig_chain() [ 459.041999] PKCS7: verify Sample DB Certificate for SCP: 01 [ 459.042002] PKCS7: - issuer Sample KEK Certificate for SCP [ 459.042014] BUG: unable to handle kernel NULL pointer dereference at (null) [ 459.042135] IP: [<ffffffff813e7b4c>] pkcs7_verify+0x72c/0x7f0 [ 459.042217] PGD 739e6067 PUD 77719067 PMD 0 [ 459.042286] Oops: 0000 [#1] PREEMPT SMP [ 459.042328] Modules linked in: [ 459.042368] CPU: 0 PID: 474 Comm: kexec Not tainted 4.7.0-rc7-WR8.0.0.0_standard+ #18 [ 459.042462] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 10/09/2014 [ 459.042586] task: ffff880073a50000 ti: ffff8800738e8000 task.ti: ffff8800738e8000 [ 459.042675] RIP: 0010:[<ffffffff813e7b4c>] [<ffffffff813e7b4c>] pkcs7_verify+0x72c/0x7f0 [ 459.042784] RSP: 0018:ffff8800738ebd58 EFLAGS: 00010246 [ 459.042845] RAX: 0000000000000000 RBX: ffff880076b7da80 RCX: 0000000000000006 [ 459.042929] RDX: 0000000000000001 RSI: ffffffff81c85001 RDI: ffffffff81ca00a9 [ 459.043014] RBP: ffff8800738ebd98 R08: 0000000000000400 R09: ffff8800788a304c [ 459.043098] R10: 0000000000000000 R11: 00000000000060ca R12: ffff8800769a2bc0 [ 459.043182] R13: ffff880077358300 R14: 0000000000000000 R15: ffff8800769a2dc0 [ 459.043268] FS: 00007f24cc741700(0000) GS:ffff880074e00000(0000) knlGS:0000000000000000 [ 459.043365] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 459.043431] CR2: 0000000000000000 CR3: 0000000073a36000 CR4: 00000000001006f0 [ 459.043514] Stack: [ 459.043530] 0000000000000000 ffffffbf00000020 31ffffff813e68b0 0000000000000002 [ 459.043644] ffff8800769a2bc0 0000000000000000 00000000007197b8 0000000000000002 [ 459.043756] ffff8800738ebdd8 ffffffff81153fb1 0000000000000000 0000000000000000 [ 459.043869] Call Trace: [ 459.043898] [<ffffffff81153fb1>] verify_pkcs7_signature+0x61/0x140 [ 459.043974] [<ffffffff813e7f0b>] verify_pefile_signature+0x2cb/0x830 [ 459.044052] [<ffffffff813e8470>] ? verify_pefile_signature+0x830/0x830 [ 459.044134] [<ffffffff81048e25>] bzImage64_verify_sig+0x15/0x20 [ 459.046332] [<ffffffff81046e09>] arch_kexec_kernel_verify_sig+0x29/0x40 [ 459.048552] [<ffffffff810f10e4>] SyS_kexec_file_load+0x1f4/0x6c0 [ 459.050768] [<ffffffff81050e36>] ? __do_page_fault+0x1b6/0x550 [ 459.052996] [<ffffffff8199241f>] entry_SYSCALL_64_fastpath+0x17/0x93 [ 459.055242] Code: e8 0a d6 ff ff 85 c0 0f 88 7a fb ff ff 4d 39 fd 4d 89 7d 08 74 45 4d 89 fd e9 14 fe ff ff 4d 8b 76 08 31 c0 48 c7 c7 a9 00 ca 81 <41> 0f b7 36 49 8d 56 02 e8 d0 91 d6 ff 4d 8b 3c 24 4d 85 ff 0f [ 459.060535] RIP [<ffffffff813e7b4c>] pkcs7_verify+0x72c/0x7f0 [ 459.063040] RSP <ffff8800738ebd58> [ 459.065456] CR2: 0000000000000000 [ 459.075998] ---[ end trace c15f0e897cda28dc ]--- Signed-off-by: Lans Zhang <jia.zhang@windriver.com> Signed-off-by: David Howells <dhowells@redhat.com> Cc: Dave Young <dyoung@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> cc: linux-crypto@vger.kernel.org cc: kexec@lists.infradead.org Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-07-18 07:10:39 +08:00
} else if (sig->auth_ids[1]) {
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
auth = sig->auth_ids[1];
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
pr_debug("- want %*phN\n", auth->len, auth->data);
for (p = pkcs7->certs; p; p = p->next) {
if (!p->skid)
continue;
pr_debug("- cmp [%u] %*phN\n",
p->index, p->skid->len, p->skid->data);
if (asymmetric_key_id_same(p->skid, auth))
goto found_issuer;
}
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
/* We didn't find the root of this chain */
pr_debug("- top\n");
return 0;
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
found_issuer_check_skid:
/* We matched issuer + serialNumber, but if there's an
* authKeyId.keyId, that must match the CA subjKeyId also.
*/
X.509: Retain the key verification data Retain the key verification data (ie. the struct public_key_signature) including the digest and the key identifiers. Note that this means that we need to take a separate copy of the digest in x509_get_sig_params() rather than lumping it in with the crypto layer data. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
if (sig->auth_ids[1] &&
!asymmetric_key_id_same(p->skid, sig->auth_ids[1])) {
X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier If an X.509 certificate has an AuthorityKeyIdentifier extension that provides an issuer and serialNumber, then make it so that these are used in preference to the keyIdentifier field also held therein for searching for the signing certificate. If both the issuer+serialNumber and the keyIdentifier are supplied, then the certificate is looked up by the former but the latter is checked as well. If the latter doesn't match the subjectKeyIdentifier of the parent certificate, EKEYREJECTED is returned. This makes it possible to chain X.509 certificates based on the issuer and serialNumber fields rather than on subjectKeyIdentifier. This is necessary as we are having to deal with keys that are represented by X.509 certificates that lack a subjectKeyIdentifier. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
pr_warn("Sig %u: X.509 chain contains auth-skid nonmatch (%u->%u)\n",
sinfo->index, x509->index, p->index);
return -EKEYREJECTED;
}
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
found_issuer:
KEYS: Overhaul key identification when searching for asymmetric keys Make use of the new match string preparsing to overhaul key identification when searching for asymmetric keys. The following changes are made: (1) Use the previously created asymmetric_key_id struct to hold the following key IDs derived from the X.509 certificate or PKCS#7 message: id: serial number + issuer skid: subjKeyId + subject authority: authKeyId + issuer (2) Replace the hex fingerprint attached to key->type_data[1] with an asymmetric_key_ids struct containing the id and the skid (if present). (3) Make the asymmetric_type match data preparse select one of two searches: (a) An iterative search for the key ID given if prefixed with "id:". The prefix is expected to be followed by a hex string giving the ID to search for. The criterion key ID is checked against all key IDs recorded on the key. (b) A direct search if the key ID is not prefixed with "id:". This will look for an exact match on the key description. (4) Make x509_request_asymmetric_key() take a key ID. This is then converted into "id:<hex>" and passed into keyring_search() where match preparsing will turn it back into a binary ID. (5) X.509 certificate verification then takes the authority key ID and looks up a key that matches it to find the public key for the certificate signature. (6) PKCS#7 certificate verification then takes the id key ID and looks up a key that matches it to find the public key for the signed information block signature. Additional changes: (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the cert to be rejected with -EBADMSG. (2) The 'fingerprint' ID is gone. This was primarily intended to convey PGP public key fingerprints. If PGP is supported in future, this should generate a key ID that carries the fingerprint. (3) Th ca_keyid= kernel command line option is now converted to a key ID and used to match the authority key ID. Possibly this should only match the actual authKeyId part and not the issuer as well. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:13 +08:00
pr_debug("- subject %s\n", p->subject);
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (p->seen) {
pr_warn("Sig %u: X.509 chain contains loop\n",
sinfo->index);
return 0;
}
PKCS#7: fix certificate chain verification When pkcs7_verify_sig_chain() is building the certificate chain for a SignerInfo using the certificates in the PKCS#7 message, it is passing the wrong arguments to public_key_verify_signature(). Consequently, when the next certificate is supposed to be used to verify the previous certificate, the next certificate is actually used to verify itself. An attacker can use this bug to create a bogus certificate chain that has no cryptographic relationship between the beginning and end. Fortunately I couldn't quite find a way to use this to bypass the overall signature verification, though it comes very close. Here's the reasoning: due to the bug, every certificate in the chain beyond the first actually has to be self-signed (where "self-signed" here refers to the actual key and signature; an attacker might still manipulate the certificate fields such that the self_signed flag doesn't actually get set, and thus the chain doesn't end immediately). But to pass trust validation (pkcs7_validate_trust()), either the SignerInfo or one of the certificates has to actually be signed by a trusted key. Since only self-signed certificates can be added to the chain, the only way for an attacker to introduce a trusted signature is to include a self-signed trusted certificate. But, when pkcs7_validate_trust_one() reaches that certificate, instead of trying to verify the signature on that certificate, it will actually look up the corresponding trusted key, which will succeed, and then try to verify the *previous* certificate, which will fail. Thus, disaster is narrowly averted (as far as I could tell). Fixes: 6c2dc5ae4ab7 ("X.509: Extract signature digest and make self-signed cert checks earlier") Cc: <stable@vger.kernel.org> # v4.7+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
2018-02-22 22:38:33 +08:00
ret = public_key_verify_signature(p->pub, x509->sig);
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (ret < 0)
return ret;
x509->signer = p;
if (x509 == p) {
pr_debug("- self-signed\n");
return 0;
}
x509 = p;
might_sleep();
}
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
unsupported_crypto_in_x509:
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
/* Just prune the certificate chain at this point if we lack some
* crypto module to go further. Note, however, we don't want to set
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
* sinfo->unsupported_crypto as the signed info block may still be
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
* validatable against an X.509 cert lower in the chain that we have a
* trusted copy of.
*/
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
return 0;
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/*
* Verify one signed information block from a PKCS#7 message.
*/
static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
int ret;
kenter(",%u", sinfo->index);
/* First of all, digest the data in the PKCS#7 message and the
* signed information block
*/
ret = pkcs7_digest(pkcs7, sinfo);
if (ret < 0)
return ret;
PKCS#7: Handle PKCS#7 messages that contain no X.509 certs The X.509 certificate list in a PKCS#7 message is optional. To save space, we can omit the inclusion of any X.509 certificates if we are sure that we can look the relevant public key up by the serial number and issuer given in a signed info block. This also supports use of a signed info block for which we can't find a matching X.509 cert in the certificate list, though it be populated. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:17 +08:00
/* Find the key for the signature if there is one */
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
ret = pkcs7_find_key(pkcs7, sinfo);
if (ret < 0)
return ret;
PKCS#7: Handle PKCS#7 messages that contain no X.509 certs The X.509 certificate list in a PKCS#7 message is optional. To save space, we can omit the inclusion of any X.509 certificates if we are sure that we can look the relevant public key up by the serial number and issuer given in a signed info block. This also supports use of a signed info block for which we can't find a matching X.509 cert in the certificate list, though it be populated. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:17 +08:00
if (!sinfo->signer)
return 0;
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
pr_devel("Using X.509[%u] for sig %u\n",
sinfo->signer->index, sinfo->index);
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
/* Check that the PKCS#7 signing time is valid according to the X.509
* certificate. We can't, however, check against the system clock
* since that may not have been set yet and may be wrong.
*/
if (test_bit(sinfo_has_signing_time, &sinfo->aa_set)) {
if (sinfo->signing_time < sinfo->signer->valid_from ||
sinfo->signing_time > sinfo->signer->valid_to) {
pr_warn("Message signed outside of X.509 validity window\n");
return -EKEYREJECTED;
}
}
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/* Verify the PKCS#7 binary against the key */
PKCS#7: Make the signature a pointer rather than embedding it Point to the public_key_signature struct from the pkcs7_signed_info struct rather than embedding it. This makes the code consistent with the X.509 signature handling and makes it possible to have a common cleanup function. We also save a copy of the digest in the signature without sharing the memory with the crypto layer metadata. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:33 +08:00
ret = public_key_verify_signature(sinfo->signer->pub, sinfo->sig);
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature Find the appropriate key in the PKCS#7 key list and verify the signature with it. There may be several keys in there forming a chain. Any link in that chain or the root of that chain may be in our keyrings. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (ret < 0)
return ret;
pr_devel("Verified signature %u\n", sinfo->index);
PKCS#7: Verify internal certificate chain Verify certificate chain in the X.509 certificates contained within the PKCS#7 message as far as possible. If any signature that we should be able to verify fails, we reject the whole lot. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
/* Verify the internal certificate chain */
return pkcs7_verify_sig_chain(pkcs7, sinfo);
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
/**
* pkcs7_verify - Verify a PKCS#7 message
* @pkcs7: The PKCS#7 message to be verified
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
* @usage: The use to which the key is being put
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
*
* Verify a PKCS#7 message is internally consistent - that is, the data digest
* matches the digest in the AuthAttrs and any signature in the message or one
* of the X.509 certificates it carries that matches another X.509 cert in the
* message can be verified.
*
* This does not look to match the contents of the PKCS#7 message against any
* external public keys.
*
* Returns, in order of descending priority:
*
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
* (*) -EKEYREJECTED if a key was selected that had a usage restriction at
* odds with the specified usage, or:
*
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
* (*) -EKEYREJECTED if a signature failed to match for which we found an
* appropriate X.509 certificate, or:
*
* (*) -EBADMSG if some part of the message was invalid, or:
*
PKCS#7: fix certificate blacklisting If there is a blacklisted certificate in a SignerInfo's certificate chain, then pkcs7_verify_sig_chain() sets sinfo->blacklisted and returns 0. But, pkcs7_verify() fails to handle this case appropriately, as it actually continues on to the line 'actual_ret = 0;', indicating that the SignerInfo has passed verification. Consequently, PKCS#7 signature verification ignores the certificate blacklist. Fix this by not considering blacklisted SignerInfos to have passed verification. Also fix the function comment with regards to when 0 is returned. Fixes: 03bb79315ddc ("PKCS#7: Handle blacklisted certificates") Cc: <stable@vger.kernel.org> # v4.12+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
2018-02-22 22:38:33 +08:00
* (*) 0 if a signature chain passed verification, or:
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
*
PKCS#7: Handle blacklisted certificates PKCS#7: Handle certificates that are blacklisted when verifying the chain of trust on the signatures on a PKCS#7 message. Signed-off-by: David Howells <dhowells@redhat.com>
2017-04-03 23:07:25 +08:00
* (*) -EKEYREJECTED if a blacklisted key was encountered, or:
*
* (*) -ENOPKG if none of the signature chains are verifiable because suitable
* crypto modules couldn't be found.
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
*/
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
int pkcs7_verify(struct pkcs7_message *pkcs7,
enum key_being_used_for usage)
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
{
struct pkcs7_signed_info *sinfo;
PKCS#7: Handle blacklisted certificates PKCS#7: Handle certificates that are blacklisted when verifying the chain of trust on the signatures on a PKCS#7 message. Signed-off-by: David Howells <dhowells@redhat.com>
2017-04-03 23:07:25 +08:00
int actual_ret = -ENOPKG;
X.509: Extract signature digest and make self-signed cert checks earlier Extract the signature digest for an X.509 certificate earlier, at the end of x509_cert_parse() rather than leaving it to the callers thereof since it has to be called anyway. Further, immediately after that, check the signature on self-signed certificates, also rather in the callers of x509_cert_parse(). We note in the x509_certificate struct the following bits of information: (1) Whether the signature is self-signed (even if we can't check the signature due to missing crypto). (2) Whether the key held in the certificate needs unsupported crypto to be used. We may get a PKCS#7 message with X.509 certs that we can't make use of - we just ignore them and give ENOPKG at the end it we couldn't verify anything if at least one of these unusable certs are in the chain of trust. (3) Whether the signature held in the certificate needs unsupported crypto to be checked. We can still use the key held in this certificate, even if we can't check the signature on it - if it is held in the system trusted keyring, for instance. We just can't add it to a ring of trusted keys or follow it further up the chain of trust. Making these checks earlier allows x509_check_signature() to be removed and replaced with direct calls to public_key_verify_signature(). Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-06 23:13:34 +08:00
int ret;
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
kenter("");
PKCS#7: Appropriately restrict authenticated attributes and content type A PKCS#7 or CMS message can have per-signature authenticated attributes that are digested as a lump and signed by the authorising key for that signature. If such attributes exist, the content digest isn't itself signed, but rather it is included in a special authattr which then contributes to the signature. Further, we already require the master message content type to be pkcs7_signedData - but there's also a separate content type for the data itself within the SignedData object and this must be repeated inside the authattrs for each signer [RFC2315 9.2, RFC5652 11.1]. We should really validate the authattrs if they exist or forbid them entirely as appropriate. To this end: (1) Alter the PKCS#7 parser to reject any message that has more than one signature where at least one signature has authattrs and at least one that does not. (2) Validate authattrs if they are present and strongly restrict them. Only the following authattrs are permitted and all others are rejected: (a) contentType. This is checked to be an OID that matches the content type in the SignedData object. (b) messageDigest. This must match the crypto digest of the data. (c) signingTime. If present, we check that this is a valid, parseable UTCTime or GeneralTime and that the date it encodes fits within the validity window of the matching X.509 cert. (d) S/MIME capabilities. We don't check the contents. (e) Authenticode SP Opus Info. We don't check the contents. (f) Authenticode Statement Type. We don't check the contents. The message is rejected if (a) or (b) are missing. If the message is an Authenticode type, the message is rejected if (e) is missing; if not Authenticode, the message is rejected if (d) - (f) are present. The S/MIME capabilities authattr (d) unfortunately has to be allowed to support kernels already signed by the pesign program. This only affects kexec. sign-file suppresses them (CMS_NOSMIMECAP). The message is also rejected if an authattr is given more than once or if it contains more than one element in its set of values. (3) Add a parameter to pkcs7_verify() to select one of the following restrictions and pass in the appropriate option from the callers: (*) VERIFYING_MODULE_SIGNATURE This requires that the SignedData content type be pkcs7-data and forbids authattrs. sign-file sets CMS_NOATTR. We could be more flexible and permit authattrs optionally, but only permit minimal content. (*) VERIFYING_FIRMWARE_SIGNATURE This requires that the SignedData content type be pkcs7-data and requires authattrs. In future, this will require an attribute holding the target firmware name in addition to the minimal set. (*) VERIFYING_UNSPECIFIED_SIGNATURE This requires that the SignedData content type be pkcs7-data but allows either no authattrs or only permits the minimal set. (*) VERIFYING_KEXEC_PE_SIGNATURE This only supports the Authenticode SPC_INDIRECT_DATA content type and requires at least an SpcSpOpusInfo authattr in addition to the minimal set. It also permits an SPC_STATEMENT_TYPE authattr (and an S/MIME capabilities authattr because the pesign program doesn't remove these). (*) VERIFYING_KEY_SIGNATURE (*) VERIFYING_KEY_SELF_SIGNATURE These are invalid in this context but are included for later use when limiting the use of X.509 certs. (4) The pkcs7_test key type is given a module parameter to select between the above options for testing purposes. For example: echo 1 >/sys/module/pkcs7_test_key/parameters/usage keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7 will attempt to check the signature on stuff.pkcs7 as if it contains a firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE). Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 22:22:27 +08:00
switch (usage) {
case VERIFYING_MODULE_SIGNATURE:
if (pkcs7->data_type != OID_data) {
pr_warn("Invalid module sig (not pkcs7-data)\n");
return -EKEYREJECTED;
}
if (pkcs7->have_authattrs) {
pr_warn("Invalid module sig (has authattrs)\n");
return -EKEYREJECTED;
}
break;
case VERIFYING_FIRMWARE_SIGNATURE:
if (pkcs7->data_type != OID_data) {
pr_warn("Invalid firmware sig (not pkcs7-data)\n");
return -EKEYREJECTED;
}
if (!pkcs7->have_authattrs) {
pr_warn("Invalid firmware sig (missing authattrs)\n");
return -EKEYREJECTED;
}
break;
case VERIFYING_KEXEC_PE_SIGNATURE:
if (pkcs7->data_type != OID_msIndirectData) {
pr_warn("Invalid kexec sig (not Authenticode)\n");
return -EKEYREJECTED;
}
/* Authattr presence checked in parser */
break;
case VERIFYING_UNSPECIFIED_SIGNATURE:
if (pkcs7->data_type != OID_data) {
pr_warn("Invalid unspecified sig (not pkcs7-data)\n");
return -EKEYREJECTED;
}
break;
default:
return -EINVAL;
}
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
ret = pkcs7_verify_one(pkcs7, sinfo);
PKCS#7: fix certificate blacklisting If there is a blacklisted certificate in a SignerInfo's certificate chain, then pkcs7_verify_sig_chain() sets sinfo->blacklisted and returns 0. But, pkcs7_verify() fails to handle this case appropriately, as it actually continues on to the line 'actual_ret = 0;', indicating that the SignerInfo has passed verification. Consequently, PKCS#7 signature verification ignores the certificate blacklist. Fix this by not considering blacklisted SignerInfos to have passed verification. Also fix the function comment with regards to when 0 is returned. Fixes: 03bb79315ddc ("PKCS#7: Handle blacklisted certificates") Cc: <stable@vger.kernel.org> # v4.12+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
2018-02-22 22:38:33 +08:00
if (sinfo->blacklisted) {
if (actual_ret == -ENOPKG)
actual_ret = -EKEYREJECTED;
continue;
}
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
if (ret < 0) {
PKCS#7: Better handling of unsupported crypto Provide better handling of unsupported crypto when verifying a PKCS#7 message. If we can't bridge the gap between a pair of X.509 certs or between a signed info block and an X.509 cert because it involves some crypto we don't support, that's not necessarily the end of the world as there may be other ways points at which we can intersect with a ring of trusted keys. Instead, only produce ENOPKG immediately if all the signed info blocks in a PKCS#7 message require unsupported crypto to bridge to the first X.509 cert. Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust validation. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-17 00:36:15 +08:00
if (ret == -ENOPKG) {
sinfo->unsupported_crypto = true;
continue;
}
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
kleave(" = %d", ret);
return ret;
}
PKCS#7: Handle blacklisted certificates PKCS#7: Handle certificates that are blacklisted when verifying the chain of trust on the signatures on a PKCS#7 message. Signed-off-by: David Howells <dhowells@redhat.com>
2017-04-03 23:07:25 +08:00
actual_ret = 0;
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
PKCS#7: Handle blacklisted certificates PKCS#7: Handle certificates that are blacklisted when verifying the chain of trust on the signatures on a PKCS#7 message. Signed-off-by: David Howells <dhowells@redhat.com>
2017-04-03 23:07:25 +08:00
kleave(" = %d", actual_ret);
return actual_ret;
PKCS#7: Digest the data in a signed-data message Digest the data in a PKCS#7 signed-data message and attach to the public_key_signature struct contained in the pkcs7_message struct. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2014-07-01 23:40:19 +08:00
}
EXPORT_SYMBOL_GPL(pkcs7_verify);
PKCS#7: Allow detached data to be supplied for signature checking purposes It is possible for a PKCS#7 message to have detached data. However, to verify the signatures on a PKCS#7 message, we have to be able to digest the data. Provide a function to supply that data. An error is given if the PKCS#7 message included embedded data. This is used in a subsequent patch to supply the data to module signing where the signature is in the form of a PKCS#7 message with detached data, whereby the detached data is the module content that is signed. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Vivek Goyal <vgoyal@redhat.com>
2015-07-21 04:16:26 +08:00
/**
* pkcs7_supply_detached_data - Supply the data needed to verify a PKCS#7 message
* @pkcs7: The PKCS#7 message
* @data: The data to be verified
* @datalen: The amount of data
*
* Supply the detached data needed to verify a PKCS#7 message. Note that no
* attempt to retain/pin the data is made. That is left to the caller. The
* data will not be modified by pkcs7_verify() and will not be freed when the
* PKCS#7 message is freed.
*
* Returns -EINVAL if data is already supplied in the message, 0 otherwise.
*/
int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
const void *data, size_t datalen)
{
if (pkcs7->data) {
pr_debug("Data already supplied\n");
return -EINVAL;
}
pkcs7->data = data;
pkcs7->data_len = datalen;
return 0;
}