2006-10-11 16:20:50 +08:00
|
|
|
/*
|
2006-10-11 16:20:53 +08:00
|
|
|
* linux/fs/ext4/symlink.c
|
2006-10-11 16:20:50 +08:00
|
|
|
*
|
|
|
|
|
* Only fast symlinks left here - the rest is done by generic code. AV, 1999
|
|
|
|
|
*
|
|
|
|
|
* Copyright (C) 1992, 1993, 1994, 1995
|
|
|
|
|
* Remy Card (card@masi.ibp.fr)
|
|
|
|
|
* Laboratoire MASI - Institut Blaise Pascal
|
|
|
|
|
* Universite Pierre et Marie Curie (Paris VI)
|
|
|
|
|
*
|
|
|
|
|
* from
|
|
|
|
|
*
|
|
|
|
|
* linux/fs/minix/symlink.c
|
|
|
|
|
*
|
|
|
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
|
|
|
*
|
2006-10-11 16:20:53 +08:00
|
|
|
* ext4 symlink handling code
|
2006-10-11 16:20:50 +08:00
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#include <linux/fs.h>
|
|
|
|
|
#include <linux/namei.h>
|
2008-04-30 06:13:32 +08:00
|
|
|
#include "ext4.h"
|
2006-10-11 16:20:50 +08:00
|
|
|
#include "xattr.h"
|
|
|
|
|
|
2015-04-16 13:55:00 +08:00
|
|
|
#ifdef CONFIG_EXT4_FS_ENCRYPTION
|
2015-11-17 23:20:54 +08:00
|
|
|
static const char *ext4_encrypted_get_link(struct dentry *dentry,
|
2015-12-30 04:58:39 +08:00
|
|
|
struct inode *inode,
|
|
|
|
|
struct delayed_call *done)
|
2015-04-16 13:55:00 +08:00
|
|
|
{
|
|
|
|
|
struct page *cpage = NULL;
|
|
|
|
|
char *caddr, *paddr = NULL;
|
|
|
|
|
struct ext4_str cstr, pstr;
|
|
|
|
|
struct ext4_encrypted_symlink_data *sd;
|
|
|
|
|
loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
|
|
|
|
|
int res;
|
|
|
|
|
u32 plen, max_size = inode->i_sb->s_blocksize;
|
|
|
|
|
|
2015-11-17 23:20:54 +08:00
|
|
|
if (!dentry)
|
|
|
|
|
return ERR_PTR(-ECHILD);
|
|
|
|
|
|
2015-06-01 01:34:22 +08:00
|
|
|
res = ext4_get_encryption_info(inode);
|
ext4 crypto: reorganize how we store keys in the inode
This is a pretty massive patch which does a number of different things:
1) The per-inode encryption information is now stored in an allocated
data structure, ext4_crypt_info, instead of directly in the node.
This reduces the size usage of an in-memory inode when it is not
using encryption.
2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
encryption structure instead. This remove an unnecessary memory
allocation and free for the fname_crypto_ctx as well as allowing us
to reuse the ctfm in a directory for multiple lookups and file
creations.
3) We also cache the inode's policy information in the ext4_crypt_info
structure so we don't have to continually read it out of the
extended attributes.
4) We now keep the keyring key in the inode's encryption structure
instead of releasing it after we are done using it to derive the
per-inode key. This allows us to test to see if the key has been
revoked; if it has, we prevent the use of the derived key and free
it.
5) When an inode is released (or when the derived key is freed), we
will use memset_explicit() to zero out the derived key, so it's not
left hanging around in memory. This implies that when a user logs
out, it is important to first revoke the key, and then unlink it,
and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
release any decrypted pages and dcache entries from the system
caches.
6) All this, and we also shrink the number of lines of code by around
100. :-)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2015-05-19 01:17:47 +08:00
|
|
|
if (res)
|
|
|
|
|
return ERR_PTR(res);
|
2015-04-16 13:55:00 +08:00
|
|
|
|
|
|
|
|
if (ext4_inode_is_fast_symlink(inode)) {
|
2015-04-27 06:48:49 +08:00
|
|
|
caddr = (char *) EXT4_I(inode)->i_data;
|
|
|
|
|
max_size = sizeof(EXT4_I(inode)->i_data);
|
2015-04-16 13:55:00 +08:00
|
|
|
} else {
|
|
|
|
|
cpage = read_mapping_page(inode->i_mapping, 0, NULL);
|
ext4 crypto: reorganize how we store keys in the inode
This is a pretty massive patch which does a number of different things:
1) The per-inode encryption information is now stored in an allocated
data structure, ext4_crypt_info, instead of directly in the node.
This reduces the size usage of an in-memory inode when it is not
using encryption.
2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
encryption structure instead. This remove an unnecessary memory
allocation and free for the fname_crypto_ctx as well as allowing us
to reuse the ctfm in a directory for multiple lookups and file
creations.
3) We also cache the inode's policy information in the ext4_crypt_info
structure so we don't have to continually read it out of the
extended attributes.
4) We now keep the keyring key in the inode's encryption structure
instead of releasing it after we are done using it to derive the
per-inode key. This allows us to test to see if the key has been
revoked; if it has, we prevent the use of the derived key and free
it.
5) When an inode is released (or when the derived key is freed), we
will use memset_explicit() to zero out the derived key, so it's not
left hanging around in memory. This implies that when a user logs
out, it is important to first revoke the key, and then unlink it,
and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
release any decrypted pages and dcache entries from the system
caches.
6) All this, and we also shrink the number of lines of code by around
100. :-)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2015-05-19 01:17:47 +08:00
|
|
|
if (IS_ERR(cpage))
|
2015-05-03 01:32:22 +08:00
|
|
|
return ERR_CAST(cpage);
|
2015-11-17 14:07:57 +08:00
|
|
|
caddr = page_address(cpage);
|
2015-04-16 13:55:00 +08:00
|
|
|
caddr[size] = 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* Symlink is encrypted */
|
|
|
|
|
sd = (struct ext4_encrypted_symlink_data *)caddr;
|
|
|
|
|
cstr.name = sd->encrypted_path;
|
2015-11-27 04:20:50 +08:00
|
|
|
cstr.len = le16_to_cpu(sd->len);
|
2015-04-16 13:55:00 +08:00
|
|
|
if ((cstr.len +
|
|
|
|
|
sizeof(struct ext4_encrypted_symlink_data) - 1) >
|
|
|
|
|
max_size) {
|
|
|
|
|
/* Symlink data on the disk is corrupted */
|
2015-10-18 04:16:04 +08:00
|
|
|
res = -EFSCORRUPTED;
|
2015-04-16 13:55:00 +08:00
|
|
|
goto errout;
|
|
|
|
|
}
|
|
|
|
|
plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
|
|
|
|
|
EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
|
|
|
|
|
paddr = kmalloc(plen + 1, GFP_NOFS);
|
|
|
|
|
if (!paddr) {
|
|
|
|
|
res = -ENOMEM;
|
|
|
|
|
goto errout;
|
|
|
|
|
}
|
|
|
|
|
pstr.name = paddr;
|
2015-05-19 01:15:47 +08:00
|
|
|
pstr.len = plen;
|
ext4 crypto: reorganize how we store keys in the inode
This is a pretty massive patch which does a number of different things:
1) The per-inode encryption information is now stored in an allocated
data structure, ext4_crypt_info, instead of directly in the node.
This reduces the size usage of an in-memory inode when it is not
using encryption.
2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
encryption structure instead. This remove an unnecessary memory
allocation and free for the fname_crypto_ctx as well as allowing us
to reuse the ctfm in a directory for multiple lookups and file
creations.
3) We also cache the inode's policy information in the ext4_crypt_info
structure so we don't have to continually read it out of the
extended attributes.
4) We now keep the keyring key in the inode's encryption structure
instead of releasing it after we are done using it to derive the
per-inode key. This allows us to test to see if the key has been
revoked; if it has, we prevent the use of the derived key and free
it.
5) When an inode is released (or when the derived key is freed), we
will use memset_explicit() to zero out the derived key, so it's not
left hanging around in memory. This implies that when a user logs
out, it is important to first revoke the key, and then unlink it,
and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
release any decrypted pages and dcache entries from the system
caches.
6) All this, and we also shrink the number of lines of code by around
100. :-)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2015-05-19 01:17:47 +08:00
|
|
|
res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
|
2015-04-16 13:55:00 +08:00
|
|
|
if (res < 0)
|
|
|
|
|
goto errout;
|
|
|
|
|
/* Null-terminate the name */
|
|
|
|
|
if (res <= plen)
|
|
|
|
|
paddr[res] = '\0';
|
2015-11-17 14:07:57 +08:00
|
|
|
if (cpage)
|
2015-04-16 13:55:00 +08:00
|
|
|
page_cache_release(cpage);
|
2015-12-30 04:58:39 +08:00
|
|
|
set_delayed_call(done, kfree_link, paddr);
|
|
|
|
|
return paddr;
|
2015-04-16 13:55:00 +08:00
|
|
|
errout:
|
2015-11-17 14:07:57 +08:00
|
|
|
if (cpage)
|
2015-04-16 13:55:00 +08:00
|
|
|
page_cache_release(cpage);
|
|
|
|
|
kfree(paddr);
|
|
|
|
|
return ERR_PTR(res);
|
|
|
|
|
}
|
|
|
|
|
|
2015-04-28 05:51:30 +08:00
|
|
|
const struct inode_operations ext4_encrypted_symlink_inode_operations = {
|
|
|
|
|
.readlink = generic_readlink,
|
2015-11-17 23:20:54 +08:00
|
|
|
.get_link = ext4_encrypted_get_link,
|
2015-04-28 05:51:30 +08:00
|
|
|
.setattr = ext4_setattr,
|
|
|
|
|
.setxattr = generic_setxattr,
|
|
|
|
|
.getxattr = generic_getxattr,
|
|
|
|
|
.listxattr = ext4_listxattr,
|
|
|
|
|
.removexattr = generic_removexattr,
|
|
|
|
|
};
|
2015-04-16 13:55:00 +08:00
|
|
|
#endif
|
|
|
|
|
|
2007-02-12 16:55:38 +08:00
|
|
|
const struct inode_operations ext4_symlink_inode_operations = {
|
2006-10-11 16:20:50 +08:00
|
|
|
.readlink = generic_readlink,
|
2015-11-17 23:20:54 +08:00
|
|
|
.get_link = page_get_link,
|
2010-05-16 14:00:00 +08:00
|
|
|
.setattr = ext4_setattr,
|
2006-10-11 16:20:50 +08:00
|
|
|
.setxattr = generic_setxattr,
|
|
|
|
|
.getxattr = generic_getxattr,
|
2006-10-11 16:20:53 +08:00
|
|
|
.listxattr = ext4_listxattr,
|
2006-10-11 16:20:50 +08:00
|
|
|
.removexattr = generic_removexattr,
|
|
|
|
|
};
|
|
|
|
|
|
2007-02-12 16:55:38 +08:00
|
|
|
const struct inode_operations ext4_fast_symlink_inode_operations = {
|
2006-10-11 16:20:50 +08:00
|
|
|
.readlink = generic_readlink,
|
2015-11-17 23:20:54 +08:00
|
|
|
.get_link = simple_get_link,
|
2010-05-16 14:00:00 +08:00
|
|
|
.setattr = ext4_setattr,
|
2006-10-11 16:20:50 +08:00
|
|
|
.setxattr = generic_setxattr,
|
|
|
|
|
.getxattr = generic_getxattr,
|
2006-10-11 16:20:53 +08:00
|
|
|
.listxattr = ext4_listxattr,
|
2006-10-11 16:20:50 +08:00
|
|
|
.removexattr = generic_removexattr,
|
|
|
|
|
};
|