diff --git a/MAINTAINERS b/MAINTAINERS index b948dfaaacd9..08360bb0468b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5417,10 +5417,12 @@ F: Documentation/filesystems/caching/ F: fs/fscache/ F: include/linux/fscache*.h -FS-CRYPTO: FILE SYSTEM LEVEL ENCRYPTION SUPPORT +FSCRYPT: FILE SYSTEM LEVEL ENCRYPTION SUPPORT M: Theodore Y. Ts'o M: Jaegeuk Kim -L: linux-fsdevel@vger.kernel.org +L: linux-fscrypt@vger.kernel.org +Q: https://patchwork.kernel.org/project/linux-fscrypt/list/ +T: git git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt.git S: Supported F: fs/crypto/ F: include/linux/fscrypt*.h diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 37b49894c762..d1bb02b1ee58 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -159,6 +159,8 @@ static int fname_decrypt(struct inode *inode, static const char *lookup_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; +#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) + /** * digest_encode() - * @@ -230,11 +232,14 @@ EXPORT_SYMBOL(fscrypt_fname_encrypted_size); int fscrypt_fname_alloc_buffer(const struct inode *inode, u32 ilen, struct fscrypt_str *crypto_str) { - unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen); + u32 olen = fscrypt_fname_encrypted_size(inode, ilen); + const u32 max_encoded_len = + max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE), + 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))); crypto_str->len = olen; - if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2) - olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2; + olen = max(olen, max_encoded_len); + /* * Allocated buffer can hold one more character to null-terminate the * string @@ -266,6 +271,10 @@ EXPORT_SYMBOL(fscrypt_fname_free_buffer); * * The caller must have allocated sufficient memory for the @oname string. * + * If the key is available, we'll decrypt the disk name; otherwise, we'll encode + * it for presentation. Short names are directly base64-encoded, while long + * names are encoded in fscrypt_digested_name format. + * * Return: 0 on success, -errno on failure */ int fscrypt_fname_disk_to_usr(struct inode *inode, @@ -274,7 +283,7 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, struct fscrypt_str *oname) { const struct qstr qname = FSTR_TO_QSTR(iname); - char buf[24]; + struct fscrypt_digested_name digested_name; if (fscrypt_is_dot_dotdot(&qname)) { oname->name[0] = '.'; @@ -289,20 +298,24 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, if (inode->i_crypt_info) return fname_decrypt(inode, iname, oname); - if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { + if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) { oname->len = digest_encode(iname->name, iname->len, oname->name); return 0; } if (hash) { - memcpy(buf, &hash, 4); - memcpy(buf + 4, &minor_hash, 4); + digested_name.hash = hash; + digested_name.minor_hash = minor_hash; } else { - memset(buf, 0, 8); + digested_name.hash = 0; + digested_name.minor_hash = 0; } - memcpy(buf + 8, iname->name + iname->len - 16, 16); + memcpy(digested_name.digest, + FSCRYPT_FNAME_DIGEST(iname->name, iname->len), + FSCRYPT_FNAME_DIGEST_SIZE); oname->name[0] = '_'; - oname->len = 1 + digest_encode(buf, 24, oname->name + 1); + oname->len = 1 + digest_encode((const char *)&digested_name, + sizeof(digested_name), oname->name + 1); return 0; } EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); @@ -336,10 +349,35 @@ int fscrypt_fname_usr_to_disk(struct inode *inode, } EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); +/** + * fscrypt_setup_filename() - prepare to search a possibly encrypted directory + * @dir: the directory that will be searched + * @iname: the user-provided filename being searched for + * @lookup: 1 if we're allowed to proceed without the key because it's + * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot + * proceed without the key because we're going to create the dir_entry. + * @fname: the filename information to be filled in + * + * Given a user-provided filename @iname, this function sets @fname->disk_name + * to the name that would be stored in the on-disk directory entry, if possible. + * If the directory is unencrypted this is simply @iname. Else, if we have the + * directory's encryption key, then @iname is the plaintext, so we encrypt it to + * get the disk_name. + * + * Else, for keyless @lookup operations, @iname is the presented ciphertext, so + * we decode it to get either the ciphertext disk_name (for short names) or the + * fscrypt_digested_name (for long names). Non-@lookup operations will be + * impossible in this case, so we fail them with ENOKEY. + * + * If successful, fscrypt_free_filename() must be called later to clean up. + * + * Return: 0 on success, -errno on failure + */ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, int lookup, struct fscrypt_name *fname) { - int ret = 0, bigname = 0; + int ret; + int digested; memset(fname, 0, sizeof(struct fscrypt_name)); fname->usr_fname = iname; @@ -373,25 +411,37 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, * We don't have the key and we are doing a lookup; decode the * user-supplied name */ - if (iname->name[0] == '_') - bigname = 1; - if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43))) - return -ENOENT; + if (iname->name[0] == '_') { + if (iname->len != + 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))) + return -ENOENT; + digested = 1; + } else { + if (iname->len > + BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)) + return -ENOENT; + digested = 0; + } - fname->crypto_buf.name = kmalloc(32, GFP_KERNEL); + fname->crypto_buf.name = + kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE, + sizeof(struct fscrypt_digested_name)), + GFP_KERNEL); if (fname->crypto_buf.name == NULL) return -ENOMEM; - ret = digest_decode(iname->name + bigname, iname->len - bigname, + ret = digest_decode(iname->name + digested, iname->len - digested, fname->crypto_buf.name); if (ret < 0) { ret = -ENOENT; goto errout; } fname->crypto_buf.len = ret; - if (bigname) { - memcpy(&fname->hash, fname->crypto_buf.name, 4); - memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4); + if (digested) { + const struct fscrypt_digested_name *n = + (const void *)fname->crypto_buf.name; + fname->hash = n->hash; + fname->minor_hash = n->minor_hash; } else { fname->disk_name.name = fname->crypto_buf.name; fname->disk_name.len = fname->crypto_buf.len; diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index e39696e64494..1e1f8a361b75 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -13,8 +13,6 @@ #include -#define FS_FNAME_CRYPTO_DIGEST_SIZE 32 - /* Encryption parameters */ #define FS_XTS_TWEAK_SIZE 16 #define FS_AES_128_ECB_KEY_SIZE 16 @@ -22,10 +20,6 @@ #define FS_AES_256_CBC_KEY_SIZE 32 #define FS_AES_256_CTS_KEY_SIZE 32 #define FS_AES_256_XTS_KEY_SIZE 64 -#define FS_MAX_KEY_SIZE 64 - -#define FS_KEY_DESC_PREFIX "fscrypt:" -#define FS_KEY_DESC_PREFIX_SIZE 8 #define FS_KEY_DERIVATION_NONCE_SIZE 16 @@ -51,13 +45,6 @@ struct fscrypt_context { #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1 -/* This is passed in from userspace into the kernel keyring */ -struct fscrypt_key { - u32 mode; - u8 raw[FS_MAX_KEY_SIZE]; - u32 size; -} __packed; - /* * A pointer to this structure is stored in the file system's in-core * representation of an inode. diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c index 8cdfddce2b34..179e578b875b 100644 --- a/fs/crypto/keyinfo.c +++ b/fs/crypto/keyinfo.c @@ -183,9 +183,6 @@ int fscrypt_get_encryption_info(struct inode *inode) if (res) return res; - if (!inode->i_sb->s_cop->get_context) - return -EOPNOTSUPP; - res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); if (res < 0) { if (!fscrypt_dummy_context_enabled(inode) || diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 4908906d54d5..210976e7a269 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -34,9 +34,6 @@ static int create_encryption_context_from_policy(struct inode *inode, { struct fscrypt_context ctx; - if (!inode->i_sb->s_cop->set_context) - return -EOPNOTSUPP; - ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1; memcpy(ctx.master_key_descriptor, policy->master_key_descriptor, FS_KEY_DESCRIPTOR_SIZE); @@ -87,8 +84,6 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) if (ret == -ENODATA) { if (!S_ISDIR(inode->i_mode)) ret = -ENOTDIR; - else if (!inode->i_sb->s_cop->empty_dir) - ret = -EOPNOTSUPP; else if (!inode->i_sb->s_cop->empty_dir(inode)) ret = -ENOTEMPTY; else @@ -118,8 +113,7 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg) struct fscrypt_policy policy; int res; - if (!inode->i_sb->s_cop->get_context || - !inode->i_sb->s_cop->is_encrypted(inode)) + if (!inode->i_sb->s_cop->is_encrypted(inode)) return -ENODATA; res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); @@ -143,27 +137,61 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg) } EXPORT_SYMBOL(fscrypt_ioctl_get_policy); +/** + * fscrypt_has_permitted_context() - is a file's encryption policy permitted + * within its directory? + * + * @parent: inode for parent directory + * @child: inode for file being looked up, opened, or linked into @parent + * + * Filesystems must call this before permitting access to an inode in a + * situation where the parent directory is encrypted (either before allowing + * ->lookup() to succeed, or for a regular file before allowing it to be opened) + * and before any operation that involves linking an inode into an encrypted + * directory, including link, rename, and cross rename. It enforces the + * constraint that within a given encrypted directory tree, all files use the + * same encryption policy. The pre-access check is needed to detect potentially + * malicious offline violations of this constraint, while the link and rename + * checks are needed to prevent online violations of this constraint. + * + * Return: 1 if permitted, 0 if forbidden. If forbidden, the caller must fail + * the filesystem operation with EPERM. + */ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) { - struct fscrypt_info *parent_ci, *child_ci; + const struct fscrypt_operations *cops = parent->i_sb->s_cop; + const struct fscrypt_info *parent_ci, *child_ci; + struct fscrypt_context parent_ctx, child_ctx; int res; - if ((parent == NULL) || (child == NULL)) { - printk(KERN_ERR "parent %p child %p\n", parent, child); - BUG_ON(1); - } - /* No restrictions on file types which are never encrypted */ if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) && !S_ISLNK(child->i_mode)) return 1; - /* no restrictions if the parent directory is not encrypted */ - if (!parent->i_sb->s_cop->is_encrypted(parent)) + /* No restrictions if the parent directory is unencrypted */ + if (!cops->is_encrypted(parent)) return 1; - /* if the child directory is not encrypted, this is always a problem */ - if (!parent->i_sb->s_cop->is_encrypted(child)) + + /* Encrypted directories must not contain unencrypted files */ + if (!cops->is_encrypted(child)) return 0; + + /* + * Both parent and child are encrypted, so verify they use the same + * encryption policy. Compare the fscrypt_info structs if the keys are + * available, otherwise retrieve and compare the fscrypt_contexts. + * + * Note that the fscrypt_context retrieval will be required frequently + * when accessing an encrypted directory tree without the key. + * Performance-wise this is not a big deal because we already don't + * really optimize for file access without the key (to the extent that + * such access is even possible), given that any attempted access + * already causes a fscrypt_context retrieval and keyring search. + * + * In any case, if an unexpected error occurs, fall back to "forbidden". + */ + res = fscrypt_get_encryption_info(parent); if (res) return 0; @@ -172,17 +200,32 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) return 0; parent_ci = parent->i_crypt_info; child_ci = child->i_crypt_info; - if (!parent_ci && !child_ci) - return 1; - if (!parent_ci || !child_ci) + + if (parent_ci && child_ci) { + return memcmp(parent_ci->ci_master_key, child_ci->ci_master_key, + FS_KEY_DESCRIPTOR_SIZE) == 0 && + (parent_ci->ci_data_mode == child_ci->ci_data_mode) && + (parent_ci->ci_filename_mode == + child_ci->ci_filename_mode) && + (parent_ci->ci_flags == child_ci->ci_flags); + } + + res = cops->get_context(parent, &parent_ctx, sizeof(parent_ctx)); + if (res != sizeof(parent_ctx)) return 0; - return (memcmp(parent_ci->ci_master_key, - child_ci->ci_master_key, - FS_KEY_DESCRIPTOR_SIZE) == 0 && - (parent_ci->ci_data_mode == child_ci->ci_data_mode) && - (parent_ci->ci_filename_mode == child_ci->ci_filename_mode) && - (parent_ci->ci_flags == child_ci->ci_flags)); + res = cops->get_context(child, &child_ctx, sizeof(child_ctx)); + if (res != sizeof(child_ctx)) + return 0; + + return memcmp(parent_ctx.master_key_descriptor, + child_ctx.master_key_descriptor, + FS_KEY_DESCRIPTOR_SIZE) == 0 && + (parent_ctx.contents_encryption_mode == + child_ctx.contents_encryption_mode) && + (parent_ctx.filenames_encryption_mode == + child_ctx.filenames_encryption_mode) && + (parent_ctx.flags == child_ctx.flags); } EXPORT_SYMBOL(fscrypt_has_permitted_context); @@ -202,9 +245,6 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child, struct fscrypt_info *ci; int res; - if (!parent->i_sb->s_cop->set_context) - return -EOPNOTSUPP; - res = fscrypt_get_encryption_info(parent); if (res < 0) return res; diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 6577a3c45815..b81f7d46f344 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1237,37 +1237,24 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block) } /* - * NOTE! unlike strncmp, ext4_match returns 1 for success, 0 for failure. + * Test whether a directory entry matches the filename being searched for. * - * `len <= EXT4_NAME_LEN' is guaranteed by caller. - * `de != NULL' is guaranteed by caller. + * Return: %true if the directory entry matches, otherwise %false. */ -static inline int ext4_match(struct ext4_filename *fname, - struct ext4_dir_entry_2 *de) +static inline bool ext4_match(const struct ext4_filename *fname, + const struct ext4_dir_entry_2 *de) { - const void *name = fname_name(fname); - u32 len = fname_len(fname); + struct fscrypt_name f; if (!de->inode) - return 0; + return false; + f.usr_fname = fname->usr_fname; + f.disk_name = fname->disk_name; #ifdef CONFIG_EXT4_FS_ENCRYPTION - if (unlikely(!name)) { - if (fname->usr_fname->name[0] == '_') { - int ret; - if (de->name_len < 16) - return 0; - ret = memcmp(de->name + de->name_len - 16, - fname->crypto_buf.name + 8, 16); - return (ret == 0) ? 1 : 0; - } - name = fname->crypto_buf.name; - len = fname->crypto_buf.len; - } + f.crypto_buf = fname->crypto_buf; #endif - if (de->name_len != len) - return 0; - return (memcmp(de->name, name, len) == 0) ? 1 : 0; + return fscrypt_match_name(&f, de->name, de->name_len); } /* @@ -1281,48 +1268,31 @@ int ext4_search_dir(struct buffer_head *bh, char *search_buf, int buf_size, struct ext4_dir_entry_2 * de; char * dlimit; int de_len; - int res; de = (struct ext4_dir_entry_2 *)search_buf; dlimit = search_buf + buf_size; while ((char *) de < dlimit) { /* this code is executed quadratically often */ /* do minimal checking `by hand' */ - if ((char *) de + de->name_len <= dlimit) { - res = ext4_match(fname, de); - if (res < 0) { - res = -1; - goto return_result; - } - if (res > 0) { - /* found a match - just to be sure, do - * a full check */ - if (ext4_check_dir_entry(dir, NULL, de, bh, - bh->b_data, - bh->b_size, offset)) { - res = -1; - goto return_result; - } - *res_dir = de; - res = 1; - goto return_result; - } - + if ((char *) de + de->name_len <= dlimit && + ext4_match(fname, de)) { + /* found a match - just to be sure, do + * a full check */ + if (ext4_check_dir_entry(dir, NULL, de, bh, bh->b_data, + bh->b_size, offset)) + return -1; + *res_dir = de; + return 1; } /* prevent looping on a bad block */ de_len = ext4_rec_len_from_disk(de->rec_len, dir->i_sb->s_blocksize); - if (de_len <= 0) { - res = -1; - goto return_result; - } + if (de_len <= 0) + return -1; offset += de_len; de = (struct ext4_dir_entry_2 *) ((char *) de + de_len); } - - res = 0; -return_result: - return res; + return 0; } static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block, @@ -1616,16 +1586,9 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi if (!IS_ERR(inode) && ext4_encrypted_inode(dir) && (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) && !fscrypt_has_permitted_context(dir, inode)) { - int nokey = ext4_encrypted_inode(inode) && - !fscrypt_has_encryption_key(inode); - if (nokey) { - iput(inode); - return ERR_PTR(-ENOKEY); - } ext4_warning(inode->i_sb, "Inconsistent encryption contexts: %lu/%lu", - (unsigned long) dir->i_ino, - (unsigned long) inode->i_ino); + dir->i_ino, inode->i_ino); iput(inode); return ERR_PTR(-EPERM); } @@ -1833,24 +1796,15 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode, int nlen, rlen; unsigned int offset = 0; char *top; - int res; de = (struct ext4_dir_entry_2 *)buf; top = buf + buf_size - reclen; while ((char *) de <= top) { if (ext4_check_dir_entry(dir, NULL, de, bh, - buf, buf_size, offset)) { - res = -EFSCORRUPTED; - goto return_result; - } - /* Provide crypto context and crypto buffer to ext4 match */ - res = ext4_match(fname, de); - if (res < 0) - goto return_result; - if (res > 0) { - res = -EEXIST; - goto return_result; - } + buf, buf_size, offset)) + return -EFSCORRUPTED; + if (ext4_match(fname, de)) + return -EEXIST; nlen = EXT4_DIR_REC_LEN(de->name_len); rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); if ((de->inode ? rlen - nlen : rlen) >= reclen) @@ -1858,15 +1812,11 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode, de = (struct ext4_dir_entry_2 *)((char *)de + rlen); offset += rlen; } - if ((char *) de > top) - res = -ENOSPC; - else { - *dest_de = de; - res = 0; - } -return_result: - return res; + return -ENOSPC; + + *dest_de = de; + return 0; } void ext4_insert_dentry(struct inode *inode, diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index 8d5c62b07b28..e64087052834 100644 --- a/fs/f2fs/dir.c +++ b/fs/f2fs/dir.c @@ -111,8 +111,6 @@ struct f2fs_dir_entry *find_target_dentry(struct fscrypt_name *fname, struct f2fs_dir_entry *de; unsigned long bit_pos = 0; int max_len = 0; - struct fscrypt_str de_name = FSTR_INIT(NULL, 0); - struct fscrypt_str *name = &fname->disk_name; if (max_slots) *max_slots = 0; @@ -130,17 +128,9 @@ struct f2fs_dir_entry *find_target_dentry(struct fscrypt_name *fname, continue; } - /* encrypted case */ - de_name.name = d->filename[bit_pos]; - de_name.len = le16_to_cpu(de->name_len); - - /* show encrypted name */ - if (fname->hash) { - if (de->hash_code == cpu_to_le32(fname->hash)) - goto found; - } else if (de_name.len == name->len && - de->hash_code == namehash && - !memcmp(de_name.name, name->name, name->len)) + if (de->hash_code == namehash && + fscrypt_match_name(fname, d->filename[bit_pos], + le16_to_cpu(de->name_len))) goto found; if (max_slots && max_len > *max_slots) @@ -170,12 +160,7 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir, struct f2fs_dir_entry *de = NULL; bool room = false; int max_slots; - f2fs_hash_t namehash; - - if(fname->hash) - namehash = cpu_to_le32(fname->hash); - else - namehash = f2fs_dentry_hash(&name); + f2fs_hash_t namehash = f2fs_dentry_hash(&name, fname); nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level); nblock = bucket_blocks(level); @@ -542,7 +527,7 @@ int f2fs_add_regular_entry(struct inode *dir, const struct qstr *new_name, level = 0; slots = GET_DENTRY_SLOTS(new_name->len); - dentry_hash = f2fs_dentry_hash(new_name); + dentry_hash = f2fs_dentry_hash(new_name, NULL); current_depth = F2FS_I(dir)->i_current_depth; if (F2FS_I(dir)->chash == dentry_hash) { diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 0a6e115562f6..05d7e2cefc56 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -2133,7 +2133,8 @@ int sanity_check_ckpt(struct f2fs_sb_info *sbi); /* * hash.c */ -f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info); +f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info, + struct fscrypt_name *fname); /* * node.c diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c index 71b7206c431e..eb2e031ea887 100644 --- a/fs/f2fs/hash.c +++ b/fs/f2fs/hash.c @@ -70,7 +70,8 @@ static void str2hashbuf(const unsigned char *msg, size_t len, *buf++ = pad; } -f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info) +f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info, + struct fscrypt_name *fname) { __u32 hash; f2fs_hash_t f2fs_hash; @@ -79,6 +80,10 @@ f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info) const unsigned char *name = name_info->name; size_t len = name_info->len; + /* encrypted bigname case */ + if (fname && !fname->disk_name.name) + return cpu_to_le32(fname->hash); + if (is_dot_dotdot(name_info)) return 0; diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c index e32a9e527968..fa729ff6b2f9 100644 --- a/fs/f2fs/inline.c +++ b/fs/f2fs/inline.c @@ -296,7 +296,7 @@ struct f2fs_dir_entry *find_in_inline_dir(struct inode *dir, return NULL; } - namehash = f2fs_dentry_hash(&name); + namehash = f2fs_dentry_hash(&name, fname); inline_dentry = inline_data_addr(ipage); @@ -533,7 +533,7 @@ int f2fs_add_inline_entry(struct inode *dir, const struct qstr *new_name, f2fs_wait_on_page_writeback(ipage, NODE, true); - name_hash = f2fs_dentry_hash(new_name); + name_hash = f2fs_dentry_hash(new_name, NULL); make_dentry_ptr(NULL, &d, (void *)dentry_blk, 2); f2fs_update_dentry(ino, mode, &d, new_name, name_hash, bit_pos); diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index 98f00a3a7f50..9a5b9fa55318 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -324,9 +324,10 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry, if (f2fs_encrypted_inode(dir) && (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) && !fscrypt_has_permitted_context(dir, inode)) { - bool nokey = f2fs_encrypted_inode(inode) && - !fscrypt_has_encryption_key(inode); - err = nokey ? -ENOKEY : -EPERM; + f2fs_msg(inode->i_sb, KERN_WARNING, + "Inconsistent encryption contexts: %lu/%lu", + dir->i_ino, inode->i_ino); + err = -EPERM; goto err_out; } return d_splice_alias(inode, dentry); diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index b777bddaa1dd..8049851cac42 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -285,6 +285,15 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry, goto out_dent; } + if (ubifs_crypt_is_encrypted(dir) && + (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) && + !fscrypt_has_permitted_context(dir, inode)) { + ubifs_warn(c, "Inconsistent encryption contexts: %lu/%lu", + dir->i_ino, inode->i_ino); + err = -EPERM; + goto out_inode; + } + done: kfree(dent); fscrypt_free_filename(&nm); @@ -295,6 +304,8 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry, d_add(dentry, inode); return NULL; +out_inode: + iput(inode); out_dent: kfree(dent); out_fname: diff --git a/include/linux/fscrypt_common.h b/include/linux/fscrypt_common.h index 10c1abfbac6c..0a30c106c1e5 100644 --- a/include/linux/fscrypt_common.h +++ b/include/linux/fscrypt_common.h @@ -46,17 +46,6 @@ struct fscrypt_symlink_data { char encrypted_path[1]; } __packed; -/** - * This function is used to calculate the disk space required to - * store a filename of length l in encrypted symlink format. - */ -static inline u32 fscrypt_symlink_data_len(u32 l) -{ - if (l < FS_CRYPTO_BLOCK_SIZE) - l = FS_CRYPTO_BLOCK_SIZE; - return (l + sizeof(struct fscrypt_symlink_data) - 1); -} - struct fscrypt_str { unsigned char *name; u32 len; diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h index 3511ca798804..ec406aed2f2f 100644 --- a/include/linux/fscrypt_notsupp.h +++ b/include/linux/fscrypt_notsupp.h @@ -147,6 +147,15 @@ static inline int fscrypt_fname_usr_to_disk(struct inode *inode, return -EOPNOTSUPP; } +static inline bool fscrypt_match_name(const struct fscrypt_name *fname, + const u8 *de_name, u32 de_name_len) +{ + /* Encryption support disabled; use standard comparison */ + if (de_name_len != fname->disk_name.len) + return false; + return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len); +} + /* bio.c */ static inline void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio) diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h index a140f47e9b27..cd4e82c17304 100644 --- a/include/linux/fscrypt_supp.h +++ b/include/linux/fscrypt_supp.h @@ -57,6 +57,80 @@ extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32, extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *, struct fscrypt_str *); +#define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32 + +/* Extracts the second-to-last ciphertext block; see explanation below */ +#define FSCRYPT_FNAME_DIGEST(name, len) \ + ((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \ + FS_CRYPTO_BLOCK_SIZE)) + +#define FSCRYPT_FNAME_DIGEST_SIZE FS_CRYPTO_BLOCK_SIZE + +/** + * fscrypt_digested_name - alternate identifier for an on-disk filename + * + * When userspace lists an encrypted directory without access to the key, + * filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE + * bytes are shown in this abbreviated form (base64-encoded) rather than as the + * full ciphertext (base64-encoded). This is necessary to allow supporting + * filenames up to NAME_MAX bytes, since base64 encoding expands the length. + * + * To make it possible for filesystems to still find the correct directory entry + * despite not knowing the full on-disk name, we encode any filesystem-specific + * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups, + * followed by the second-to-last ciphertext block of the filename. Due to the + * use of the CBC-CTS encryption mode, the second-to-last ciphertext block + * depends on the full plaintext. (Note that ciphertext stealing causes the + * last two blocks to appear "flipped".) This makes accidental collisions very + * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they + * share the same filesystem-specific hashes. + * + * However, this scheme isn't immune to intentional collisions, which can be + * created by anyone able to create arbitrary plaintext filenames and view them + * without the key. Making the "digest" be a real cryptographic hash like + * SHA-256 over the full ciphertext would prevent this, although it would be + * less efficient and harder to implement, especially since the filesystem would + * need to calculate it for each directory entry examined during a search. + */ +struct fscrypt_digested_name { + u32 hash; + u32 minor_hash; + u8 digest[FSCRYPT_FNAME_DIGEST_SIZE]; +}; + +/** + * fscrypt_match_name() - test whether the given name matches a directory entry + * @fname: the name being searched for + * @de_name: the name from the directory entry + * @de_name_len: the length of @de_name in bytes + * + * Normally @fname->disk_name will be set, and in that case we simply compare + * that to the name stored in the directory entry. The only exception is that + * if we don't have the key for an encrypted directory and a filename in it is + * very long, then we won't have the full disk_name and we'll instead need to + * match against the fscrypt_digested_name. + * + * Return: %true if the name matches, otherwise %false. + */ +static inline bool fscrypt_match_name(const struct fscrypt_name *fname, + const u8 *de_name, u32 de_name_len) +{ + if (unlikely(!fname->disk_name.name)) { + const struct fscrypt_digested_name *n = + (const void *)fname->crypto_buf.name; + if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_')) + return false; + if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) + return false; + return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len), + n->digest, FSCRYPT_FNAME_DIGEST_SIZE); + } + + if (de_name_len != fname->disk_name.len) + return false; + return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len); +} + /* bio.c */ extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *); extern void fscrypt_pullback_bio_page(struct page **, bool); diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 048a85e9f017..24e61a54feaa 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -279,12 +279,25 @@ struct fscrypt_policy { __u8 filenames_encryption_mode; __u8 flags; __u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; -} __packed; +}; #define FS_IOC_SET_ENCRYPTION_POLICY _IOR('f', 19, struct fscrypt_policy) #define FS_IOC_GET_ENCRYPTION_PWSALT _IOW('f', 20, __u8[16]) #define FS_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct fscrypt_policy) +/* Parameters for passing an encryption key into the kernel keyring */ +#define FS_KEY_DESC_PREFIX "fscrypt:" +#define FS_KEY_DESC_PREFIX_SIZE 8 + +/* Structure that userspace passes to the kernel keyring */ +#define FS_MAX_KEY_SIZE 64 + +struct fscrypt_key { + __u32 mode; + __u8 raw[FS_MAX_KEY_SIZE]; + __u32 size; +}; + /* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS) *