diff options
Diffstat (limited to 'include/linux/fscrypt.h')
| -rw-r--r-- | include/linux/fscrypt.h | 122 |
1 files changed, 45 insertions, 77 deletions
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 1a7bffe78ed5..556f4adf5dc5 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -72,6 +72,21 @@ static inline bool fscrypt_has_encryption_key(const struct inode *inode) return READ_ONCE(inode->i_crypt_info) != NULL; } +/** + * fscrypt_needs_contents_encryption() - check whether an inode needs + * contents encryption + * + * Return: %true iff the inode is an encrypted regular file and the kernel was + * built with fscrypt support. + * + * If you need to know whether the encrypt bit is set even when the kernel was + * built without fscrypt support, you must use IS_ENCRYPTED() directly instead. + */ +static inline bool fscrypt_needs_contents_encryption(const struct inode *inode) +{ + return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode); +} + static inline bool fscrypt_dummy_context_enabled(struct inode *inode) { return inode->i_sb->s_cop->dummy_context && @@ -153,82 +168,14 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname) extern int fscrypt_fname_alloc_buffer(const struct inode *, u32, struct fscrypt_str *); extern void fscrypt_fname_free_buffer(struct fscrypt_str *); -extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32, - const struct fscrypt_str *, 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); -} +extern int fscrypt_fname_disk_to_usr(const struct inode *inode, + u32 hash, u32 minor_hash, + const struct fscrypt_str *iname, + struct fscrypt_str *oname); +extern bool fscrypt_match_name(const struct fscrypt_name *fname, + const u8 *de_name, u32 de_name_len); +extern u64 fscrypt_fname_siphash(const struct inode *dir, + const struct qstr *name); /* bio.c */ extern void fscrypt_decrypt_bio(struct bio *); @@ -246,6 +193,8 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir, unsigned int flags); extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, struct fscrypt_name *fname); +extern int fscrypt_prepare_setflags(struct inode *inode, + unsigned int oldflags, unsigned int flags); extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, unsigned int max_len, struct fscrypt_str *disk_link); @@ -267,6 +216,11 @@ static inline bool fscrypt_has_encryption_key(const struct inode *inode) return false; } +static inline bool fscrypt_needs_contents_encryption(const struct inode *inode) +{ + return false; +} + static inline bool fscrypt_dummy_context_enabled(struct inode *inode) { return false; @@ -438,7 +392,7 @@ static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) return; } -static inline int fscrypt_fname_disk_to_usr(struct inode *inode, +static inline int fscrypt_fname_disk_to_usr(const struct inode *inode, u32 hash, u32 minor_hash, const struct fscrypt_str *iname, struct fscrypt_str *oname) @@ -455,6 +409,13 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname, return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len); } +static inline u64 fscrypt_fname_siphash(const struct inode *dir, + const struct qstr *name) +{ + WARN_ON_ONCE(1); + return 0; +} + /* bio.c */ static inline void fscrypt_decrypt_bio(struct bio *bio) { @@ -497,6 +458,13 @@ static inline int __fscrypt_prepare_lookup(struct inode *dir, return -EOPNOTSUPP; } +static inline int fscrypt_prepare_setflags(struct inode *inode, + unsigned int oldflags, + unsigned int flags) +{ + return 0; +} + static inline int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, unsigned int max_len, |