diff options
| -rw-r--r-- | fs/crypto/keysetup.c | 12 | ||||
| -rw-r--r-- | fs/crypto/policy.c | 4 | ||||
| -rw-r--r-- | include/linux/fscrypt.h | 29 |
3 files changed, 37 insertions, 8 deletions
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index 7f85fc645602..fea6226afc2b 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -518,7 +518,17 @@ int fscrypt_get_encryption_info(struct inode *inode) if (res) goto out; + /* + * Multiple tasks may race to set ->i_crypt_info, so use + * cmpxchg_release(). This pairs with the smp_load_acquire() in + * fscrypt_get_info(). I.e., here we publish ->i_crypt_info with a + * RELEASE barrier so that other tasks can ACQUIRE it. + */ if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) { + /* + * We won the race and set ->i_crypt_info to our crypt_info. + * Now link it into the master key's inode list. + */ if (master_key) { struct fscrypt_master_key *mk = master_key->payload.data[0]; @@ -589,7 +599,7 @@ EXPORT_SYMBOL(fscrypt_free_inode); */ int fscrypt_drop_inode(struct inode *inode) { - const struct fscrypt_info *ci = READ_ONCE(inode->i_crypt_info); + const struct fscrypt_info *ci = fscrypt_get_info(inode); const struct fscrypt_master_key *mk; /* diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 8e667aadf271..2d73fd39ad96 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -352,7 +352,7 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) union fscrypt_context ctx; int ret; - ci = READ_ONCE(inode->i_crypt_info); + ci = fscrypt_get_info(inode); if (ci) { /* key available, use the cached policy */ *policy = ci->ci_policy; @@ -641,7 +641,7 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child, if (res < 0) return res; - ci = READ_ONCE(parent->i_crypt_info); + ci = fscrypt_get_info(parent); if (ci == NULL) return -ENOKEY; diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index bb257411365f..991ff8575d0e 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -74,10 +74,15 @@ struct fscrypt_operations { struct request_queue **devs); }; -static inline bool fscrypt_has_encryption_key(const struct inode *inode) +static inline struct fscrypt_info *fscrypt_get_info(const struct inode *inode) { - /* pairs with cmpxchg_release() in fscrypt_get_encryption_info() */ - return READ_ONCE(inode->i_crypt_info) != NULL; + /* + * Pairs with the cmpxchg_release() in fscrypt_get_encryption_info(). + * I.e., another task may publish ->i_crypt_info concurrently, executing + * a RELEASE barrier. We need to use smp_load_acquire() here to safely + * ACQUIRE the memory the other task published. + */ + return smp_load_acquire(&inode->i_crypt_info); } /** @@ -234,9 +239,9 @@ static inline void fscrypt_set_ops(struct super_block *sb, } #else /* !CONFIG_FS_ENCRYPTION */ -static inline bool fscrypt_has_encryption_key(const struct inode *inode) +static inline struct fscrypt_info *fscrypt_get_info(const struct inode *inode) { - return false; + return NULL; } static inline bool fscrypt_needs_contents_encryption(const struct inode *inode) @@ -620,6 +625,20 @@ static inline bool fscrypt_inode_uses_fs_layer_crypto(const struct inode *inode) } /** + * fscrypt_has_encryption_key() - check whether an inode has had its key set up + * @inode: the inode to check + * + * Return: %true if the inode has had its encryption key set up, else %false. + * + * Usually this should be preceded by fscrypt_get_encryption_info() to try to + * set up the key first. + */ +static inline bool fscrypt_has_encryption_key(const struct inode *inode) +{ + return fscrypt_get_info(inode) != NULL; +} + +/** * fscrypt_require_key() - require an inode's encryption key * @inode: the inode we need the key for * |