Re: [PATCH 6/6] fscrypt: for v2 policies, support "fscrypt:" key prefix only

[Michael Halcrow]

On Wed, Jul 12, 2017 at 02:00:35PM -0700, Eric Biggers wrote:
> From: Eric Biggers 
> 
> Since v2 encryption policies are opt-in, take the opportunity to also
> drop support for the legacy filesystem-specific key description prefixes
> "ext4:", "f2fs:", and "ubifs:", instead requiring the generic prefix
> "fscrypt:".  The generic prefix is preferred since it works for all
> filesystems.  Also there is a performance benefit from not having to
> search the keyrings twice.
> 
> The old prefixes remain supported for v1 encryption policies.
> 
> Signed-off-by: Eric Biggers 

Reviewed-by: Michael Halcrow 

> ---
>  fs/crypto/fscrypt_private.h |  3 +--
>  fs/crypto/keyinfo.c | 16 
>  fs/crypto/policy.c  |  2 +-
>  3 files changed, 6 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
> index 4b158717a8c3..201906ff7033 100644
> --- a/fs/crypto/fscrypt_private.h
> +++ b/fs/crypto/fscrypt_private.h
> @@ -167,8 +167,7 @@ extern struct page *fscrypt_alloc_bounce_page(struct 
> fscrypt_ctx *ctx,
> gfp_t gfp_flags);
>  
>  /* keyinfo.c */
> -extern int fscrypt_compute_key_hash(const struct inode *inode,
> - const struct fscrypt_policy *policy,
> +extern int fscrypt_compute_key_hash(const struct fscrypt_policy *policy,
>   u8 hash[FSCRYPT_KEY_HASH_SIZE]);
>  extern void __exit fscrypt_essiv_cleanup(void);
>  
> diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
> index bf60e76f9599..e20b5e85c1b3 100644
> --- a/fs/crypto/keyinfo.c
> +++ b/fs/crypto/keyinfo.c
> @@ -385,8 +385,7 @@ find_and_lock_keyring_key(const char *prefix,
>  }
>  
>  static struct fscrypt_master_key *
> -load_master_key_from_keyring(const struct inode *inode,
> -  const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
> +load_master_key_from_keyring(const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
>unsigned int min_keysize)
>  {
>   struct key *keyring_key;
> @@ -395,11 +394,6 @@ load_master_key_from_keyring(const struct inode *inode,
>  
>   keyring_key = find_and_lock_keyring_key(FS_KEY_DESC_PREFIX, descriptor,
>   min_keysize, );
> - if (keyring_key == ERR_PTR(-ENOKEY) && inode->i_sb->s_cop->key_prefix) {
> - keyring_key = find_and_lock_keyring_key(
> - inode->i_sb->s_cop->key_prefix,
> - descriptor, min_keysize, );
> - }
>   if (IS_ERR(keyring_key))
>   return ERR_CAST(keyring_key);
>  
> @@ -441,8 +435,7 @@ find_or_create_master_key(const struct inode *inode,
>   /*
>* The needed master key isn't in memory yet.  Load it from the keyring.
>*/
> - master_key = load_master_key_from_keyring(inode,
> -   ctx->master_key_descriptor,
> + master_key = load_master_key_from_keyring(ctx->master_key_descriptor,
> min_keysize);
>   if (IS_ERR(master_key))
>   return master_key;
> @@ -676,8 +669,7 @@ void __exit fscrypt_essiv_cleanup(void)
>   crypto_free_shash(essiv_hash_tfm);
>  }
>  
> -int fscrypt_compute_key_hash(const struct inode *inode,
> -  const struct fscrypt_policy *policy,
> +int fscrypt_compute_key_hash(const struct fscrypt_policy *policy,
>u8 hash[FSCRYPT_KEY_HASH_SIZE])
>  {
>   struct fscrypt_master_key *k;
> @@ -691,7 +683,7 @@ int fscrypt_compute_key_hash(const struct inode *inode,
>   max(available_modes[policy->contents_encryption_mode].keysize,
>   available_modes[policy->filenames_encryption_mode].keysize);
>  
> - k = load_master_key_from_keyring(inode, policy->master_key_descriptor,
> + k = load_master_key_from_keyring(policy->master_key_descriptor,
>min_keysize);
>   if (IS_ERR(k))
>   return PTR_ERR(k);
> diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
> index 7661c66a3533..cd8c9c7cc9a9 100644
> --- a/fs/crypto/policy.c
> +++ b/fs/crypto/policy.c
> @@ -117,7 +117,7 @@ int fscrypt_ioctl_set_policy(struct file *filp, const 
> void __user *arg)
>   pr_warn_once("%s (pid %d) is setting less secure v0 encryption 
> policy; recommend upgrading to v2.\n",
>current->comm, current->pid);
>   } else {
> - ret = fscrypt_compute_key_hash(inode, , key_hash);
> + ret = fscrypt_compute_key_hash(, key_hash);
>   if (ret)
>   return ret;
>   }
> -- 
> 2.13.2.932.g7449e964c-goog
> 

[PATCH 6/6] fscrypt: for v2 policies, support "fscrypt:" key prefix only

[Eric Biggers]

From: Eric Biggers 

Since v2 encryption policies are opt-in, take the opportunity to also
drop support for the legacy filesystem-specific key description prefixes
"ext4:", "f2fs:", and "ubifs:", instead requiring the generic prefix
"fscrypt:".  The generic prefix is preferred since it works for all
filesystems.  Also there is a performance benefit from not having to
search the keyrings twice.

The old prefixes remain supported for v1 encryption policies.

Signed-off-by: Eric Biggers 
---
 fs/crypto/fscrypt_private.h |  3 +--
 fs/crypto/keyinfo.c | 16 
 fs/crypto/policy.c  |  2 +-
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 4b158717a8c3..201906ff7033 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -167,8 +167,7 @@ extern struct page *fscrypt_alloc_bounce_page(struct 
fscrypt_ctx *ctx,
  gfp_t gfp_flags);
 
 /* keyinfo.c */
-extern int fscrypt_compute_key_hash(const struct inode *inode,
-   const struct fscrypt_policy *policy,
+extern int fscrypt_compute_key_hash(const struct fscrypt_policy *policy,
u8 hash[FSCRYPT_KEY_HASH_SIZE]);
 extern void __exit fscrypt_essiv_cleanup(void);
 
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index bf60e76f9599..e20b5e85c1b3 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -385,8 +385,7 @@ find_and_lock_keyring_key(const char *prefix,
 }
 
 static struct fscrypt_master_key *
-load_master_key_from_keyring(const struct inode *inode,
-const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
+load_master_key_from_keyring(const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
 unsigned int min_keysize)
 {
struct key *keyring_key;
@@ -395,11 +394,6 @@ load_master_key_from_keyring(const struct inode *inode,
 
keyring_key = find_and_lock_keyring_key(FS_KEY_DESC_PREFIX, descriptor,
min_keysize, );
-   if (keyring_key == ERR_PTR(-ENOKEY) && inode->i_sb->s_cop->key_prefix) {
-   keyring_key = find_and_lock_keyring_key(
-   inode->i_sb->s_cop->key_prefix,
-   descriptor, min_keysize, );
-   }
if (IS_ERR(keyring_key))
return ERR_CAST(keyring_key);
 
@@ -441,8 +435,7 @@ find_or_create_master_key(const struct inode *inode,
/*
 * The needed master key isn't in memory yet.  Load it from the keyring.
 */
-   master_key = load_master_key_from_keyring(inode,
- ctx->master_key_descriptor,
+   master_key = load_master_key_from_keyring(ctx->master_key_descriptor,
  min_keysize);
if (IS_ERR(master_key))
return master_key;
@@ -676,8 +669,7 @@ void __exit fscrypt_essiv_cleanup(void)
crypto_free_shash(essiv_hash_tfm);
 }
 
-int fscrypt_compute_key_hash(const struct inode *inode,
-const struct fscrypt_policy *policy,
+int fscrypt_compute_key_hash(const struct fscrypt_policy *policy,
 u8 hash[FSCRYPT_KEY_HASH_SIZE])
 {
struct fscrypt_master_key *k;
@@ -691,7 +683,7 @@ int fscrypt_compute_key_hash(const struct inode *inode,
max(available_modes[policy->contents_encryption_mode].keysize,
available_modes[policy->filenames_encryption_mode].keysize);
 
-   k = load_master_key_from_keyring(inode, policy->master_key_descriptor,
+   k = load_master_key_from_keyring(policy->master_key_descriptor,
 min_keysize);
if (IS_ERR(k))
return PTR_ERR(k);
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 7661c66a3533..cd8c9c7cc9a9 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -117,7 +117,7 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void 
__user *arg)
pr_warn_once("%s (pid %d) is setting less secure v0 encryption 
policy; recommend upgrading to v2.\n",
 current->comm, current->pid);
} else {
-   ret = fscrypt_compute_key_hash(inode, , key_hash);
+   ret = fscrypt_compute_key_hash(, key_hash);
if (ret)
return ret;
}
-- 
2.13.2.932.g7449e964c-goog