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| author |   Eric Biggers <ebiggers@google.com> | 2020-03-14 13:50:49 -0700 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2020-03-19 21:56:54 -0700 |
| commit | e98ad464750c0894bc560d10503dae8ff90ccdac (patch) | |
| tree | 2bce5db834db04e054bdc2c08bec50e2396af50c /include/linux/fscrypt.h | |
| parent | Linux 5.6-rc4 (diff) | |
| download | wireguard-linux-e98ad464750c0894bc560d10503dae8ff90ccdac.tar.xz wireguard-linux-e98ad464750c0894bc560d10503dae8ff90ccdac.zip | |
fscrypt: add FS_IOC_GET_ENCRYPTION_NONCE ioctl
Add an ioctl FS_IOC_GET_ENCRYPTION_NONCE which retrieves the nonce from
an encrypted file or directory. The nonce is the 16-byte random value
stored in the inode's encryption xattr. It is normally used together
with the master key to derive the inode's actual encryption key.
The nonces are needed by automated tests that verify the correctness of
the ciphertext on-disk. Except for the IV_INO_LBLK_64 case, there's no
way to replicate a file's ciphertext without knowing that file's nonce.
The nonces aren't secret, and the existing ciphertext verification tests
in xfstests retrieve them from disk using debugfs or dump.f2fs. But in
environments that lack these debugging tools, getting the nonces by
manually parsing the filesystem structure would be very hard.
To make this important type of testing much easier, let's just add an
ioctl that retrieves the nonce.
Link: https://lore.kernel.org/r/20200314205052.93294-2-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'include/linux/fscrypt.h')
| -rw-r--r-- | include/linux/fscrypt.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 556f4adf5dc5..e3c2d2a15525 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -139,6 +139,7 @@ extern void fscrypt_free_bounce_page(struct page *bounce_page); extern int fscrypt_ioctl_set_policy(struct file *, const void __user *); extern int fscrypt_ioctl_get_policy(struct file *, void __user *); extern int fscrypt_ioctl_get_policy_ex(struct file *, void __user *); +extern int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg); extern int fscrypt_has_permitted_context(struct inode *, struct inode *); extern int fscrypt_inherit_context(struct inode *, struct inode *, void *, bool); @@ -300,6 +301,11 @@ static inline int fscrypt_ioctl_get_policy_ex(struct file *filp, return -EOPNOTSUPP; } +static inline int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg) +{ + return -EOPNOTSUPP; +} + static inline int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) { |