[PATCH 4.4 006/118] fscrypto: require write access to mount to set encryption policy

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Eric Biggers 

commit ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream.

Since setting an encryption policy requires writing metadata to the
filesystem, it should be guarded by mnt_want_write/mnt_drop_write.
Otherwise, a user could cause a write to a frozen or readonly
filesystem.  This was handled correctly by f2fs but not by ext4.  Make
fscrypt_process_policy() handle it rather than relying on the filesystem
to get it right.

Signed-off-by: Eric Biggers 
Cc: sta...@vger.kernel.org # 4.1+; check fs/{ext4,f2fs}
Signed-off-by: Theodore Ts'o 
Acked-by: Jaegeuk Kim 
Signed-off-by: Greg Kroah-Hartman 

---
 fs/ext4/ioctl.c |6 ++
 1 file changed, 6 insertions(+)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -629,7 +629,13 @@ resizefs_out:
goto encryption_policy_out;
}
 
+   err = mnt_want_write_file(filp);
+   if (err)
+   goto encryption_policy_out;
+
err = ext4_process_policy(, inode);
+
+   mnt_drop_write_file(filp);
 encryption_policy_out:
return err;
 #else

[PATCH 4.4 006/118] fscrypto: require write access to mount to set encryption policy

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Eric Biggers 

commit ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream.

Since setting an encryption policy requires writing metadata to the
filesystem, it should be guarded by mnt_want_write/mnt_drop_write.
Otherwise, a user could cause a write to a frozen or readonly
filesystem.  This was handled correctly by f2fs but not by ext4.  Make
fscrypt_process_policy() handle it rather than relying on the filesystem
to get it right.

Signed-off-by: Eric Biggers 
Cc: sta...@vger.kernel.org # 4.1+; check fs/{ext4,f2fs}
Signed-off-by: Theodore Ts'o 
Acked-by: Jaegeuk Kim 
Signed-off-by: Greg Kroah-Hartman 

---
 fs/ext4/ioctl.c |6 ++
 1 file changed, 6 insertions(+)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -629,7 +629,13 @@ resizefs_out:
goto encryption_policy_out;
}
 
+   err = mnt_want_write_file(filp);
+   if (err)
+   goto encryption_policy_out;
+
err = ext4_process_policy(, inode);
+
+   mnt_drop_write_file(filp);
 encryption_policy_out:
return err;
 #else