(Fixing Cc list: the F2FS mailing list is
linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx, not linux-f2fs@xxxxxxxxxxxxxxx.)
On Thu, Sep 08, 2016 at 10:57:08AM -0700, Eric Biggers wrote:
> On an ext4 or f2fs filesystem with file encryption supported, a user
> could set an encryption policy on any empty directory(*) to which they
> had readonly access. This is obviously problematic, since such a
> directory might be owned by another user and the new encryption policy
> would prevent that other user from creating files in their own directory
> (for example).
>
> Fix this by requiring inode_owner_or_capable() permission to set an
> encryption policy. This means that either the caller must own the file,
> or the caller must have the capability CAP_FOWNER.
>
> (*) Or also on any regular file, for f2fs v4.6 and later and ext4
> v4.8-rc1 and later; a separate bug fix is coming for that.
>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 4.1+; check fs/{ext4,f2fs}
> ---
> fs/crypto/policy.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
> index 0f9961e..c9800b1 100644
> --- a/fs/crypto/policy.c
> +++ b/fs/crypto/policy.c
> @@ -95,6 +95,9 @@ static int create_encryption_context_from_policy(struct inode *inode,
> int fscrypt_process_policy(struct inode *inode,
> const struct fscrypt_policy *policy)
> {
> + if (!inode_owner_or_capable(inode))
> + return -EACCES;
> +
> if (policy->version != 0)
> return -EINVAL;
>
> --
> 2.8.0.rc3.226.g39d4020
>
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