Re: [PATCH v2 03/10] fs: tweak fsuidgid_has_mapping()
From: Seth Forshee <hidden>
Date: 2021-12-02 17:12:22
On Tue, Nov 30, 2021 at 01:10:25PM +0100, Christian Brauner wrote:
From: Christian Brauner <redacted>
If the caller's fs{g,u}id aren't mapped in the mount's idmapping we can
return early and skip the check whether the mapped fs{g,u}id also have a
mapping in the filesystem's idmapping. If the fs{g,u}id aren't mapped in
the mount's idmapping they consequently can't be mapped in the
filesystem's idmapping. So there's no point in checking that.
Link: https://lore.kernel.org/r/20211123114227.3124056-4-brauner@kernel.org (local) (v1)
Cc: Seth Forshee <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <redacted>Reviewed-by: Seth Forshee <redacted>
quoted hunk ↗ jump to hunk
--- /* v2 */ unchanged --- include/linux/fs.h | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)diff --git a/include/linux/fs.h b/include/linux/fs.h index f5d1ae0a783a..28ab20ce0adc 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h@@ -1695,10 +1695,18 @@ static inline void inode_fsgid_set(struct inode *inode, static inline bool fsuidgid_has_mapping(struct super_block *sb, struct user_namespace *mnt_userns) { - struct user_namespace *s_user_ns = sb->s_user_ns; + struct user_namespace *fs_userns = sb->s_user_ns; + kuid_t kuid; + kgid_t kgid; - return kuid_has_mapping(s_user_ns, mapped_fsuid(mnt_userns)) && - kgid_has_mapping(s_user_ns, mapped_fsgid(mnt_userns)); + kuid = mapped_fsuid(mnt_userns); + if (!uid_valid(kuid)) + return false; + kgid = mapped_fsgid(mnt_userns); + if (!gid_valid(kgid)) + return false; + return kuid_has_mapping(fs_userns, kuid) && + kgid_has_mapping(fs_userns, kgid); } extern struct timespec64 current_time(struct inode *inode);-- 2.30.2