Unverified Commit 476860b3 authored by Christian Brauner's avatar Christian Brauner
Browse files

fs: tweak fsuidgid_has_mapping() 

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 (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-4-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-4-brauner@kernel.org


Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarSeth Forshee <sforshee@digitalocean.com>
Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent a793d79e

include/linux/fs.h

+11 −3
Original line number Diff line number Diff line
@@ -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);