lkml.org 
[lkml]   [2022]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.15 15/28] fs: tweak fsuidgid_has_mapping()
Date
From: Christian Brauner <christian.brauner@ubuntu.com>

commit 476860b3eb4a50958243158861d5340066df5af2 upstream.

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: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/fs.h | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1697,10 +1697,18 @@ static inline void inode_fsgid_set(struc
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);

\
 
 \ /
  Last update: 2022-06-30 16:11    [W:0.140 / U:0.884 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site