On Tue, Nov 23, 2021 at 3:29 PM Christian Brauner <brauner@xxxxxxxxxx> wrote: > > From: Christian Brauner <christian.brauner@xxxxxxxxxx> > > 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. > > Cc: Seth Forshee <sforshee@xxxxxxxxxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > CC: linux-fsdevel@xxxxxxxxxxxxxxx > Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx> > --- Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx> > 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 eb69e8b035fa..161b5936094e 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 >