Hi,
Am Fr., 19. März 2021 um 20:58 Uhr schrieb Vivek Goyal <vgoyal@xxxxxxxxxx>:
> posix_acl_update_mode() determines what's the equivalent mode and if SGID
> needs to be cleared or not. I need to make use of this code in fuse
> as well. Fuse will send this information to virtiofs file server and
> file server will take care of clearing SGID if it needs to be done.
>
> Hence move this code in a separate helper so that more than one place
> can call into it.
>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> fs/posix_acl.c | 3 +--
> include/linux/posix_acl.h | 11 +++++++++++
> 2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/fs/posix_acl.c b/fs/posix_acl.c
> index f3309a7edb49..2d62494c4a5b 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -684,8 +684,7 @@ int posix_acl_update_mode(struct user_namespace *mnt_userns,
> return error;
> if (error == 0)
> *acl = NULL;
> - if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
> - !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
> + if (posix_acl_mode_clear_sgid(mnt_userns, inode))
> mode &= ~S_ISGID;
> *mode_p = mode;
> return 0;
> diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
> index 307094ebb88c..073c5e546de3 100644
> --- a/include/linux/posix_acl.h
> +++ b/include/linux/posix_acl.h
> @@ -59,6 +59,17 @@ posix_acl_release(struct posix_acl *acl)
> }
>
>
> +static inline bool
> +posix_acl_mode_clear_sgid(struct user_namespace *mnt_userns,
> + struct inode *inode)
> +{
> + if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
> + !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
> + return true;
> +
> + return false;
That's just
return !in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID);
The same pattern we have in posix_acl_update_mode also exists in
setattr_copy and inode_init_owner, and almost the same pattern exists
in setattr_prepare, so can this be cleaned up as well? The function
also isn't POSIX ACL specific, so the function name is misleading.
> +}
> +
> /* posix_acl.c */
>
> extern void posix_acl_init(struct posix_acl *, int);
> --
> 2.25.4
Thanks,
Andreas
