[SRU][J/K][PATCH] UBUNTU: [SAUCE] shiftfs: fix permanent -EOVERFLOW inside the CT

Dimitri John Ledkov dimitri.ledkov at canonical.com
Thu Nov 17 15:31:46 UTC 2022


I started to review this, and trying to understand difference between
this patch and what we have done in kinetic
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/kinetic/commit/?id=4c934edc66ec7467ca2da4f8670a6a712289a3a3

On Thu, 17 Nov 2022 at 14:24, Alexander Mikhalitsyn
<aleksandr.mikhalitsyn at canonical.com> wrote:
>
> BugLink: https://bugs.launchpad.net/bugs/1990849
>
> We haven't supported idmapped layers with shiftfs and moreover, that makes
> no sense. Once lower fs support idmapped mounts when shiftfs is not needed.
>
> Starting from linux-image-5.15.0-48-generic users started seeing EOVERFLOW
> errors from the userspace side on a trivial fs operations inside the containers.
>
> This is caused by patches ("fs: tweak fsuidgid_has_mapping()"),
> ("fs: support mapped mounts of mapped filesystems"). These patches extends
> and enables idmapped mounts support in Ubuntu kernel, but the problem is
> that shiftfs was not properly ported.
>
> See also:
> ("namei: prepare for idmapped mounts")
> https://lore.kernel.org/all/20210121131959.646623-15-christian.brauner@ubuntu.com/
> ("overlayfs: do not mount on top of idmapped mounts")
> https://lore.kernel.org/all/20210121131959.646623-29-christian.brauner@ubuntu.com/
> as a reference.
>
> Fixes: d347e71d2c0 ("UBUNTU: [SAUCE] shiftfs: support kernel 5.15")
> Reported-by: Thomas Parrott <thomas.parrott at canonical.com>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn at canonical.com>
> ---
>  fs/shiftfs.c | 42 ++++++++++++++++++++++++++----------------
>  1 file changed, 26 insertions(+), 16 deletions(-)
>
> diff --git a/fs/shiftfs.c b/fs/shiftfs.c
> index 76c54bc12018..9ea6e7ef06f9 100644
> --- a/fs/shiftfs.c
> +++ b/fs/shiftfs.c
> @@ -379,8 +379,8 @@ static int shiftfs_xattr_set(const struct xattr_handler *handler,
>                              int flags)
>  {
>         if (!value)
> -               return shiftfs_removexattr(ns, dentry, name);
> -       return shiftfs_setxattr(ns, dentry, inode, name, value, size, flags);
> +               return shiftfs_removexattr(&init_user_ns, dentry, name);
> +       return shiftfs_setxattr(&init_user_ns, dentry, inode, name, value, size, flags);
>  }
>
>  static int shiftfs_inode_test(struct inode *inode, void *data)
> @@ -545,7 +545,7 @@ static int shiftfs_create(struct user_namespace *ns,
>  {
>         mode |= S_IFREG;
>
> -       return shiftfs_create_object(ns, dir, dentry, mode, NULL, NULL, excl);
> +       return shiftfs_create_object(&init_user_ns, dir, dentry, mode, NULL, NULL, excl);
>  }
>
>  static int shiftfs_mkdir(struct user_namespace *ns, struct inode *dir, struct dentry *dentry,
> @@ -553,7 +553,7 @@ static int shiftfs_mkdir(struct user_namespace *ns, struct inode *dir, struct de
>  {
>         mode |= S_IFDIR;
>
> -       return shiftfs_create_object(ns, dir, dentry, mode, NULL, NULL, false);
> +       return shiftfs_create_object(&init_user_ns, dir, dentry, mode, NULL, NULL, false);
>  }
>
>  static int shiftfs_link(struct dentry *hardlink, struct inode *dir,
> @@ -569,13 +569,13 @@ static int shiftfs_mknod(struct user_namespace *ns,
>         if (!S_ISFIFO(mode) && !S_ISSOCK(mode))
>                 return -EPERM;
>
> -       return shiftfs_create_object(ns, dir, dentry, mode, NULL, NULL, false);
> +       return shiftfs_create_object(&init_user_ns, dir, dentry, mode, NULL, NULL, false);
>  }
>
>  static int shiftfs_symlink(struct user_namespace *ns, struct inode *dir, struct dentry *dentry,
>                            const char *symlink)
>  {
> -       return shiftfs_create_object(ns, dir, dentry, S_IFLNK, symlink, NULL, false);
> +       return shiftfs_create_object(&init_user_ns, dir, dentry, S_IFLNK, symlink, NULL, false);
>  }
>
>  static int shiftfs_rm(struct inode *dir, struct dentry *dentry, bool rmdir)
> @@ -633,10 +633,10 @@ static int shiftfs_rename(struct user_namespace *ns,
>         struct inode *loweri_dir_old = lowerd_dir_old->d_inode,
>                      *loweri_dir_new = lowerd_dir_new->d_inode;
>         struct renamedata rd = {
> -               .old_mnt_userns = ns,
> +               .old_mnt_userns = &init_user_ns,
>                 .old_dir        = loweri_dir_old,
>                 .old_dentry     = lowerd_old,
> -               .new_mnt_userns = ns,
> +               .new_mnt_userns = &init_user_ns,
>                 .new_dir        = loweri_dir_new,
>                 .new_dentry     = lowerd_new,
>         };
> @@ -716,12 +716,12 @@ static int shiftfs_permission(struct user_namespace *ns, struct inode *inode, in
>                 return -ECHILD;
>         }
>
> -       err = generic_permission(ns, inode, mask);
> +       err = generic_permission(&init_user_ns, inode, mask);
>         if (err)
>                 return err;
>
>         oldcred = shiftfs_override_creds(inode->i_sb);
> -       err = inode_permission(ns, loweri, mask);
> +       err = inode_permission(&init_user_ns, loweri, mask);
>         revert_creds(oldcred);
>
>         return err;
> @@ -760,7 +760,7 @@ static int shiftfs_tmpfile(struct user_namespace *ns,
>                 return -EOPNOTSUPP;
>
>         oldcred = shiftfs_override_creds(dir->i_sb);
> -       err = loweri->i_op->tmpfile(ns, loweri, lowerd, mode);
> +       err = loweri->i_op->tmpfile(&init_user_ns, loweri, lowerd, mode);
>         revert_creds(oldcred);
>
>         return err;
> @@ -776,7 +776,7 @@ static int shiftfs_setattr(struct user_namespace *ns, struct dentry *dentry, str
>         struct shiftfs_super_info *sbinfo = sb->s_fs_info;
>         int err;
>
> -       err = setattr_prepare(ns, dentry, attr);
> +       err = setattr_prepare(&init_user_ns, dentry, attr);
>         if (err)
>                 return err;
>
> @@ -793,7 +793,7 @@ static int shiftfs_setattr(struct user_namespace *ns, struct dentry *dentry, str
>
>         inode_lock(loweri);
>         oldcred = shiftfs_override_creds(dentry->d_sb);
> -       err = notify_change(ns, lowerd, &newattr, NULL);
> +       err = notify_change(&init_user_ns, lowerd, &newattr, NULL);
>         revert_creds(oldcred);
>         inode_unlock(loweri);
>
> @@ -973,17 +973,17 @@ shiftfs_posix_acl_xattr_set(const struct xattr_handler *handler,
>                 return -EOPNOTSUPP;
>         if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
>                 return value ? -EACCES : 0;
> -       if (!inode_owner_or_capable(ns, inode))
> +       if (!inode_owner_or_capable(&init_user_ns, inode))
>                 return -EPERM;
>
>         if (value) {
>                 shift_acl_xattr_ids(inode->i_sb->s_user_ns,
>                                     loweri->i_sb->s_user_ns,
>                                     (void *)value, size);
> -               err = shiftfs_setxattr(ns, dentry, inode, handler->name, value,
> +               err = shiftfs_setxattr(&init_user_ns, dentry, inode, handler->name, value,
>                                        size, flags);
>         } else {
> -               err = shiftfs_removexattr(ns, dentry, handler->name);
> +               err = shiftfs_removexattr(&init_user_ns, dentry, handler->name);
>         }
>
>         if (!err)
> @@ -2017,6 +2017,16 @@ static int shiftfs_fill_super(struct super_block *sb, void *raw_data,
>                 goto out_put_path;
>         }
>
> +       /*
> +        * It makes no sense to handle idmapped layers from shiftfs.
> +        * And we didn't support it properly anyway.
> +        */
> +       if (is_idmapped_mnt(path.mnt)) {
> +               err = -EINVAL;
> +               pr_err("idmapped layers are currently not supported\n");
> +               goto out_put_path;
> +       }
> +
>         sb->s_flags |= SB_POSIXACL;
>
>         if (sbinfo->mark) {
> --
> 2.34.1
>
>
> --
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team



-- 
okurrr,

Dimitri



More information about the kernel-team mailing list