NACK[K]: [SRU][J/K][PATCH] UBUNTU: [SAUCE] shiftfs: fix permanent -EOVERFLOW inside the CT
Andrea Righi
andrea.righi at canonical.com
Fri Nov 18 08:58:17 UTC 2022
On Thu, Nov 17, 2022 at 03:23:47PM +0100, Alexander Mikhalitsyn 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>
We already have something similar in kinetic/master-next (using
&init_user_ns), we had to do that, because otherwise we were breaking
lxd (see the commit already mentioned by Dimitri).
So, I don't disagree with this patch, but it needs to be rebased on top
of master-next to properly apply it.
Thanks,
-Andrea
> ---
> 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
>
>
> --
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