[SRU][J/K][PATCH] UBUNTU: [SAUCE] shiftfs: fix permanent -EOVERFLOW inside the CT
Aleksandr Mikhalitsyn
aleksandr.mikhalitsyn at canonical.com
Thu Nov 17 15:50:32 UTC 2022
On Thu, Nov 17, 2022 at 4:32 PM Dimitri John Ledkov
<dimitri.ledkov at canonical.com> wrote:
>
> 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
Thanks! I've not seen this patch before (seems it's not in
kinetic/master), it's interesting why it wasn't ported to Jammy tree.
Speaking about the difference, I think we have to add a check about
/*
* 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;
}
and also as I can see we need to change
if (!inode_owner_or_capable(ns, inode))
return -EPERM;
to
if (!inode_owner_or_capable(&init_user_ns, inode))
return -EPERM;
as in my version.
Regards,
Alex
>
> 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
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