On Tue, Sep 27, 2022 at 06:55:37PM -0400, Paul Moore wrote: > On Mon, Sep 26, 2022 at 11:24 AM Christian Brauner <brauner@xxxxxxxxxx> wrote: > > > > In previous patches we implemented get and set inode operations for all > > non-stacking filesystems that support posix acls but didn't yet > > implement get and/or set acl inode operations. This specifically > > affected cifs and 9p. > > > > Now we can build a posix acl api based solely on get and set inode > > operations. We add a new vfs_remove_acl() api that can be used to set > > posix acls. This finally removes all type unsafety and type conversion > > issues explained in detail in [1] that we aim to get rid of. > > > > After we finished building the vfs api we can switch stacking > > filesystems to rely on the new posix api and then finally switch the > > xattr system calls themselves to rely on the posix acl api. > > > > Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@xxxxxxxxxx [1] > > Signed-off-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx> > > --- > > > > Notes: > > /* v2 */ > > unchanged > > > > fs/posix_acl.c | 65 +++++++++++++++++++++++++++++++++++++++ > > include/linux/posix_acl.h | 8 +++++ > > 2 files changed, 73 insertions(+) > > ... > > > diff --git a/fs/posix_acl.c b/fs/posix_acl.c > > index 18873be583a9..40038851bfe1 100644 > > --- a/fs/posix_acl.c > > +++ b/fs/posix_acl.c > > @@ -1484,3 +1484,68 @@ struct posix_acl *vfs_get_acl(struct user_namespace *mnt_userns, > > return acl; > > } > > EXPORT_SYMBOL(vfs_get_acl); > > + > > +/** > > + * vfs_remove_acl - remove posix acls > > + * @mnt_userns: user namespace of the mount > > + * @dentry: the dentry based on which to retrieve the posix acls > > + * @acl_name: the name of the posix acl > > + * > > + * This function removes posix acls. > > + * > > + * Return: On success 0, on error negative errno. > > + */ > > +int vfs_remove_acl(struct user_namespace *mnt_userns, struct dentry *dentry, > > + const char *acl_name) > > +{ > > + int acl_type; > > + int error; > > + struct inode *inode = d_inode(dentry); > > + struct inode *delegated_inode = NULL; > > + > > + acl_type = posix_acl_type(acl_name); > > + if (acl_type < 0) > > + return -EINVAL; > > + > > +retry_deleg: > > + inode_lock(inode); > > + > > + /* > > + * We only care about restrictions the inode struct itself places upon > > + * us otherwise POSIX ACLs aren't subject to any VFS restrictions. > > + */ > > + error = xattr_permission(mnt_userns, inode, acl_name, MAY_WRITE); > > + if (error) > > + goto out_inode_unlock; > > + > > + error = security_inode_removexattr(mnt_userns, dentry, acl_name); > > + if (error) > > + goto out_inode_unlock; > > Similar to my comments in patch 16/30 for vfs_get_acl(), I would > suggest a dedicated ACL remove hook here. Yes, it's still a little > bit silly, but if we are going to make one dedicated hook, we might as > well do them all. Sure, I don't mind doing that. I'll add the infrastructure and then the individual LSMs can add their own hooks.
