[PATCH -next] lsm: fix default return value for inode_set(remove)xattr

[Paul Moore]

On Wed, May 1, 2024 at 12:02 PM Paul Moore <paul at paul-moore.com> wrote:
> On Mon, Apr 29, 2024 at 7:47 AM felix <fuzhen5 at huawei.com> wrote:
> >
> > From: Felix Fu <fuzhen5 at huawei.com>
> >
> > The return value of security_inode_set(remove)xattr should
> > be 1. If it return 0, cap_inode_setxattr would not be
> > executed when no lsm exist, which is not what we expected,
> > any user could set some security.* xattr for a file.
> >
> > Before commit 260017f31a8c ("lsm: use default hook return
> > value in call_int_hook()") was approved, this issue would
> > still happened when lsm only include bpf, because bpf_lsm_
> > inode_setxattr return 0 by default which cause cap_inode_set
> > xattr to be not executed.
> >
> > Fixes: 260017f31a8c ("lsm: use default hook return value in call_int_hook()")
> > Signed-off-by: Felix Fu <fuzhen5 at huawei.com>
> > ---
> >  include/linux/lsm_hook_defs.h | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
>
> Adding the LSM list as that is the important list for this patch.

It's also worth noting the discussion below from earlier this year.  I
just spent a little bit of time working on a different solution which
I personally find more acceptable; I'm building a test kernel now,
assuming it works I'll post it as a RFC.

https://lore.kernel.org/linux-security-module/20240129133058.1627971-1-omosnace@redhat.com/

-- 
paul-moore.com