On Mon, Oct 10, 2022 at 5:58 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
>
> Commit 4ff09db1b79b ("bpf: net: Change sk_getsockopt() to take the
> sockptr_t argument") made it possible to call sk_getsockopt()
> with both user and kernel address space buffers through the use of
> the sockptr_t type. Unfortunately at the time of conversion the
> security_socket_getpeersec_stream() LSM hook was written to only
> accept userspace buffers, and in a desire to avoid having to change
> the LSM hook the commit author simply passed the sockptr_t's
> userspace buffer pointer. Since the only sk_getsockopt() callers
> at the time of conversion which used kernel sockptr_t buffers did
> not allow SO_PEERSEC, and hence the
> security_socket_getpeersec_stream() hook, this was acceptable but
> also very fragile as future changes presented the possibility of
> silently passing kernel space pointers to the LSM hook.
>
> There are several ways to protect against this, including careful
> code review of future commits, but since relying on code review to
> catch bugs is a recipe for disaster and the upstream eBPF maintainer
> is "strongly against defensive programming", this patch updates the
> LSM hook, and all of the implementations to support sockptr_t and
> safely handle both user and kernel space buffers.
>
> Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
> ---
> include/linux/lsm_hook_defs.h | 2 +-
> include/linux/lsm_hooks.h | 4 ++--
> include/linux/security.h | 11 +++++++----
> net/core/sock.c | 3 ++-
> security/apparmor/lsm.c | 29 +++++++++++++----------------
> security/security.c | 6 +++---
> security/selinux/hooks.c | 13 ++++++-------
> security/smack/smack_lsm.c | 19 ++++++++++---------
> 8 files changed, 44 insertions(+), 43 deletions(-)
Casey and John, could you please look over the Smack and AppArmor bits
of this patch when you get a chance? I did my best on the conversion,
but I would appreciate a review by the experts :)
--
paul-moore.com
