From: Casey Schaufler <casey@schaufler-ca.com>
To: KP Singh <kpsingh@chromium.org>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
linux-security-module@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
James Morris <jmorris@namei.org>,
Anders Roxell <anders.roxell@linaro.org>
Subject: Re: [PATCH bpf] security: Fix hook iteration for secid_to_secctx
Date: Wed, 20 May 2020 08:15:49 -0700 [thread overview]
Message-ID: <5f540fb8-93ec-aa6b-eb30-b3907f5791ff@schaufler-ca.com> (raw)
In-Reply-To: <20200520125616.193765-1-kpsingh@chromium.org>
On 5/20/2020 5:56 AM, KP Singh wrote:
> From: KP Singh <kpsingh@google.com>
>
> secid_to_secctx is not stackable, and since the BPF LSM registers this
> hook by default, the call_int_hook logic is not suitable which
> "bails-on-fail" and casues issues when other LSMs register this hook and
> eventually breaks Audit.
>
> In order to fix this, directly iterate over the security hooks instead
> of using call_int_hook as suggested in:
>
> https: //lore.kernel.org/bpf/9d0eb6c6-803a-ff3a-5603-9ad6d9edfc00@schaufler-ca.com/#t
>
> Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks")
> Fixes: 625236ba3832 ("security: Fix the default value of secid_to_secctx hook"
> Reported-by: Alexei Starovoitov <ast@kernel.org>
> Signed-off-by: KP Singh <kpsingh@google.com>
This looks fine.
> ---
> security/security.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/security/security.c b/security/security.c
> index 7fed24b9d57e..51de970fbb1e 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1965,8 +1965,20 @@ EXPORT_SYMBOL(security_ismaclabel);
>
> int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
> {
> - return call_int_hook(secid_to_secctx, -EOPNOTSUPP, secid, secdata,
> - seclen);
> + struct security_hook_list *hp;
> + int rc;
> +
> + /*
> + * Currently, only one LSM can implement secid_to_secctx (i.e this
> + * LSM hook is not "stackable").
> + */
> + hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) {
> + rc = hp->hook.secid_to_secctx(secid, secdata, seclen);
> + if (rc != LSM_RET_DEFAULT(secid_to_secctx))
> + return rc;
> + }
> +
> + return LSM_RET_DEFAULT(secid_to_secctx);
> }
> EXPORT_SYMBOL(security_secid_to_secctx);
>
next prev parent reply other threads:[~2020-05-20 15:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 12:56 [PATCH bpf] security: Fix hook iteration for secid_to_secctx KP Singh
2020-05-20 15:15 ` Casey Schaufler [this message]
2020-05-21 1:35 ` Alexei Starovoitov
2020-05-21 2:02 ` James Morris
2020-05-21 3:12 ` Alexei Starovoitov
2020-06-19 12:49 ` Ondrej Mosnacek
2020-06-19 13:13 ` KP Singh
2020-06-19 14:16 ` Ondrej Mosnacek
2020-06-21 21:54 ` KP Singh
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5f540fb8-93ec-aa6b-eb30-b3907f5791ff@schaufler-ca.com \
--to=casey@schaufler-ca.com \
--cc=anders.roxell@linaro.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=jmorris@namei.org \
--cc=kpsingh@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).