From: Tyler Hicks <tyhicks@canonical.com>
To: Steve Grubb <sgrubb@redhat.com>
Cc: linux-audit@redhat.com, Paul Moore <paul@paul-moore.com>,
Eric Paris <eparis@redhat.com>, Kees Cook <keescook@chromium.org>,
Andy Lutomirski <luto@amacapital.net>,
Will Drewry <wad@chromium.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] seccomp: Audit SECCOMP_RET_ERRNO actions with errno values
Date: Mon, 2 Jan 2017 17:42:47 +0000 [thread overview]
Message-ID: <20170102174246.GA17677@sec> (raw)
In-Reply-To: <5284369.V7krsaxZyN@x2>
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On 2017-01-02 12:20:53, Steve Grubb wrote:
> On Monday, January 2, 2017 4:53:10 PM EST Tyler Hicks wrote:
> > Generate audit records for SECCOMP_RET_ERRNO actions, which were
> > previously not audited.
> >
> > Additionally, include the errno value that will be set in the audit
> > message.
> >
> > Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
> > ---
> > include/linux/audit.h | 19 ++++++++++++++++++-
> > kernel/auditsc.c | 3 +++
> > kernel/seccomp.c | 4 +++-
> > 3 files changed, 24 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index 8c588c3..6815812 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -87,7 +87,10 @@ struct audit_field {
> >
> > struct audit_seccomp_info {
> > int code;
> > - long signr;
> > + union {
> > + int errno;
> > + long signr;
> > + };
> > };
> >
> > extern int is_audit_feature_set(int which);
> > @@ -319,6 +322,20 @@ static inline void audit_inode_child(struct inode
> > *parent, }
> > void audit_core_dumps(long signr);
> >
> > +static inline void audit_seccomp_errno(unsigned long syscall, int errno,
> > + int code)
> > +{
> > + if (!audit_enabled)
> > + return;
> > +
> > + if (errno || unlikely(!audit_dummy_context())) {
> > + struct audit_seccomp_info info = { .code = code,
> > + .errno = errno };
> > +
> > + __audit_seccomp(syscall, &info);
> > + }
> > +}
> > +
> > static inline void audit_seccomp_signal(unsigned long syscall, long signr,
> > int code)
> > {
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index b3472f2..db5fc9d 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -2426,6 +2426,9 @@ void __audit_seccomp(unsigned long syscall, struct
> > audit_seccomp_info *info) audit_log_task(ab);
> >
> > switch (info->code) {
> > + case SECCOMP_RET_ERRNO:
> > + audit_log_format(ab, " errno=%d", info->errno);
> > + break;
>
> "exit" is the field name that syscalls use to return errno to user space. I'd
> rather not see another field created that maps to the same thing. You can check
> the translation with the auformat utility:
Thanks for having a look at the field name I was using. Although I
prefer "errno" over "exit" in terms of clarity, I agree that it makes
sense to be consistent with the field names across record types. "exit"
works for me.
>
> http://people.redhat.com/sgrubb/files/auformat.tar.gz
>
> $ ausearch --start today --just-one -m syscall -sv no --raw | ./auformat "%EXIT\n"
>
> Also, I am working to normalize all the records. That mean every event record
> of the same type has the same fields, in the same order, with the same
> representation. I would think "exit" could be added to the current record after
> syscall so that its ordered similarly to a syscall record.
This patch goes against your normalization efforts in more ways than
just the placement of the "exit" field. If the action is
SECCOMP_RET_KILL, a "sig" field is present but if the action is
SECCOMP_RET_ERRNO, the "sig" field will not be present but the "errno"
field will be present. This happens all within the AUDIT_SECCOMP record
type. How would you suggest normalizing AUDIT_SECCOMP records for
different seccomp return actions?
Tyler
>
> -Steve
>
> > case SECCOMP_RET_KILL:
> > audit_log_format(ab, " sig=%ld", info->signr);
> > break;
> > diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> > index 54c01b6..e99c566 100644
> > --- a/kernel/seccomp.c
> > +++ b/kernel/seccomp.c
> > @@ -576,9 +576,11 @@ static int __seccomp_filter(int this_syscall, const
> > struct seccomp_data *sd, /* Set low-order bits as an errno, capped at
> > MAX_ERRNO. */
> > if (data > MAX_ERRNO)
> > data = MAX_ERRNO;
> > +
> > + audit_seccomp_errno(this_syscall, data, action);
> > syscall_set_return_value(current, task_pt_regs(current),
> > -data, 0);
> > - goto skip;
> > + return -1;
> >
> > case SECCOMP_RET_TRAP:
> > /* Show the handler the original registers. */
>
>
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next prev parent reply other threads:[~2017-01-02 17:44 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-02 16:53 [PATCH 0/2] Begin auditing SECCOMP_RET_ERRNO return actions Tyler Hicks
2017-01-02 16:53 ` [PATCH 1/2] seccomp: Allow for auditing functionality specific to " Tyler Hicks
2017-01-02 16:53 ` [PATCH 2/2] seccomp: Audit SECCOMP_RET_ERRNO actions with errno values Tyler Hicks
2017-01-02 17:20 ` Steve Grubb
2017-01-02 17:42 ` Tyler Hicks [this message]
2017-01-02 18:49 ` Steve Grubb
2017-01-02 22:55 ` Paul Moore
2017-01-02 22:47 ` [PATCH 0/2] Begin auditing SECCOMP_RET_ERRNO return actions Paul Moore
2017-01-03 5:56 ` Andy Lutomirski
2017-01-03 19:31 ` Paul Moore
2017-01-03 13:31 ` Tyler Hicks
2017-01-03 19:42 ` Paul Moore
2017-01-03 20:44 ` Kees Cook
2017-01-03 20:53 ` Steve Grubb
2017-01-03 20:54 ` Paul Moore
2017-01-03 21:03 ` Kees Cook
2017-01-03 21:13 ` Paul Moore
2017-01-03 21:21 ` Kees Cook
2017-01-03 21:31 ` Paul Moore
2017-01-03 21:44 ` Kees Cook
2017-01-04 1:58 ` Tyler Hicks
2017-01-04 4:43 ` Richard Guy Briggs
2017-01-04 6:31 ` Kees Cook
2017-01-04 2:04 ` Tyler Hicks
2017-01-03 5:57 ` Andy Lutomirski
2017-01-03 13:53 ` Tyler Hicks
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