Re: [PATCH 2/2] seccomp: Audit SECCOMP_RET_ERRNO actions with errno values

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(a)canonical.com&gt; > > --- > > > > 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?

> > 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. */