[PATCH ghak64 V3] audit: add saddr_fam filter field

[Paul Moore]

On Thu, May 9, 2019 at 8:02 PM Richard Guy Briggs <rgb at redhat.com> wrote:
>
> Provide a method to filter out sockaddr and bind calls by network
> address family.
>
> Existing SOCKADDR records are listed for any network activity.
> Implement the AUDIT_SADDR_FAM field selector to be able to classify or
> limit records to specific network address families, such as AF_INET or
> AF_INET6.
>
> An example of a network record that is unlikely to be useful and flood
> the logs:
>
> type=SOCKADDR msg=audit(07/27/2017 12:18:27.019:845) : saddr={ fam=local
> path=/var/run/nscd/socket }
> type=SYSCALL msg=audit(07/27/2017 12:18:27.019:845) : arch=x86_64
> syscall=connect success=no exit=ENOENT(No such file or directory) a0=0x3
> a1=0x7fff229c4980 a2=0x6e a3=0x6 items=1 ppid=3301 pid=6145 auid=sgrubb
> uid=sgrubb gid=sgrubb euid=sgrubb suid=sgrubb fsuid=sgrubb egid=sgrubb
> sgid=sgrubb fsgid=sgrubb tty=pts3 ses=4 comm=bash exe=/usr/bin/bash
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> key=network-test
>
> Please see the audit-testsuite PR at
> https://github.com/linux-audit/audit-testsuite/pull/87
> Please see the github issue
> https://github.com/linux-audit/audit-kernel/issues/64
> Please see the github issue for the accompanying userspace support
> https://github.com/linux-audit/audit-userspace/issues/93
>
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
> ---
> Changelog:
> v2:
> - rebase on ghak73 v2
> - check for valid range of saddr_fam value
> v3:
> - eliminate AF_UNSPEC check
>
>  include/uapi/linux/audit.h | 1 +
>  kernel/auditfilter.c       | 5 +++++
>  kernel/auditsc.c           | 5 +++++
>  3 files changed, 11 insertions(+)
>
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index a1280af20336..c89c6495983d 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -281,6 +281,7 @@
>  #define AUDIT_OBJ_GID  110
>  #define AUDIT_FIELD_COMPARE    111
>  #define AUDIT_EXE      112
> +#define AUDIT_SADDR_FAM        113
>
>  #define AUDIT_ARG0      200
>  #define AUDIT_ARG1      (AUDIT_ARG0+1)
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index 5beb2244d5ba..df8a7d6184dc 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -387,6 +387,7 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
>         case AUDIT_SUCCESS:
>         case AUDIT_INODE:
>         case AUDIT_SESSIONID:
> +       case AUDIT_SADDR_FAM:
>                 /* bit ops are only useful on syscall args */
>                 if (f->op == Audit_bitmask || f->op == Audit_bittest)
>                         return -EINVAL;
> @@ -438,6 +439,10 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
>                 if (f->val > AUDIT_MAX_FIELD_COMPARE)
>                         return -EINVAL;
>                 break;
> +       case AUDIT_SADDR_FAM:
> +               if (f->val >= AF_MAX)
> +                       return -EINVAL;
> +               break;

The f->val check looks better, thank you.  However, I just noticed
that it appears you've added two AUDIT_SADDR_FAM cases to the switch
statement?

>         default:
>                 break;
>         }
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 4bd0ec60a0e8..aab364804b9b 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -623,6 +623,11 @@ static int audit_filter_rules(struct task_struct *tsk,
>                 case AUDIT_LOGINUID_SET:
>                         result = audit_comparator(audit_loginuid_set(tsk), f->op, f->val);
>                         break;
> +               case AUDIT_SADDR_FAM:
> +                       if (ctx->sockaddr)
> +                               result = audit_comparator(ctx->sockaddr->ss_family,
> +                                                         f->op, f->val);
> +                       break;
>                 case AUDIT_SUBJ_USER:
>                 case AUDIT_SUBJ_ROLE:
>                 case AUDIT_SUBJ_TYPE:

-- 
paul moore
www.paul-moore.com