Re: [PATCH 1/1] audit: log binding and unbinding to netlink multicast

On 2017-10-13 19:58, Steve Grubb wrote: > Log information about programs connecting and disconnecting to the audit > netlink multicast socket. This is needed so that during investigations a > security officer can tell who or what had access to the audit trail. This > helps to meet the FAU_SAR.2 requirement for Common Criteria. Sample > event: > > type=UNKNOWN[1332] msg=audit(1507924331.540:3): pid=1 uid=0 > auid=4294967295 tty=(none) ses=4294967295 subj=kernel comm="systemd" > exe="/usr/lib/systemd/systemd" nlnk-grp=1 op=connect res=1

> Signed-off-by: sgrubb <sgrubb(a)redhat.com&gt; Reviewed-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > include/uapi/linux/audit.h | 1 + > kernel/audit.c | 48 ++++++++++++++++++++++++++++++++++++++++++---- > 2 files changed, 45 insertions(+), 4 deletions(-) > > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index 0714a66f0e0c..892e63d9f2c1 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -112,6 +112,7 @@ > #define AUDIT_FEATURE_CHANGE 1328 /* audit log listing feature changes */ > #define AUDIT_REPLACE 1329 /* Replace auditd if this packet unanswerd */ > #define AUDIT_KERN_MODULE 1330 /* Kernel Module events */ > +#define AUDIT_EVENT_LISTENER 1332 /* Task joined multicast read socket */ I assume this is waiting on another patch to be reviewed and merged... IIRC the maintainer prefers to deal with that merge conflict rather than accidentally leave a gap if the dependent patch doesn't get merged. > #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ > #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ > diff --git a/kernel/audit.c b/kernel/audit.c > index 1baabc9539b4..3d2461be83a8 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -1476,22 +1476,61 @@ static void audit_receive(struct sk_buff *skb) > mutex_unlock(&audit_cmd_mutex); > } > > +/* Log information about who is connecting to the audit multicast socket */ > +static void audit_log_multicast_bind(int group, const char *op, int err) > +{ > + const struct cred *cred; > + struct tty_struct *tty; > + char comm[sizeof(current->comm)]; > + struct audit_buffer *ab; > + > + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_EVENT_LISTENER); > + if (!ab) > + return; > + > + cred = current_cred(); > + tty = audit_get_tty(current); > + > + audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u", > + task_pid_nr(current), > + from_kuid(&init_user_ns, cred->uid), > + from_kuid(&init_user_ns, audit_get_loginuid(current)), > + tty ? tty_name(tty) : "(none)", > + audit_get_sessionid(current)); > + audit_put_tty(tty); > + audit_log_task_context(ab); /* subj= */ > + audit_log_format(ab, " comm="); > + audit_log_untrustedstring(ab, get_task_comm(comm, current)); > + audit_log_d_path_exe(ab, current->mm); /* exe= */ > + audit_log_format(ab, " nlnk-grp=%d op=%s res=%d", group, op, !err); > + audit_log_end(ab); > +} > + > /* Run custom bind function on netlink socket group connect or bind requests. */ > -static int audit_bind(struct net *net, int group) > +static int audit_multicast_bind(struct net *net, int group) > { > + int err = 0; > + > if (!capable(CAP_AUDIT_READ)) > - return -EPERM; > + err = -EPERM; > + audit_log_multicast_bind(group, "connect", err); > > - return 0; > + return err; > +} > + > +static void audit_multicast_unbind(struct net *net, int group) > +{ > + audit_log_multicast_bind(group, "disconnect", 0); > } > > static int __net_init audit_net_init(struct net *net) > { > struct netlink_kernel_cfg cfg = { > .input = audit_receive, > - .bind = audit_bind, > + .bind = audit_multicast_bind, > .flags = NL_CFG_F_NONROOT_RECV, > .groups = AUDIT_NLGRP_MAX, > + .unbind = audit_multicast_unbind, > }; > > struct audit_net *aunet = net_generic(net, audit_net_id); > -- > 2.13.6 > > > -- > Linux-audit mailing list > Linux-audit(a)redhat.com > https://www.redhat.com/mailman/listinfo/linux-audit - RGB -- Richard Guy Briggs <rgb(a)redhat.com&gt; Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635