Re: [PATCH ghak90 V5 05/10] audit: add containerid support for ptrace and signals

[Ondrej Mosnacek <omosnace@redhat.com>]

On Fri, Mar 15, 2019 at 7:34 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> Add audit container identifier support to ptrace and signals.  In
> particular, the "ref" field provides a way to label the auxiliary record
> to which it is associated.
>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> Acked-by: Serge Hallyn <serge@hallyn.com>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
>  include/linux/audit.h |  1 +
>  kernel/audit.c        |  2 ++
>  kernel/audit.h        |  2 ++
>  kernel/auditsc.c      | 23 +++++++++++++++++------
>  4 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 43438192ca2a..ebd6625ca80e 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -35,6 +35,7 @@ struct audit_sig_info {
>         uid_t           uid;
>         pid_t           pid;
>         char            ctx[0];
> +       u64             cid;
>  };

It seems like this structure implicitly defines the format of some
message that is sent to userspace... If so, how will userspace detect
that a new format (including the cid) is being used? Even assuming the
fixed order as pointed out by Neil, the message still seems to be
variable-sized so userspace cannot even use the length to infer that.
Am I missing something here? (I hope I am :)

>
>  struct audit_buffer;
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 8cc0e88d7f2a..cfa659b3f6c4 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -138,6 +138,7 @@ struct audit_net {
>  kuid_t         audit_sig_uid = INVALID_UID;
>  pid_t          audit_sig_pid = -1;
>  u32            audit_sig_sid = 0;
> +u64            audit_sig_cid = AUDIT_CID_UNSET;
>
>  /* Records can be lost in several ways:
>     0) [suppressed in audit_alloc]
> @@ -1515,6 +1516,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>                         memcpy(sig_data->ctx, ctx, len);
>                         security_release_secctx(ctx, len);
>                 }
> +               sig_data->cid = audit_sig_cid;
>                 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
>                                  sig_data, sizeof(*sig_data) + len);
>                 kfree(sig_data);
> diff --git a/kernel/audit.h b/kernel/audit.h
> index c00e2ee3c6b3..c5ac6436317e 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -148,6 +148,7 @@ struct audit_context {
>         kuid_t              target_uid;
>         unsigned int        target_sessionid;
>         u32                 target_sid;
> +       u64                 target_cid;
>         char                target_comm[TASK_COMM_LEN];
>
>         struct audit_tree_refs *trees, *first_trees;
> @@ -344,6 +345,7 @@ extern void audit_filter_inodes(struct task_struct *tsk,
>  extern pid_t audit_sig_pid;
>  extern kuid_t audit_sig_uid;
>  extern u32 audit_sig_sid;
> +extern u64 audit_sig_cid;
>
>  extern int audit_filter(int msgtype, unsigned int listtype);
>
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index a8c8b44b954d..f04e115df5dc 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -113,6 +113,7 @@ struct audit_aux_data_pids {
>         kuid_t                  target_uid[AUDIT_AUX_PIDS];
>         unsigned int            target_sessionid[AUDIT_AUX_PIDS];
>         u32                     target_sid[AUDIT_AUX_PIDS];
> +       u64                     target_cid[AUDIT_AUX_PIDS];
>         char                    target_comm[AUDIT_AUX_PIDS][TASK_COMM_LEN];
>         int                     pid_count;
>  };
> @@ -1514,7 +1515,7 @@ static void audit_log_exit(void)
>         for (aux = context->aux_pids; aux; aux = aux->next) {
>                 struct audit_aux_data_pids *axs = (void *)aux;
>
> -               for (i = 0; i < axs->pid_count; i++)
> +               for (i = 0; i < axs->pid_count; i++) {
>                         if (audit_log_pid_context(context, axs->target_pid[i],
>                                                   axs->target_auid[i],
>                                                   axs->target_uid[i],
> @@ -1522,14 +1523,20 @@ static void audit_log_exit(void)
>                                                   axs->target_sid[i],
>                                                   axs->target_comm[i]))
>                                 call_panic = 1;
> +                       audit_log_contid(context, axs->target_cid[i]);
> +               }
>         }
>
> -       if (context->target_pid &&
> -           audit_log_pid_context(context, context->target_pid,
> -                                 context->target_auid, context->target_uid,
> -                                 context->target_sessionid,
> -                                 context->target_sid, context->target_comm))
> +       if (context->target_pid) {
> +               if (audit_log_pid_context(context, context->target_pid,
> +                                         context->target_auid,
> +                                         context->target_uid,
> +                                         context->target_sessionid,
> +                                         context->target_sid,
> +                                         context->target_comm))
>                         call_panic = 1;
> +               audit_log_contid(context, context->target_cid);
> +       }
>
>         if (context->pwd.dentry && context->pwd.mnt) {
>                 ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD);
> @@ -2360,6 +2367,7 @@ void __audit_ptrace(struct task_struct *t)
>         context->target_uid = task_uid(t);
>         context->target_sessionid = audit_get_sessionid(t);
>         security_task_getsecid(t, &context->target_sid);
> +       context->target_cid = audit_get_contid(t);
>         memcpy(context->target_comm, t->comm, TASK_COMM_LEN);
>  }
>
> @@ -2387,6 +2395,7 @@ int audit_signal_info(int sig, struct task_struct *t)
>                 else
>                         audit_sig_uid = uid;
>                 security_task_getsecid(current, &audit_sig_sid);
> +               audit_sig_cid = audit_get_contid(current);
>         }
>
>         if (!audit_signals || audit_dummy_context())
> @@ -2400,6 +2409,7 @@ int audit_signal_info(int sig, struct task_struct *t)
>                 ctx->target_uid = t_uid;
>                 ctx->target_sessionid = audit_get_sessionid(t);
>                 security_task_getsecid(t, &ctx->target_sid);
> +               ctx->target_cid = audit_get_contid(t);
>                 memcpy(ctx->target_comm, t->comm, TASK_COMM_LEN);
>                 return 0;
>         }
> @@ -2421,6 +2431,7 @@ int audit_signal_info(int sig, struct task_struct *t)
>         axp->target_uid[axp->pid_count] = t_uid;
>         axp->target_sessionid[axp->pid_count] = audit_get_sessionid(t);
>         security_task_getsecid(t, &axp->target_sid[axp->pid_count]);
> +       axp->target_cid[axp->pid_count] = audit_get_contid(t);
>         memcpy(axp->target_comm[axp->pid_count], t->comm, TASK_COMM_LEN);
>         axp->pid_count++;
>
> --
> 1.8.3.1
>


-- 
Ondrej Mosnacek <omosnace at redhat dot com>
Software Engineer, Security Technologies
Red Hat, Inc.