On 2019-03-27 22:17, Ondrej Mosnacek wrote:

On Fri, Mar 15, 2019 at 7:34 PM Richard Guy Briggs [off-list ref] wrote:

quoted

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 <redacted>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Richard Guy Briggs <redacted>
---
 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 :)

How humble of you again.  No, you're not missing something.  This ends
up being an api change...  That can be fixed in userspace by checking
for AUDIT_FEATURE_BITMAP_CONTAINERID, but how do we make a newer kernel
not break an older userspace...  I think this was the original rationale
for adding it after the ctx but totally missing the fact that the latter
is a variable-length field.

This patch really should be split into audit_sig_cid changes in a patch
by itself and target_cid changes which could go with the second and
fourth patches.

quoted

 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.

- RGB

--
Richard Guy Briggs [off-list ref]
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