On 2019-03-27 22:04, Richard Guy Briggs wrote:

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

quoted

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.

The way to address this on Steve Grubb's advice is to create a new
message type that incorporates a new struct with the structure above,
leaving the old one with the old message type deprecated.  I've coded
this up along with userspace support.

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.

I've also done this which Paul had already asked for, not quite in this
form.

I believe this addresses all the outstanding issues.

quoted

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++;

Ondrej Mosnacek <omosnace at redhat dot com>

- RGB

- 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