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

[Neil Horman <nhorman@tuxdriver.com>]

On Fri, Mar 15, 2019 at 02:29:53PM -0400, Richard Guy Briggs 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;
>  };
Sorry, just noticed this.  How does this work?  Given that ctx[] is a variable
length array, one assumes that the receiver of this message (userspace
applications by the looks of it, presume that the ctx data occupies the skb from
the byte following pid to the end of the transmitted buffer.  How are they to
know that the last byte is actually the cid value?  Wouldn't it be better to
move cid above ctx[0], so that the semantics of the variable length data are
preserved?

Or am I missing something?

otherwise this looks ok to me.
Neil

>  
>  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
> 
>