connector: Added coredumping event to the process connector

Process connector can now also detect coredumping events.

Main aim of patch is get notified at start of coredumping, instead of
having to wait for it to finish and then being notified through EXIT
event.

Could be used for instance by process-managers that want to get
notified as soon as possible about process failures, and not
necessarily beeing notified after coredump, which could be in the
order of minutes depending on size of coredump, piping and so on.
Signed-off-by: Jesper Derehag <jderehag@hotmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/connector/cn_proc.c

@@ -232,6 +232,31 @@ void proc_comm_connector(struct task_struct *task)
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }
 
+void proc_coredump_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE];
+	struct timespec ts;
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = (struct cn_msg *)buffer;
+	ev = (struct proc_event *)msg->data;
+	get_seq(&msg->seq, &ev->cpu);
+	ktime_get_ts(&ts); /* get high res monotonic timestamp */
+	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
+	ev->what = PROC_EVENT_COREDUMP;
+	ev->event_data.coredump.process_pid = task->pid;
+	ev->event_data.coredump.process_tgid = task->tgid;
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
+}
+
 void proc_exit_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;

include/linux/cn_proc.h

@@ -26,6 +26,7 @@ void proc_id_connector(struct task_struct *task, int which_id);
 void proc_sid_connector(struct task_struct *task);
 void proc_ptrace_connector(struct task_struct *task, int which_id);
 void proc_comm_connector(struct task_struct *task);
+void proc_coredump_connector(struct task_struct *task);
 void proc_exit_connector(struct task_struct *task);
 #else
 static inline void proc_fork_connector(struct task_struct *task)
@@ -48,6 +49,9 @@ static inline void proc_ptrace_connector(struct task_struct *task,
 					 int ptrace_id)
 {}
 
+static inline void proc_coredump_connector(struct task_struct *task)
+{}
+
 static inline void proc_exit_connector(struct task_struct *task)
 {}
 #endif	/* CONFIG_PROC_EVENTS */

include/uapi/linux/cn_proc.h

@@ -56,7 +56,9 @@ struct proc_event {
 		PROC_EVENT_PTRACE = 0x00000100,
 		PROC_EVENT_COMM = 0x00000200,
 		/* "next" should be 0x00000400 */
-		/* "last" is the last process event: exit */
+		/* "last" is the last process event: exit,
+		 * while "next to last" is coredumping event */
+		PROC_EVENT_COREDUMP = 0x40000000,
 		PROC_EVENT_EXIT = 0x80000000
 	} what;
 	__u32 cpu;
@@ -110,11 +112,17 @@ struct proc_event {
 			char           comm[16];
 		} comm;
 
+		struct coredump_proc_event {
+			__kernel_pid_t process_pid;
+			__kernel_pid_t process_tgid;
+		} coredump;
+
 		struct exit_proc_event {
 			__kernel_pid_t process_pid;
 			__kernel_pid_t process_tgid;
 			__u32 exit_code, exit_signal;
 		} exit;
+
 	} event_data;
 };
 

kernel/signal.c

@@ -32,6 +32,7 @@
 #include <linux/user_namespace.h>
 #include <linux/uprobes.h>
 #include <linux/compat.h>
+#include <linux/cn_proc.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/signal.h>
 
@@ -2350,6 +2351,7 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 		if (sig_kernel_coredump(signr)) {
 			if (print_fatal_signals)
 				print_fatal_signal(info->si_signo);
+			proc_coredump_connector(current);
 			/*
 			 * If it was able to dump core, this kills all
 			 * other threads in the group and synchronizes with