[PATCH] Process Events Connector

This patch adds a connector that reports fork, exec, id change, and exit
events for all processes to userspace. It replaces the fork_advisor patch
that ELSA is currently using. Applications that may find these events
useful include accounting/auditing (e.g. ELSA), system activity monitoring
(e.g. top), security, and resource management (e.g. CKRM).

Signed-off-by: Matt Helsley <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/connector/Kconfig

···
 	  Connector support can also be built as a module.  If so, the module
 	  will be called cn.ko.
 
+config PROC_EVENTS
+	boolean "Report process events to userspace"
+	depends on CONNECTOR=y
+	default y
+	---help---
+	  Provide a connector that reports process events to userspace. Send
+	  events such as fork, exec, id change (uid, gid, suid, etc), and exit.
+
 endmenu

drivers/connector/Makefile

···
 obj-$(CONFIG_CONNECTOR)		+= cn.o
+obj-$(CONFIG_PROC_EVENTS)	+= cn_proc.o
 
 cn-y				+= cn_queue.o connector.o

drivers/connector/cn_proc.c

···
+/*
+ * cn_proc.c - process events connector
+ *
+ * Copyright (C) Matt Helsley, IBM Corp. 2005
+ * Based on cn_fork.c by Guillaume Thouvenin <[e-mail]>
+ * Original copyright notice follows:
+ * Copyright (C) 2005 BULL SA.
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+
+#include <linux/cn_proc.h>
+
+#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event))
+
+static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
+static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
+
+/* proc_counts is used as the sequence number of the netlink message */
+static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
+
+static inline void get_seq(__u32 *ts, int *cpu)
+{
+	*ts = get_cpu_var(proc_event_counts)++;
+	*cpu = smp_processor_id();
+	put_cpu_var(proc_counts);
+}
+
+void proc_fork_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE];
+
+	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);
+	ev->what = PROC_EVENT_FORK;
+	ev->event_data.fork.parent_pid = task->real_parent->pid;
+	ev->event_data.fork.parent_tgid = task->real_parent->tgid;
+	ev->event_data.fork.child_pid = task->pid;
+	ev->event_data.fork.child_tgid = task->tgid;
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	/*  If cn_netlink_send() failed, the data is not sent */
+	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
+}
+
+void proc_exec_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE];
+
+	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);
+	ev->what = PROC_EVENT_EXEC;
+	ev->event_data.exec.process_pid = task->pid;
+	ev->event_data.exec.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_id_connector(struct task_struct *task, int which_id)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE];
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = (struct cn_msg*)buffer;
+	ev = (struct proc_event*)msg->data;
+	ev->what = which_id;
+	ev->event_data.id.process_pid = task->pid;
+	ev->event_data.id.process_tgid = task->tgid;
+	if (which_id == PROC_EVENT_UID) {
+	 	ev->event_data.id.r.ruid = task->uid;
+	 	ev->event_data.id.e.euid = task->euid;
+	} else if (which_id == PROC_EVENT_GID) {
+	   	ev->event_data.id.r.rgid = task->gid;
+	   	ev->event_data.id.e.egid = task->egid;
+	} else
+	     	return;
+	get_seq(&msg->seq, &ev->cpu);
+
+	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;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE];
+
+	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);
+	ev->what = PROC_EVENT_EXIT;
+	ev->event_data.exit.process_pid = task->pid;
+	ev->event_data.exit.process_tgid = task->tgid;
+	ev->event_data.exit.exit_code = task->exit_code;
+	ev->event_data.exit.exit_signal = task->exit_signal;
+
+	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);
+}
+
+/*
+ * Send an acknowledgement message to userspace
+ *
+ * Use 0 for success, EFOO otherwise.
+ * Note: this is the negative of conventional kernel error
+ * values because it's not being returned via syscall return
+ * mechanisms.
+ */
+static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE];
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = (struct cn_msg*)buffer;
+	ev = (struct proc_event*)msg->data;
+	msg->seq = rcvd_seq;
+	ev->cpu = -1;
+	ev->what = PROC_EVENT_NONE;
+	ev->event_data.ack.err = err;
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = rcvd_ack + 1;
+	msg->len = sizeof(*ev);
+	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
+}
+
+/**
+ * cn_proc_mcast_ctl
+ * @data: message sent from userspace via the connector
+ */
+static void cn_proc_mcast_ctl(void *data)
+{
+	struct cn_msg *msg = data;
+	enum proc_cn_mcast_op *mc_op = NULL;
+	int err = 0;
+
+	if (msg->len != sizeof(*mc_op))
+		return;
+
+	mc_op = (enum proc_cn_mcast_op*)msg->data;
+	switch (*mc_op) {
+	case PROC_CN_MCAST_LISTEN:
+		atomic_inc(&proc_event_num_listeners);
+		break;
+	case PROC_CN_MCAST_IGNORE:
+		atomic_dec(&proc_event_num_listeners);
+		break;
+	default:
+		err = EINVAL;
+		break;
+	}
+	cn_proc_ack(err, msg->seq, msg->ack);
+}
+
+/*
+ * cn_proc_init - initialization entry point
+ *
+ * Adds the connector callback to the connector driver.
+ */
+static int __init cn_proc_init(void)
+{
+	int err;
+
+	if ((err = cn_add_callback(&cn_proc_event_id, "cn_proc",
+	 			   &cn_proc_mcast_ctl))) {
+		printk(KERN_WARNING "cn_proc failed to register\n");
+		return err;
+	}
+	return 0;
+}
+
+module_init(cn_proc_init);

fs/exec.c

···
 #include <linux/syscalls.h>
 #include <linux/rmap.h>
 #include <linux/acct.h>
+#include <linux/cn_proc.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
···
 					fput(bprm->file);
 				bprm->file = NULL;
 				current->did_exec = 1;
+				proc_exec_connector(current);
 				return retval;
 			}
 			read_lock(&binfmt_lock);

include/linux/cn_proc.h

···
+/*
+ * cn_proc.h - process events connector
+ *
+ * Copyright (C) Matt Helsley, IBM Corp. 2005
+ * Based on cn_fork.h by Nguyen Anh Quynh and Guillaume Thouvenin
+ * Original copyright notice follows:
+ * Copyright (C) 2005 Nguyen Anh Quynh <[e-mail]>
+ * Copyright (C) 2005 Guillaume Thouvenin <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef CN_PROC_H
+#define CN_PROC_H
+
+#include <linux/types.h>
+#include <linux/connector.h>
+
+/*
+ * Userspace sends this enum to register with the kernel that it is listening
+ * for events on the connector.
+ */
+enum proc_cn_mcast_op {
+	PROC_CN_MCAST_LISTEN = 1,
+	PROC_CN_MCAST_IGNORE = 2
+};
+
+/*
+ * From the user's point of view, the process
+ * ID is the thread group ID and thread ID is the internal
+ * kernel "pid". So, fields are assigned as follow:
+ *
+ *  In user space     -  In  kernel space
+ *
+ * parent process ID  =  parent->tgid
+ * parent thread  ID  =  parent->pid
+ * child  process ID  =  child->tgid
+ * child  thread  ID  =  child->pid
+ */
+
+struct proc_event {
+	enum what {
+		/* Use successive bits so the enums can be used to record
+		 * sets of events as well
+		 */
+		PROC_EVENT_NONE = 0x00000000,
+		PROC_EVENT_FORK = 0x00000001,
+		PROC_EVENT_EXEC = 0x00000002,
+		PROC_EVENT_UID  = 0x00000004,
+		PROC_EVENT_GID  = 0x00000040,
+		/* "next" should be 0x00000400 */
+		/* "last" is the last process event: exit */
+		PROC_EVENT_EXIT = 0x80000000
+	} what;
+	__u32 cpu;
+	union { /* must be last field of proc_event struct */
+		struct {
+			__u32 err;
+		} ack;
+
+		struct fork_proc_event {
+			pid_t parent_pid;
+			pid_t parent_tgid;
+			pid_t child_pid;
+			pid_t child_tgid;
+		} fork;
+
+		struct exec_proc_event {
+			pid_t process_pid;
+			pid_t process_tgid;
+		} exec;
+
+		struct id_proc_event {
+			pid_t process_pid;
+			pid_t process_tgid;
+			union {
+				uid_t ruid; /* current->uid */
+				gid_t rgid; /* current->gid */
+			} r;
+			union {
+				uid_t euid;
+				gid_t egid;
+			} e;
+		} id;
+
+		struct exit_proc_event {
+			pid_t process_pid;
+			pid_t process_tgid;
+			__u32 exit_code, exit_signal;
+		} exit;
+	} event_data;
+};
+
+#ifdef __KERNEL__
+#ifdef CONFIG_PROC_EVENTS
+void proc_fork_connector(struct task_struct *task);
+void proc_exec_connector(struct task_struct *task);
+void proc_id_connector(struct task_struct *task, int which_id);
+void proc_exit_connector(struct task_struct *task);
+#else
+static inline void proc_fork_connector(struct task_struct *task)
+{}
+
+static inline void proc_exec_connector(struct task_struct *task)
+{}
+
+static inline void proc_id_connector(struct task_struct *task,
+				     int which_id)
+{}
+
+static inline void proc_exit_connector(struct task_struct *task)
+{}
+#endif	/* CONFIG_PROC_EVENTS */
+#endif	/* __KERNEL__ */
+#endif	/* CN_PROC_H */

include/linux/connector.h

···
 #define CN_IDX_CONNECTOR		0xffffffff
 #define CN_VAL_CONNECTOR		0xffffffff
 
+/*
+ * Process Events connector unique ids -- used for message routing
+ */
+#define CN_IDX_PROC			0x1
+#define CN_VAL_PROC			0x1
+
 #define CN_NETLINK_USERS		1
 
 /*

kernel/exit.c

···
 #include <linux/cpuset.h>
 #include <linux/syscalls.h>
 #include <linux/signal.h>
+#include <linux/cn_proc.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
···
 		module_put(tsk->binfmt->module);
 
 	tsk->exit_code = code;
+	proc_exit_connector(tsk);
 	exit_notify(tsk);
 #ifdef CONFIG_NUMA
 	mpol_free(tsk->mempolicy);

kernel/fork.c

···
 #include <linux/profile.h>
 #include <linux/rmap.h>
 #include <linux/acct.h>
+#include <linux/cn_proc.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
···
 			__get_cpu_var(process_counts)++;
 	}
 
+	proc_fork_connector(p);
 	if (!current->signal->tty && p->signal->tty)
 		p->signal->tty = NULL;
 

kernel/sys.c

···
 #include <linux/suspend.h>
 #include <linux/tty.h>
 #include <linux/signal.h>
+#include <linux/cn_proc.h>
 
 #include <linux/compat.h>
 #include <linux/syscalls.h>
···
 	current->egid = new_egid;
 	current->gid = new_rgid;
 	key_fsgid_changed(current);
+	proc_id_connector(current, PROC_EVENT_GID);
 	return 0;
 }
 
···
 		return -EPERM;
 
 	key_fsgid_changed(current);
+	proc_id_connector(current, PROC_EVENT_GID);
 	return 0;
 }
   
···
 	current->fsuid = current->euid;
 
 	key_fsuid_changed(current);
+	proc_id_connector(current, PROC_EVENT_UID);
 
 	return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RE);
 }
···
 	current->suid = new_suid;
 
 	key_fsuid_changed(current);
+	proc_id_connector(current, PROC_EVENT_UID);
 
 	return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_ID);
 }
···
 		current->suid = suid;
 
 	key_fsuid_changed(current);
+	proc_id_connector(current, PROC_EVENT_UID);
 
 	return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RES);
 }
···
 		current->sgid = sgid;
 
 	key_fsgid_changed(current);
+	proc_id_connector(current, PROC_EVENT_GID);
 	return 0;
 }
 
···
 	}
 
 	key_fsuid_changed(current);
+	proc_id_connector(current, PROC_EVENT_UID);
 
 	security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS);
 
···
 		}
 		current->fsgid = gid;
 		key_fsgid_changed(current);
+		proc_id_connector(current, PROC_EVENT_GID);
 	}
 	return old_fsgid;
 }