397 lines
11 KiB
C
397 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* cn_proc.c - process events connector
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*
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* Copyright (C) Matt Helsley, IBM Corp. 2005
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* Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
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* Original copyright notice follows:
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* Copyright (C) 2005 BULL SA.
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*/
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#include <linux/kernel.h>
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#include <linux/ktime.h>
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#include <linux/init.h>
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#include <linux/connector.h>
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#include <linux/gfp.h>
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#include <linux/ptrace.h>
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#include <linux/atomic.h>
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#include <linux/pid_namespace.h>
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#include <linux/cn_proc.h>
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/*
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* Size of a cn_msg followed by a proc_event structure. Since the
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* sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
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* add one 4-byte word to the size here, and then start the actual
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* cn_msg structure 4 bytes into the stack buffer. The result is that
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* the immediately following proc_event structure is aligned to 8 bytes.
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*/
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#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)
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/* See comment above; we test our assumption about sizeof struct cn_msg here. */
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static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
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{
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BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
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return (struct cn_msg *)(buffer + 4);
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}
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static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
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static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
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/* proc_event_counts is used as the sequence number of the netlink message */
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static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
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static inline void send_msg(struct cn_msg *msg)
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{
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preempt_disable();
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msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
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((struct proc_event *)msg->data)->cpu = smp_processor_id();
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/*
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* Preemption remains disabled during send to ensure the messages are
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* ordered according to their sequence numbers.
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*
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* If cn_netlink_send() fails, the data is not sent.
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*/
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cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
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preempt_enable();
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}
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void proc_fork_connector(struct task_struct *task)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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struct task_struct *parent;
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_FORK;
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rcu_read_lock();
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parent = rcu_dereference(task->real_parent);
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ev->event_data.fork.parent_pid = parent->pid;
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ev->event_data.fork.parent_tgid = parent->tgid;
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rcu_read_unlock();
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ev->event_data.fork.child_pid = task->pid;
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ev->event_data.fork.child_tgid = task->tgid;
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_exec_connector(struct task_struct *task)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_EXEC;
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ev->event_data.exec.process_pid = task->pid;
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ev->event_data.exec.process_tgid = task->tgid;
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_id_connector(struct task_struct *task, int which_id)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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const struct cred *cred;
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->what = which_id;
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ev->event_data.id.process_pid = task->pid;
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ev->event_data.id.process_tgid = task->tgid;
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rcu_read_lock();
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cred = __task_cred(task);
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if (which_id == PROC_EVENT_UID) {
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ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
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ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
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} else if (which_id == PROC_EVENT_GID) {
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ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
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ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
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} else {
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rcu_read_unlock();
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return;
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}
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rcu_read_unlock();
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ev->timestamp_ns = ktime_get_ns();
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_sid_connector(struct task_struct *task)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_SID;
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ev->event_data.sid.process_pid = task->pid;
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ev->event_data.sid.process_tgid = task->tgid;
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_PTRACE;
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ev->event_data.ptrace.process_pid = task->pid;
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ev->event_data.ptrace.process_tgid = task->tgid;
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if (ptrace_id == PTRACE_ATTACH) {
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ev->event_data.ptrace.tracer_pid = current->pid;
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ev->event_data.ptrace.tracer_tgid = current->tgid;
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} else if (ptrace_id == PTRACE_DETACH) {
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ev->event_data.ptrace.tracer_pid = 0;
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ev->event_data.ptrace.tracer_tgid = 0;
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} else
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return;
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_comm_connector(struct task_struct *task)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_COMM;
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ev->event_data.comm.process_pid = task->pid;
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ev->event_data.comm.process_tgid = task->tgid;
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get_task_comm(ev->event_data.comm.comm, task);
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_coredump_connector(struct task_struct *task)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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struct task_struct *parent;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_COREDUMP;
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ev->event_data.coredump.process_pid = task->pid;
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ev->event_data.coredump.process_tgid = task->tgid;
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rcu_read_lock();
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if (pid_alive(task)) {
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parent = rcu_dereference(task->real_parent);
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ev->event_data.coredump.parent_pid = parent->pid;
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ev->event_data.coredump.parent_tgid = parent->tgid;
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}
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rcu_read_unlock();
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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void proc_exit_connector(struct task_struct *task)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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struct task_struct *parent;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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ev->timestamp_ns = ktime_get_ns();
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ev->what = PROC_EVENT_EXIT;
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ev->event_data.exit.process_pid = task->pid;
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ev->event_data.exit.process_tgid = task->tgid;
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ev->event_data.exit.exit_code = task->exit_code;
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ev->event_data.exit.exit_signal = task->exit_signal;
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rcu_read_lock();
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if (pid_alive(task)) {
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parent = rcu_dereference(task->real_parent);
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ev->event_data.exit.parent_pid = parent->pid;
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ev->event_data.exit.parent_tgid = parent->tgid;
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}
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rcu_read_unlock();
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = 0; /* not used */
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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/*
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* Send an acknowledgement message to userspace
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*
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* Use 0 for success, EFOO otherwise.
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* Note: this is the negative of conventional kernel error
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* values because it's not being returned via syscall return
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* mechanisms.
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*/
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static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
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{
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struct cn_msg *msg;
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struct proc_event *ev;
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__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
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if (atomic_read(&proc_event_num_listeners) < 1)
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return;
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msg = buffer_to_cn_msg(buffer);
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ev = (struct proc_event *)msg->data;
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memset(&ev->event_data, 0, sizeof(ev->event_data));
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msg->seq = rcvd_seq;
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ev->timestamp_ns = ktime_get_ns();
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ev->cpu = -1;
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ev->what = PROC_EVENT_NONE;
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ev->event_data.ack.err = err;
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memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
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msg->ack = rcvd_ack + 1;
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msg->len = sizeof(*ev);
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msg->flags = 0; /* not used */
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send_msg(msg);
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}
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/**
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* cn_proc_mcast_ctl
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* @data: message sent from userspace via the connector
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*/
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static void cn_proc_mcast_ctl(struct cn_msg *msg,
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struct netlink_skb_parms *nsp)
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{
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enum proc_cn_mcast_op *mc_op = NULL;
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int err = 0;
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if (msg->len != sizeof(*mc_op))
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return;
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/*
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* Events are reported with respect to the initial pid
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* and user namespaces so ignore requestors from
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* other namespaces.
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*/
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if ((current_user_ns() != &init_user_ns) ||
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(task_active_pid_ns(current) != &init_pid_ns))
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return;
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/* Can only change if privileged. */
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if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
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err = EPERM;
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goto out;
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}
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mc_op = (enum proc_cn_mcast_op *)msg->data;
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switch (*mc_op) {
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case PROC_CN_MCAST_LISTEN:
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atomic_inc(&proc_event_num_listeners);
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break;
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case PROC_CN_MCAST_IGNORE:
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atomic_dec(&proc_event_num_listeners);
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break;
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default:
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err = EINVAL;
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break;
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}
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out:
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cn_proc_ack(err, msg->seq, msg->ack);
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}
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/*
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* cn_proc_init - initialization entry point
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*
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* Adds the connector callback to the connector driver.
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*/
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static int __init cn_proc_init(void)
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{
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int err = cn_add_callback(&cn_proc_event_id,
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"cn_proc",
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&cn_proc_mcast_ctl);
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if (err) {
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pr_warn("cn_proc failed to register\n");
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return err;
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}
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return 0;
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}
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device_initcall(cn_proc_init);
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