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![Li RongQing](/assets/img/avatar_default.png)
proc_exit_connector() uses ->real_parent lockless. This is not
safe that its parent can go away at any moment, so use RCU to
protect it, and ensure that this task is not released.
[ 747.624551] ==================================================================
[ 747.632946] BUG: KASAN: use-after-free in proc_exit_connector+0x1f7/0x310
[ 747.640686] Read of size 4 at addr ffff88a0276988e0 by task sshd/2882
[ 747.648032]
[ 747.649804] CPU: 11 PID: 2882 Comm: sshd Tainted: G E 4.19.26-rc2 #11
[ 747.658629] Hardware name: IBM x3550M4 -[7914OFV]-/00AM544, BIOS -[D7E142BUS-1.71]- 07/31/2014
[ 747.668419] Call Trace:
[ 747.671269] dump_stack+0xf0/0x19b
[ 747.675186] ? show_regs_print_info+0x5/0x5
[ 747.679988] ? kmsg_dump_rewind_nolock+0x59/0x59
[ 747.685302] print_address_description+0x6a/0x270
[ 747.691162] kasan_report+0x258/0x380
[ 747.695835] ? proc_exit_connector+0x1f7/0x310
[ 747.701402] proc_exit_connector+0x1f7/0x310
[ 747.706767] ? proc_coredump_connector+0x2d0/0x2d0
[ 747.712715] ? _raw_write_unlock_irq+0x29/0x50
[ 747.718270] ? _raw_write_unlock_irq+0x29/0x50
[ 747.723820] ? ___preempt_schedule+0x16/0x18
[ 747.729193] ? ___preempt_schedule+0x16/0x18
[ 747.734574] do_exit+0xa11/0x14f0
[ 747.738880] ? mm_update_next_owner+0x590/0x590
[ 747.744525] ? debug_show_all_locks+0x3c0/0x3c0
[ 747.761448] ? ktime_get_coarse_real_ts64+0xeb/0x1c0
[ 747.767589] ? lockdep_hardirqs_on+0x1a6/0x290
[ 747.773154] ? check_chain_key+0x139/0x1f0
[ 747.778345] ? check_flags.part.35+0x240/0x240
[ 747.783908] ? __lock_acquire+0x2300/0x2300
[ 747.789171] ? _raw_spin_unlock_irqrestore+0x59/0x70
[ 747.795316] ? _raw_spin_unlock_irqrestore+0x59/0x70
[ 747.801457] ? do_raw_spin_unlock+0x10f/0x1e0
[ 747.806914] ? do_raw_spin_trylock+0x120/0x120
[ 747.812481] ? preempt_count_sub+0x14/0xc0
[ 747.817645] ? _raw_spin_unlock+0x2e/0x50
[ 747.822708] ? __handle_mm_fault+0x12db/0x1fa0
[ 747.828367] ? __pmd_alloc+0x2d0/0x2d0
[ 747.833143] ? check_noncircular+0x50/0x50
[ 747.838309] ? match_held_lock+0x7f/0x340
[ 747.843380] ? check_noncircular+0x50/0x50
[ 747.848561] ? handle_mm_fault+0x21a/0x5f0
[ 747.853730] ? check_flags.part.35+0x240/0x240
[ 747.859290] ? check_chain_key+0x139/0x1f0
[ 747.864474] ? __do_page_fault+0x40f/0x760
[ 747.869655] ? __audit_syscall_entry+0x4b/0x1f0
[ 747.875319] ? syscall_trace_enter+0x1d5/0x7b0
[ 747.880877] ? trace_raw_output_preemptirq_template+0x90/0x90
[ 747.887895] ? trace_raw_output_sys_exit+0x80/0x80
[ 747.893860] ? up_read+0x3b/0x90
[ 747.898142] ? stop_critical_timings+0x260/0x260
[ 747.903909] do_group_exit+0xe0/0x1c0
[ 747.908591] ? __x64_sys_exit+0x30/0x30
[ 747.913460] ? trace_raw_output_preemptirq_template+0x90/0x90
[ 747.920485] ? tracer_hardirqs_on+0x270/0x270
[ 747.925956] __x64_sys_exit_group+0x28/0x30
[ 747.931214] do_syscall_64+0x117/0x400
[ 747.935988] ? syscall_return_slowpath+0x2f0/0x2f0
[ 747.941931] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 747.947788] ? trace_hardirqs_on_caller+0x1d0/0x1d0
[ 747.953838] ? lockdep_sys_exit+0x16/0x8e
[ 747.958915] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 747.964784] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 747.971021] RIP: 0033:0x7f572f154c68
[ 747.975606] Code: Bad RIP value.
[ 747.979791] RSP: 002b:00007ffed2dfaa58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[ 747.989324] RAX: ffffffffffffffda RBX: 00007f572f431840 RCX: 00007f572f154c68
[ 747.997910] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001
[ 748.006495] RBP: 0000000000000001 R08: 00000000000000e7 R09: fffffffffffffee0
[ 748.015079] R10: 00007f572f4387e8 R11: 0000000000000246 R12: 00007f572f431840
[ 748.023664] R13: 000055a7f90f2c50 R14: 000055a7f96e2310 R15: 000055a7f96e2310
[ 748.032287]
[ 748.034509] Allocated by task 2300:
[ 748.038982] kasan_kmalloc+0xa0/0xd0
[ 748.043562] kmem_cache_alloc_node+0xf5/0x2e0
[ 748.049018] copy_process+0x1781/0x4790
[ 748.053884] _do_fork+0x166/0x9a0
[ 748.058163] do_syscall_64+0x117/0x400
[ 748.062943] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 748.069180]
[ 748.071405] Freed by task 15395:
[ 748.075591] __kasan_slab_free+0x130/0x180
[ 748.080752] kmem_cache_free+0xc2/0x310
[ 748.085619] free_task+0xea/0x130
[ 748.089901] __put_task_struct+0x177/0x230
[ 748.095063] finish_task_switch+0x51b/0x5d0
[ 748.100315] __schedule+0x506/0xfa0
[ 748.104791] schedule+0xca/0x260
[ 748.108978] futex_wait_queue_me+0x27e/0x420
[ 748.114333] futex_wait+0x251/0x550
[ 748.118814] do_futex+0x75b/0xf80
[ 748.123097] __x64_sys_futex+0x231/0x2a0
[ 748.128065] do_syscall_64+0x117/0x400
[ 748.132835] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 748.139066]
[ 748.141289] The buggy address belongs to the object at ffff88a027698000
[ 748.141289] which belongs to the cache task_struct of size 12160
[ 748.156589] The buggy address is located 2272 bytes inside of
[ 748.156589] 12160-byte region [ffff88a027698000, ffff88a02769af80)
[ 748.171114] The buggy address belongs to the page:
[ 748.177055] page:ffffea00809da600 count:1 mapcount:0 mapping:ffff888107d01e00 index:0x0 compound_mapcount: 0
[ 748.189136] flags: 0x57ffffc0008100(slab|head)
[ 748.194688] raw: 0057ffffc0008100 ffffea00809a3200 0000000300000003 ffff888107d01e00
[ 748.204424] raw: 0000000000000000 0000000000020002 00000001ffffffff 0000000000000000
[ 748.214146] page dumped because: kasan: bad access detected
[ 748.220976]
[ 748.223197] Memory state around the buggy address:
[ 748.229128] ffff88a027698780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.238271] ffff88a027698800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.247414] >ffff88a027698880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.256564] ^
[ 748.264267] ffff88a027698900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.273493] ffff88a027698980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.282630] ==================================================================
Fixes: b086ff8725
("connector: add parent pid and tgid to coredump and exit events")
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
410 lines
11 KiB
C
410 lines
11 KiB
C
/*
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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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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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);
|
|
|
|
if (atomic_read(&proc_event_num_listeners) < 1)
|
|
return;
|
|
|
|
msg = buffer_to_cn_msg(buffer);
|
|
ev = (struct proc_event *)msg->data;
|
|
memset(&ev->event_data, 0, sizeof(ev->event_data));
|
|
ev->timestamp_ns = ktime_get_ns();
|
|
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;
|
|
|
|
rcu_read_lock();
|
|
if (pid_alive(task)) {
|
|
parent = rcu_dereference(task->real_parent);
|
|
ev->event_data.exit.parent_pid = parent->pid;
|
|
ev->event_data.exit.parent_tgid = parent->tgid;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
|
|
msg->ack = 0; /* not used */
|
|
msg->len = sizeof(*ev);
|
|
msg->flags = 0; /* not used */
|
|
send_msg(msg);
|
|
}
|
|
|
|
/*
|
|
* 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] __aligned(8);
|
|
|
|
if (atomic_read(&proc_event_num_listeners) < 1)
|
|
return;
|
|
|
|
msg = buffer_to_cn_msg(buffer);
|
|
ev = (struct proc_event *)msg->data;
|
|
memset(&ev->event_data, 0, sizeof(ev->event_data));
|
|
msg->seq = rcvd_seq;
|
|
ev->timestamp_ns = ktime_get_ns();
|
|
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);
|
|
msg->flags = 0; /* not used */
|
|
send_msg(msg);
|
|
}
|
|
|
|
/**
|
|
* cn_proc_mcast_ctl
|
|
* @data: message sent from userspace via the connector
|
|
*/
|
|
static void cn_proc_mcast_ctl(struct cn_msg *msg,
|
|
struct netlink_skb_parms *nsp)
|
|
{
|
|
enum proc_cn_mcast_op *mc_op = NULL;
|
|
int err = 0;
|
|
|
|
if (msg->len != sizeof(*mc_op))
|
|
return;
|
|
|
|
/*
|
|
* Events are reported with respect to the initial pid
|
|
* and user namespaces so ignore requestors from
|
|
* other namespaces.
|
|
*/
|
|
if ((current_user_ns() != &init_user_ns) ||
|
|
(task_active_pid_ns(current) != &init_pid_ns))
|
|
return;
|
|
|
|
/* Can only change if privileged. */
|
|
if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
|
|
err = EPERM;
|
|
goto out;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
out:
|
|
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 = cn_add_callback(&cn_proc_event_id,
|
|
"cn_proc",
|
|
&cn_proc_mcast_ctl);
|
|
if (err) {
|
|
pr_warn("cn_proc failed to register\n");
|
|
return err;
|
|
}
|
|
return 0;
|
|
}
|
|
device_initcall(cn_proc_init);
|