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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015 Thomas Meyer ([email protected])
4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
5 */
6
7#include <stdio.h>
8#include <stdlib.h>
9#include <unistd.h>
10#include <errno.h>
11#include <signal.h>
12#include <fcntl.h>
13#include <limits.h>
14#include <linux/futex.h>
15#include <sys/mman.h>
16#include <sys/ptrace.h>
17#include <sys/prctl.h>
18#include <sys/wait.h>
19#include <asm/unistd.h>
20#include <init.h>
21#include <longjmp.h>
22#include <os.h>
23#include <skas/skas.h>
24
25void os_alarm_process(int pid)
26{
27 if (pid <= 0)
28 return;
29
30 kill(pid, SIGALRM);
31}
32
33void os_kill_process(int pid, int reap_child)
34{
35 if (pid <= 0)
36 return;
37
38 /* Block signals until child is reaped */
39 block_signals();
40
41 kill(pid, SIGKILL);
42 if (reap_child)
43 CATCH_EINTR(waitpid(pid, NULL, __WALL));
44
45 unblock_signals();
46}
47
48/* Kill off a ptraced child by all means available. kill it normally first,
49 * then PTRACE_KILL it, then PTRACE_CONT it in case it's in a run state from
50 * which it can't exit directly.
51 */
52
53void os_kill_ptraced_process(int pid, int reap_child)
54{
55 if (pid <= 0)
56 return;
57
58 /* Block signals until child is reaped */
59 block_signals();
60
61 kill(pid, SIGKILL);
62 ptrace(PTRACE_KILL, pid);
63 ptrace(PTRACE_CONT, pid);
64 if (reap_child)
65 CATCH_EINTR(waitpid(pid, NULL, __WALL));
66
67 unblock_signals();
68}
69
70pid_t os_reap_child(void)
71{
72 int status;
73
74 /* Try to reap a child */
75 return waitpid(-1, &status, WNOHANG);
76}
77
78/* Don't use the glibc version, which caches the result in TLS. It misses some
79 * syscalls, and also breaks with clone(), which does not unshare the TLS.
80 */
81
82int os_getpid(void)
83{
84 return syscall(__NR_getpid);
85}
86
87int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
88 int r, int w, int x)
89{
90 void *loc;
91 int prot;
92
93 prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
94 (x ? PROT_EXEC : 0);
95
96 loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED,
97 fd, off);
98 if (loc == MAP_FAILED)
99 return -errno;
100 return 0;
101}
102
103int os_protect_memory(void *addr, unsigned long len, int r, int w, int x)
104{
105 int prot = ((r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
106 (x ? PROT_EXEC : 0));
107
108 if (mprotect(addr, len, prot) < 0)
109 return -errno;
110
111 return 0;
112}
113
114int os_unmap_memory(void *addr, int len)
115{
116 int err;
117
118 err = munmap(addr, len);
119 if (err < 0)
120 return -errno;
121 return 0;
122}
123
124#ifndef MADV_REMOVE
125#define MADV_REMOVE KERNEL_MADV_REMOVE
126#endif
127
128int os_drop_memory(void *addr, int length)
129{
130 int err;
131
132 err = madvise(addr, length, MADV_REMOVE);
133 if (err < 0)
134 err = -errno;
135 return err;
136}
137
138int __init can_drop_memory(void)
139{
140 void *addr;
141 int fd, ok = 0;
142
143 printk(UM_KERN_INFO "Checking host MADV_REMOVE support...");
144 fd = create_mem_file(UM_KERN_PAGE_SIZE);
145 if (fd < 0) {
146 printk(UM_KERN_ERR "Creating test memory file failed, "
147 "err = %d\n", -fd);
148 goto out;
149 }
150
151 addr = mmap64(NULL, UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
152 MAP_SHARED, fd, 0);
153 if (addr == MAP_FAILED) {
154 printk(UM_KERN_ERR "Mapping test memory file failed, "
155 "err = %d\n", -errno);
156 goto out_close;
157 }
158
159 if (madvise(addr, UM_KERN_PAGE_SIZE, MADV_REMOVE) != 0) {
160 printk(UM_KERN_ERR "MADV_REMOVE failed, err = %d\n", -errno);
161 goto out_unmap;
162 }
163
164 printk(UM_KERN_CONT "OK\n");
165 ok = 1;
166
167out_unmap:
168 munmap(addr, UM_KERN_PAGE_SIZE);
169out_close:
170 close(fd);
171out:
172 return ok;
173}
174
175void init_new_thread_signals(void)
176{
177 set_handler(SIGSEGV);
178 set_handler(SIGTRAP);
179 set_handler(SIGFPE);
180 set_handler(SIGILL);
181 set_handler(SIGBUS);
182 signal(SIGHUP, SIG_IGN);
183 set_handler(SIGIO);
184 /* We (currently) only use the child reaper IRQ in seccomp mode */
185 if (using_seccomp)
186 set_handler(SIGCHLD);
187 signal(SIGWINCH, SIG_IGN);
188}
189
190void os_set_pdeathsig(void)
191{
192 prctl(PR_SET_PDEATHSIG, SIGKILL);
193}
194
195int os_futex_wait(void *uaddr, unsigned int val)
196{
197 int r;
198
199 CATCH_EINTR(r = syscall(__NR_futex, uaddr, FUTEX_WAIT, val,
200 NULL, NULL, 0));
201 return r < 0 ? -errno : r;
202}
203
204int os_futex_wake(void *uaddr)
205{
206 int r;
207
208 CATCH_EINTR(r = syscall(__NR_futex, uaddr, FUTEX_WAKE, INT_MAX,
209 NULL, NULL, 0));
210 return r < 0 ? -errno : r;
211}