1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 4 */ 5 6 #include <stdlib.h> 7 #include <string.h> 8 #include <unistd.h> 9 #include <errno.h> 10 #include <sched.h> 11 #include <pthread.h> 12 #include <linux/limits.h> 13 #include <sys/socket.h> 14 #include <sys/wait.h> 15 #include <kern_util.h> 16 #include <os.h> 17 #include <um_malloc.h> 18 19 struct helper_data { 20 void (*pre_exec)(void*); 21 void *pre_data; 22 char **argv; 23 int fd; 24 char *buf; 25 }; 26 27 static int helper_child(void *arg) 28 { 29 struct helper_data *data = arg; 30 char **argv = data->argv; 31 int err, ret; 32 33 if (data->pre_exec != NULL) 34 (*data->pre_exec)(data->pre_data); 35 err = execvp_noalloc(data->buf, argv[0], argv); 36 37 /* If the exec succeeds, we don't get here */ 38 CATCH_EINTR(ret = write(data->fd, &err, sizeof(err))); 39 40 return 0; 41 } 42 43 /* Returns either the pid of the child process we run or -E* on failure. */ 44 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) 45 { 46 struct helper_data data; 47 unsigned long stack, sp; 48 int pid, fds[2], ret, n; 49 50 stack = alloc_stack(0, __uml_cant_sleep()); 51 if (stack == 0) 52 return -ENOMEM; 53 54 ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds); 55 if (ret < 0) { 56 ret = -errno; 57 printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n", 58 errno); 59 goto out_free; 60 } 61 62 ret = os_set_exec_close(fds[1]); 63 if (ret < 0) { 64 printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, " 65 "ret = %d\n", -ret); 66 goto out_close; 67 } 68 69 sp = stack + UM_KERN_PAGE_SIZE; 70 data.pre_exec = pre_exec; 71 data.pre_data = pre_data; 72 data.argv = argv; 73 data.fd = fds[1]; 74 data.buf = __uml_cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) : 75 uml_kmalloc(PATH_MAX, UM_GFP_KERNEL); 76 pid = clone(helper_child, (void *) sp, CLONE_VM, &data); 77 if (pid < 0) { 78 ret = -errno; 79 printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n", 80 errno); 81 goto out_free2; 82 } 83 84 close(fds[1]); 85 fds[1] = -1; 86 87 /* 88 * Read the errno value from the child, if the exec failed, or get 0 if 89 * the exec succeeded because the pipe fd was set as close-on-exec. 90 */ 91 n = read(fds[0], &ret, sizeof(ret)); 92 if (n == 0) { 93 ret = pid; 94 } else { 95 if (n < 0) { 96 n = -errno; 97 printk(UM_KERN_ERR "run_helper : read on pipe failed, " 98 "ret = %d\n", -n); 99 ret = n; 100 } 101 CATCH_EINTR(waitpid(pid, NULL, __WALL)); 102 } 103 104 if (ret < 0) 105 printk(UM_KERN_ERR "run_helper : failed to exec %s on host: %s\n", 106 argv[0], strerror(-ret)); 107 108 out_free2: 109 kfree(data.buf); 110 out_close: 111 if (fds[1] != -1) 112 close(fds[1]); 113 close(fds[0]); 114 out_free: 115 free_stack(stack, 0); 116 return ret; 117 } 118 119 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 120 unsigned long *stack_out) 121 { 122 unsigned long stack, sp; 123 int pid, status, err; 124 125 /* To share memory space, use os_run_helper_thread() instead. */ 126 if (flags & CLONE_VM) 127 return -EINVAL; 128 129 stack = alloc_stack(0, __uml_cant_sleep()); 130 if (stack == 0) 131 return -ENOMEM; 132 133 sp = stack + UM_KERN_PAGE_SIZE; 134 pid = clone(proc, (void *) sp, flags, arg); 135 if (pid < 0) { 136 err = -errno; 137 printk(UM_KERN_ERR "run_helper_thread : clone failed, " 138 "errno = %d\n", errno); 139 return err; 140 } 141 if (stack_out == NULL) { 142 CATCH_EINTR(pid = waitpid(pid, &status, __WALL)); 143 if (pid < 0) { 144 err = -errno; 145 printk(UM_KERN_ERR "run_helper_thread - wait failed, " 146 "errno = %d\n", errno); 147 pid = err; 148 } 149 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) 150 printk(UM_KERN_ERR "run_helper_thread - thread " 151 "returned status 0x%x\n", status); 152 free_stack(stack, 0); 153 } else 154 *stack_out = stack; 155 return pid; 156 } 157 158 int helper_wait(int pid) 159 { 160 int ret, status; 161 int wflags = __WALL; 162 163 CATCH_EINTR(ret = waitpid(pid, &status, wflags)); 164 if (ret < 0) { 165 printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, " 166 "errno = %d\n", pid, errno); 167 return -errno; 168 } else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { 169 printk(UM_KERN_ERR "helper_wait : process %d exited with " 170 "status 0x%x\n", pid, status); 171 return -ECHILD; 172 } else 173 return 0; 174 } 175 176 struct os_helper_thread { 177 pthread_t handle; 178 }; 179 180 int os_run_helper_thread(struct os_helper_thread **td_out, 181 void *(*routine)(void *), void *arg) 182 { 183 struct os_helper_thread *td; 184 sigset_t sigset, oset; 185 int err, flags; 186 187 flags = __uml_cant_sleep() ? UM_GFP_ATOMIC : UM_GFP_KERNEL; 188 td = uml_kmalloc(sizeof(*td), flags); 189 if (!td) 190 return -ENOMEM; 191 192 sigfillset(&sigset); 193 if (sigprocmask(SIG_SETMASK, &sigset, &oset) < 0) { 194 err = -errno; 195 kfree(td); 196 return err; 197 } 198 199 err = pthread_create(&td->handle, NULL, routine, arg); 200 201 if (sigprocmask(SIG_SETMASK, &oset, NULL) < 0) 202 panic("Failed to restore the signal mask: %d", errno); 203 204 if (err != 0) 205 kfree(td); 206 else 207 *td_out = td; 208 209 return -err; 210 } 211 212 void os_kill_helper_thread(struct os_helper_thread *td) 213 { 214 pthread_cancel(td->handle); 215 pthread_join(td->handle, NULL); 216 kfree(td); 217 } 218 219 void os_fix_helper_thread_signals(void) 220 { 221 sigset_t sigset; 222 223 sigemptyset(&sigset); 224 225 sigaddset(&sigset, SIGWINCH); 226 sigaddset(&sigset, SIGPIPE); 227 sigaddset(&sigset, SIGPROF); 228 sigaddset(&sigset, SIGINT); 229 sigaddset(&sigset, SIGTERM); 230 sigaddset(&sigset, SIGCHLD); 231 sigaddset(&sigset, SIGALRM); 232 sigaddset(&sigset, SIGIO); 233 sigaddset(&sigset, SIGUSR1); 234 235 pthread_sigmask(SIG_SETMASK, &sigset, NULL); 236 } 237