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 <linux/limits.h> 12 #include <sys/socket.h> 13 #include <sys/wait.h> 14 #include <kern_util.h> 15 #include <os.h> 16 #include <um_malloc.h> 17 18 struct helper_data { 19 void (*pre_exec)(void*); 20 void *pre_data; 21 char **argv; 22 int fd; 23 char *buf; 24 }; 25 helper_child(void * arg)26 static int helper_child(void *arg) 27 { 28 struct helper_data *data = arg; 29 char **argv = data->argv; 30 int err, ret; 31 32 if (data->pre_exec != NULL) 33 (*data->pre_exec)(data->pre_data); 34 err = execvp_noalloc(data->buf, argv[0], argv); 35 36 /* If the exec succeeds, we don't get here */ 37 CATCH_EINTR(ret = write(data->fd, &err, sizeof(err))); 38 39 return 0; 40 } 41 42 /* Returns either the pid of the child process we run or -E* on failure. */ run_helper(void (* pre_exec)(void *),void * pre_data,char ** argv)43 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) 44 { 45 struct helper_data data; 46 unsigned long stack, sp; 47 int pid, fds[2], ret, n; 48 49 stack = alloc_stack(0, __uml_cant_sleep()); 50 if (stack == 0) 51 return -ENOMEM; 52 53 ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds); 54 if (ret < 0) { 55 ret = -errno; 56 printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n", 57 errno); 58 goto out_free; 59 } 60 61 ret = os_set_exec_close(fds[1]); 62 if (ret < 0) { 63 printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, " 64 "ret = %d\n", -ret); 65 goto out_close; 66 } 67 68 sp = stack + UM_KERN_PAGE_SIZE; 69 data.pre_exec = pre_exec; 70 data.pre_data = pre_data; 71 data.argv = argv; 72 data.fd = fds[1]; 73 data.buf = __uml_cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) : 74 uml_kmalloc(PATH_MAX, UM_GFP_KERNEL); 75 pid = clone(helper_child, (void *) sp, CLONE_VM, &data); 76 if (pid < 0) { 77 ret = -errno; 78 printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n", 79 errno); 80 goto out_free2; 81 } 82 83 close(fds[1]); 84 fds[1] = -1; 85 86 /* 87 * Read the errno value from the child, if the exec failed, or get 0 if 88 * the exec succeeded because the pipe fd was set as close-on-exec. 89 */ 90 n = read(fds[0], &ret, sizeof(ret)); 91 if (n == 0) { 92 ret = pid; 93 } else { 94 if (n < 0) { 95 n = -errno; 96 printk(UM_KERN_ERR "run_helper : read on pipe failed, " 97 "ret = %d\n", -n); 98 ret = n; 99 } 100 CATCH_EINTR(waitpid(pid, NULL, __WALL)); 101 } 102 103 if (ret < 0) 104 printk(UM_KERN_ERR "run_helper : failed to exec %s on host: %s\n", 105 argv[0], strerror(-ret)); 106 107 out_free2: 108 kfree(data.buf); 109 out_close: 110 if (fds[1] != -1) 111 close(fds[1]); 112 close(fds[0]); 113 out_free: 114 free_stack(stack, 0); 115 return ret; 116 } 117 run_helper_thread(int (* proc)(void *),void * arg,unsigned int flags,unsigned long * stack_out)118 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 119 unsigned long *stack_out) 120 { 121 unsigned long stack, sp; 122 int pid, status, err; 123 124 stack = alloc_stack(0, __uml_cant_sleep()); 125 if (stack == 0) 126 return -ENOMEM; 127 128 sp = stack + UM_KERN_PAGE_SIZE; 129 pid = clone(proc, (void *) sp, flags, arg); 130 if (pid < 0) { 131 err = -errno; 132 printk(UM_KERN_ERR "run_helper_thread : clone failed, " 133 "errno = %d\n", errno); 134 return err; 135 } 136 if (stack_out == NULL) { 137 CATCH_EINTR(pid = waitpid(pid, &status, __WALL)); 138 if (pid < 0) { 139 err = -errno; 140 printk(UM_KERN_ERR "run_helper_thread - wait failed, " 141 "errno = %d\n", errno); 142 pid = err; 143 } 144 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) 145 printk(UM_KERN_ERR "run_helper_thread - thread " 146 "returned status 0x%x\n", status); 147 free_stack(stack, 0); 148 } else 149 *stack_out = stack; 150 return pid; 151 } 152 helper_wait(int pid)153 int helper_wait(int pid) 154 { 155 int ret, status; 156 int wflags = __WALL; 157 158 CATCH_EINTR(ret = waitpid(pid, &status, wflags)); 159 if (ret < 0) { 160 printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, " 161 "errno = %d\n", pid, errno); 162 return -errno; 163 } else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { 164 printk(UM_KERN_ERR "helper_wait : process %d exited with " 165 "status 0x%x\n", pid, status); 166 return -ECHILD; 167 } else 168 return 0; 169 } 170