1 /* 2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 */ 5 6 #include <stdlib.h> 7 #include <unistd.h> 8 #include <errno.h> 9 #include <sched.h> 10 #include <linux/limits.h> 11 #include <sys/socket.h> 12 #include <sys/wait.h> 13 #include "kern_constants.h" 14 #include "kern_util.h" 15 #include "os.h" 16 #include "um_malloc.h" 17 #include "user.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; 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 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, __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 - sizeof(void *); 70 data.pre_exec = pre_exec; 71 data.pre_data = pre_data; 72 data.argv = argv; 73 data.fd = fds[1]; 74 data.buf = __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, __WCLONE)); 102 } 103 104 out_free2: 105 kfree(data.buf); 106 out_close: 107 if (fds[1] != -1) 108 close(fds[1]); 109 close(fds[0]); 110 out_free: 111 free_stack(stack, 0); 112 return ret; 113 } 114 115 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 116 unsigned long *stack_out) 117 { 118 unsigned long stack, sp; 119 int pid, status, err; 120 121 stack = alloc_stack(0, __cant_sleep()); 122 if (stack == 0) 123 return -ENOMEM; 124 125 sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *); 126 pid = clone(proc, (void *) sp, flags, arg); 127 if (pid < 0) { 128 err = -errno; 129 printk(UM_KERN_ERR "run_helper_thread : clone failed, " 130 "errno = %d\n", errno); 131 return err; 132 } 133 if (stack_out == NULL) { 134 CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE)); 135 if (pid < 0) { 136 err = -errno; 137 printk(UM_KERN_ERR "run_helper_thread - wait failed, " 138 "errno = %d\n", errno); 139 pid = err; 140 } 141 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) 142 printk(UM_KERN_ERR "run_helper_thread - thread " 143 "returned status 0x%x\n", status); 144 free_stack(stack, 0); 145 } else 146 *stack_out = stack; 147 return pid; 148 } 149 150 int helper_wait(int pid) 151 { 152 int ret, status; 153 int wflags = __WCLONE; 154 155 CATCH_EINTR(ret = waitpid(pid, &status, wflags)); 156 if (ret < 0) { 157 printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, " 158 "errno = %d\n", pid, errno); 159 return -errno; 160 } else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { 161 printk(UM_KERN_ERR "helper_wait : process %d exited with " 162 "status 0x%x\n", pid, status); 163 return -ECHILD; 164 } else 165 return 0; 166 } 167