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