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
helper_child(void * arg)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. */
run_helper(void (* pre_exec)(void *),void * pre_data,char ** argv)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
run_helper_thread(int (* proc)(void *),void * arg,unsigned int flags,unsigned long * stack_out)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
helper_wait(int pid)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