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