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 | 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. */ |
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 | |
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 | |
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 | |