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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /kernel/kmod.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'kernel/kmod.c')
-rw-r--r--kernel/kmod.c256
1 files changed, 256 insertions, 0 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c
new file mode 100644
index 000000000000..eed53d4f5230
--- /dev/null
+++ b/kernel/kmod.c
@@ -0,0 +1,256 @@
1/*
2 kmod, the new module loader (replaces kerneld)
3 Kirk Petersen
4
5 Reorganized not to be a daemon by Adam Richter, with guidance
6 from Greg Zornetzer.
7
8 Modified to avoid chroot and file sharing problems.
9 Mikael Pettersson
10
11 Limit the concurrent number of kmod modprobes to catch loops from
12 "modprobe needs a service that is in a module".
13 Keith Owens <kaos@ocs.com.au> December 1999
14
15 Unblock all signals when we exec a usermode process.
16 Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000
17
18 call_usermodehelper wait flag, and remove exec_usermodehelper.
19 Rusty Russell <rusty@rustcorp.com.au> Jan 2003
20*/
21#define __KERNEL_SYSCALLS__
22
23#include <linux/config.h>
24#include <linux/module.h>
25#include <linux/sched.h>
26#include <linux/syscalls.h>
27#include <linux/unistd.h>
28#include <linux/kmod.h>
29#include <linux/smp_lock.h>
30#include <linux/slab.h>
31#include <linux/namespace.h>
32#include <linux/completion.h>
33#include <linux/file.h>
34#include <linux/workqueue.h>
35#include <linux/security.h>
36#include <linux/mount.h>
37#include <linux/kernel.h>
38#include <linux/init.h>
39#include <asm/uaccess.h>
40
41extern int max_threads;
42
43static struct workqueue_struct *khelper_wq;
44
45#ifdef CONFIG_KMOD
46
47/*
48 modprobe_path is set via /proc/sys.
49*/
50char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
51
52/**
53 * request_module - try to load a kernel module
54 * @fmt: printf style format string for the name of the module
55 * @varargs: arguements as specified in the format string
56 *
57 * Load a module using the user mode module loader. The function returns
58 * zero on success or a negative errno code on failure. Note that a
59 * successful module load does not mean the module did not then unload
60 * and exit on an error of its own. Callers must check that the service
61 * they requested is now available not blindly invoke it.
62 *
63 * If module auto-loading support is disabled then this function
64 * becomes a no-operation.
65 */
66int request_module(const char *fmt, ...)
67{
68 va_list args;
69 char module_name[MODULE_NAME_LEN];
70 unsigned int max_modprobes;
71 int ret;
72 char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
73 static char *envp[] = { "HOME=/",
74 "TERM=linux",
75 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
76 NULL };
77 static atomic_t kmod_concurrent = ATOMIC_INIT(0);
78#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
79 static int kmod_loop_msg;
80
81 va_start(args, fmt);
82 ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
83 va_end(args);
84 if (ret >= MODULE_NAME_LEN)
85 return -ENAMETOOLONG;
86
87 /* If modprobe needs a service that is in a module, we get a recursive
88 * loop. Limit the number of running kmod threads to max_threads/2 or
89 * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
90 * would be to run the parents of this process, counting how many times
91 * kmod was invoked. That would mean accessing the internals of the
92 * process tables to get the command line, proc_pid_cmdline is static
93 * and it is not worth changing the proc code just to handle this case.
94 * KAO.
95 *
96 * "trace the ppid" is simple, but will fail if someone's
97 * parent exits. I think this is as good as it gets. --RR
98 */
99 max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
100 atomic_inc(&kmod_concurrent);
101 if (atomic_read(&kmod_concurrent) > max_modprobes) {
102 /* We may be blaming an innocent here, but unlikely */
103 if (kmod_loop_msg++ < 5)
104 printk(KERN_ERR
105 "request_module: runaway loop modprobe %s\n",
106 module_name);
107 atomic_dec(&kmod_concurrent);
108 return -ENOMEM;
109 }
110
111 ret = call_usermodehelper(modprobe_path, argv, envp, 1);
112 atomic_dec(&kmod_concurrent);
113 return ret;
114}
115EXPORT_SYMBOL(request_module);
116#endif /* CONFIG_KMOD */
117
118struct subprocess_info {
119 struct completion *complete;
120 char *path;
121 char **argv;
122 char **envp;
123 int wait;
124 int retval;
125};
126
127/*
128 * This is the task which runs the usermode application
129 */
130static int ____call_usermodehelper(void *data)
131{
132 struct subprocess_info *sub_info = data;
133 int retval;
134
135 /* Unblock all signals. */
136 flush_signals(current);
137 spin_lock_irq(&current->sighand->siglock);
138 flush_signal_handlers(current, 1);
139 sigemptyset(&current->blocked);
140 recalc_sigpending();
141 spin_unlock_irq(&current->sighand->siglock);
142
143 /* We can run anywhere, unlike our parent keventd(). */
144 set_cpus_allowed(current, CPU_MASK_ALL);
145
146 retval = -EPERM;
147 if (current->fs->root)
148 retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
149
150 /* Exec failed? */
151 sub_info->retval = retval;
152 do_exit(0);
153}
154
155/* Keventd can't block, but this (a child) can. */
156static int wait_for_helper(void *data)
157{
158 struct subprocess_info *sub_info = data;
159 pid_t pid;
160 struct k_sigaction sa;
161
162 /* Install a handler: if SIGCLD isn't handled sys_wait4 won't
163 * populate the status, but will return -ECHILD. */
164 sa.sa.sa_handler = SIG_IGN;
165 sa.sa.sa_flags = 0;
166 siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
167 do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
168 allow_signal(SIGCHLD);
169
170 pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
171 if (pid < 0) {
172 sub_info->retval = pid;
173 } else {
174 /*
175 * Normally it is bogus to call wait4() from in-kernel because
176 * wait4() wants to write the exit code to a userspace address.
177 * But wait_for_helper() always runs as keventd, and put_user()
178 * to a kernel address works OK for kernel threads, due to their
179 * having an mm_segment_t which spans the entire address space.
180 *
181 * Thus the __user pointer cast is valid here.
182 */
183 sys_wait4(pid, (int __user *) &sub_info->retval, 0, NULL);
184 }
185
186 complete(sub_info->complete);
187 return 0;
188}
189
190/* This is run by khelper thread */
191static void __call_usermodehelper(void *data)
192{
193 struct subprocess_info *sub_info = data;
194 pid_t pid;
195
196 /* CLONE_VFORK: wait until the usermode helper has execve'd
197 * successfully We need the data structures to stay around
198 * until that is done. */
199 if (sub_info->wait)
200 pid = kernel_thread(wait_for_helper, sub_info,
201 CLONE_FS | CLONE_FILES | SIGCHLD);
202 else
203 pid = kernel_thread(____call_usermodehelper, sub_info,
204 CLONE_VFORK | SIGCHLD);
205
206 if (pid < 0) {
207 sub_info->retval = pid;
208 complete(sub_info->complete);
209 } else if (!sub_info->wait)
210 complete(sub_info->complete);
211}
212
213/**
214 * call_usermodehelper - start a usermode application
215 * @path: pathname for the application
216 * @argv: null-terminated argument list
217 * @envp: null-terminated environment list
218 * @wait: wait for the application to finish and return status.
219 *
220 * Runs a user-space application. The application is started
221 * asynchronously if wait is not set, and runs as a child of keventd.
222 * (ie. it runs with full root capabilities).
223 *
224 * Must be called from process context. Returns a negative error code
225 * if program was not execed successfully, or 0.
226 */
227int call_usermodehelper(char *path, char **argv, char **envp, int wait)
228{
229 DECLARE_COMPLETION(done);
230 struct subprocess_info sub_info = {
231 .complete = &done,
232 .path = path,
233 .argv = argv,
234 .envp = envp,
235 .wait = wait,
236 .retval = 0,
237 };
238 DECLARE_WORK(work, __call_usermodehelper, &sub_info);
239
240 if (!khelper_wq)
241 return -EBUSY;
242
243 if (path[0] == '\0')
244 return 0;
245
246 queue_work(khelper_wq, &work);
247 wait_for_completion(&done);
248 return sub_info.retval;
249}
250EXPORT_SYMBOL(call_usermodehelper);
251
252void __init usermodehelper_init(void)
253{
254 khelper_wq = create_singlethread_workqueue("khelper");
255 BUG_ON(!khelper_wq);
256}