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 @@
+/*
+        kmod, the new module loader (replaces kerneld)
+        Kirk Petersen
+        Reorganized not to be a daemon by Adam Richter, with guidance
+        from Greg Zornetzer.
+        Modified to avoid chroot and file sharing problems.
+        Mikael Pettersson
+        Limit the concurrent number of kmod modprobes to catch loops from
+        "modprobe needs a service that is in a module".
+        Keith Owens <kaos@ocs.com.au> December 1999
+        Unblock all signals when we exec a usermode process.
+        Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000
+        call_usermodehelper wait flag, and remove exec_usermodehelper.
+        Rusty Russell <rusty@rustcorp.com.au>  Jan 2003
+*/
+#define __KERNEL_SYSCALLS__
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/unistd.h>
+#include <linux/kmod.h>
+#include <linux/smp_lock.h>
+#include <linux/slab.h>
+#include <linux/namespace.h>
+#include <linux/completion.h>
+#include <linux/file.h>
+#include <linux/workqueue.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+extern int max_threads;
+static struct workqueue_struct *khelper_wq;
+#ifdef CONFIG_KMOD
+/*
+        modprobe_path is set via /proc/sys.
+*/
+char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
+/**
+ * request_module - try to load a kernel module
+ * @fmt:     printf style format string for the name of the module
+ * @varargs: arguements as specified in the format string
+ *
+ * Load a module using the user mode module loader. The function returns
+ * zero on success or a negative errno code on failure. Note that a
+ * successful module load does not mean the module did not then unload
+ * and exit on an error of its own. Callers must check that the service
+ * they requested is now available not blindly invoke it.
+ *
+ * If module auto-loading support is disabled then this function
+ * becomes a no-operation.
+ */
+int request_module(const char *fmt, ...)
+{
+        va_list args;
+        char module_name[MODULE_NAME_LEN];
+        unsigned int max_modprobes;
+        int ret;
+        char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
+        static char *envp[] = { "HOME=/",
+                                "TERM=linux",
+                                "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+                                NULL };
+        static atomic_t kmod_concurrent = ATOMIC_INIT(0);
+#define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
+        static int kmod_loop_msg;
+        va_start(args, fmt);
+        ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
+        va_end(args);
+        if (ret >= MODULE_NAME_LEN)
+                return -ENAMETOOLONG;
+        /* If modprobe needs a service that is in a module, we get a recursive
+         * loop.  Limit the number of running kmod threads to max_threads/2 or
+         * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
+         * would be to run the parents of this process, counting how many times
+         * kmod was invoked.  That would mean accessing the internals of the
+         * process tables to get the command line, proc_pid_cmdline is static
+         * and it is not worth changing the proc code just to handle this case. 
+         * KAO.
+         *
+         * "trace the ppid" is simple, but will fail if someone's
+         * parent exits.  I think this is as good as it gets. --RR
+         */
+        max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
+        atomic_inc(&kmod_concurrent);
+        if (atomic_read(&kmod_concurrent) > max_modprobes) {
+                /* We may be blaming an innocent here, but unlikely */
+                if (kmod_loop_msg++ < 5)
+                        printk(KERN_ERR
+                               "request_module: runaway loop modprobe %s\n",
+                               module_name);
+                atomic_dec(&kmod_concurrent);
+                return -ENOMEM;
+        }
+        ret = call_usermodehelper(modprobe_path, argv, envp, 1);
+        atomic_dec(&kmod_concurrent);
+        return ret;
+}
+EXPORT_SYMBOL(request_module);
+#endif /* CONFIG_KMOD */
+struct subprocess_info {
+        struct completion *complete;
+        char *path;
+        char **argv;
+        char **envp;
+        int wait;
+        int retval;
+};
+/*
+ * This is the task which runs the usermode application
+ */
+static int ____call_usermodehelper(void *data)
+{
+        struct subprocess_info *sub_info = data;
+        int retval;
+        /* Unblock all signals. */
+        flush_signals(current);
+        spin_lock_irq(&current->sighand->siglock);
+        flush_signal_handlers(current, 1);
+        sigemptyset(&current->blocked);
+        recalc_sigpending();
+        spin_unlock_irq(&current->sighand->siglock);
+        /* We can run anywhere, unlike our parent keventd(). */
+        set_cpus_allowed(current, CPU_MASK_ALL);
+        retval = -EPERM;
+        if (current->fs->root)
+                retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
+        /* Exec failed? */
+        sub_info->retval = retval;
+        do_exit(0);
+}
+/* Keventd can't block, but this (a child) can. */
+static int wait_for_helper(void *data)
+{
+        struct subprocess_info *sub_info = data;
+        pid_t pid;
+        struct k_sigaction sa;
+        /* Install a handler: if SIGCLD isn't handled sys_wait4 won't
+         * populate the status, but will return -ECHILD. */
+        sa.sa.sa_handler = SIG_IGN;
+        sa.sa.sa_flags = 0;
+        siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
+        do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
+        allow_signal(SIGCHLD);
+        pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
+        if (pid < 0) {
+                sub_info->retval = pid;
+        } else {
+                /*
+                 * Normally it is bogus to call wait4() from in-kernel because
+                 * wait4() wants to write the exit code to a userspace address.
+                 * But wait_for_helper() always runs as keventd, and put_user()
+                 * to a kernel address works OK for kernel threads, due to their
+                 * having an mm_segment_t which spans the entire address space.
+                 *
+                 * Thus the __user pointer cast is valid here.
+                 */
+                sys_wait4(pid, (int __user *) &sub_info->retval, 0, NULL);
+        }
+        complete(sub_info->complete);
+        return 0;
+}
+/* This is run by khelper thread  */
+static void __call_usermodehelper(void *data)
+{
+        struct subprocess_info *sub_info = data;
+        pid_t pid;
+        /* CLONE_VFORK: wait until the usermode helper has execve'd
+         * successfully We need the data structures to stay around
+         * until that is done.  */
+        if (sub_info->wait)
+                pid = kernel_thread(wait_for_helper, sub_info,
+                                    CLONE_FS | CLONE_FILES | SIGCHLD);
+        else
+                pid = kernel_thread(____call_usermodehelper, sub_info,
+                                    CLONE_VFORK | SIGCHLD);
+        if (pid < 0) {
+                sub_info->retval = pid;
+                complete(sub_info->complete);
+        } else if (!sub_info->wait)
+                complete(sub_info->complete);
+}
+/**
+ * call_usermodehelper - start a usermode application
+ * @path: pathname for the application
+ * @argv: null-terminated argument list
+ * @envp: null-terminated environment list
+ * @wait: wait for the application to finish and return status.
+ *
+ * Runs a user-space application.  The application is started
+ * asynchronously if wait is not set, and runs as a child of keventd.
+ * (ie. it runs with full root capabilities).
+ *
+ * Must be called from process context.  Returns a negative error code
+ * if program was not execed successfully, or 0.
+ */
+int call_usermodehelper(char *path, char **argv, char **envp, int wait)
+{
+        DECLARE_COMPLETION(done);
+        struct subprocess_info sub_info = {
+                .complete       = &done,
+                .path           = path,
+                .argv           = argv,
+                .envp           = envp,
+                .wait           = wait,
+                .retval         = 0,
+        };
+        DECLARE_WORK(work, __call_usermodehelper, &sub_info);
+        if (!khelper_wq)
+                return -EBUSY;
+        if (path[0] == '\0')
+                return 0;
+        queue_work(khelper_wq, &work);
+        wait_for_completion(&done);
+        return sub_info.retval;
+}
+EXPORT_SYMBOL(call_usermodehelper);
+void __init usermodehelper_init(void)
+{
+        khelper_wq = create_singlethread_workqueue("khelper");
+        BUG_ON(!khelper_wq);
+}

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
	41	extern int max_threads;
	42
	43	static struct workqueue_struct *khelper_wq;
	44
	45	#ifdef CONFIG_KMOD
	46
	47	/*
	48	modprobe_path is set via /proc/sys.
	49	*/
	50	char 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	*/
	66	int 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	}
	115	EXPORT_SYMBOL(request_module);
	116	#endif /* CONFIG_KMOD */
	117
	118	struct 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	*/
	130	static 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. */
	156	static 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 */
	191	static 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	*/
	227	int 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	}
	250	EXPORT_SYMBOL(call_usermodehelper);
	251
	252	void __init usermodehelper_init(void)
	253	{
	254	khelper_wq = create_singlethread_workqueue("khelper");
	255	BUG_ON(!khelper_wq);
	256	}