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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
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 @@
+/*
+ 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);
+}

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