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-rw-r--r--kernel/kmod.c510
1 files changed, 510 insertions, 0 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c
new file mode 100644
index 0000000..3d3c3ea
--- /dev/null
+++ b/kernel/kmod.c
@@ -0,0 +1,510 @@
+/*
+ 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
+*/
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/unistd.h>
+#include <linux/kmod.h>
+#include <linux/slab.h>
+#include <linux/mnt_namespace.h>
+#include <linux/completion.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/workqueue.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/resource.h>
+#include <linux/notifier.h>
+#include <linux/suspend.h>
+#include <asm/uaccess.h>
+
+extern int max_threads;
+
+static struct workqueue_struct *khelper_wq;
+
+#ifdef CONFIG_MODULES
+
+/*
+ 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_MODULES */
+
+struct subprocess_info {
+ struct work_struct work;
+ struct completion *complete;
+ char *path;
+ char **argv;
+ char **envp;
+ struct key *ring;
+ enum umh_wait wait;
+ int retval;
+ struct file *stdin;
+ void (*cleanup)(char **argv, char **envp);
+};
+
+/*
+ * This is the task which runs the usermode application
+ */
+static int ____call_usermodehelper(void *data)
+{
+ struct subprocess_info *sub_info = data;
+ struct key *new_session, *old_session;
+ int retval;
+
+ /* Unblock all signals and set the session keyring. */
+ new_session = key_get(sub_info->ring);
+ spin_lock_irq(&current->sighand->siglock);
+ old_session = __install_session_keyring(current, new_session);
+ flush_signal_handlers(current, 1);
+ sigemptyset(&current->blocked);
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+
+ key_put(old_session);
+
+ /* Install input pipe when needed */
+ if (sub_info->stdin) {
+ struct files_struct *f = current->files;
+ struct fdtable *fdt;
+ /* no races because files should be private here */
+ sys_close(0);
+ fd_install(0, sub_info->stdin);
+ spin_lock(&f->file_lock);
+ fdt = files_fdtable(f);
+ FD_SET(0, fdt->open_fds);
+ FD_CLR(0, fdt->close_on_exec);
+ spin_unlock(&f->file_lock);
+
+ /* and disallow core files too */
+ current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
+ }
+
+ /* We can run anywhere, unlike our parent keventd(). */
+ set_cpus_allowed_ptr(current, CPU_MASK_ALL_PTR);
+
+ /*
+ * Our parent is keventd, which runs with elevated scheduling priority.
+ * Avoid propagating that into the userspace child.
+ */
+ set_user_nice(current, 0);
+
+ retval = kernel_execve(sub_info->path, sub_info->argv, sub_info->envp);
+
+ /* Exec failed? */
+ sub_info->retval = retval;
+ do_exit(0);
+}
+
+void call_usermodehelper_freeinfo(struct subprocess_info *info)
+{
+ if (info->cleanup)
+ (*info->cleanup)(info->argv, info->envp);
+ kfree(info);
+}
+EXPORT_SYMBOL(call_usermodehelper_freeinfo);
+
+/* 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;
+
+ /* Install a handler: if SIGCLD isn't handled sys_wait4 won't
+ * populate the status, but will return -ECHILD. */
+ allow_signal(SIGCHLD);
+
+ pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
+ if (pid < 0) {
+ sub_info->retval = pid;
+ } else {
+ int ret;
+
+ /*
+ * 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 *)&ret, 0, NULL);
+
+ /*
+ * If ret is 0, either ____call_usermodehelper failed and the
+ * real error code is already in sub_info->retval or
+ * sub_info->retval is 0 anyway, so don't mess with it then.
+ */
+ if (ret)
+ sub_info->retval = ret;
+ }
+
+ if (sub_info->wait == UMH_NO_WAIT)
+ call_usermodehelper_freeinfo(sub_info);
+ else
+ complete(sub_info->complete);
+ return 0;
+}
+
+/* This is run by khelper thread */
+static void __call_usermodehelper(struct work_struct *work)
+{
+ struct subprocess_info *sub_info =
+ container_of(work, struct subprocess_info, work);
+ pid_t pid;
+ enum umh_wait wait = sub_info->wait;
+
+ /* CLONE_VFORK: wait until the usermode helper has execve'd
+ * successfully We need the data structures to stay around
+ * until that is done. */
+ if (wait == UMH_WAIT_PROC || wait == UMH_NO_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);
+
+ switch (wait) {
+ case UMH_NO_WAIT:
+ break;
+
+ case UMH_WAIT_PROC:
+ if (pid > 0)
+ break;
+ sub_info->retval = pid;
+ /* FALLTHROUGH */
+
+ case UMH_WAIT_EXEC:
+ complete(sub_info->complete);
+ }
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
+ * (used for preventing user land processes from being created after the user
+ * land has been frozen during a system-wide hibernation or suspend operation).
+ */
+static int usermodehelper_disabled;
+
+/* Number of helpers running */
+static atomic_t running_helpers = ATOMIC_INIT(0);
+
+/*
+ * Wait queue head used by usermodehelper_pm_callback() to wait for all running
+ * helpers to finish.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
+
+/*
+ * Time to wait for running_helpers to become zero before the setting of
+ * usermodehelper_disabled in usermodehelper_pm_callback() fails
+ */
+#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
+
+/**
+ * usermodehelper_disable - prevent new helpers from being started
+ */
+int usermodehelper_disable(void)
+{
+ long retval;
+
+ usermodehelper_disabled = 1;
+ smp_mb();
+ /*
+ * From now on call_usermodehelper_exec() won't start any new
+ * helpers, so it is sufficient if running_helpers turns out to
+ * be zero at one point (it may be increased later, but that
+ * doesn't matter).
+ */
+ retval = wait_event_timeout(running_helpers_waitq,
+ atomic_read(&running_helpers) == 0,
+ RUNNING_HELPERS_TIMEOUT);
+ if (retval)
+ return 0;
+
+ usermodehelper_disabled = 0;
+ return -EAGAIN;
+}
+
+/**
+ * usermodehelper_enable - allow new helpers to be started again
+ */
+void usermodehelper_enable(void)
+{
+ usermodehelper_disabled = 0;
+}
+
+static void helper_lock(void)
+{
+ atomic_inc(&running_helpers);
+ smp_mb__after_atomic_inc();
+}
+
+static void helper_unlock(void)
+{
+ if (atomic_dec_and_test(&running_helpers))
+ wake_up(&running_helpers_waitq);
+}
+#else /* CONFIG_PM_SLEEP */
+#define usermodehelper_disabled 0
+
+static inline void helper_lock(void) {}
+static inline void helper_unlock(void) {}
+#endif /* CONFIG_PM_SLEEP */
+
+/**
+ * call_usermodehelper_setup - prepare to call a usermode helper
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ * @gfp_mask: gfp mask for memory allocation
+ *
+ * Returns either %NULL on allocation failure, or a subprocess_info
+ * structure. This should be passed to call_usermodehelper_exec to
+ * exec the process and free the structure.
+ */
+struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+ char **envp, gfp_t gfp_mask)
+{
+ struct subprocess_info *sub_info;
+ sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
+ if (!sub_info)
+ goto out;
+
+ INIT_WORK(&sub_info->work, __call_usermodehelper);
+ sub_info->path = path;
+ sub_info->argv = argv;
+ sub_info->envp = envp;
+
+ out:
+ return sub_info;
+}
+EXPORT_SYMBOL(call_usermodehelper_setup);
+
+/**
+ * call_usermodehelper_setkeys - set the session keys for usermode helper
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @session_keyring: the session keyring for the process
+ */
+void call_usermodehelper_setkeys(struct subprocess_info *info,
+ struct key *session_keyring)
+{
+ info->ring = session_keyring;
+}
+EXPORT_SYMBOL(call_usermodehelper_setkeys);
+
+/**
+ * call_usermodehelper_setcleanup - set a cleanup function
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @cleanup: a cleanup function
+ *
+ * The cleanup function is just befor ethe subprocess_info is about to
+ * be freed. This can be used for freeing the argv and envp. The
+ * Function must be runnable in either a process context or the
+ * context in which call_usermodehelper_exec is called.
+ */
+void call_usermodehelper_setcleanup(struct subprocess_info *info,
+ void (*cleanup)(char **argv, char **envp))
+{
+ info->cleanup = cleanup;
+}
+EXPORT_SYMBOL(call_usermodehelper_setcleanup);
+
+/**
+ * call_usermodehelper_stdinpipe - set up a pipe to be used for stdin
+ * @sub_info: a subprocess_info returned by call_usermodehelper_setup
+ * @filp: set to the write-end of a pipe
+ *
+ * This constructs a pipe, and sets the read end to be the stdin of the
+ * subprocess, and returns the write-end in *@filp.
+ */
+int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
+ struct file **filp)
+{
+ struct file *f;
+
+ f = create_write_pipe(0);
+ if (IS_ERR(f))
+ return PTR_ERR(f);
+ *filp = f;
+
+ f = create_read_pipe(f, 0);
+ if (IS_ERR(f)) {
+ free_write_pipe(*filp);
+ return PTR_ERR(f);
+ }
+ sub_info->stdin = f;
+
+ return 0;
+}
+EXPORT_SYMBOL(call_usermodehelper_stdinpipe);
+
+/**
+ * call_usermodehelper_exec - start a usermode application
+ * @sub_info: information about the subprocessa
+ * @wait: wait for the application to finish and return status.
+ * when -1 don't wait at all, but you get no useful error back when
+ * the program couldn't be exec'ed. This makes it safe to call
+ * from interrupt context.
+ *
+ * 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).
+ */
+int call_usermodehelper_exec(struct subprocess_info *sub_info,
+ enum umh_wait wait)
+{
+ DECLARE_COMPLETION_ONSTACK(done);
+ int retval = 0;
+
+ helper_lock();
+ if (sub_info->path[0] == '\0')
+ goto out;
+
+ if (!khelper_wq || usermodehelper_disabled) {
+ retval = -EBUSY;
+ goto out;
+ }
+
+ sub_info->complete = &done;
+ sub_info->wait = wait;
+
+ queue_work(khelper_wq, &sub_info->work);
+ if (wait == UMH_NO_WAIT) /* task has freed sub_info */
+ goto unlock;
+ wait_for_completion(&done);
+ retval = sub_info->retval;
+
+out:
+ call_usermodehelper_freeinfo(sub_info);
+unlock:
+ helper_unlock();
+ return retval;
+}
+EXPORT_SYMBOL(call_usermodehelper_exec);
+
+/**
+ * call_usermodehelper_pipe - call a usermode helper process with a pipe stdin
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ * @filp: set to the write-end of a pipe
+ *
+ * This is a simple wrapper which executes a usermode-helper function
+ * with a pipe as stdin. It is implemented entirely in terms of
+ * lower-level call_usermodehelper_* functions.
+ */
+int call_usermodehelper_pipe(char *path, char **argv, char **envp,
+ struct file **filp)
+{
+ struct subprocess_info *sub_info;
+ int ret;
+
+ sub_info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL);
+ if (sub_info == NULL)
+ return -ENOMEM;
+
+ ret = call_usermodehelper_stdinpipe(sub_info, filp);
+ if (ret < 0)
+ goto out;
+
+ return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
+
+ out:
+ call_usermodehelper_freeinfo(sub_info);
+ return ret;
+}
+EXPORT_SYMBOL(call_usermodehelper_pipe);
+
+void __init usermodehelper_init(void)
+{
+ khelper_wq = create_singlethread_workqueue("khelper");
+ BUG_ON(!khelper_wq);
+}
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