#include <linux/resource.h>
#include <linux/notifier.h>
#include <linux/suspend.h>
+#include <linux/rwsem.h>
+#include <linux/ptrace.h>
+#include <linux/async.h>
#include <asm/uaccess.h>
#include <trace/events/module.h>
static struct workqueue_struct *khelper_wq;
+/*
+ * kmod_thread_locker is used for deadlock avoidance. There is no explicit
+ * locking to protect this global - it is private to the singleton khelper
+ * thread and should only ever be modified by that thread.
+ */
+static const struct task_struct *kmod_thread_locker;
+
#define CAP_BSET (void *)1
#define CAP_PI (void *)2
static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
static DEFINE_SPINLOCK(umh_sysctl_lock);
+static DECLARE_RWSEM(umhelper_sem);
#ifdef CONFIG_MODULES
*/
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
+static void free_modprobe_argv(struct subprocess_info *info)
+{
+ kfree(info->argv[3]); /* check call_modprobe() */
+ kfree(info->argv);
+}
+
+static int call_modprobe(char *module_name, int wait)
+{
+ struct subprocess_info *info;
+ static char *envp[] = {
+ "HOME=/",
+ "TERM=linux",
+ "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+ NULL
+ };
+
+ char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
+ if (!argv)
+ goto out;
+
+ module_name = kstrdup(module_name, GFP_KERNEL);
+ if (!module_name)
+ goto free_argv;
+
+ argv[0] = modprobe_path;
+ argv[1] = "-q";
+ argv[2] = "--";
+ argv[3] = module_name; /* check free_modprobe_argv() */
+ argv[4] = NULL;
+
+ info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
+ NULL, free_modprobe_argv, NULL);
+ if (!info)
+ goto free_module_name;
+
+ return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
+
+free_module_name:
+ kfree(module_name);
+free_argv:
+ kfree(argv);
+out:
+ return -ENOMEM;
+}
+
/**
* __request_module - try to load a kernel module
* @wait: wait (or not) for the operation to complete
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;
+ /*
+ * We don't allow synchronous module loading from async. Module
+ * init may invoke async_synchronize_full() which will end up
+ * waiting for this task which already is waiting for the module
+ * loading to complete, leading to a deadlock.
+ */
+ WARN_ON_ONCE(wait && current_is_async());
+
va_start(args, fmt);
ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
va_end(args);
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)
+ if (kmod_loop_msg < 5) {
printk(KERN_ERR
"request_module: runaway loop modprobe %s\n",
module_name);
+ kmod_loop_msg++;
+ }
atomic_dec(&kmod_concurrent);
return -ENOMEM;
}
trace_module_request(module_name, wait, _RET_IP_);
- ret = call_usermodehelper_fns(modprobe_path, argv, envp,
- wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC,
- NULL, NULL, NULL);
+ ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
atomic_dec(&kmod_concurrent);
return ret;
commit_creds(new);
- retval = kernel_execve(sub_info->path,
- (const char *const *)sub_info->argv,
- (const char *const *)sub_info->envp);
+ retval = do_execve(sub_info->path,
+ (const char __user *const __user *)sub_info->argv,
+ (const char __user *const __user *)sub_info->envp);
+ if (!retval)
+ return 0;
/* Exec failed? */
fail:
do_exit(0);
}
-void call_usermodehelper_freeinfo(struct subprocess_info *info)
+static int call_helper(void *data)
+{
+ /* Worker thread started blocking khelper thread. */
+ kmod_thread_locker = current;
+ return ____call_usermodehelper(data);
+}
+
+static void call_usermodehelper_freeinfo(struct subprocess_info *info)
{
if (info->cleanup)
(*info->cleanup)(info);
kfree(info);
}
-EXPORT_SYMBOL(call_usermodehelper_freeinfo);
+
+static void umh_complete(struct subprocess_info *sub_info)
+{
+ struct completion *comp = xchg(&sub_info->complete, NULL);
+ /*
+ * See call_usermodehelper_exec(). If xchg() returns NULL
+ * we own sub_info, the UMH_KILLABLE caller has gone away.
+ */
+ if (comp)
+ complete(comp);
+ else
+ call_usermodehelper_freeinfo(sub_info);
+}
/* Keventd can't block, but this (a child) can. */
static int wait_for_helper(void *data)
sub_info->retval = ret;
}
- complete(sub_info->complete);
- return 0;
+ umh_complete(sub_info);
+ do_exit(0);
}
/* This is run by khelper thread */
{
struct subprocess_info *sub_info =
container_of(work, struct subprocess_info, work);
- enum umh_wait wait = sub_info->wait;
+ int wait = sub_info->wait & ~UMH_KILLABLE;
pid_t pid;
/* CLONE_VFORK: wait until the usermode helper has execve'd
if (wait == UMH_WAIT_PROC)
pid = kernel_thread(wait_for_helper, sub_info,
CLONE_FS | CLONE_FILES | SIGCHLD);
- else
- pid = kernel_thread(____call_usermodehelper, sub_info,
+ else {
+ pid = kernel_thread(call_helper, sub_info,
CLONE_VFORK | SIGCHLD);
+ /* Worker thread stopped blocking khelper thread. */
+ kmod_thread_locker = NULL;
+ }
switch (wait) {
case UMH_NO_WAIT:
case UMH_WAIT_EXEC:
if (pid < 0)
sub_info->retval = pid;
- complete(sub_info->complete);
+ umh_complete(sub_info);
}
}
* 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).
+ * Should always be manipulated under umhelper_sem acquired for write.
*/
-static int usermodehelper_disabled;
+static enum umh_disable_depth usermodehelper_disabled = UMH_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
+ * Wait queue head used by usermodehelper_disable() to wait for all running
* helpers to finish.
*/
static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
+/*
+ * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
+ * to become 'false'.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
+
/*
* Time to wait for running_helpers to become zero before the setting of
- * usermodehelper_disabled in usermodehelper_pm_callback() fails
+ * usermodehelper_disabled in usermodehelper_disable() fails
*/
#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
+int usermodehelper_read_trylock(void)
+{
+ DEFINE_WAIT(wait);
+ int ret = 0;
+
+ down_read(&umhelper_sem);
+ for (;;) {
+ prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
+ TASK_INTERRUPTIBLE);
+ if (!usermodehelper_disabled)
+ break;
+
+ if (usermodehelper_disabled == UMH_DISABLED)
+ ret = -EAGAIN;
+
+ up_read(&umhelper_sem);
+
+ if (ret)
+ break;
+
+ schedule();
+ try_to_freeze();
+
+ down_read(&umhelper_sem);
+ }
+ finish_wait(&usermodehelper_disabled_waitq, &wait);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
+
+long usermodehelper_read_lock_wait(long timeout)
+{
+ DEFINE_WAIT(wait);
+
+ if (timeout < 0)
+ return -EINVAL;
+
+ down_read(&umhelper_sem);
+ for (;;) {
+ prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (!usermodehelper_disabled)
+ break;
+
+ up_read(&umhelper_sem);
+
+ timeout = schedule_timeout(timeout);
+ if (!timeout)
+ break;
+
+ down_read(&umhelper_sem);
+ }
+ finish_wait(&usermodehelper_disabled_waitq, &wait);
+ return timeout;
+}
+EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
+
+void usermodehelper_read_unlock(void)
+{
+ up_read(&umhelper_sem);
+}
+EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
+
/**
- * usermodehelper_disable - prevent new helpers from being started
+ * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
+ * @depth: New value to assign to usermodehelper_disabled.
+ *
+ * Change the value of usermodehelper_disabled (under umhelper_sem locked for
+ * writing) and wakeup tasks waiting for it to change.
*/
-int usermodehelper_disable(void)
+void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
+{
+ down_write(&umhelper_sem);
+ usermodehelper_disabled = depth;
+ wake_up(&usermodehelper_disabled_waitq);
+ up_write(&umhelper_sem);
+}
+
+/**
+ * __usermodehelper_disable - Prevent new helpers from being started.
+ * @depth: New value to assign to usermodehelper_disabled.
+ *
+ * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
+ */
+int __usermodehelper_disable(enum umh_disable_depth depth)
{
long retval;
- usermodehelper_disabled = 1;
- smp_mb();
+ if (!depth)
+ return -EINVAL;
+
+ down_write(&umhelper_sem);
+ usermodehelper_disabled = depth;
+ up_write(&umhelper_sem);
+
/*
* From now on call_usermodehelper_exec() won't start any new
* helpers, so it is sufficient if running_helpers turns out to
if (retval)
return 0;
- usermodehelper_disabled = 0;
+ __usermodehelper_set_disable_depth(UMH_ENABLED);
return -EAGAIN;
}
-/**
- * usermodehelper_enable - allow new helpers to be started again
- */
-void usermodehelper_enable(void)
-{
- usermodehelper_disabled = 0;
-}
-
-/**
- * usermodehelper_is_disabled - check if new helpers are allowed to be started
- */
-bool usermodehelper_is_disabled(void)
-{
- return usermodehelper_disabled;
-}
-EXPORT_SYMBOL_GPL(usermodehelper_is_disabled);
-
static void helper_lock(void)
{
atomic_inc(&running_helpers);
* @argv: arg vector for process
* @envp: environment for process
* @gfp_mask: gfp mask for memory allocation
+ * @cleanup: a cleanup function
+ * @init: an init function
+ * @data: arbitrary context sensitive data
*
* 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.
+ *
+ * The init function is used to customize the helper process prior to
+ * exec. A non-zero return code causes the process to error out, exit,
+ * and return the failure to the calling process
+ *
+ * The cleanup function is just before 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.
*/
struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
- char **envp, gfp_t gfp_mask)
+ char **envp, gfp_t gfp_mask,
+ int (*init)(struct subprocess_info *info, struct cred *new),
+ void (*cleanup)(struct subprocess_info *info),
+ void *data)
{
struct subprocess_info *sub_info;
sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
sub_info->path = path;
sub_info->argv = argv;
sub_info->envp = envp;
+
+ sub_info->cleanup = cleanup;
+ sub_info->init = init;
+ sub_info->data = data;
out:
return sub_info;
}
EXPORT_SYMBOL(call_usermodehelper_setup);
-/**
- * call_usermodehelper_setfns - set a cleanup/init function
- * @info: a subprocess_info returned by call_usermodehelper_setup
- * @cleanup: a cleanup function
- * @init: an init function
- * @data: arbitrary context sensitive data
- *
- * The init function is used to customize the helper process prior to
- * exec. A non-zero return code causes the process to error out, exit,
- * and return the failure to the calling process
- *
- * The cleanup function is just before 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_setfns(struct subprocess_info *info,
- int (*init)(struct subprocess_info *info, struct cred *new),
- void (*cleanup)(struct subprocess_info *info),
- void *data)
-{
- info->cleanup = cleanup;
- info->init = init;
- info->data = data;
-}
-EXPORT_SYMBOL(call_usermodehelper_setfns);
-
/**
* 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
+ * when UMH_NO_WAIT 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)
+int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
{
DECLARE_COMPLETION_ONSTACK(done);
int retval = 0;
helper_lock();
+ if (!sub_info->path) {
+ retval = -EINVAL;
+ goto out;
+ }
+
if (sub_info->path[0] == '\0')
goto out;
retval = -EBUSY;
goto out;
}
+ /*
+ * Worker thread must not wait for khelper thread at below
+ * wait_for_completion() if the thread was created with CLONE_VFORK
+ * flag, for khelper thread is already waiting for the thread at
+ * wait_for_completion() in do_fork().
+ */
+ if (wait != UMH_NO_WAIT && current == kmod_thread_locker) {
+ 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;
+
+ if (wait & UMH_KILLABLE) {
+ retval = wait_for_completion_killable(&done);
+ if (!retval)
+ goto wait_done;
+
+ /* umh_complete() will see NULL and free sub_info */
+ if (xchg(&sub_info->complete, NULL))
+ goto unlock;
+ /* fallthrough, umh_complete() was already called */
+ }
+
wait_for_completion(&done);
+wait_done:
retval = sub_info->retval;
-
out:
call_usermodehelper_freeinfo(sub_info);
unlock:
}
EXPORT_SYMBOL(call_usermodehelper_exec);
+/**
+ * call_usermodehelper() - prepare and start a usermode application
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ * @wait: wait for the application to finish and return status.
+ * when UMH_NO_WAIT 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.
+ *
+ * This function is the equivalent to use call_usermodehelper_setup() and
+ * call_usermodehelper_exec().
+ */
+int call_usermodehelper(char *path, char **argv, char **envp, int wait)
+{
+ struct subprocess_info *info;
+ gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
+
+ info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
+ NULL, NULL, NULL);
+ if (info == NULL)
+ return -ENOMEM;
+
+ return call_usermodehelper_exec(info, wait);
+}
+EXPORT_SYMBOL(call_usermodehelper);
+
static int proc_cap_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
projects / firefly-linux-kernel-4.4.55.git / blobdiff