1 files changed, 156 insertions, 45 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index a0a88543934e..05698a7415fe 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -60,6 +60,43 @@ static DECLARE_RWSEM(umhelper_sem);
 */
 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)
+{
+        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;
+
+        return call_usermodehelper_fns(modprobe_path, argv, envp,
+                wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL);
+free_argv:
+        kfree(argv);
+out:
+        return -ENOMEM;
+}
+
 /**
  * __request_module - try to load a kernel module
  * @wait: wait (or not) for the operation to complete
@@ -81,11 +118,6 @@ int __request_module(bool wait, const char *fmt, ...)
         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;
@@ -128,9 +160,7 @@ int __request_module(bool wait, const char *fmt, ...)
 
         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;
@@ -188,7 +218,7 @@ static int ____call_usermodehelper(void *data)
         /* Exec failed? */
 fail:
         sub_info->retval = retval;
-        do_exit(0);
+        return 0;
 }
 
 void call_usermodehelper_freeinfo(struct subprocess_info *info)
@@ -199,6 +229,19 @@ void call_usermodehelper_freeinfo(struct subprocess_info *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)
 {
@@ -235,7 +278,7 @@ static int wait_for_helper(void *data)
                         sub_info->retval = ret;
         }
 
-        complete(sub_info->complete);
+        umh_complete(sub_info);
         return 0;
 }
 
@@ -244,7 +287,7 @@ static void __call_usermodehelper(struct work_struct *work)
 {
         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
@@ -269,7 +312,7 @@ static void __call_usermodehelper(struct work_struct *work)
         case UMH_WAIT_EXEC:
                 if (pid < 0)
                         sub_info->retval = pid;
-                complete(sub_info->complete);
+                umh_complete(sub_info);
         }
 }
 
@@ -279,7 +322,7 @@ static void __call_usermodehelper(struct work_struct *work)
  * 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 = 1;
+static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
 
 /* Number of helpers running */
 static atomic_t running_helpers = ATOMIC_INIT(0);
@@ -291,32 +334,110 @@ static atomic_t running_helpers = ATOMIC_INIT(0);
 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_disable() fails
  */
 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
 
-void read_lock_usermodehelper(void)
+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(read_lock_usermodehelper);
+EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
 
-void read_unlock_usermodehelper(void)
+void usermodehelper_read_unlock(void)
 {
         up_read(&umhelper_sem);
 }
-EXPORT_SYMBOL_GPL(read_unlock_usermodehelper);
+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;
 
+        if (!depth)
+                return -EINVAL;
+
         down_write(&umhelper_sem);
-        usermodehelper_disabled = 1;
+        usermodehelper_disabled = depth;
         up_write(&umhelper_sem);
 
         /*
@@ -331,31 +452,10 @@ int usermodehelper_disable(void)
         if (retval)
                 return 0;
 
-        down_write(&umhelper_sem);
-        usermodehelper_disabled = 0;
-        up_write(&umhelper_sem);
+        __usermodehelper_set_disable_depth(UMH_ENABLED);
         return -EAGAIN;
 }
 
-/**
- * usermodehelper_enable - allow new helpers to be started again
- */
-void usermodehelper_enable(void)
-{
-        down_write(&umhelper_sem);
-        usermodehelper_disabled = 0;
-        up_write(&umhelper_sem);
-}
-
-/**
- * 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);
@@ -435,8 +535,7 @@ EXPORT_SYMBOL(call_usermodehelper_setfns);
  * 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;
@@ -456,9 +555,21 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
         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: