#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;
char **argv;
char **envp;
struct key *ring;
- int wait;
+ enum umh_wait wait;
int retval;
struct file *stdin;
+ void (*cleanup)(char **argv, char **envp);
};
/*
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;
- 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, NULL);
allow_signal(SIGCHLD);
pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
sub_info->retval = ret;
}
- if (sub_info->wait < 0)
- kfree(sub_info);
+ if (sub_info->wait == UMH_NO_WAIT)
+ call_usermodehelper_freeinfo(sub_info);
else
complete(sub_info->complete);
return 0;
struct subprocess_info *sub_info =
container_of(work, struct subprocess_info, work);
pid_t pid;
- int wait = sub_info->wait;
+ 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)
+ 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);
- if (wait < 0)
- return;
+ switch (wait) {
+ case UMH_NO_WAIT:
+ break;
- if (pid < 0) {
+ case UMH_WAIT_PROC:
+ if (pid > 0)
+ break;
sub_info->retval = pid;
+ /* FALLTHROUGH */
+
+ case UMH_WAIT_EXEC:
complete(sub_info->complete);
- } else if (!wait)
- complete(sub_info->complete);
+ }
+}
+
+#ifdef CONFIG_PM
+/*
+ * 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)
+
+static int usermodehelper_pm_callback(struct notifier_block *nfb,
+ unsigned long action,
+ void *ignored)
+{
+ long retval;
+
+ switch (action) {
+ case PM_HIBERNATION_PREPARE:
+ case PM_SUSPEND_PREPARE:
+ 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 NOTIFY_OK;
+ } else {
+ usermodehelper_disabled = 0;
+ return NOTIFY_BAD;
+ }
+ case PM_POST_HIBERNATION:
+ case PM_POST_SUSPEND:
+ usermodehelper_disabled = 0;
+ return NOTIFY_OK;
+ }
+
+ return NOTIFY_DONE;
+}
+
+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);
+}
+
+static void register_pm_notifier_callback(void)
+{
+ pm_notifier(usermodehelper_pm_callback, 0);
}
+#else /* CONFIG_PM */
+#define usermodehelper_disabled 0
+
+static inline void helper_lock(void) {}
+static inline void helper_unlock(void) {}
+static inline void register_pm_notifier_callback(void) {}
+#endif /* CONFIG_PM */
/**
- * call_usermodehelper_keys - start a usermode application
- * @path: pathname for the application
- * @argv: null-terminated argument list
- * @envp: null-terminated environment list
- * @session_keyring: session keyring for process (NULL for an empty keyring)
+ * call_usermodehelper_setup - prepare to call a usermode helper
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ *
+ * 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)
+{
+ struct subprocess_info *sub_info;
+ sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC);
+ 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();
+ if (IS_ERR(f))
+ return PTR_ERR(f);
+ *filp = f;
+
+ f = create_read_pipe(f);
+ 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
* 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_keys(char *path, char **argv, char **envp,
- struct key *session_keyring, int wait)
+int call_usermodehelper_exec(struct subprocess_info *sub_info,
+ enum umh_wait wait)
{
DECLARE_COMPLETION_ONSTACK(done);
- struct subprocess_info *sub_info;
int retval;
- if (!khelper_wq)
- return -EBUSY;
-
- if (path[0] == '\0')
- return 0;
+ helper_lock();
+ if (sub_info->path[0] == '\0') {
+ retval = 0;
+ goto out;
+ }
- sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC);
- if (!sub_info)
- return -ENOMEM;
+ if (!khelper_wq || usermodehelper_disabled) {
+ retval = -EBUSY;
+ goto out;
+ }
- INIT_WORK(&sub_info->work, __call_usermodehelper);
sub_info->complete = &done;
- sub_info->path = path;
- sub_info->argv = argv;
- sub_info->envp = envp;
- sub_info->ring = session_keyring;
sub_info->wait = wait;
queue_work(khelper_wq, &sub_info->work);
- if (wait < 0) /* task has freed sub_info */
+ if (wait == UMH_NO_WAIT) /* task has freed sub_info */
return 0;
wait_for_completion(&done);
retval = sub_info->retval;
- kfree(sub_info);
+
+ out:
+ call_usermodehelper_freeinfo(sub_info);
+ helper_unlock();
return retval;
}
-EXPORT_SYMBOL(call_usermodehelper_keys);
+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)
{
- DECLARE_COMPLETION(done);
- struct subprocess_info sub_info = {
- .work = __WORK_INITIALIZER(sub_info.work,
- __call_usermodehelper),
- .complete = &done,
- .path = path,
- .argv = argv,
- .envp = envp,
- .retval = 0,
- };
- struct file *f;
-
- if (!khelper_wq)
- return -EBUSY;
+ struct subprocess_info *sub_info;
+ int ret;
- if (path[0] == '\0')
- return 0;
+ sub_info = call_usermodehelper_setup(path, argv, envp);
+ if (sub_info == NULL)
+ return -ENOMEM;
- f = create_write_pipe();
- if (IS_ERR(f))
- return PTR_ERR(f);
- *filp = f;
+ ret = call_usermodehelper_stdinpipe(sub_info, filp);
+ if (ret < 0)
+ goto out;
- f = create_read_pipe(f);
- if (IS_ERR(f)) {
- free_write_pipe(*filp);
- return PTR_ERR(f);
- }
- sub_info.stdin = f;
+ return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
- queue_work(khelper_wq, &sub_info.work);
- wait_for_completion(&done);
- return sub_info.retval;
+ out:
+ call_usermodehelper_freeinfo(sub_info);
+ return ret;
}
EXPORT_SYMBOL(call_usermodehelper_pipe);
{
khelper_wq = create_singlethread_workqueue("khelper");
BUG_ON(!khelper_wq);
+ register_pm_notifier_callback();
}
Code Review / linux-2.6.git / blobdiff