microblaze: uaccess: fix put_user and get_user macros
[linux-2.6.git] / kernel / kmod.c
index 842f801..bf0e231 100644 (file)
        call_usermodehelper wait flag, and remove exec_usermodehelper.
        Rusty Russell <rusty@rustcorp.com.au>  Jan 2003
 */
-#define __KERNEL_SYSCALLS__
-
 #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/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>
 
+#include <trace/events/module.h>
+
 extern int max_threads;
 
 static struct workqueue_struct *khelper_wq;
 
-#ifdef CONFIG_KMOD
+#ifdef CONFIG_MODULES
 
 /*
        modprobe_path is set via /proc/sys.
@@ -49,9 +51,10 @@ static struct workqueue_struct *khelper_wq;
 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
+ * __request_module - try to load a kernel module
+ * @wait: wait (or not) for the operation to complete
+ * @fmt: printf style format string for the name of the module
+ * @...: arguments 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
@@ -62,7 +65,7 @@ char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
  * If module auto-loading support is disabled then this function
  * becomes a no-operation.
  */
-int request_module(const char *fmt, ...)
+int __request_module(bool wait, const char *fmt, ...)
 {
        va_list args;
        char module_name[MODULE_NAME_LEN];
@@ -83,6 +86,10 @@ int request_module(const char *fmt, ...)
        if (ret >= MODULE_NAME_LEN)
                return -ENAMETOOLONG;
 
+       ret = security_kernel_module_request(module_name);
+       if (ret)
+               return ret;
+
        /* 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
@@ -107,21 +114,27 @@ int request_module(const char *fmt, ...)
                return -ENOMEM;
        }
 
-       ret = call_usermodehelper(modprobe_path, argv, envp, 1);
+       trace_module_request(module_name, wait, _RET_IP_);
+
+       ret = call_usermodehelper(modprobe_path, argv, envp,
+                       wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
        atomic_dec(&kmod_concurrent);
        return ret;
 }
-EXPORT_SYMBOL(request_module);
-#endif /* CONFIG_KMOD */
+EXPORT_SYMBOL(__request_module);
+#endif /* CONFIG_MODULES */
 
 struct subprocess_info {
+       struct work_struct work;
        struct completion *complete;
+       struct cred *cred;
        char *path;
        char **argv;
        char **envp;
-       struct key *ring;
-       int wait;
+       enum umh_wait wait;
        int retval;
+       struct file *stdin;
+       void (*cleanup)(char **argv, char **envp);
 };
 
 /*
@@ -130,46 +143,72 @@ struct subprocess_info {
 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);
-       flush_signals(current);
+       BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
+
+       /* Unblock all signals */
        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 the credentials */
+       commit_creds(sub_info->cred);
+       sub_info->cred = NULL;
+
+       /* 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(current, CPU_MASK_ALL);
+       set_cpus_allowed_ptr(current, cpu_all_mask);
 
-       retval = -EPERM;
-       if (current->fs->root)
-               retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
+       /*
+        * 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);
+       if (info->cred)
+               put_cred(info->cred);
+       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);
@@ -198,75 +237,301 @@ static int wait_for_helper(void *data)
                        sub_info->retval = ret;
        }
 
-       complete(sub_info->complete);
+       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(void *data)
+static void __call_usermodehelper(struct work_struct *work)
 {
-       struct subprocess_info *sub_info = data;
+       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;
+
+       BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
 
        /* 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 (pid < 0) {
+       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);
-       } else if (!wait)
-               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;
+       sub_info->cred = prepare_usermodehelper_creds();
+       if (!sub_info->cred) {
+               kfree(sub_info);
+               return NULL;
+       }
+
+  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)
+{
+#ifdef CONFIG_KEYS
+       struct thread_group_cred *tgcred = info->cred->tgcred;
+       key_put(tgcred->session_keyring);
+       tgcred->session_keyring = key_get(session_keyring);
+#else
+       BUG();
+#endif
+}
+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_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_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).
- *
- * 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 = {
-               .complete       = &done,
-               .path           = path,
-               .argv           = argv,
-               .envp           = envp,
-               .ring           = session_keyring,
-               .wait           = wait,
-               .retval         = 0,
-       };
-       DECLARE_WORK(work, __call_usermodehelper, &sub_info);
-
-       if (!khelper_wq)
-               return -EBUSY;
-
-       if (path[0] == '\0')
-               return 0;
+       int retval = 0;
+
+       BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
+       validate_creds(sub_info->cred);
+
+       helper_lock();
+       if (sub_info->path[0] == '\0')
+               goto out;
 
-       queue_work(khelper_wq, &work);
+       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);
-       return sub_info.retval;
+       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) {
+               call_usermodehelper_freeinfo(sub_info);
+               return ret;
+       }
+
+       ret = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
+       if (ret < 0)    /* Failed to execute helper, close pipe */
+               filp_close(*filp, NULL);
+
+       return ret;
 }
-EXPORT_SYMBOL(call_usermodehelper_keys);
+EXPORT_SYMBOL(call_usermodehelper_pipe);
 
 void __init usermodehelper_init(void)
 {