umh: creds: kill subprocess_info->cred logic

Now that nobody ever changes subprocess_info->cred we can kill this member
and related code.  ____call_usermodehelper() always runs in the context of
freshly forked kernel thread, it has the proper ->cred copied from its
parent kthread, keventd.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 52507c3..75c0fa8 100644 (file)
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -156,7 +156,6 @@ extern int copy_creds(struct task_struct *, unsigned long);
 extern struct cred *cred_alloc_blank(void);
 extern struct cred *prepare_creds(void);
 extern struct cred *prepare_exec_creds(void);
-extern struct cred *prepare_usermodehelper_creds(void);
 extern int commit_creds(struct cred *);
 extern void abort_creds(struct cred *);
 extern const struct cred *override_creds(const struct cred *);

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index d876dce..6efd7a7 100644 (file)
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -56,7 +56,6 @@ enum umh_wait {
 struct subprocess_info {
        struct work_struct work;
        struct completion *complete;
-       struct cred *cred;
        char *path;
        char **argv;
        char **envp;

diff --git a/kernel/cred.c b/kernel/cred.c
index 2c24870..a2d5504 100644 (file)
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -346,66 +346,6 @@ struct cred *prepare_exec_creds(void)
        return new;
 }
 
-/*
- * prepare new credentials for the usermode helper dispatcher
- */
-struct cred *prepare_usermodehelper_creds(void)
-{
-#ifdef CONFIG_KEYS
-       struct thread_group_cred *tgcred = NULL;
-#endif
-       struct cred *new;
-
-#ifdef CONFIG_KEYS
-       tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC);
-       if (!tgcred)
-               return NULL;
-#endif
-
-       new = kmem_cache_alloc(cred_jar, GFP_ATOMIC);
-       if (!new)
-               goto free_tgcred;
-
-       kdebug("prepare_usermodehelper_creds() alloc %p", new);
-
-       memcpy(new, &init_cred, sizeof(struct cred));
-
-       atomic_set(&new->usage, 1);
-       set_cred_subscribers(new, 0);
-       get_group_info(new->group_info);
-       get_uid(new->user);
-
-#ifdef CONFIG_KEYS
-       new->thread_keyring = NULL;
-       new->request_key_auth = NULL;
-       new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT;
-
-       atomic_set(&tgcred->usage, 1);
-       spin_lock_init(&tgcred->lock);
-       new->tgcred = tgcred;
-#endif
-
-#ifdef CONFIG_SECURITY
-       new->security = NULL;
-#endif
-       if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0)
-               goto error;
-       validate_creds(new);
-
-       BUG_ON(atomic_read(&new->usage) != 1);
-       return new;
-
-error:
-       put_cred(new);
-       return NULL;
-
-free_tgcred:
-#ifdef CONFIG_KEYS
-       kfree(tgcred);
-#endif
-       return NULL;
-}
-
 /*
  * Copy credentials for the new process created by fork()
  *

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 743d388..6194ec2 100644 (file)
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -134,8 +134,6 @@ static int ____call_usermodehelper(void *data)
        struct subprocess_info *sub_info = data;
        int retval;
 
-       BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
        /* Unblock all signals */
        spin_lock_irq(&current->sighand->siglock);
        flush_signal_handlers(current, 1);
@@ -143,10 +141,6 @@ static int ____call_usermodehelper(void *data)
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);
 
-       /* Install the credentials */
-       commit_creds(sub_info->cred);
-       sub_info->cred = NULL;
-
        /* We can run anywhere, unlike our parent keventd(). */
        set_cpus_allowed_ptr(current, cpu_all_mask);
 
@@ -174,8 +168,6 @@ void call_usermodehelper_freeinfo(struct subprocess_info *info)
 {
        if (info->cleanup)
                (*info->cleanup)(info);
-       if (info->cred)
-               put_cred(info->cred);
        kfree(info);
 }
 EXPORT_SYMBOL(call_usermodehelper_freeinfo);
@@ -231,8 +223,6 @@ static void __call_usermodehelper(struct work_struct *work)
        pid_t pid;
        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.  */
@@ -355,12 +345,6 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
        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;
 }
@@ -411,9 +395,6 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
        DECLARE_COMPLETION_ONSTACK(done);
        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;