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>

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>
Oleg Nesterov · Linus Torvalds
1 parent 685bfd2c48
Showing 4 changed files with 0 additions and 81 deletions Side-by-side Diff
include/linux/cred.h
include/linux/kmod.h
kernel/cred.c
kernel/kmod.c
@@ -156,7 +156,6 @@
 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 *);
@@ -56,7 +56,6 @@
 struct subprocess_info {
 	struct work_struct work;
 	struct completion *complete;
-	struct cred *cred;
 	char *path;
 	char **argv;
 	char **envp;
@@ -347,66 +347,6 @@
 }
  
 /*
- * 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()
  *
  * We share if we can, but under some circumstances we have to generate a new
@@ -134,8 +134,6 @@
 	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 @@
 	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 @@
 {
 	if (info->cleanup)
 		(*info->cleanup)(info);
-	if (info->cred)
-		put_cred(info->cred);
 	kfree(info);
 }
 EXPORT_SYMBOL(call_usermodehelper_freeinfo);
@@ -231,8 +223,6 @@
 	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 @@
 	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;
 }
@@ -410,9 +394,6 @@
 {
 	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')
...	...	@@ -156,7 +156,6 @@
156	156	extern struct cred *cred_alloc_blank(void);
157	157	extern struct cred *prepare_creds(void);
158	158	extern struct cred *prepare_exec_creds(void);
159		-extern struct cred *prepare_usermodehelper_creds(void);
160	159	extern int commit_creds(struct cred *);
161	160	extern void abort_creds(struct cred *);
162	161	extern const struct cred override_creds(const struct cred );
...	...	@@ -56,7 +56,6 @@
56	56	struct subprocess_info {
57	57	struct work_struct work;
58	58	struct completion *complete;
59		- struct cred *cred;
60	59	char *path;
61	60	char **argv;
62	61	char **envp;
...	...	@@ -347,66 +347,6 @@
347	347	}
348	348
349	349	/*
350		- * prepare new credentials for the usermode helper dispatcher
351		- */
352		-struct cred *prepare_usermodehelper_creds(void)
353		-{
354		-#ifdef CONFIG_KEYS
355		- struct thread_group_cred *tgcred = NULL;
356		-#endif
357		- struct cred *new;
358		-
359		-#ifdef CONFIG_KEYS
360		- tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC);
361		- if (!tgcred)
362		- return NULL;
363		-#endif
364		-
365		- new = kmem_cache_alloc(cred_jar, GFP_ATOMIC);
366		- if (!new)
367		- goto free_tgcred;
368		-
369		- kdebug("prepare_usermodehelper_creds() alloc %p", new);
370		-
371		- memcpy(new, &init_cred, sizeof(struct cred));
372		-
373		- atomic_set(&new->usage, 1);
374		- set_cred_subscribers(new, 0);
375		- get_group_info(new->group_info);
376		- get_uid(new->user);
377		-
378		-#ifdef CONFIG_KEYS
379		- new->thread_keyring = NULL;
380		- new->request_key_auth = NULL;
381		- new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT;
382		-
383		- atomic_set(&tgcred->usage, 1);
384		- spin_lock_init(&tgcred->lock);
385		- new->tgcred = tgcred;
386		-#endif
387		-
388		-#ifdef CONFIG_SECURITY
389		- new->security = NULL;
390		-#endif
391		- if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0)
392		- goto error;
393		- validate_creds(new);
394		-
395		- BUG_ON(atomic_read(&new->usage) != 1);
396		- return new;
397		-
398		-error:
399		- put_cred(new);
400		- return NULL;
401		-
402		-free_tgcred:
403		-#ifdef CONFIG_KEYS
404		- kfree(tgcred);
405		-#endif
406		- return NULL;
407		-}
408		-
409		-/*
410	350	* Copy credentials for the new process created by fork()
411	351	*
412	352	* We share if we can, but under some circumstances we have to generate a new
...	...	@@ -134,8 +134,6 @@
134	134	struct subprocess_info *sub_info = data;
135	135	int retval;
136	136
137		- BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
138		-
139	137	/* Unblock all signals */
140	138	spin_lock_irq(&current->sighand->siglock);
141	139	flush_signal_handlers(current, 1);
...	...	@@ -143,10 +141,6 @@
143	141	recalc_sigpending();
144	142	spin_unlock_irq(&current->sighand->siglock);
145	143
146		- /* Install the credentials */
147		- commit_creds(sub_info->cred);
148		- sub_info->cred = NULL;
149		-
150	144	/* We can run anywhere, unlike our parent keventd(). */
151	145	set_cpus_allowed_ptr(current, cpu_all_mask);
152	146
...	...	@@ -174,8 +168,6 @@
174	168	{
175	169	if (info->cleanup)
176	170	(*info->cleanup)(info);
177		- if (info->cred)
178		- put_cred(info->cred);
179	171	kfree(info);
180	172	}
181	173	EXPORT_SYMBOL(call_usermodehelper_freeinfo);
...	...	@@ -231,8 +223,6 @@
231	223	pid_t pid;
232	224	enum umh_wait wait = sub_info->wait;
233	225
234		- BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
235		-
236	226	/* CLONE_VFORK: wait until the usermode helper has execve'd
237	227	* successfully We need the data structures to stay around
238	228	* until that is done. */
...	...	@@ -355,12 +345,6 @@
355	345	sub_info->path = path;
356	346	sub_info->argv = argv;
357	347	sub_info->envp = envp;
358		- sub_info->cred = prepare_usermodehelper_creds();
359		- if (!sub_info->cred) {
360		- kfree(sub_info);
361		- return NULL;
362		- }
363		-
364	348	out:
365	349	return sub_info;
366	350	}
...	...	@@ -410,9 +394,6 @@
410	394	{
411	395	DECLARE_COMPLETION_ONSTACK(done);
412	396	int retval = 0;
413		-
414		- BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
415		- validate_creds(sub_info->cred);
416	397
417	398	helper_lock();
418	399	if (sub_info->path[0] == '\0')