1 files changed, 85 insertions, 294 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
index 421b1149c651..9676965c0981 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -4,6 +4,9 @@
  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */
+
+#define pr_fmt(fmt) "CRED: " fmt
+
 #include <linux/export.h>
 #include <linux/cred.h>
 #include <linux/slab.h>
@@ -33,17 +36,13 @@ do {									\
 static struct kmem_cache *cred_jar;
 
 /* init to 2 - one for init_task, one to ensure it is never freed */
-struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
+static struct group_info init_groups = { .usage = REFCOUNT_INIT(2) };
 
 /*
  * The initial credentials for the initial task
  */
 struct cred init_cred = {
 	.usage			= ATOMIC_INIT(4),
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	.subscribers		= ATOMIC_INIT(2),
-	.magic			= CRED_MAGIC,
-#endif
 	.uid			= GLOBAL_ROOT_UID,
 	.gid			= GLOBAL_ROOT_GID,
 	.suid			= GLOBAL_ROOT_UID,
@@ -60,33 +59,9 @@ struct cred init_cred = {
 	.user			= INIT_USER,
 	.user_ns		= &init_user_ns,
 	.group_info		= &init_groups,
+	.ucounts		= &init_ucounts,
 };
 
-static inline void set_cred_subscribers(struct cred *cred, int n)
-{
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	atomic_set(&cred->subscribers, n);
-#endif
-}
-
-static inline int read_cred_subscribers(const struct cred *cred)
-{
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	return atomic_read(&cred->subscribers);
-#else
-	return 0;
-#endif
-}
-
-static inline void alter_cred_subscribers(const struct cred *_cred, int n)
-{
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	struct cred *cred = (struct cred *) _cred;
-
-	atomic_add(n, &cred->subscribers);
-#endif
-}
-
 /*
  * The RCU callback to actually dispose of a set of credentials
  */
@@ -96,20 +71,9 @@ static void put_cred_rcu(struct rcu_head *rcu)
 
 	kdebug("put_cred_rcu(%p)", cred);
 
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	if (cred->magic != CRED_MAGIC_DEAD ||
-	    atomic_read(&cred->usage) != 0 ||
-	    read_cred_subscribers(cred) != 0)
-		panic("CRED: put_cred_rcu() sees %p with"
-		      " mag %x, put %p, usage %d, subscr %d\n",
-		      cred, cred->magic, cred->put_addr,
-		      atomic_read(&cred->usage),
-		      read_cred_subscribers(cred));
-#else
-	if (atomic_read(&cred->usage) != 0)
-		panic("CRED: put_cred_rcu() sees %p with usage %d\n",
-		      cred, atomic_read(&cred->usage));
-#endif
+	if (atomic_long_read(&cred->usage) != 0)
+		panic("CRED: put_cred_rcu() sees %p with usage %ld\n",
+		      cred, atomic_long_read(&cred->usage));
 
 	security_cred_free(cred);
 	key_put(cred->session_keyring);
@@ -119,6 +83,8 @@ static void put_cred_rcu(struct rcu_head *rcu)
 	if (cred->group_info)
 		put_group_info(cred->group_info);
 	free_uid(cred->user);
+	if (cred->ucounts)
+		put_ucounts(cred->ucounts);
 	put_user_ns(cred->user_ns);
 	kmem_cache_free(cred_jar, cred);
 }
@@ -131,16 +97,10 @@ static void put_cred_rcu(struct rcu_head *rcu)
  */
 void __put_cred(struct cred *cred)
 {
-	kdebug("__put_cred(%p{%d,%d})", cred,
-	       atomic_read(&cred->usage),
-	       read_cred_subscribers(cred));
-
-	BUG_ON(atomic_read(&cred->usage) != 0);
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	BUG_ON(read_cred_subscribers(cred) != 0);
-	cred->magic = CRED_MAGIC_DEAD;
-	cred->put_addr = __builtin_return_address(0);
-#endif
+	kdebug("__put_cred(%p{%ld})", cred,
+	       atomic_long_read(&cred->usage));
+
+	BUG_ON(atomic_long_read(&cred->usage) != 0);
 	BUG_ON(cred == current->cred);
 	BUG_ON(cred == current->real_cred);
 
@@ -156,23 +116,23 @@ EXPORT_SYMBOL(__put_cred);
  */
 void exit_creds(struct task_struct *tsk)
 {
-	struct cred *cred;
+	struct cred *real_cred, *cred;
 
-	kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
-	       atomic_read(&tsk->cred->usage),
-	       read_cred_subscribers(tsk->cred));
+	kdebug("exit_creds(%u,%p,%p,{%ld})", tsk->pid, tsk->real_cred, tsk->cred,
+	       atomic_long_read(&tsk->cred->usage));
 
-	cred = (struct cred *) tsk->real_cred;
+	real_cred = (struct cred *) tsk->real_cred;
 	tsk->real_cred = NULL;
-	validate_creds(cred);
-	alter_cred_subscribers(cred, -1);
-	put_cred(cred);
 
 	cred = (struct cred *) tsk->cred;
 	tsk->cred = NULL;
-	validate_creds(cred);
-	alter_cred_subscribers(cred, -1);
-	put_cred(cred);
+
+	if (real_cred == cred) {
+		put_cred_many(cred, 2);
+	} else {
+		put_cred(real_cred);
+		put_cred(cred);
+	}
 
 #ifdef CONFIG_KEYS_REQUEST_CACHE
 	key_put(tsk->cached_requested_key);
@@ -218,11 +178,7 @@ struct cred *cred_alloc_blank(void)
 	if (!new)
 		return NULL;
 
-	atomic_set(&new->usage, 1);
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	new->magic = CRED_MAGIC;
-#endif
-
+	atomic_long_set(&new->usage, 1);
 	if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
 		goto error;
 
@@ -253,8 +209,6 @@ struct cred *prepare_creds(void)
 	const struct cred *old;
 	struct cred *new;
 
-	validate_process_creds();
-
 	new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
 	if (!new)
 		return NULL;
@@ -265,8 +219,7 @@ struct cred *prepare_creds(void)
 	memcpy(new, old, sizeof(struct cred));
 
 	new->non_rcu = 0;
-	atomic_set(&new->usage, 1);
-	set_cred_subscribers(new, 0);
+	atomic_long_set(&new->usage, 1);
 	get_group_info(new->group_info);
 	get_uid(new->user);
 	get_user_ns(new->user_ns);
@@ -282,9 +235,13 @@ struct cred *prepare_creds(void)
 	new->security = NULL;
 #endif
 
+	new->ucounts = get_ucounts(new->ucounts);
+	if (!new->ucounts)
+		goto error;
+
 	if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
 		goto error;
-	validate_creds(new);
+
 	return new;
 
 error:
@@ -345,13 +302,10 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
 #endif
 		clone_flags & CLONE_THREAD
 	    ) {
-		p->real_cred = get_cred(p->cred);
-		get_cred(p->cred);
-		alter_cred_subscribers(p->cred, 2);
-		kdebug("share_creds(%p{%d,%d})",
-		       p->cred, atomic_read(&p->cred->usage),
-		       read_cred_subscribers(p->cred));
-		atomic_inc(&p->cred->user->processes);
+		p->real_cred = get_cred_many(p->cred, 2);
+		kdebug("share_creds(%p{%ld})",
+		       p->cred, atomic_long_read(&p->cred->usage));
+		inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
 		return 0;
 	}
 
@@ -363,6 +317,9 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
 		ret = create_user_ns(new);
 		if (ret < 0)
 			goto error_put;
+		ret = set_cred_ucounts(new);
+		if (ret < 0)
+			goto error_put;
 	}
 
 #ifdef CONFIG_KEYS
@@ -384,10 +341,8 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
 	}
 #endif
 
-	atomic_inc(&new->user->processes);
 	p->cred = p->real_cred = get_cred(new);
-	alter_cred_subscribers(new, 2);
-	validate_creds(new);
+	inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
 	return 0;
 
 error_put:
@@ -439,17 +394,11 @@ int commit_creds(struct cred *new)
 	struct task_struct *task = current;
 	const struct cred *old = task->real_cred;
 
-	kdebug("commit_creds(%p{%d,%d})", new,
-	       atomic_read(&new->usage),
-	       read_cred_subscribers(new));
+	kdebug("commit_creds(%p{%ld})", new,
+	       atomic_long_read(&new->usage));
 
 	BUG_ON(task->cred != old);
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	BUG_ON(read_cred_subscribers(old) < 2);
-	validate_creds(old);
-	validate_creds(new);
-#endif
-	BUG_ON(atomic_read(&new->usage) < 1);
+	BUG_ON(atomic_long_read(&new->usage) < 1);
 
 	get_cred(new); /* we will require a ref for the subj creds too */
 
@@ -484,14 +433,12 @@ int commit_creds(struct cred *new)
 	 * RLIMIT_NPROC limits on user->processes have already been checked
 	 * in set_user().
 	 */
-	alter_cred_subscribers(new, 2);
-	if (new->user != old->user)
-		atomic_inc(&new->user->processes);
+	if (new->user != old->user || new->user_ns != old->user_ns)
+		inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
 	rcu_assign_pointer(task->real_cred, new);
 	rcu_assign_pointer(task->cred, new);
-	if (new->user != old->user)
-		atomic_dec(&old->user->processes);
-	alter_cred_subscribers(old, -2);
+	if (new->user != old->user || new->user_ns != old->user_ns)
+		dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
 
 	/* send notifications */
 	if (!uid_eq(new->uid,   old->uid)  ||
@@ -507,8 +454,7 @@ int commit_creds(struct cred *new)
 		proc_id_connector(task, PROC_EVENT_GID);
 
 	/* release the old obj and subj refs both */
-	put_cred(old);
-	put_cred(old);
+	put_cred_many(old, 2);
 	return 0;
 }
 EXPORT_SYMBOL(commit_creds);
@@ -522,84 +468,15 @@ EXPORT_SYMBOL(commit_creds);
  */
 void abort_creds(struct cred *new)
 {
-	kdebug("abort_creds(%p{%d,%d})", new,
-	       atomic_read(&new->usage),
-	       read_cred_subscribers(new));
+	kdebug("abort_creds(%p{%ld})", new,
+	       atomic_long_read(&new->usage));
 
-#ifdef CONFIG_DEBUG_CREDENTIALS
-	BUG_ON(read_cred_subscribers(new) != 0);
-#endif
-	BUG_ON(atomic_read(&new->usage) < 1);
+	BUG_ON(atomic_long_read(&new->usage) < 1);
 	put_cred(new);
 }
 EXPORT_SYMBOL(abort_creds);
 
 /**
- * override_creds - Override the current process's subjective credentials
- * @new: The credentials to be assigned
- *
- * Install a set of temporary override subjective credentials on the current
- * process, returning the old set for later reversion.
- */
-const struct cred *override_creds(const struct cred *new)
-{
-	const struct cred *old = current->cred;
-
-	kdebug("override_creds(%p{%d,%d})", new,
-	       atomic_read(&new->usage),
-	       read_cred_subscribers(new));
-
-	validate_creds(old);
-	validate_creds(new);
-
-	/*
-	 * NOTE! This uses 'get_new_cred()' rather than 'get_cred()'.
-	 *
-	 * That means that we do not clear the 'non_rcu' flag, since
-	 * we are only installing the cred into the thread-synchronous
-	 * '->cred' pointer, not the '->real_cred' pointer that is
-	 * visible to other threads under RCU.
-	 *
-	 * Also note that we did validate_creds() manually, not depending
-	 * on the validation in 'get_cred()'.
-	 */
-	get_new_cred((struct cred *)new);
-	alter_cred_subscribers(new, 1);
-	rcu_assign_pointer(current->cred, new);
-	alter_cred_subscribers(old, -1);
-
-	kdebug("override_creds() = %p{%d,%d}", old,
-	       atomic_read(&old->usage),
-	       read_cred_subscribers(old));
-	return old;
-}
-EXPORT_SYMBOL(override_creds);
-
-/**
- * revert_creds - Revert a temporary subjective credentials override
- * @old: The credentials to be restored
- *
- * Revert a temporary set of override subjective credentials to an old set,
- * discarding the override set.
- */
-void revert_creds(const struct cred *old)
-{
-	const struct cred *override = current->cred;
-
-	kdebug("revert_creds(%p{%d,%d})", old,
-	       atomic_read(&old->usage),
-	       read_cred_subscribers(old));
-
-	validate_creds(old);
-	validate_creds(override);
-	alter_cred_subscribers(old, 1);
-	rcu_assign_pointer(current->cred, old);
-	alter_cred_subscribers(override, -1);
-	put_cred(override);
-}
-EXPORT_SYMBOL(revert_creds);
-
-/**
  * cred_fscmp - Compare two credentials with respect to filesystem access.
  * @a: The first credential
  * @b: The second credential
@@ -653,14 +530,34 @@ int cred_fscmp(const struct cred *a, const struct cred *b)
 }
 EXPORT_SYMBOL(cred_fscmp);
 
+int set_cred_ucounts(struct cred *new)
+{
+	struct ucounts *new_ucounts, *old_ucounts = new->ucounts;
+
+	/*
+	 * This optimization is needed because alloc_ucounts() uses locks
+	 * for table lookups.
+	 */
+	if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->uid))
+		return 0;
+
+	if (!(new_ucounts = alloc_ucounts(new->user_ns, new->uid)))
+		return -EAGAIN;
+
+	new->ucounts = new_ucounts;
+	put_ucounts(old_ucounts);
+
+	return 0;
+}
+
 /*
  * initialise the credentials stuff
  */
 void __init cred_init(void)
 {
 	/* allocate a slab in which we can store credentials */
-	cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
-			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
+	cred_jar = KMEM_CACHE(cred,
+			      SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
 }
 
 /**
@@ -671,9 +568,9 @@ void __init cred_init(void)
  * override a task's own credentials so that work can be done on behalf of that
  * task that requires a different subjective context.
  *
- * @daemon is used to provide a base for the security record, but can be NULL.
- * If @daemon is supplied, then the security data will be derived from that;
- * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
+ * @daemon is used to provide a base cred, with the security data derived from
+ * that; if this is "&init_task", they'll be set to 0, no groups, full
+ * capabilities, and no keys.
  *
  * The caller may change these controls afterwards if desired.
  *
@@ -684,23 +581,20 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
 	const struct cred *old;
 	struct cred *new;
 
+	if (WARN_ON_ONCE(!daemon))
+		return NULL;
+
 	new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
 	if (!new)
 		return NULL;
 
 	kdebug("prepare_kernel_cred() alloc %p", new);
 
-	if (daemon)
-		old = get_task_cred(daemon);
-	else
-		old = get_cred(&init_cred);
-
-	validate_creds(old);
+	old = get_task_cred(daemon);
 
 	*new = *old;
 	new->non_rcu = 0;
-	atomic_set(&new->usage, 1);
-	set_cred_subscribers(new, 0);
+	atomic_long_set(&new->usage, 1);
 	get_uid(new->user);
 	get_user_ns(new->user_ns);
 	get_group_info(new->group_info);
@@ -716,11 +610,14 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
 #ifdef CONFIG_SECURITY
 	new->security = NULL;
 #endif
+	new->ucounts = get_ucounts(new->ucounts);
+	if (!new->ucounts)
+		goto error;
+
 	if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
 		goto error;
 
 	put_cred(old);
-	validate_creds(new);
 	return new;
 
 error:
@@ -785,109 +682,3 @@ int set_create_files_as(struct cred *new, struct inode *inode)
 	return security_kernel_create_files_as(new, inode);
 }
 EXPORT_SYMBOL(set_create_files_as);
-
-#ifdef CONFIG_DEBUG_CREDENTIALS
-
-bool creds_are_invalid(const struct cred *cred)
-{
-	if (cred->magic != CRED_MAGIC)
-		return true;
-	return false;
-}
-EXPORT_SYMBOL(creds_are_invalid);
-
-/*
- * dump invalid credentials
- */
-static void dump_invalid_creds(const struct cred *cred, const char *label,
-			       const struct task_struct *tsk)
-{
-	printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
-	       label, cred,
-	       cred == &init_cred ? "[init]" : "",
-	       cred == tsk->real_cred ? "[real]" : "",
-	       cred == tsk->cred ? "[eff]" : "");
-	printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
-	       cred->magic, cred->put_addr);
-	printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
-	       atomic_read(&cred->usage),
-	       read_cred_subscribers(cred));
-	printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
-		from_kuid_munged(&init_user_ns, cred->uid),
-		from_kuid_munged(&init_user_ns, cred->euid),
-		from_kuid_munged(&init_user_ns, cred->suid),
-		from_kuid_munged(&init_user_ns, cred->fsuid));
-	printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
-		from_kgid_munged(&init_user_ns, cred->gid),
-		from_kgid_munged(&init_user_ns, cred->egid),
-		from_kgid_munged(&init_user_ns, cred->sgid),
-		from_kgid_munged(&init_user_ns, cred->fsgid));
-#ifdef CONFIG_SECURITY
-	printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
-	if ((unsigned long) cred->security >= PAGE_SIZE &&
-	    (((unsigned long) cred->security & 0xffffff00) !=
-	     (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
-		printk(KERN_ERR "CRED: ->security {%x, %x}\n",
-		       ((u32*)cred->security)[0],
-		       ((u32*)cred->security)[1]);
-#endif
-}
-
-/*
- * report use of invalid credentials
- */
-void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
-{
-	printk(KERN_ERR "CRED: Invalid credentials\n");
-	printk(KERN_ERR "CRED: At %s:%u\n", file, line);
-	dump_invalid_creds(cred, "Specified", current);
-	BUG();
-}
-EXPORT_SYMBOL(__invalid_creds);
-
-/*
- * check the credentials on a process
- */
-void __validate_process_creds(struct task_struct *tsk,
-			      const char *file, unsigned line)
-{
-	if (tsk->cred == tsk->real_cred) {
-		if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
-			     creds_are_invalid(tsk->cred)))
-			goto invalid_creds;
-	} else {
-		if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
-			     read_cred_subscribers(tsk->cred) < 1 ||
-			     creds_are_invalid(tsk->real_cred) ||
-			     creds_are_invalid(tsk->cred)))
-			goto invalid_creds;
-	}
-	return;
-
-invalid_creds:
-	printk(KERN_ERR "CRED: Invalid process credentials\n");
-	printk(KERN_ERR "CRED: At %s:%u\n", file, line);
-
-	dump_invalid_creds(tsk->real_cred, "Real", tsk);
-	if (tsk->cred != tsk->real_cred)
-		dump_invalid_creds(tsk->cred, "Effective", tsk);
-	else
-		printk(KERN_ERR "CRED: Effective creds == Real creds\n");
-	BUG();
-}
-EXPORT_SYMBOL(__validate_process_creds);
-
-/*
- * check creds for do_exit()
- */
-void validate_creds_for_do_exit(struct task_struct *tsk)
-{
-	kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
-	       tsk->real_cred, tsk->cred,
-	       atomic_read(&tsk->cred->usage),
-	       read_cred_subscribers(tsk->cred));
-
-	__validate_process_creds(tsk, __FILE__, __LINE__);
-}
-
-#endif /* CONFIG_DEBUG_CREDENTIALS */