Merge branch 'linus' into cpus4096

1 files changed, 152 insertions, 16 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 35a50db9b6ce..fe4713347275 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -160,12 +160,13 @@ static struct ctl_table root_table[];
 static struct ctl_table_root sysctl_table_root;
 static struct ctl_table_header root_table_header = {
 	.ctl_table = root_table,
-	.ctl_entry = LIST_HEAD_INIT(sysctl_table_root.header_list),
+	.ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),
 	.root = &sysctl_table_root,
+	.set = &sysctl_table_root.default_set,
 };
 static struct ctl_table_root sysctl_table_root = {
 	.root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),
-	.header_list = LIST_HEAD_INIT(root_table_header.ctl_entry),
+	.default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),
 };
 
 static struct ctl_table kern_table[];
@@ -1386,6 +1387,9 @@ static void start_unregistering(struct ctl_table_header *p)
 		spin_unlock(&sysctl_lock);
 		wait_for_completion(&wait);
 		spin_lock(&sysctl_lock);
+	} else {
+		/* anything non-NULL; we'll never dereference it */
+		p->unregistering = ERR_PTR(-EINVAL);
 	}
 	/*
 	 * do not remove from the list until nobody holds it; walking the
@@ -1394,6 +1398,32 @@ static void start_unregistering(struct ctl_table_header *p)
 	list_del_init(&p->ctl_entry);
 }
 
+void sysctl_head_get(struct ctl_table_header *head)
+{
+	spin_lock(&sysctl_lock);
+	head->count++;
+	spin_unlock(&sysctl_lock);
+}
+
+void sysctl_head_put(struct ctl_table_header *head)
+{
+	spin_lock(&sysctl_lock);
+	if (!--head->count)
+		kfree(head);
+	spin_unlock(&sysctl_lock);
+}
+
+struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
+{
+	if (!head)
+		BUG();
+	spin_lock(&sysctl_lock);
+	if (!use_table(head))
+		head = ERR_PTR(-ENOENT);
+	spin_unlock(&sysctl_lock);
+	return head;
+}
+
 void sysctl_head_finish(struct ctl_table_header *head)
 {
 	if (!head)
@@ -1403,14 +1433,20 @@ void sysctl_head_finish(struct ctl_table_header *head)
 	spin_unlock(&sysctl_lock);
 }
 
+static struct ctl_table_set *
+lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
+{
+	struct ctl_table_set *set = &root->default_set;
+	if (root->lookup)
+		set = root->lookup(root, namespaces);
+	return set;
+}
+
 static struct list_head *
 lookup_header_list(struct ctl_table_root *root, struct nsproxy *namespaces)
 {
-	struct list_head *header_list;
-	header_list = &root->header_list;
-	if (root->lookup)
-		header_list = root->lookup(root, namespaces);
-	return header_list;
+	struct ctl_table_set *set = lookup_header_set(root, namespaces);
+	return &set->list;
 }
 
 struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces,
@@ -1480,9 +1516,9 @@ static int do_sysctl_strategy(struct ctl_table_root *root,
 	int op = 0, rc;
 
 	if (oldval)
-		op |= 004;
+		op |= MAY_READ;
 	if (newval)
-		op |= 002;
+		op |= MAY_WRITE;
 	if (sysctl_perm(root, table, op))
 		return -EPERM;
 
@@ -1524,7 +1560,7 @@ repeat:
 		if (n == table->ctl_name) {
 			int error;
 			if (table->child) {
-				if (sysctl_perm(root, table, 001))
+				if (sysctl_perm(root, table, MAY_EXEC))
 					return -EPERM;
 				name++;
 				nlen--;
@@ -1599,7 +1635,7 @@ static int test_perm(int mode, int op)
 		mode >>= 6;
 	else if (in_egroup_p(0))
 		mode >>= 3;
-	if ((mode & op & 0007) == op)
+	if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
 		return 0;
 	return -EACCES;
 }
@@ -1609,7 +1645,7 @@ int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
 	int error;
 	int mode;
 
-	error = security_sysctl(table, op);
+	error = security_sysctl(table, op & (MAY_READ | MAY_WRITE | MAY_EXEC));
 	if (error)
 		return error;
 
@@ -1644,6 +1680,54 @@ static __init int sysctl_init(void)
 
 core_initcall(sysctl_init);
 
+static struct ctl_table *is_branch_in(struct ctl_table *branch,
+				      struct ctl_table *table)
+{
+	struct ctl_table *p;
+	const char *s = branch->procname;
+
+	/* branch should have named subdirectory as its first element */
+	if (!s || !branch->child)
+		return NULL;
+
+	/* ... and nothing else */
+	if (branch[1].procname || branch[1].ctl_name)
+		return NULL;
+
+	/* table should contain subdirectory with the same name */
+	for (p = table; p->procname || p->ctl_name; p++) {
+		if (!p->child)
+			continue;
+		if (p->procname && strcmp(p->procname, s) == 0)
+			return p;
+	}
+	return NULL;
+}
+
+/* see if attaching q to p would be an improvement */
+static void try_attach(struct ctl_table_header *p, struct ctl_table_header *q)
+{
+	struct ctl_table *to = p->ctl_table, *by = q->ctl_table;
+	struct ctl_table *next;
+	int is_better = 0;
+	int not_in_parent = !p->attached_by;
+
+	while ((next = is_branch_in(by, to)) != NULL) {
+		if (by == q->attached_by)
+			is_better = 1;
+		if (to == p->attached_by)
+			not_in_parent = 1;
+		by = by->child;
+		to = next->child;
+	}
+
+	if (is_better && not_in_parent) {
+		q->attached_by = by;
+		q->attached_to = to;
+		q->parent = p;
+	}
+}
+
 /**
  * __register_sysctl_paths - register a sysctl hierarchy
  * @root: List of sysctl headers to register on
@@ -1720,10 +1804,10 @@ struct ctl_table_header *__register_sysctl_paths(
 	struct nsproxy *namespaces,
 	const struct ctl_path *path, struct ctl_table *table)
 {
-	struct list_head *header_list;
 	struct ctl_table_header *header;
 	struct ctl_table *new, **prevp;
 	unsigned int n, npath;
+	struct ctl_table_set *set;
 
 	/* Count the path components */
 	for (npath = 0; path[npath].ctl_name || path[npath].procname; ++npath)
@@ -1765,6 +1849,7 @@ struct ctl_table_header *__register_sysctl_paths(
 	header->unregistering = NULL;
 	header->root = root;
 	sysctl_set_parent(NULL, header->ctl_table);
+	header->count = 1;
 #ifdef CONFIG_SYSCTL_SYSCALL_CHECK
 	if (sysctl_check_table(namespaces, header->ctl_table)) {
 		kfree(header);
@@ -1772,8 +1857,20 @@ struct ctl_table_header *__register_sysctl_paths(
 	}
 #endif
 	spin_lock(&sysctl_lock);
-	header_list = lookup_header_list(root, namespaces);
-	list_add_tail(&header->ctl_entry, header_list);
+	header->set = lookup_header_set(root, namespaces);
+	header->attached_by = header->ctl_table;
+	header->attached_to = root_table;
+	header->parent = &root_table_header;
+	for (set = header->set; set; set = set->parent) {
+		struct ctl_table_header *p;
+		list_for_each_entry(p, &set->list, ctl_entry) {
+			if (p->unregistering)
+				continue;
+			try_attach(p, header);
+		}
+	}
+	header->parent->count++;
+	list_add_tail(&header->ctl_entry, &header->set->list);
 	spin_unlock(&sysctl_lock);
 
 	return header;
@@ -1828,8 +1925,37 @@ void unregister_sysctl_table(struct ctl_table_header * header)
 
 	spin_lock(&sysctl_lock);
 	start_unregistering(header);
+	if (!--header->parent->count) {
+		WARN_ON(1);
+		kfree(header->parent);
+	}
+	if (!--header->count)
+		kfree(header);
 	spin_unlock(&sysctl_lock);
-	kfree(header);
+}
+
+int sysctl_is_seen(struct ctl_table_header *p)
+{
+	struct ctl_table_set *set = p->set;
+	int res;
+	spin_lock(&sysctl_lock);
+	if (p->unregistering)
+		res = 0;
+	else if (!set->is_seen)
+		res = 1;
+	else
+		res = set->is_seen(set);
+	spin_unlock(&sysctl_lock);
+	return res;
+}
+
+void setup_sysctl_set(struct ctl_table_set *p,
+	struct ctl_table_set *parent,
+	int (*is_seen)(struct ctl_table_set *))
+{
+	INIT_LIST_HEAD(&p->list);
+	p->parent = parent ? parent : &sysctl_table_root.default_set;
+	p->is_seen = is_seen;
 }
 
 #else /* !CONFIG_SYSCTL */
@@ -1848,6 +1974,16 @@ void unregister_sysctl_table(struct ctl_table_header * table)
 {
 }
 
+void setup_sysctl_set(struct ctl_table_set *p,
+	struct ctl_table_set *parent,
+	int (*is_seen)(struct ctl_table_set *))
+{
+}
+
+void sysctl_head_put(struct ctl_table_header *head)
+{
+}
+
 #endif /* CONFIG_SYSCTL */
 
 /*