1 files changed, 150 insertions, 16 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 35a50db9b6ce..911d846f0503 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 +1680,52 @@ static __init int sysctl_init(void)
 
 core_initcall(sysctl_init);
 
+static int 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 0;
+
+        /* ... and nothing else */
+        if (branch[1].procname || branch[1].ctl_name)
+                return 0;
+
+        /* 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 1;
+        }
+        return 0;
+}
+
+/* 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;
+        int is_better = 0;
+        int not_in_parent = !p->attached_by;
+
+        while (is_branch_in(by, to)) {
+                if (by == q->attached_by)
+                        is_better = 1;
+                if (to == p->attached_by)
+                        not_in_parent = 1;
+                by = by->child;
+                to = to->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 +1802,10 @@ 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 +1847,7 @@ 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 +1855,20 @@ 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 +1923,37 @@ 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 +1972,16 @@ 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 */
 
 /*