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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-24 01:08:58 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-24 01:08:58 (GMT)
commitf1d38e423a697b7aa06e12d3ca4753bcc1aa3531 (patch)
tree1cbfd86070f724d5ffe53146d4c67edf14cccf98 /kernel/sysctl.c
parentdae430c6f6e5d0b98c238c340a41a39e221e8940 (diff)
parent4e474a00d7ff746ed177ddae14fa8b2d4bad7a00 (diff)
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Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl
Pull sysctl updates from Eric Biederman: - Rewrite of sysctl for speed and clarity. Insert/remove/Lookup in sysctl are all now O(NlogN) operations, and are no longer bottlenecks in the process of adding and removing network devices. sysctl is now focused on being a filesystem instead of system call and the code can all be found in fs/proc/proc_sysctl.c. Hopefully this means the code is now approachable. Much thanks is owed to Lucian Grinjincu for keeping at this until something was found that was usable. - The recent proc_sys_poll oops found by the fuzzer during hibernation is fixed. * git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl: (36 commits) sysctl: protect poll() in entries that may go away sysctl: Don't call sysctl_follow_link unless we are a link. sysctl: Comments to make the code clearer. sysctl: Correct error return from get_subdir sysctl: An easier to read version of find_subdir sysctl: fix memset parameters in setup_sysctl_set() sysctl: remove an unused variable sysctl: Add register_sysctl for normal sysctl users sysctl: Index sysctl directories with rbtrees. sysctl: Make the header lists per directory. sysctl: Move sysctl_check_dups into insert_header sysctl: Modify __register_sysctl_paths to take a set instead of a root and an nsproxy sysctl: Replace root_list with links between sysctl_table_sets. sysctl: Add sysctl_print_dir and use it in get_subdir sysctl: Stop requiring explicit management of sysctl directories sysctl: Add a root pointer to ctl_table_set sysctl: Rewrite proc_sys_readdir in terms of first_entry and next_entry sysctl: Rewrite proc_sys_lookup introducing find_entry and lookup_entry. sysctl: Normalize the root_table data structure. sysctl: Factor out insert_header and erase_header ...
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c501
1 files changed, 3 insertions, 498 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 11d5304..d48ff4f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -193,20 +193,6 @@ static int sysrq_sysctl_handler(ctl_table *table, int write,
#endif
-static struct ctl_table root_table[];
-static struct ctl_table_root sysctl_table_root;
-static struct ctl_table_header root_table_header = {
- {{.count = 1,
- .ctl_table = root_table,
- .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),
- .default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),
-};
-
static struct ctl_table kern_table[];
static struct ctl_table vm_table[];
static struct ctl_table fs_table[];
@@ -223,7 +209,7 @@ int sysctl_legacy_va_layout;
/* The default sysctl tables: */
-static struct ctl_table root_table[] = {
+static struct ctl_table sysctl_base_table[] = {
{
.procname = "kernel",
.mode = 0555,
@@ -1560,490 +1546,12 @@ static struct ctl_table dev_table[] = {
{ }
};
-static DEFINE_SPINLOCK(sysctl_lock);
-
-/* called under sysctl_lock */
-static int use_table(struct ctl_table_header *p)
-{
- if (unlikely(p->unregistering))
- return 0;
- p->used++;
- return 1;
-}
-
-/* called under sysctl_lock */
-static void unuse_table(struct ctl_table_header *p)
-{
- if (!--p->used)
- if (unlikely(p->unregistering))
- complete(p->unregistering);
-}
-
-/* called under sysctl_lock, will reacquire if has to wait */
-static void start_unregistering(struct ctl_table_header *p)
-{
- /*
- * if p->used is 0, nobody will ever touch that entry again;
- * we'll eliminate all paths to it before dropping sysctl_lock
- */
- if (unlikely(p->used)) {
- struct completion wait;
- init_completion(&wait);
- p->unregistering = &wait;
- 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
- * list in do_sysctl() relies on that.
- */
- 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_rcu(head, rcu);
- 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)
- return;
- spin_lock(&sysctl_lock);
- unuse_table(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 ctl_table_set *set = lookup_header_set(root, namespaces);
- return &set->list;
-}
-
-struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces,
- struct ctl_table_header *prev)
-{
- struct ctl_table_root *root;
- struct list_head *header_list;
- struct ctl_table_header *head;
- struct list_head *tmp;
-
- spin_lock(&sysctl_lock);
- if (prev) {
- head = prev;
- tmp = &prev->ctl_entry;
- unuse_table(prev);
- goto next;
- }
- tmp = &root_table_header.ctl_entry;
- for (;;) {
- head = list_entry(tmp, struct ctl_table_header, ctl_entry);
-
- if (!use_table(head))
- goto next;
- spin_unlock(&sysctl_lock);
- return head;
- next:
- root = head->root;
- tmp = tmp->next;
- header_list = lookup_header_list(root, namespaces);
- if (tmp != header_list)
- continue;
-
- do {
- root = list_entry(root->root_list.next,
- struct ctl_table_root, root_list);
- if (root == &sysctl_table_root)
- goto out;
- header_list = lookup_header_list(root, namespaces);
- } while (list_empty(header_list));
- tmp = header_list->next;
- }
-out:
- spin_unlock(&sysctl_lock);
- return NULL;
-}
-
-struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
-{
- return __sysctl_head_next(current->nsproxy, prev);
-}
-
-void register_sysctl_root(struct ctl_table_root *root)
-{
- spin_lock(&sysctl_lock);
- list_add_tail(&root->root_list, &sysctl_table_root.root_list);
- spin_unlock(&sysctl_lock);
-}
-
-/*
- * sysctl_perm does NOT grant the superuser all rights automatically, because
- * some sysctl variables are readonly even to root.
- */
-
-static int test_perm(int mode, int op)
-{
- if (!current_euid())
- mode >>= 6;
- else if (in_egroup_p(0))
- mode >>= 3;
- if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
- return 0;
- return -EACCES;
-}
-
-int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
-{
- int mode;
-
- if (root->permissions)
- mode = root->permissions(root, current->nsproxy, table);
- else
- mode = table->mode;
-
- return test_perm(mode, op);
-}
-
-static void sysctl_set_parent(struct ctl_table *parent, struct ctl_table *table)
-{
- for (; table->procname; table++) {
- table->parent = parent;
- if (table->child)
- sysctl_set_parent(table, table->child);
- }
-}
-
-static __init int sysctl_init(void)
+int __init sysctl_init(void)
{
- sysctl_set_parent(NULL, root_table);
-#ifdef CONFIG_SYSCTL_SYSCALL_CHECK
- sysctl_check_table(current->nsproxy, root_table);
-#endif
+ register_sysctl_table(sysctl_base_table);
return 0;
}
-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)
- return NULL;
-
- /* table should contain subdirectory with the same name */
- for (p = table; p->procname; 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
- * @namespaces: Data to compute which lists of sysctl entries are visible
- * @path: The path to the directory the sysctl table is in.
- * @table: the top-level table structure
- *
- * Register a sysctl table hierarchy. @table should be a filled in ctl_table
- * array. A completely 0 filled entry terminates the table.
- *
- * The members of the &struct ctl_table structure are used as follows:
- *
- * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
- * enter a sysctl file
- *
- * data - a pointer to data for use by proc_handler
- *
- * maxlen - the maximum size in bytes of the data
- *
- * mode - the file permissions for the /proc/sys file, and for sysctl(2)
- *
- * child - a pointer to the child sysctl table if this entry is a directory, or
- * %NULL.
- *
- * proc_handler - the text handler routine (described below)
- *
- * de - for internal use by the sysctl routines
- *
- * extra1, extra2 - extra pointers usable by the proc handler routines
- *
- * Leaf nodes in the sysctl tree will be represented by a single file
- * under /proc; non-leaf nodes will be represented by directories.
- *
- * sysctl(2) can automatically manage read and write requests through
- * the sysctl table. The data and maxlen fields of the ctl_table
- * struct enable minimal validation of the values being written to be
- * performed, and the mode field allows minimal authentication.
- *
- * There must be a proc_handler routine for any terminal nodes
- * mirrored under /proc/sys (non-terminals are handled by a built-in
- * directory handler). Several default handlers are available to
- * cover common cases -
- *
- * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
- * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
- * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
- *
- * It is the handler's job to read the input buffer from user memory
- * and process it. The handler should return 0 on success.
- *
- * This routine returns %NULL on a failure to register, and a pointer
- * to the table header on success.
- */
-struct ctl_table_header *__register_sysctl_paths(
- struct ctl_table_root *root,
- struct nsproxy *namespaces,
- const struct ctl_path *path, struct ctl_table *table)
-{
- 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].procname; ++npath)
- ;
-
- /*
- * For each path component, allocate a 2-element ctl_table array.
- * The first array element will be filled with the sysctl entry
- * for this, the second will be the sentinel (procname == 0).
- *
- * We allocate everything in one go so that we don't have to
- * worry about freeing additional memory in unregister_sysctl_table.
- */
- header = kzalloc(sizeof(struct ctl_table_header) +
- (2 * npath * sizeof(struct ctl_table)), GFP_KERNEL);
- if (!header)
- return NULL;
-
- new = (struct ctl_table *) (header + 1);
-
- /* Now connect the dots */
- prevp = &header->ctl_table;
- for (n = 0; n < npath; ++n, ++path) {
- /* Copy the procname */
- new->procname = path->procname;
- new->mode = 0555;
-
- *prevp = new;
- prevp = &new->child;
-
- new += 2;
- }
- *prevp = table;
- header->ctl_table_arg = table;
-
- INIT_LIST_HEAD(&header->ctl_entry);
- header->used = 0;
- 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);
- return NULL;
- }
-#endif
- spin_lock(&sysctl_lock);
- 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;
-}
-
-/**
- * register_sysctl_table_path - register a sysctl table hierarchy
- * @path: The path to the directory the sysctl table is in.
- * @table: the top-level table structure
- *
- * Register a sysctl table hierarchy. @table should be a filled in ctl_table
- * array. A completely 0 filled entry terminates the table.
- *
- * See __register_sysctl_paths for more details.
- */
-struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
- struct ctl_table *table)
-{
- return __register_sysctl_paths(&sysctl_table_root, current->nsproxy,
- path, table);
-}
-
-/**
- * register_sysctl_table - register a sysctl table hierarchy
- * @table: the top-level table structure
- *
- * Register a sysctl table hierarchy. @table should be a filled in ctl_table
- * array. A completely 0 filled entry terminates the table.
- *
- * See register_sysctl_paths for more details.
- */
-struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
-{
- static const struct ctl_path null_path[] = { {} };
-
- return register_sysctl_paths(null_path, table);
-}
-
-/**
- * unregister_sysctl_table - unregister a sysctl table hierarchy
- * @header: the header returned from register_sysctl_table
- *
- * Unregisters the sysctl table and all children. proc entries may not
- * actually be removed until they are no longer used by anyone.
- */
-void unregister_sysctl_table(struct ctl_table_header * header)
-{
- might_sleep();
-
- if (header == NULL)
- return;
-
- spin_lock(&sysctl_lock);
- start_unregistering(header);
- if (!--header->parent->count) {
- WARN_ON(1);
- kfree_rcu(header->parent, rcu);
- }
- if (!--header->count)
- kfree_rcu(header, rcu);
- spin_unlock(&sysctl_lock);
-}
-
-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 */
-struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
-{
- return NULL;
-}
-
-struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
- struct ctl_table *table)
-{
- return NULL;
-}
-
-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 */
/*
@@ -3009,6 +2517,3 @@ EXPORT_SYMBOL(proc_dointvec_ms_jiffies);
EXPORT_SYMBOL(proc_dostring);
EXPORT_SYMBOL(proc_doulongvec_minmax);
EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax);
-EXPORT_SYMBOL(register_sysctl_table);
-EXPORT_SYMBOL(register_sysctl_paths);
-EXPORT_SYMBOL(unregister_sysctl_table);