Commit bff97cf1 authored by Joel Granados's avatar Joel Granados Committed by Luis Chamberlain
Browse files

sysctl: Add a size arg to __register_sysctl_table 



We make these changes in order to prepare __register_sysctl_table and
its callers for when we remove the sentinel element (empty element at
the end of ctl_table arrays). We don't actually remove any sentinels in
this commit, but we *do* make sure to use ARRAY_SIZE so the table_size
is available when the removal occurs.

We add a table_size argument to __register_sysctl_table and adjust
callers, all of which pass ctl_table pointers and need an explicit call
to ARRAY_SIZE. We implement a size calculation in register_net_sysctl in
order to forward the size of the array pointer received from the network
register calls.

The new table_size argument does not yet have any effect in the
init_header call which is still dependent on the sentinel's presence.
table_size *does* however drive the `kzalloc` allocation in
__register_sysctl_table with no adverse effects as the allocated memory
is either one element greater than the calculated ctl_table array (for
the calls in ipc_sysctl.c, mq_sysctl.c and ucount.c) or the exact size
of the calculated ctl_table array (for the call from sysctl_net.c and
register_sysctl). This approach will allows us to "just" remove the
sentinel without further changes to __register_sysctl_table as
table_size will represent the exact size for all the callers at that
point.

Signed-off-by: default avatarJoel Granados <j.granados@samsung.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent b1f01e2b

fs/proc/proc_sysctl.c

+12 −11
Original line number Diff line number Diff line
@@ -1312,6 +1312,7 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path) 
 * 	 should not be free'd after registration. So it should not be

 * 	 used on stack. It can either be a global or dynamically allocated

 * 	 by the caller and free'd later after sysctl unregistration.

 * @table_size : The number of elements in table

 *

 * Register a sysctl table hierarchy. @table should be a filled in ctl_table

 * array. A completely 0 filled entry terminates the table.
@@ -1354,27 +1355,20 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path) 
 */

struct ctl_table_header *__register_sysctl_table(

	struct ctl_table_set *set,

	const char *path, struct ctl_table *table)

	const char *path, struct ctl_table *table, size_t table_size)

{

	struct ctl_table_root *root = set->dir.header.root;

	struct ctl_table_header *header;

	struct ctl_table_header h_tmp;

	struct ctl_dir *dir;

	struct ctl_table *entry;

	struct ctl_node *node;

	int nr_entries = 0;



	h_tmp.ctl_table = table;

	list_for_each_table_entry(entry, (&h_tmp))

		nr_entries++;



	header = kzalloc(sizeof(struct ctl_table_header) +

			 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL_ACCOUNT);

			 sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);

	if (!header)

		return NULL;



	node = (struct ctl_node *)(header + 1);

	init_header(header, root, set, node, table, nr_entries);

	init_header(header, root, set, node, table, table_size);

	if (sysctl_check_table(path, header))

		goto fail;
@@ -1423,8 +1417,15 @@ struct ctl_table_header *__register_sysctl_table( 
 */

struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)

{

	int count = 0;

	struct ctl_table *entry;

	struct ctl_table_header t_hdr;



	t_hdr.ctl_table = table;

	list_for_each_table_entry(entry, (&t_hdr))

		count++;

	return __register_sysctl_table(&sysctl_table_root.default_set,

					path, table);

					path, table, count);

}

EXPORT_SYMBOL(register_sysctl);

include/linux/sysctl.h

+1 −1
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ extern void retire_sysctl_set(struct ctl_table_set *set); 


struct ctl_table_header *__register_sysctl_table(

	struct ctl_table_set *set,

	const char *path, struct ctl_table *table);

	const char *path, struct ctl_table *table, size_t table_size);

struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);

void unregister_sysctl_table(struct ctl_table_header * table);

ipc/ipc_sysctl.c

+3 −1
Original line number Diff line number Diff line
@@ -259,7 +259,9 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns) 
				tbl[i].data = NULL;

		}



		ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set, "kernel", tbl);

		ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set,

							  "kernel", tbl,

							  ARRAY_SIZE(ipc_sysctls));

	}

	if (!ns->ipc_sysctls) {

		kfree(tbl);

ipc/mq_sysctl.c

+3 −1
Original line number Diff line number Diff line
@@ -109,7 +109,9 @@ bool setup_mq_sysctls(struct ipc_namespace *ns) 
				tbl[i].data = NULL;

		}



		ns->mq_sysctls = __register_sysctl_table(&ns->mq_set, "fs/mqueue", tbl);

		ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,

							 "fs/mqueue", tbl,

							 ARRAY_SIZE(mq_sysctls));

	}

	if (!ns->mq_sysctls) {

		kfree(tbl);

kernel/ucount.c

+2 −1
Original line number Diff line number Diff line
@@ -104,7 +104,8 @@ bool setup_userns_sysctls(struct user_namespace *ns) 
		for (i = 0; i < UCOUNT_COUNTS; i++) {

			tbl[i].data = &ns->ucount_max[i];

		}

		ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);

		ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl,

						      ARRAY_SIZE(user_table));

	}

	if (!ns->sysctls) {

		kfree(tbl);