Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b1d0a5d0 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: x_tables: add and use xt_check_proc_name 



recent and hashlimit both create /proc files, but only check that
name is 0 terminated.

This can trigger WARN() from procfs when name is "" or "/".
Add helper for this and then use it for both.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Reported-by: default avatar <syzbot+0502b00edac2a0680b61@syzkaller.appspotmail.com>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 932909d9

include/linux/netfilter/x_tables.h

+2 −0
Original line number Diff line number Diff line
@@ -285,6 +285,8 @@ unsigned int *xt_alloc_entry_offsets(unsigned int size); 
bool xt_find_jump_offset(const unsigned int *offsets,

			 unsigned int target, unsigned int size);



int xt_check_proc_name(const char *name, unsigned int size);



int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,

		   bool inv_proto);

int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,

net/netfilter/x_tables.c

+30 −0
Original line number Diff line number Diff line
@@ -423,6 +423,36 @@ textify_hooks(char *buf, size_t size, unsigned int mask, uint8_t nfproto) 
	return buf;

}



/**

 * xt_check_proc_name - check that name is suitable for /proc file creation

 *

 * @name: file name candidate

 * @size: length of buffer

 *

 * some x_tables modules wish to create a file in /proc.

 * This function makes sure that the name is suitable for this

 * purpose, it checks that name is NUL terminated and isn't a 'special'

 * name, like "..".

 *

 * returns negative number on error or 0 if name is useable.

 */

int xt_check_proc_name(const char *name, unsigned int size)

{

	if (name[0] == '\0')

		return -EINVAL;



	if (strnlen(name, size) == size)

		return -ENAMETOOLONG;



	if (strcmp(name, ".") == 0 ||

	    strcmp(name, "..") == 0 ||

	    strchr(name, '/'))

		return -EINVAL;



	return 0;

}

EXPORT_SYMBOL(xt_check_proc_name);



int xt_check_match(struct xt_mtchk_param *par,

		   unsigned int size, u_int8_t proto, bool inv_proto)

{

net/netfilter/xt_hashlimit.c

+10 −6
Original line number Diff line number Diff line
@@ -917,8 +917,9 @@ static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par) 
	struct hashlimit_cfg3 cfg = {};

	int ret;



	if (info->name[sizeof(info->name) - 1] != '\0')

		return -EINVAL;

	ret = xt_check_proc_name(info->name, sizeof(info->name));

	if (ret)

		return ret;



	ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
@@ -935,8 +936,9 @@ static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par) 
	struct hashlimit_cfg3 cfg = {};

	int ret;



	if (info->name[sizeof(info->name) - 1] != '\0')

		return -EINVAL;

	ret = xt_check_proc_name(info->name, sizeof(info->name));

	if (ret)

		return ret;



	ret = cfg_copy(&cfg, (void *)&info->cfg, 2);
@@ -950,9 +952,11 @@ static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par) 
static int hashlimit_mt_check(const struct xt_mtchk_param *par)

{

	struct xt_hashlimit_mtinfo3 *info = par->matchinfo;

	int ret;



	if (info->name[sizeof(info->name) - 1] != '\0')

		return -EINVAL;

	ret = xt_check_proc_name(info->name, sizeof(info->name));

	if (ret)

		return ret;



	return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,

					 info->name, 3);

net/netfilter/xt_recent.c

+3 −3
Original line number Diff line number Diff line
@@ -361,9 +361,9 @@ static int recent_mt_check(const struct xt_mtchk_param *par, 
				    info->hit_count, XT_RECENT_MAX_NSTAMPS - 1);

		return -EINVAL;

	}

	if (info->name[0] == '\0' ||

	    strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)

		return -EINVAL;

	ret = xt_check_proc_name(info->name, sizeof(info->name));

	if (ret)

		return ret;



	if (ip_pkt_list_tot && info->hit_count < ip_pkt_list_tot)

		nstamp_mask = roundup_pow_of_two(ip_pkt_list_tot) - 1;