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Patch "netfilter: x_tables: add and use xt_check_proc_name" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Apr 3, 2018

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This is a note to let you know that I've just added the patch titled

netfilter: x_tables: add and use xt_check_proc_name

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
netfilter-x_tables-add-and-use-xt_check_proc_name.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From b1d0a5d0cba4597c0394997b2d5fced3e3841b4e Mon Sep 17 00:00:00 2001

From: Florian Westphal <[email protected]>
Date: Sat, 10 Mar 2018 01:15:45 +0100
Subject: netfilter: x_tables: add and use xt_check_proc_name

From: Florian Westphal <[email protected]>

commit b1d0a5d0cba4597c0394997b2d5fced3e3841b4e upstream.

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 <[email protected]>
Reported-by Eric Dumazet <[email protected]>
Reported-by <[email protected]>
Signed-off-by Florian Westphal <[email protected]>
Signed-off-by Pablo Neira Ayuso <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 include/linux/netfilter/x_tables.h |    2 ++
 net/netfilter/x_tables.c           |   30 ++++++++++++++++++++++++++++++
 net/netfilter/xt_hashlimit.c       |    5 +++--
 net/netfilter/xt_recent.c          |    6 +++---
 4 files changed, 38 insertions(+), 5 deletions(-)
include/linux/netfilter/x_tables.h +2 -0
@@ -247,6 +247,8 @@ unsigned int *xt_alloc_entry_offsets(uns
 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
@@ -366,6 +366,36 @@ textify_hooks(char *buf, size_t size, un
 	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 +3 -2
@@ -668,8 +668,9 @@ static int hashlimit_mt_check(const stru
 
 	if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
 		return -EINVAL;
-	if (info->name[sizeof(info->name)-1] != '\0')
-		return -EINVAL;
+	ret = xt_check_proc_name(info->name, sizeof(info->name));
+	if (ret)
+		return ret;
 	if (par->family == NFPROTO_IPV4) {
 		if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
 			return -EINVAL;
net/netfilter/xt_recent.c +3 -3
@@ -364,9 +364,9 @@ static int recent_mt_check(const struct
 			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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/netfilter-x_tables-add-and-use-xt_check_proc_name.patch queue-4.4/xfrm_user-uncoditionally-validate-esn-replay-attribute-struct.patch queue-4.4/netfilter-bridge-ebt_among-add-more-missing-match-size-checks.patch queue-4.4/netfilter-drop-template-ct-when-conntrack-is-skipped.patch