From 2747cab9c49b570347c86ff59daec93a1432b0bc Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Wed, 27 Apr 2022 14:37:00 +0200
Subject: [PATCH] mnl: do not use expr->identifier to fetch device name

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2070924
Upstream Status: nftables commit 78bbe7f7a55be

commit 78bbe7f7a55be48909067e25900de27623d8fa6a
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date:   Wed Feb 19 21:05:26 2020 +0100

    mnl: do not use expr->identifier to fetch device name

    This string might not be nul-terminated, resulting in spurious errors
    when adding netdev chains.

    Fixes: 3fdc7541fba0 ("src: add multidevice support for netdev chain")
    Fixes: 92911b362e90 ("src: add support to add flowtables")
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/mnl.c          | 33 +++++++++++++++++++++++++++++----
 src/parser_bison.y |  6 +++---
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/src/mnl.c b/src/mnl.c
index 44cf1a4..f881d97 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -26,6 +26,7 @@
 
 #include <mnl.h>
 #include <string.h>
+#include <net/if.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>
 #include <fcntl.h>
@@ -529,7 +530,9 @@ int mnl_nft_chain_add(struct netlink_ctx *ctx, const struct cmd *cmd,
 {
 	int priority, policy, i = 0;
 	struct nftnl_chain *nlc;
+	unsigned int ifname_len;
 	const char **dev_array;
+	char ifname[IFNAMSIZ];
 	struct nlmsghdr *nlh;
 	struct expr *expr;
 	int dev_array_len;
@@ -562,7 +565,12 @@ int mnl_nft_chain_add(struct netlink_ctx *ctx, const struct cmd *cmd,
 			dev_array = xmalloc(sizeof(char *) * 8);
 			dev_array_len = 8;
 			list_for_each_entry(expr, &cmd->chain->dev_expr->expressions, list) {
-				dev_array[i++] = expr->identifier;
+				ifname_len = div_round_up(expr->len, BITS_PER_BYTE);
+				memset(ifname, 0, sizeof(ifname));
+				mpz_export_data(ifname, expr->value,
+						BYTEORDER_HOST_ENDIAN,
+						ifname_len);
+				dev_array[i++] = xstrdup(ifname);
 				if (i == dev_array_len) {
 					dev_array_len *= 2;
 					dev_array = xrealloc(dev_array,
@@ -577,6 +585,10 @@ int mnl_nft_chain_add(struct netlink_ctx *ctx, const struct cmd *cmd,
 				nftnl_chain_set_data(nlc, NFTNL_CHAIN_DEVICES, dev_array,
 						     sizeof(char *) * dev_array_len);
 
+			i = 0;
+			while (dev_array[i] != NULL)
+				xfree(dev_array[i++]);
+
 			xfree(dev_array);
 		}
 	}
@@ -1488,7 +1500,9 @@ int mnl_nft_flowtable_add(struct netlink_ctx *ctx, const struct cmd *cmd,
 			  unsigned int flags)
 {
 	struct nftnl_flowtable *flo;
+	unsigned int ifname_len;
 	const char **dev_array;
+	char ifname[IFNAMSIZ];
 	struct nlmsghdr *nlh;
 	int i = 0, len = 1;
 	struct expr *expr;
@@ -1513,13 +1527,24 @@ int mnl_nft_flowtable_add(struct netlink_ctx *ctx, const struct cmd *cmd,
 	list_for_each_entry(expr, &cmd->flowtable->dev_expr->expressions, list)
 		len++;
 
-	dev_array = calloc(len, sizeof(char *));
-	list_for_each_entry(expr, &cmd->flowtable->dev_expr->expressions, list)
-		dev_array[i++] = expr->identifier;
+	dev_array = xmalloc(sizeof(char *) * len);
+
+	list_for_each_entry(expr, &cmd->flowtable->dev_expr->expressions, list) {
+		ifname_len = div_round_up(expr->len, BITS_PER_BYTE);
+		memset(ifname, 0, sizeof(ifname));
+		mpz_export_data(ifname, expr->value, BYTEORDER_HOST_ENDIAN,
+				ifname_len);
+		dev_array[i++] = xstrdup(ifname);
+	}
 
 	dev_array[i] = NULL;
 	nftnl_flowtable_set_data(flo, NFTNL_FLOWTABLE_DEVICES,
 				 dev_array, sizeof(char *) * len);
+
+	i = 0;
+	while (dev_array[i] != NULL)
+		xfree(dev_array[i++]);
+
 	free(dev_array);
 
 	netlink_dump_flowtable(flo, ctx);
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 2cdf8ec..dc87571 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1909,9 +1909,9 @@ flowtable_list_expr	:	flowtable_expr_member
 
 flowtable_expr_member	:	STRING
 			{
-				$$ = symbol_expr_alloc(&@$, SYMBOL_VALUE,
-						       current_scope(state),
-						       $1);
+				$$ = constant_expr_alloc(&@$, &string_type,
+							 BYTEORDER_HOST_ENDIAN,
+							 strlen($1) * BITS_PER_BYTE, $1);
 				xfree($1);
 			}
 			;
-- 
2.34.1