[PATCH nft 2/2,v4] cache: validate handle string length

[PATCH nft 2/2,v4] cache: validate handle string length

[Pablo Neira Ayuso]

Maximum supported string length for handle is NFT_NAME_MAXLEN, report an
error if user is exceeding this limit.

By validating from the cache evaluation phase, both the native and json
parsers handle input are validated.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v4: table is optional for CMD_OBJ_CHAINS.
    use h->... instead of cmd->... for flowtable.

 src/cache.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)

diff --git a/src/cache.c b/src/cache.c
index 9e2fe950a884..d0c645daa5c0 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -16,6 +16,7 @@
 #include <mnl.h>
 #include <libnftnl/chain.h>
 #include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
 
 static unsigned int evaluate_cache_add(struct cmd *cmd, unsigned int flags)
 {
@@ -262,6 +263,108 @@ static unsigned int evaluate_cache_list(struct nft_ctx *nft, struct cmd *cmd,
 	return flags;
 }
 
+static int nft_cmd_validate(const struct cmd *cmd, struct list_head *msgs)
+{
+	const struct handle *h = &cmd->handle;
+	const struct location *loc;
+
+	switch (cmd->obj) {
+	case CMD_OBJ_TABLE:
+		if (h->table.name &&
+		    strlen(h->table.name) > NFT_NAME_MAXLEN) {
+			loc = &h->table.location;
+			goto err_name_too_long;
+		}
+		break;
+	case CMD_OBJ_RULE:
+	case CMD_OBJ_CHAIN:
+	case CMD_OBJ_CHAINS:
+		if (h->table.name &&
+		    strlen(h->table.name) > NFT_NAME_MAXLEN) {
+			loc = &h->table.location;
+			goto err_name_too_long;
+		}
+		if (h->chain.name &&
+		    strlen(h->chain.name) > NFT_NAME_MAXLEN) {
+			loc = &h->chain.location;
+			goto err_name_too_long;
+		}
+		break;
+	case CMD_OBJ_ELEMENTS:
+	case CMD_OBJ_SET:
+	case CMD_OBJ_SETS:
+	case CMD_OBJ_MAP:
+	case CMD_OBJ_MAPS:
+	case CMD_OBJ_METER:
+	case CMD_OBJ_METERS:
+		if (h->table.name &&
+		    strlen(h->table.name) > NFT_NAME_MAXLEN) {
+			loc = &h->table.location;
+			goto err_name_too_long;
+		}
+		if (h->set.name &&
+		    strlen(h->set.name) > NFT_NAME_MAXLEN) {
+			loc = &h->set.location;
+			goto err_name_too_long;
+		}
+		break;
+	case CMD_OBJ_FLOWTABLE:
+	case CMD_OBJ_FLOWTABLES:
+		if (h->table.name &&
+		    strlen(h->table.name) > NFT_NAME_MAXLEN) {
+			loc = &h->table.location;
+			goto err_name_too_long;
+		}
+		if (h->flowtable.name &&
+		    strlen(h->flowtable.name) > NFT_NAME_MAXLEN) {
+			loc = &h->flowtable.location;
+			goto err_name_too_long;
+		}
+		break;
+	case CMD_OBJ_INVALID:
+	case CMD_OBJ_EXPR:
+	case CMD_OBJ_RULESET:
+	case CMD_OBJ_MARKUP:
+	case CMD_OBJ_MONITOR:
+	case CMD_OBJ_SETELEMS:
+	case CMD_OBJ_HOOKS:
+		break;
+	case CMD_OBJ_COUNTER:
+	case CMD_OBJ_COUNTERS:
+	case CMD_OBJ_QUOTA:
+	case CMD_OBJ_QUOTAS:
+	case CMD_OBJ_LIMIT:
+	case CMD_OBJ_LIMITS:
+	case CMD_OBJ_SECMARK:
+	case CMD_OBJ_SECMARKS:
+	case CMD_OBJ_SYNPROXY:
+	case CMD_OBJ_SYNPROXYS:
+	case CMD_OBJ_CT_HELPER:
+	case CMD_OBJ_CT_HELPERS:
+	case CMD_OBJ_CT_TIMEOUT:
+	case CMD_OBJ_CT_EXPECT:
+		if (h->table.name &&
+		    strlen(h->table.name) > NFT_NAME_MAXLEN) {
+			loc = &h->table.location;
+			goto err_name_too_long;
+		}
+		if (h->obj.name &&
+		    strlen(h->obj.name) > NFT_NAME_MAXLEN) {
+			loc = &h->obj.location;
+			goto err_name_too_long;
+		}
+		break;
+	}
+
+	return 0;
+
+err_name_too_long:
+	erec_queue(error(loc, "name too long, %d characters maximum allowed",
+			 NFT_NAME_MAXLEN),
+		   msgs);
+	return -1;
+}
+
 int nft_cache_evaluate(struct nft_ctx *nft, struct list_head *cmds,
 		       struct list_head *msgs, struct nft_cache_filter *filter,
 		       unsigned int *pflags)
@@ -270,6 +373,9 @@ int nft_cache_evaluate(struct nft_ctx *nft, struct list_head *cmds,
 	struct cmd *cmd;
 
 	list_for_each_entry(cmd, cmds, list) {
+		if (nft_cmd_validate(cmd, msgs) < 0)
+			return -1;
+
 		if (filter->list.table && cmd->op != CMD_LIST)
 			memset(&filter->list, 0, sizeof(filter->list));
 
-- 
2.30.2