From f6594c372afd5cec8b1e9ee9ea8f8819d59c6fb1 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 19 Dec 2022 20:09:00 +0100 Subject: netfilter: nf_tables: perform type checking for existing sets If a ruleset declares a set name that matches an existing set in the kernel, then validate that this declaration really refers to the same set, otherwise bail out with EEXIST. Currently, the kernel reports success when adding a set that already exists in the kernel. This usually results in EINVAL errors at a later stage, when the user adds elements to the set, if the set declaration mismatches the existing set representation in the kernel. Add a new function to check that the set declaration really refers to the same existing set in the kernel. Fixes: 96518518cc41 ("netfilter: add nftables") Reported-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 36 +++++++++++++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-) (limited to 'net') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index b9b0ae29f5f6..319887f4d3ef 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -4441,6 +4441,34 @@ err_set_expr_alloc: return err; } +static bool nft_set_is_same(const struct nft_set *set, + const struct nft_set_desc *desc, + struct nft_expr *exprs[], u32 num_exprs, u32 flags) +{ + int i; + + if (set->ktype != desc->ktype || + set->dtype != desc->dtype || + set->flags != flags || + set->klen != desc->klen || + set->dlen != desc->dlen || + set->field_count != desc->field_count || + set->num_exprs != num_exprs) + return false; + + for (i = 0; i < desc->field_count; i++) { + if (set->field_len[i] != desc->field_len[i]) + return false; + } + + for (i = 0; i < num_exprs; i++) { + if (set->exprs[i]->ops != exprs[i]->ops) + return false; + } + + return true; +} + static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info, const struct nlattr * const nla[]) { @@ -4595,10 +4623,16 @@ static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info, if (err < 0) return err; + err = 0; + if (!nft_set_is_same(set, &desc, exprs, num_exprs, flags)) { + NL_SET_BAD_ATTR(extack, nla[NFTA_SET_NAME]); + err = -EEXIST; + } + for (i = 0; i < num_exprs; i++) nft_expr_destroy(&ctx, exprs[i]); - return 0; + return err; } if (!(info->nlh->nlmsg_flags & NLM_F_CREATE)) -- cgit v1.2.3