4.19-stable review patch. If anyone has any objections, please let me know.
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From: Florian Westphal fw@strlen.de
[ Upstream commit b462579b2b86a8f5230543cadd3a4836be27baf7 ]
nftables has two types of sets/maps, one where userspace defines the name, and anonymous sets/maps, where userspace defines a template name.
For the latter, kernel requires presence of exactly one "%d". nftables uses "__set%d" and "__map%d" for this. The kernel will expand the format specifier and replaces it with the smallest unused number.
As-is, userspace could define a template name that allows to move the set name past the 256 bytes upperlimit (post-expansion).
I don't see how this could be a problem, but I would prefer if userspace cannot do this, so add a limit of 16 bytes for the '%d' template name.
16 bytes is the old total upper limit for set names that existed when nf_tables was merged initially.
Fixes: 387454901bd6 ("netfilter: nf_tables: Allow set names of up to 255 chars") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nf_tables_api.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index e0c224dea316..4465b832305f 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -26,6 +26,7 @@ #include <net/sock.h>
#define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-")) +#define NFT_SET_MAX_ANONLEN 16
unsigned int nf_tables_net_id __read_mostly;
@@ -3184,6 +3185,9 @@ static int nf_tables_set_alloc_name(struct nft_ctx *ctx, struct nft_set *set, if (p[1] != 'd' || strchr(p + 2, '%')) return -EINVAL;
+ if (strnlen(name, NFT_SET_MAX_ANONLEN) >= NFT_SET_MAX_ANONLEN) + return -EINVAL; + inuse = (unsigned long *)get_zeroed_page(GFP_KERNEL); if (inuse == NULL) return -ENOMEM;