diff mbox series

[net,4/6] netfilter: nf_tables: restrict anonymous set and map names to 16 bytes

Message ID 20240124191248.75463-5-pablo@netfilter.org (mailing list archive)
State Accepted
Commit b462579b2b86a8f5230543cadd3a4836be27baf7
Delegated to: Netdev Maintainers
Headers show
Series [net,1/6] netfilter: nf_tables: cleanup documentation | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net, async
netdev/ynl success SINGLE THREAD; Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1093 this patch: 1093
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 0 of 0 maintainers
netdev/build_clang success Errors and warnings before: 1095 this patch: 1095
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1111 this patch: 1111
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest pending net-next-2024-01-25--03-00

Commit Message

Pablo Neira Ayuso Jan. 24, 2024, 7:12 p.m. UTC 
From: Florian Westphal <fw@strlen.de>

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>
---
 net/netfilter/nf_tables_api.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4b55533ce5ca..02f45424644b 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -24,6 +24,7 @@ 
 #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;
 
@@ -4413,6 +4414,9 @@  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;