The level of struct nft_ctx is updated by nf_tables_check_loops().
That is used to validate jumpstack depth.
But jumpstack validation routine doesn't update and validate recursively.
So, in some cases, chain depth can be bigger than the NFT_JUMP_STACK_SIZE.
After this patch, The jumpstack validation routine is located in
the nft_chain_validate().
When new rules or new set elements are added,
the nft_table_validate() is called by the nf_tables_newrule
and the nf_tables_newsetelem.
The nft_table_validate() calls the nft_chain_validate()
that visit all their children chains recursively.
So it can update depth of chain certainly.
Reproducer:
%cat ./test.sh
#!/bin/bash
nft add table ip filter
nft add chain ip filter input { type filter hook input priority 0\; }
for ((i=0;i<20;i++)); do
nft add chain ip filter a$i
done
nft add rule ip filter input jump a1
for ((i=0;i<10;i++)); do
nft add rule ip filter a$i jump a$((i+1))
done
for ((i=11;i<19;i++)); do
nft add rule ip filter a$i jump a$((i+1))
done
nft add rule ip filter a10 jump a11
Result:
[ 253.931782] WARNING: CPU: 1 PID: 0 at net/netfilter/nf_tables_core.c:186 nft_do_chain+0xacc/0xdf0 [nf_tables]
[ 253.931915] Modules linked in: nf_tables nfnetlink ip_tables x_tables
[ 253.932153] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.18.0-rc3+ #48
[ 253.932153] RIP: 0010:nft_do_chain+0xacc/0xdf0 [nf_tables]
[ 253.932153] Code: 83 f8 fb 0f 84 c7 00 00 00 e9 d0 00 00 00 83 f8 fd 74 0e 83 f8 ff 0f 84 b4 00 00 00 e9 bd 00 00 00 83 bd 64 fd ff ff 0f 76 09 <0f> 0b 31 c0 e9 bc 02 00 00 44 8b ad 64 fd
[ 253.933807] RSP: 0018:ffff88011b807570 EFLAGS: 00010212
[ 253.933807] RAX: 00000000fffffffd RBX: ffff88011b807660 RCX: 0000000000000000
[ 253.933807] RDX: 0000000000000010 RSI: ffff880112b39d78 RDI: ffff88011b807670
[ 253.933807] RBP: ffff88011b807850 R08: ffffed0023700ece R09: ffffed0023700ecd
[ 253.933807] R10: ffff88011b80766f R11: ffffed0023700ece R12: ffff88011b807898
[ 253.933807] R13: ffff880112b39d80 R14: ffff880112b39d60 R15: dffffc0000000000
[ 253.933807] FS: 0000000000000000(0000) GS:ffff88011b800000(0000) knlGS:0000000000000000
[ 253.933807] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 253.933807] CR2: 00000000014f1008 CR3: 000000006b216000 CR4: 00000000001006e0
[ 253.933807] Call Trace:
[ 253.933807] <IRQ>
[ 253.933807] ? sched_clock_cpu+0x132/0x170
[ 253.933807] ? __nft_trace_packet+0x180/0x180 [nf_tables]
[ 253.933807] ? sched_clock_cpu+0x132/0x170
[ 253.933807] ? debug_show_all_locks+0x290/0x290
[ 253.933807] ? __lock_acquire+0x4835/0x4af0
[ 253.933807] ? inet_ehash_locks_alloc+0x1a0/0x1a0
[ 253.933807] ? unwind_next_frame+0x159e/0x1840
[ 253.933807] ? __read_once_size_nocheck.constprop.4+0x5/0x10
[ 253.933807] ? nft_do_chain_ipv4+0x197/0x1e0 [nf_tables]
[ 253.933807] ? nft_do_chain+0x5/0xdf0 [nf_tables]
[ 253.933807] nft_do_chain_ipv4+0x197/0x1e0 [nf_tables]
[ 253.933807] ? nft_do_chain_arp+0xb0/0xb0 [nf_tables]
[ 253.933807] ? __lock_is_held+0x9d/0x130
[ 253.933807] nf_hook_slow+0xc4/0x150
[ 253.933807] ip_local_deliver+0x28b/0x380
[ 253.933807] ? ip_call_ra_chain+0x3e0/0x3e0
[ 253.933807] ? ip_rcv_finish+0x1610/0x1610
[ 253.933807] ip_rcv+0xbcc/0xcc0
[ 253.933807] ? debug_show_all_locks+0x290/0x290
[ 253.933807] ? ip_local_deliver+0x380/0x380
[ 253.933807] ? __lock_is_held+0x9d/0x130
[ 253.933807] ? ip_local_deliver+0x380/0x380
[ 253.933807] __netif_receive_skb_core+0x1c9c/0x2240
V2:
- add missing initialize code, requested by Pablo Neira Ayuso
Signed-off-by: Taehee Yoo <ap420073@xxxxxxxxx>
---
include/net/netfilter/nf_tables.h | 4 ++--
net/netfilter/nf_tables_api.c | 11 ++++-------
net/netfilter/nft_immediate.c | 3 +++
net/netfilter/nft_lookup.c | 13 +++++++++++--
4 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 08c005c..4e82a4c 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -150,6 +150,7 @@ static inline void nft_data_debug(const struct nft_data *data)
* @portid: netlink portID of the original message
* @seq: netlink sequence number
* @family: protocol family
+ * @level: depth of the chains
* @report: notify via unicast netlink message
*/
struct nft_ctx {
@@ -160,6 +161,7 @@ struct nft_ctx {
u32 portid;
u32 seq;
u8 family;
+ u8 level;
bool report;
};
@@ -865,7 +867,6 @@ enum nft_chain_flags {
* @table: table that this chain belongs to
* @handle: chain handle
* @use: number of jump references to this chain
- * @level: length of longest path to this chain
* @flags: bitmask of enum nft_chain_flags
* @name: name of the chain
*/
@@ -878,7 +879,6 @@ struct nft_chain {
struct nft_table *table;
u64 handle;
u32 use;
- u16 level;
u8 flags:6,
genmask:2;
char *name;
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 896d4a3..d41fa2c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -75,6 +75,7 @@ static void nft_ctx_init(struct nft_ctx *ctx,
{
ctx->net = net;
ctx->family = family;
+ ctx->level = 0;
ctx->table = table;
ctx->chain = chain;
ctx->nla = nla;
@@ -2384,6 +2385,9 @@ int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain)
struct nft_rule *rule;
int err;
+ if (ctx->level == NFT_JUMP_STACK_SIZE)
+ return -EMLINK;
+
list_for_each_entry(rule, &chain->rules, list) {
if (!nft_is_active_next(ctx->net, rule))
continue;
@@ -6837,13 +6841,6 @@ int nft_validate_register_store(const struct nft_ctx *ctx,
err = nf_tables_check_loops(ctx, data->verdict.chain);
if (err < 0)
return err;
-
- if (ctx->chain->level + 1 >
- data->verdict.chain->level) {
- if (ctx->chain->level + 1 == NFT_JUMP_STACK_SIZE)
- return -EMLINK;
- data->verdict.chain->level = ctx->chain->level + 1;
- }
}
return 0;
diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index 15adf8c..9f0542e 100644
--- a/net/netfilter/nft_immediate.c
+++ b/net/netfilter/nft_immediate.c
@@ -99,6 +99,7 @@ static int nft_immediate_validate(const struct nft_ctx *ctx,
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
const struct nft_data *data;
+ struct nft_ctx *pctx = (struct nft_ctx *)ctx;
int err;
if (priv->dreg != NFT_REG_VERDICT)
@@ -109,9 +110,11 @@ static int nft_immediate_validate(const struct nft_ctx *ctx,
switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
+ pctx->level++;
err = nft_chain_validate(ctx, data->verdict.chain);
if (err < 0)
return err;
+ pctx->level--;
break;
default:
break;
diff --git a/net/netfilter/nft_lookup.c b/net/netfilter/nft_lookup.c
index 42e6fad..af13093 100644
--- a/net/netfilter/nft_lookup.c
+++ b/net/netfilter/nft_lookup.c
@@ -156,6 +156,8 @@ static int nft_lookup_validate_setelem(const struct nft_ctx *ctx,
{
const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
const struct nft_data *data;
+ struct nft_ctx *pctx = (struct nft_ctx *)ctx;
+ int err;
if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
*nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
@@ -165,10 +167,17 @@ static int nft_lookup_validate_setelem(const struct nft_ctx *ctx,
switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
- return nft_chain_validate(ctx, data->verdict.chain);
+ pctx->level++;
+ err = nft_chain_validate(ctx, data->verdict.chain);
+ if (err < 0)
+ return err;
+ pctx->level--;
+ break;
default:
- return 0;
+ break;
}
+
+ return 0;
}
static int nft_lookup_validate(const struct nft_ctx *ctx,
--
2.9.3
--
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