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Message-Id: <20210622220001.198508-6-pablo@netfilter.org>
Date: Tue, 22 Jun 2021 23:59:58 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 5/8] netfilter: nf_tables: memleak in hw offload abort path
Release flow from the abort path, this is easy to reproduce since
b72920f6e4a9 ("netfilter: nftables: counter hardware offload support").
If the preparation phase fails, then the abort path is exercised without
releasing the flow rule object.
unreferenced object 0xffff8881f0fa7700 (size 128):
comm "nft", pid 1335, jiffies 4294931120 (age 4163.740s)
hex dump (first 32 bytes):
08 e4 de 13 82 88 ff ff 98 e4 de 13 82 88 ff ff ................
48 e4 de 13 82 88 ff ff 01 00 00 00 00 00 00 00 H...............
backtrace:
[<00000000634547e7>] flow_rule_alloc+0x26/0x80
[<00000000c8426156>] nft_flow_rule_create+0xc9/0x3f0 [nf_tables]
[<0000000075ff8e46>] nf_tables_newrule+0xc79/0x10a0 [nf_tables]
[<00000000ba65e40e>] nfnetlink_rcv_batch+0xaac/0xf90 [nfnetlink]
[<00000000505c614a>] nfnetlink_rcv+0x1bb/0x1f0 [nfnetlink]
[<00000000eb78e1fe>] netlink_unicast+0x34b/0x480
[<00000000a8f72c94>] netlink_sendmsg+0x3af/0x690
[<000000009cb1ddf4>] sock_sendmsg+0x96/0xa0
[<0000000039d06e44>] ____sys_sendmsg+0x3fe/0x440
[<00000000137e82ca>] ___sys_sendmsg+0xd8/0x140
[<000000000c6bf6a6>] __sys_sendmsg+0xb3/0x130
[<0000000043bd6268>] do_syscall_64+0x40/0xb0
[<00000000afdebc2d>] entry_SYSCALL_64_after_hwframe+0x44/0xae
Remove flow rule release from the offload commit path, otherwise error
from the offload commit phase might trigger a double-free due to the
execution of the abort_offload -> abort. After this patch, the abort
path takes care of releasing the flow rule.
This fix also needs to move the nft_flow_rule_create() call before the
transaction object is added otherwise the abort path might find a NULL
pointer to the flow rule object for the NFT_CHAIN_HW_OFFLOAD case.
While at it, rename BASIC-like goto tags to slightly more meaningful
names rather than adding a new "err3" tag.
Fixes: 63b48c73ff56 ("netfilter: nf_tables_offload: undo updates if transaction fails")
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
net/netfilter/nf_tables_api.c | 51 +++++++++++++++++++------------
net/netfilter/nf_tables_offload.c | 17 -----------
2 files changed, 31 insertions(+), 37 deletions(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index bf4d6ec9fc55..ca9ec8721e6c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3243,9 +3243,9 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
u8 genmask = nft_genmask_next(info->net);
struct nft_rule *rule, *old_rule = NULL;
struct nft_expr_info *expr_info = NULL;
+ struct nft_flow_rule *flow = NULL;
int family = nfmsg->nfgen_family;
struct net *net = info->net;
- struct nft_flow_rule *flow;
struct nft_userdata *udata;
struct nft_table *table;
struct nft_chain *chain;
@@ -3340,13 +3340,13 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
err = -EINVAL;
if (nla_type(tmp) != NFTA_LIST_ELEM)
- goto err1;
+ goto err_release_expr;
if (n == NFT_RULE_MAXEXPRS)
- goto err1;
+ goto err_release_expr;
err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
if (err < 0) {
NL_SET_BAD_ATTR(extack, tmp);
- goto err1;
+ goto err_release_expr;
}
size += expr_info[n].ops->size;
n++;
@@ -3355,7 +3355,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
/* Check for overflow of dlen field */
err = -EFBIG;
if (size >= 1 << 12)
- goto err1;
+ goto err_release_expr;
if (nla[NFTA_RULE_USERDATA]) {
ulen = nla_len(nla[NFTA_RULE_USERDATA]);
@@ -3366,7 +3366,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
err = -ENOMEM;
rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL);
if (rule == NULL)
- goto err1;
+ goto err_release_expr;
nft_activate_next(net, rule);
@@ -3385,7 +3385,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
if (err < 0) {
NL_SET_BAD_ATTR(extack, expr_info[i].attr);
- goto err2;
+ goto err_release_rule;
}
if (expr_info[i].ops->validate)
@@ -3395,16 +3395,24 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
expr = nft_expr_next(expr);
}
+ if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
+ flow = nft_flow_rule_create(net, rule);
+ if (IS_ERR(flow)) {
+ err = PTR_ERR(flow);
+ goto err_release_rule;
+ }
+ }
+
if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
if (trans == NULL) {
err = -ENOMEM;
- goto err2;
+ goto err_destroy_flow_rule;
}
err = nft_delrule(&ctx, old_rule);
if (err < 0) {
nft_trans_destroy(trans);
- goto err2;
+ goto err_destroy_flow_rule;
}
list_add_tail_rcu(&rule->list, &old_rule->list);
@@ -3412,7 +3420,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
if (!trans) {
err = -ENOMEM;
- goto err2;
+ goto err_destroy_flow_rule;
}
if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
@@ -3430,21 +3438,19 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
kvfree(expr_info);
chain->use++;
+ if (flow)
+ nft_trans_flow_rule(trans) = flow;
+
if (nft_net->validate_state == NFT_VALIDATE_DO)
return nft_table_validate(net, table);
- if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
- flow = nft_flow_rule_create(net, rule);
- if (IS_ERR(flow))
- return PTR_ERR(flow);
-
- nft_trans_flow_rule(trans) = flow;
- }
-
return 0;
-err2:
+
+err_destroy_flow_rule:
+ nft_flow_rule_destroy(flow);
+err_release_rule:
nf_tables_rule_release(&ctx, rule);
-err1:
+err_release_expr:
for (i = 0; i < n; i++) {
if (expr_info[i].ops) {
module_put(expr_info[i].ops->type->owner);
@@ -8839,11 +8845,16 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
nft_rule_expr_deactivate(&trans->ctx,
nft_trans_rule(trans),
NFT_TRANS_ABORT);
+ if (trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD)
+ nft_flow_rule_destroy(nft_trans_flow_rule(trans));
break;
case NFT_MSG_DELRULE:
trans->ctx.chain->use++;
nft_clear(trans->ctx.net, nft_trans_rule(trans));
nft_rule_expr_activate(&trans->ctx, nft_trans_rule(trans));
+ if (trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD)
+ nft_flow_rule_destroy(nft_trans_flow_rule(trans));
+
nft_trans_destroy(trans);
break;
case NFT_MSG_NEWSET:
diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index a48c5fd53a80..ec701b84844f 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -594,23 +594,6 @@ int nft_flow_rule_offload_commit(struct net *net)
}
}
- list_for_each_entry(trans, &nft_net->commit_list, list) {
- if (trans->ctx.family != NFPROTO_NETDEV)
- continue;
-
- switch (trans->msg_type) {
- case NFT_MSG_NEWRULE:
- case NFT_MSG_DELRULE:
- if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD))
- continue;
-
- nft_flow_rule_destroy(nft_trans_flow_rule(trans));
- break;
- default:
- break;
- }
- }
-
return err;
}
--
2.30.2
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