[PATCH net 0/4] Netfilter fixes for net

[PATCH net 0/4] Netfilter fixes for net

[Pablo Neira Ayuso]

Hi Jakub, David,

The following patchset contains Netfilter fixes for net:

1) Incorrect loop in error path of nft_set_elem_expr_clone(),
   from Colin Ian King.

2) Missing xt_table_get_private_protected() to access table
   private data in x_tables, from Subash Abhinov Kasiviswanathan.

3) Possible oops in ipset hash type resize, from Vasily Averin.

4) Fix shift-out-of-bounds in ipset hash type, also from Vasily.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf.git

Thanks!

----------------------------------------------------------------

The following changes since commit 3db1a3fa98808aa90f95ec3e0fa2fc7abf28f5c9:

  Merge tag 'staging-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging (2020-12-15 14:18:40 -0800)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf.git HEAD

for you to fetch changes up to 5c8193f568ae16f3242abad6518dc2ca6c8eef86:

  netfilter: ipset: fix shift-out-of-bounds in htable_bits() (2020-12-17 19:44:52 +0100)

----------------------------------------------------------------
Colin Ian King (1):
      netfilter: nftables: fix incorrect increment of loop counter

Subash Abhinov Kasiviswanathan (1):
      netfilter: x_tables: Update remaining dereference to RCU

Vasily Averin (2):
      netfilter: ipset: fixes possible oops in mtype_resize
      netfilter: ipset: fix shift-out-of-bounds in htable_bits()

 net/ipv4/netfilter/arp_tables.c       |  2 +-
 net/ipv4/netfilter/ip_tables.c        |  2 +-
 net/ipv6/netfilter/ip6_tables.c       |  2 +-
 net/netfilter/ipset/ip_set_hash_gen.h | 42 +++++++++++++++--------------------
 net/netfilter/nf_tables_api.c         |  4 ++--
 5 files changed, 23 insertions(+), 29 deletions(-)

[PATCH net 1/4] netfilter: nftables: fix incorrect increment of loop counter

[Pablo Neira Ayuso]

From: Colin Ian King <colin.king@canonical.com>

The intention of the err_expr cleanup path is to iterate over the
allocated expr_array objects and free them, starting from i - 1 and
working down to the start of the array. Currently the loop counter
is being incremented instead of decremented and also the index i is
being used instead of k, repeatedly destroying the same expr_array
element.  Fix this by decrementing k and using k as the index into
expr_array.

Addresses-Coverity: ("Infinite loop")
Fixes: 8cfd9b0f8515 ("netfilter: nftables: generalize set expressions support")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8d5aa0ac45f4..4186b1e52d58 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5254,8 +5254,8 @@ static int nft_set_elem_expr_clone(const struct nft_ctx *ctx,
 	return 0;
 
 err_expr:
-	for (k = i - 1; k >= 0; k++)
-		nft_expr_destroy(ctx, expr_array[i]);
+	for (k = i - 1; k >= 0; k--)
+		nft_expr_destroy(ctx, expr_array[k]);
 
 	return -ENOMEM;
 }
-- 
2.20.1

Re: [PATCH net 1/4] netfilter: nftables: fix incorrect increment of loop counter

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (refs/heads/master):

On Fri, 18 Dec 2020 13:04:06 +0100 you wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The intention of the err_expr cleanup path is to iterate over the
> allocated expr_array objects and free them, starting from i - 1 and
> working down to the start of the array. Currently the loop counter
> is being incremented instead of decremented and also the index i is
> being used instead of k, repeatedly destroying the same expr_array
> element.  Fix this by decrementing k and using k as the index into
> expr_array.
> 
> [...]

Here is the summary with links:
  - [net,1/4] netfilter: nftables: fix incorrect increment of loop counter
    https://git.kernel.org/netdev/net/c/161b838e25c6
  - [net,2/4] netfilter: x_tables: Update remaining dereference to RCU
    https://git.kernel.org/netdev/net/c/443d6e86f821
  - [net,3/4] netfilter: ipset: fixes possible oops in mtype_resize
    https://git.kernel.org/netdev/net/c/2b33d6ffa9e3
  - [net,4/4] netfilter: ipset: fix shift-out-of-bounds in htable_bits()
    https://git.kernel.org/netdev/net/c/5c8193f568ae

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[PATCH net 2/4] netfilter: x_tables: Update remaining dereference to RCU

[Pablo Neira Ayuso]

From: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

This fixes the dereference to fetch the RCU pointer when holding
the appropriate xtables lock.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: cc00bcaa5899 ("netfilter: x_tables: Switch synchronization to RCU")
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/ipv4/netfilter/arp_tables.c | 2 +-
 net/ipv4/netfilter/ip_tables.c  | 2 +-
 net/ipv6/netfilter/ip6_tables.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 563b62b76a5f..c576a63d09db 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1379,7 +1379,7 @@ static int compat_get_entries(struct net *net,
 	xt_compat_lock(NFPROTO_ARP);
 	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
 	if (!IS_ERR(t)) {
-		const struct xt_table_info *private = t->private;
+		const struct xt_table_info *private = xt_table_get_private_protected(t);
 		struct xt_table_info info;
 
 		ret = compat_table_info(private, &info);
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 6e2851f8d3a3..e8f6f9d86237 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1589,7 +1589,7 @@ compat_get_entries(struct net *net, struct compat_ipt_get_entries __user *uptr,
 	xt_compat_lock(AF_INET);
 	t = xt_find_table_lock(net, AF_INET, get.name);
 	if (!IS_ERR(t)) {
-		const struct xt_table_info *private = t->private;
+		const struct xt_table_info *private = xt_table_get_private_protected(t);
 		struct xt_table_info info;
 		ret = compat_table_info(private, &info);
 		if (!ret && get.size == info.size)
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index c4f532f4d311..0d453fa9e327 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1598,7 +1598,7 @@ compat_get_entries(struct net *net, struct compat_ip6t_get_entries __user *uptr,
 	xt_compat_lock(AF_INET6);
 	t = xt_find_table_lock(net, AF_INET6, get.name);
 	if (!IS_ERR(t)) {
-		const struct xt_table_info *private = t->private;
+		const struct xt_table_info *private = xt_table_get_private_protected(t);
 		struct xt_table_info info;
 		ret = compat_table_info(private, &info);
 		if (!ret && get.size == info.size)
-- 
2.20.1

[PATCH net 3/4] netfilter: ipset: fixes possible oops in mtype_resize

[Pablo Neira Ayuso]

From: Vasily Averin <vvs@virtuozzo.com>

currently mtype_resize() can cause oops

        t = ip_set_alloc(htable_size(htable_bits));
        if (!t) {
                ret = -ENOMEM;
                goto out;
        }
        t->hregion = ip_set_alloc(ahash_sizeof_regions(htable_bits));

Increased htable_bits can force htable_size() to return 0.
In own turn ip_set_alloc(0) returns not 0 but ZERO_SIZE_PTR,
so follwoing access to t->hregion should trigger an OOPS.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipset/ip_set_hash_gen.h | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index 5f1208ad049e..1e7dddf824ae 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -640,7 +640,7 @@ mtype_resize(struct ip_set *set, bool retried)
 	struct htype *h = set->data;
 	struct htable *t, *orig;
 	u8 htable_bits;
-	size_t dsize = set->dsize;
+	size_t hsize, dsize = set->dsize;
 #ifdef IP_SET_HASH_WITH_NETS
 	u8 flags;
 	struct mtype_elem *tmp;
@@ -664,14 +664,12 @@ mtype_resize(struct ip_set *set, bool retried)
 retry:
 	ret = 0;
 	htable_bits++;
-	if (!htable_bits) {
-		/* In case we have plenty of memory :-) */
-		pr_warn("Cannot increase the hashsize of set %s further\n",
-			set->name);
-		ret = -IPSET_ERR_HASH_FULL;
-		goto out;
-	}
-	t = ip_set_alloc(htable_size(htable_bits));
+	if (!htable_bits)
+		goto hbwarn;
+	hsize = htable_size(htable_bits);
+	if (!hsize)
+		goto hbwarn;
+	t = ip_set_alloc(hsize);
 	if (!t) {
 		ret = -ENOMEM;
 		goto out;
@@ -813,6 +811,12 @@ mtype_resize(struct ip_set *set, bool retried)
 	if (ret == -EAGAIN)
 		goto retry;
 	goto out;
+
+hbwarn:
+	/* In case we have plenty of memory :-) */
+	pr_warn("Cannot increase the hashsize of set %s further\n", set->name);
+	ret = -IPSET_ERR_HASH_FULL;
+	goto out;
 }
 
 /* Get the current number of elements and ext_size in the set  */
-- 
2.20.1

[PATCH net 4/4] netfilter: ipset: fix shift-out-of-bounds in htable_bits()

[Pablo Neira Ayuso]

From: Vasily Averin <vvs@virtuozzo.com>

htable_bits() can call jhash_size(32) and trigger shift-out-of-bounds

UBSAN: shift-out-of-bounds in net/netfilter/ipset/ip_set_hash_gen.h:151:6
shift exponent 32 is too large for 32-bit type 'unsigned int'
CPU: 0 PID: 8498 Comm: syz-executor519
 Not tainted 5.10.0-rc7-next-20201208-syzkaller #0
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
 htable_bits net/netfilter/ipset/ip_set_hash_gen.h:151 [inline]
 hash_mac_create.cold+0x58/0x9b net/netfilter/ipset/ip_set_hash_gen.h:1524
 ip_set_create+0x610/0x1380 net/netfilter/ipset/ip_set_core.c:1115
 nfnetlink_rcv_msg+0xecc/0x1180 net/netfilter/nfnetlink.c:252
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
 nfnetlink_rcv+0x1ac/0x420 net/netfilter/nfnetlink.c:600
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x907/0xe40 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2345
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2399
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2432
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

This patch replaces htable_bits() by simple fls(hashsize - 1) call:
it alone returns valid nbits both for round and non-round hashsizes.
It is normal to set any nbits here because it is validated inside
following htable_size() call which returns 0 for nbits>31.

Fixes: 1feab10d7e6d("netfilter: ipset: Unified hash type generation")
Reported-by: syzbot+d66bfadebca46cf61a2b@syzkaller.appspotmail.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipset/ip_set_hash_gen.h | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index 1e7dddf824ae..6186358eac7c 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -141,20 +141,6 @@ htable_size(u8 hbits)
 	return hsize * sizeof(struct hbucket *) + sizeof(struct htable);
 }
 
-/* Compute htable_bits from the user input parameter hashsize */
-static u8
-htable_bits(u32 hashsize)
-{
-	/* Assume that hashsize == 2^htable_bits */
-	u8 bits = fls(hashsize - 1);
-
-	if (jhash_size(bits) != hashsize)
-		/* Round up to the first 2^n value */
-		bits = fls(hashsize);
-
-	return bits;
-}
-
 #ifdef IP_SET_HASH_WITH_NETS
 #if IPSET_NET_COUNT > 1
 #define __CIDR(cidr, i)		(cidr[i])
@@ -1525,7 +1511,11 @@ IPSET_TOKEN(HTYPE, _create)(struct net *net, struct ip_set *set,
 	if (!h)
 		return -ENOMEM;
 
-	hbits = htable_bits(hashsize);
+	/* Compute htable_bits from the user input parameter hashsize.
+	 * Assume that hashsize == 2^htable_bits,
+	 * otherwise round up to the first 2^n value.
+	 */
+	hbits = fls(hashsize - 1);
 	hsize = htable_size(hbits);
 	if (hsize == 0) {
 		kfree(h);
-- 
2.20.1