diff mbox series

[SRU,J,v2,1/1] netfilter: nf_tables: restore set elements when delete set fails

Message ID 20240801153813.61841-3-hannah.peuckmann@canonical.com
State New
Headers show
Series CVE-2024-27012 | expand

Commit Message

Hannah Peuckmann Aug. 1, 2024, 3:38 p.m. UTC 
From: Pablo Neira Ayuso <pablo@netfilter.org>

From abort path, nft_mapelem_activate() needs to restore refcounters to
the original state. Currently, it uses the set->ops->walk() to iterate
over these set elements. The existing set iterator skips inactive
elements in the next generation, this does not work from the abort path
to restore the original state since it has to skip active elements
instead (not inactive ones).

This patch moves the check for inactive elements to the set iterator
callback, then it reverses the logic for the .activate case which
needs to skip active elements.

Toggle next generation bit for elements when delete set command is
invoked and call nft_clear() from .activate (abort) path to restore the
next generation bit.

The splat below shows an object in mappings memleak:

[43929.457523] ------------[ cut here ]------------
[43929.457532] WARNING: CPU: 0 PID: 1139 at include/net/netfilter/nf_tables.h:1237 nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[...]
[43929.458014] RIP: 0010:nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[43929.458076] Code: 83 f8 01 77 ab 49 8d 7c 24 08 e8 37 5e d0 de 49 8b 6c 24 08 48 8d 7d 50 e8 e9 5c d0 de 8b 45 50 8d 50 ff 89 55 50 85 c0 75 86 <0f> 0b eb 82 0f 0b eb b3 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90
[43929.458081] RSP: 0018:ffff888140f9f4b0 EFLAGS: 00010246
[43929.458086] RAX: 0000000000000000 RBX: ffff8881434f5288 RCX: dffffc0000000000
[43929.458090] RDX: 00000000ffffffff RSI: ffffffffa26d28a7 RDI: ffff88810ecc9550
[43929.458093] RBP: ffff88810ecc9500 R08: 0000000000000001 R09: ffffed10281f3e8f
[43929.458096] R10: 0000000000000003 R11: ffff0000ffff0000 R12: ffff8881434f52a0
[43929.458100] R13: ffff888140f9f5f4 R14: ffff888151c7a800 R15: 0000000000000002
[43929.458103] FS:  00007f0c687c4740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000
[43929.458107] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[43929.458111] CR2: 00007f58dbe5b008 CR3: 0000000123602005 CR4: 00000000001706f0
[43929.458114] Call Trace:
[43929.458118]  <TASK>
[43929.458121]  ? __warn+0x9f/0x1a0
[43929.458127]  ? nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[43929.458188]  ? report_bug+0x1b1/0x1e0
[43929.458196]  ? handle_bug+0x3c/0x70
[43929.458200]  ? exc_invalid_op+0x17/0x40
[43929.458211]  ? nft_setelem_data_deactivate+0xd7/0xf0 [nf_tables]
[43929.458271]  ? nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[43929.458332]  nft_mapelem_deactivate+0x24/0x30 [nf_tables]
[43929.458392]  nft_rhash_walk+0xdd/0x180 [nf_tables]
[43929.458453]  ? __pfx_nft_rhash_walk+0x10/0x10 [nf_tables]
[43929.458512]  ? rb_insert_color+0x2e/0x280
[43929.458520]  nft_map_deactivate+0xdc/0x1e0 [nf_tables]
[43929.458582]  ? __pfx_nft_map_deactivate+0x10/0x10 [nf_tables]
[43929.458642]  ? __pfx_nft_mapelem_deactivate+0x10/0x10 [nf_tables]
[43929.458701]  ? __rcu_read_unlock+0x46/0x70
[43929.458709]  nft_delset+0xff/0x110 [nf_tables]
[43929.458769]  nft_flush_table+0x16f/0x460 [nf_tables]
[43929.458830]  nf_tables_deltable+0x501/0x580 [nf_tables]

Fixes: 628bd3e49cba ("netfilter: nf_tables: drop map element references from preparation phase")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

(backported from commit e79b47a8615d42c68aaeb68971593333667382ed linux-6.9.y)
[hannsofie: context adjustments in nf_tables_api.c and nft_set_pipapo.c]
CVE-2024-27012
Signed-off-by: Hannah Peuckmann <hannah.peuckmann@canonical.com>
---
 net/netfilter/nf_tables_api.c  | 46 +++++++++++++++++++++++++++++-----
 net/netfilter/nft_set_bitmap.c |  4 +--
 net/netfilter/nft_set_hash.c   |  8 ++----
 net/netfilter/nft_set_pipapo.c |  4 +--
 net/netfilter/nft_set_rbtree.c |  4 +--
 5 files changed, 45 insertions(+), 21 deletions(-)

Comments

Manuel Diewald Aug. 2, 2024, 10:53 a.m. UTC | #1 
On Thu, Aug 01, 2024 at 05:38:13PM +0200, Hannah Peuckmann wrote:
> From: Pablo Neira Ayuso <pablo@netfilter.org>
> 
> From abort path, nft_mapelem_activate() needs to restore refcounters to
> the original state. Currently, it uses the set->ops->walk() to iterate
> over these set elements. The existing set iterator skips inactive
> elements in the next generation, this does not work from the abort path
> to restore the original state since it has to skip active elements
> instead (not inactive ones).
> 
> This patch moves the check for inactive elements to the set iterator
> callback, then it reverses the logic for the .activate case which
> needs to skip active elements.
> 
> Toggle next generation bit for elements when delete set command is
> invoked and call nft_clear() from .activate (abort) path to restore the
> next generation bit.
> 
> The splat below shows an object in mappings memleak:
> 
> [43929.457523] ------------[ cut here ]------------
> [43929.457532] WARNING: CPU: 0 PID: 1139 at include/net/netfilter/nf_tables.h:1237 nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
> [...]
> [43929.458014] RIP: 0010:nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
> [43929.458076] Code: 83 f8 01 77 ab 49 8d 7c 24 08 e8 37 5e d0 de 49 8b 6c 24 08 48 8d 7d 50 e8 e9 5c d0 de 8b 45 50 8d 50 ff 89 55 50 85 c0 75 86 <0f> 0b eb 82 0f 0b eb b3 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90
> [43929.458081] RSP: 0018:ffff888140f9f4b0 EFLAGS: 00010246
> [43929.458086] RAX: 0000000000000000 RBX: ffff8881434f5288 RCX: dffffc0000000000
> [43929.458090] RDX: 00000000ffffffff RSI: ffffffffa26d28a7 RDI: ffff88810ecc9550
> [43929.458093] RBP: ffff88810ecc9500 R08: 0000000000000001 R09: ffffed10281f3e8f
> [43929.458096] R10: 0000000000000003 R11: ffff0000ffff0000 R12: ffff8881434f52a0
> [43929.458100] R13: ffff888140f9f5f4 R14: ffff888151c7a800 R15: 0000000000000002
> [43929.458103] FS:  00007f0c687c4740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000
> [43929.458107] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [43929.458111] CR2: 00007f58dbe5b008 CR3: 0000000123602005 CR4: 00000000001706f0
> [43929.458114] Call Trace:
> [43929.458118]  <TASK>
> [43929.458121]  ? __warn+0x9f/0x1a0
> [43929.458127]  ? nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
> [43929.458188]  ? report_bug+0x1b1/0x1e0
> [43929.458196]  ? handle_bug+0x3c/0x70
> [43929.458200]  ? exc_invalid_op+0x17/0x40
> [43929.458211]  ? nft_setelem_data_deactivate+0xd7/0xf0 [nf_tables]
> [43929.458271]  ? nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
> [43929.458332]  nft_mapelem_deactivate+0x24/0x30 [nf_tables]
> [43929.458392]  nft_rhash_walk+0xdd/0x180 [nf_tables]
> [43929.458453]  ? __pfx_nft_rhash_walk+0x10/0x10 [nf_tables]
> [43929.458512]  ? rb_insert_color+0x2e/0x280
> [43929.458520]  nft_map_deactivate+0xdc/0x1e0 [nf_tables]
> [43929.458582]  ? __pfx_nft_map_deactivate+0x10/0x10 [nf_tables]
> [43929.458642]  ? __pfx_nft_mapelem_deactivate+0x10/0x10 [nf_tables]
> [43929.458701]  ? __rcu_read_unlock+0x46/0x70
> [43929.458709]  nft_delset+0xff/0x110 [nf_tables]
> [43929.458769]  nft_flush_table+0x16f/0x460 [nf_tables]
> [43929.458830]  nf_tables_deltable+0x501/0x580 [nf_tables]
> 
> Fixes: 628bd3e49cba ("netfilter: nf_tables: drop map element references from preparation phase")
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> 
> (backported from commit e79b47a8615d42c68aaeb68971593333667382ed linux-6.9.y)
> [hannsofie: context adjustments in nf_tables_api.c and nft_set_pipapo.c]
> CVE-2024-27012
> Signed-off-by: Hannah Peuckmann <hannah.peuckmann@canonical.com>
> ---
>  net/netfilter/nf_tables_api.c  | 46 +++++++++++++++++++++++++++++-----
>  net/netfilter/nft_set_bitmap.c |  4 +--
>  net/netfilter/nft_set_hash.c   |  8 ++----
>  net/netfilter/nft_set_pipapo.c |  4 +--
>  net/netfilter/nft_set_rbtree.c |  4 +--
>  5 files changed, 45 insertions(+), 21 deletions(-)
> 
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index 0ba358207006..67b2dfb25f29 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -594,6 +594,12 @@ static int nft_mapelem_deactivate(const struct nft_ctx *ctx,
>  				  const struct nft_set_iter *iter,
>  				  struct nft_set_elem *elem)
>  {
> +	struct nft_set_ext *ext = nft_set_elem_ext(set, elem);
> +
> +	if (!nft_set_elem_active(ext, iter->genmask))
> +		return 0;
> +
> +	nft_set_elem_change_active(ctx->net, set, ext);
>  	nft_setelem_data_deactivate(ctx->net, set, elem);
>  
>  	return 0;
> @@ -618,8 +624,8 @@ static void nft_map_catchall_deactivate(const struct nft_ctx *ctx,
>  		if (!nft_set_elem_active(ext, genmask))
>  			continue;
>  
> -		elem.priv = catchall->elem;
> -		nft_setelem_data_deactivate(ctx->net, set, &elem);
> +		nft_set_elem_change_active(ctx->net, set, ext);
> +		nft_setelem_data_deactivate(ctx->net, set, catchall->elem);

I think this hunk merges code from upstream that we should not. The
function nft_setelem_data_deactivate() will access elem->priv, so you
cannot pass catchall->elem directly if I understand the code correctly.
It most likely still compiles fine because all the pointers involved
seem to be opaque void pointers. However, behavior might be unexpected
or incorrect. Changes to this code were introduced with

0e1ea651c971 netfilter: nf_tables: shrink memory consumption of set elements

which we do not carry in jammy, as you point out in your cover letter.
The patch should only add

+             nft_set_elem_change_active(ctx->net, set, ext);

and leave the call to nft_setelem_data_deactivate() unmodified, similar
to the upstream commit.

>  		break;
>  	}
>  }

Thank you for addressing the things pointed out in the previous
submission!

Everything looks good now except for one small issue, see inline
comment.
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 0ba358207006..67b2dfb25f29 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -594,6 +594,12 @@  static int nft_mapelem_deactivate(const struct nft_ctx *ctx,
 				  const struct nft_set_iter *iter,
 				  struct nft_set_elem *elem)
 {
+	struct nft_set_ext *ext = nft_set_elem_ext(set, elem);
+
+	if (!nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
+	nft_set_elem_change_active(ctx->net, set, ext);
 	nft_setelem_data_deactivate(ctx->net, set, elem);
 
 	return 0;
@@ -618,8 +624,8 @@  static void nft_map_catchall_deactivate(const struct nft_ctx *ctx,
 		if (!nft_set_elem_active(ext, genmask))
 			continue;
 
-		elem.priv = catchall->elem;
-		nft_setelem_data_deactivate(ctx->net, set, &elem);
+		nft_set_elem_change_active(ctx->net, set, ext);
+		nft_setelem_data_deactivate(ctx->net, set, catchall->elem);
 		break;
 	}
 }
@@ -3508,6 +3514,9 @@  int nft_setelem_validate(const struct nft_ctx *ctx, struct nft_set *set,
 	const struct nft_data *data;
 	int err;
 
+	if (!nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
 	    *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
 		return 0;
@@ -3531,7 +3540,9 @@  int nft_setelem_validate(const struct nft_ctx *ctx, struct nft_set *set,
 
 int nft_set_catchall_validate(const struct nft_ctx *ctx, struct nft_set *set)
 {
-	u8 genmask = nft_genmask_next(ctx->net);
+	struct nft_set_iter dummy_iter = {
+		.genmask	= nft_genmask_next(ctx->net),
+	};
 	struct nft_set_elem_catchall *catchall;
 	struct nft_set_elem elem;
 	struct nft_set_ext *ext;
@@ -3539,11 +3550,11 @@  int nft_set_catchall_validate(const struct nft_ctx *ctx, struct nft_set *set)
 
 	list_for_each_entry_rcu(catchall, &set->catchall_list, list) {
 		ext = nft_set_elem_ext(set, catchall->elem);
-		if (!nft_set_elem_active(ext, genmask))
+		if (!nft_set_elem_active(ext, dummy_iter.genmask))
 			continue;
 
 		elem.priv = catchall->elem;
-		ret = nft_setelem_validate(ctx, set, NULL, &elem);
+		ret = nft_setelem_validate(ctx, set, &dummy_iter, &elem);
 		if (ret < 0)
 			return ret;
 	}
@@ -5017,6 +5028,11 @@  static int nf_tables_bind_check_setelem(const struct nft_ctx *ctx,
 					const struct nft_set_iter *iter,
 					struct nft_set_elem *elem)
 {
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem);
+
+	if (!nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
 	return nft_setelem_data_validate(ctx, set, elem);
 }
 
@@ -5111,6 +5127,13 @@  static int nft_mapelem_activate(const struct nft_ctx *ctx,
 				const struct nft_set_iter *iter,
 				struct nft_set_elem *elem)
 {
+	struct nft_set_ext *ext = nft_set_elem_ext(set, elem);
+
+	/* called from abort path, reverse check to undo changes. */
+	if (nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
+	nft_clear(ctx->net, ext);
 	nft_setelem_data_activate(ctx->net, set, elem);
 
 	return 0;
@@ -5130,6 +5153,7 @@  static void nft_map_catchall_activate(const struct nft_ctx *ctx,
 			continue;
 
 		elem.priv = catchall->elem;
+		nft_clear(ctx->net, ext);
 		nft_setelem_data_activate(ctx->net, set, &elem);
 		break;
 	}
@@ -5400,6 +5424,9 @@  static int nf_tables_dump_setelem(const struct nft_ctx *ctx,
 	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
 	struct nft_set_dump_args *args;
 
+	if (!nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
 	if (nft_set_elem_expired(ext) || nft_set_elem_is_dead(ext))
 		return 0;
 
@@ -6084,7 +6111,7 @@  static void nft_setelem_activate(struct net *net, struct nft_set *set,
 	struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
 
 	if (nft_setelem_is_catchall(set, elem)) {
-		nft_set_elem_change_active(net, set, ext);
+		nft_clear(net, ext);
 	} else {
 		set->ops->activate(net, set, elem);
 	}
@@ -6750,9 +6777,13 @@  static int nft_setelem_flush(const struct nft_ctx *ctx,
 			     const struct nft_set_iter *iter,
 			     struct nft_set_elem *elem)
 {
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem);
 	struct nft_trans *trans;
 	int err;
 
+	if (!nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
 	trans = nft_trans_alloc_gfp(ctx, NFT_MSG_DELSETELEM,
 				    sizeof(struct nft_trans_elem), GFP_ATOMIC);
 	if (!trans)
@@ -10036,6 +10067,9 @@  static int nf_tables_loop_check_setelem(const struct nft_ctx *ctx,
 {
 	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
 
+	if (!nft_set_elem_active(ext, iter->genmask))
+		return 0;
+
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
 	    *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
 		return 0;
diff --git a/net/netfilter/nft_set_bitmap.c b/net/netfilter/nft_set_bitmap.c
index 60122539fee6..028955a9cb09 100644
--- a/net/netfilter/nft_set_bitmap.c
+++ b/net/netfilter/nft_set_bitmap.c
@@ -171,7 +171,7 @@  static void nft_bitmap_activate(const struct net *net,
 	nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
 	/* Enter 11 state. */
 	priv->bitmap[idx] |= (genmask << off);
-	nft_set_elem_change_active(net, set, &be->ext);
+	nft_clear(net, &be->ext);
 }
 
 static bool nft_bitmap_flush(const struct net *net,
@@ -223,8 +223,6 @@  static void nft_bitmap_walk(const struct nft_ctx *ctx,
 	list_for_each_entry_rcu(be, &priv->list, head) {
 		if (iter->count < iter->skip)
 			goto cont;
-		if (!nft_set_elem_active(&be->ext, iter->genmask))
-			goto cont;
 
 		elem.priv = be;
 
diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index 2013de934cef..3a96d4a77a22 100644
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -189,7 +189,7 @@  static void nft_rhash_activate(const struct net *net, const struct nft_set *set,
 {
 	struct nft_rhash_elem *he = elem->priv;
 
-	nft_set_elem_change_active(net, set, &he->ext);
+	nft_clear(net, &he->ext);
 }
 
 static bool nft_rhash_flush(const struct net *net,
@@ -277,8 +277,6 @@  static void nft_rhash_walk(const struct nft_ctx *ctx, struct nft_set *set,
 
 		if (iter->count < iter->skip)
 			goto cont;
-		if (!nft_set_elem_active(&he->ext, iter->genmask))
-			goto cont;
 
 		elem.priv = he;
 
@@ -587,7 +585,7 @@  static void nft_hash_activate(const struct net *net, const struct nft_set *set,
 {
 	struct nft_hash_elem *he = elem->priv;
 
-	nft_set_elem_change_active(net, set, &he->ext);
+	nft_clear(net, &he->ext);
 }
 
 static bool nft_hash_flush(const struct net *net,
@@ -641,8 +639,6 @@  static void nft_hash_walk(const struct nft_ctx *ctx, struct nft_set *set,
 		hlist_for_each_entry_rcu(he, &priv->table[i], node) {
 			if (iter->count < iter->skip)
 				goto cont;
-			if (!nft_set_elem_active(&he->ext, iter->genmask))
-				goto cont;
 
 			elem.priv = he;
 
diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index f2f8d15c9eda..ae81c5af9f71 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -1767,7 +1767,7 @@  static void nft_pipapo_activate(const struct net *net,
 {
 	struct nft_pipapo_elem *e = elem->priv;
 
-	nft_set_elem_change_active(net, set, &e->ext);
+	nft_clear(net, &e->ext);
 }
 
 /**
@@ -2069,8 +2069,6 @@  static void nft_pipapo_walk(const struct nft_ctx *ctx, struct nft_set *set,
 
 		e = f->mt[r].e;
 
-		if (!nft_set_elem_active(&e->ext, iter->genmask))
-			goto cont;
 
 		elem.priv = e;
 
diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index 5bf5572e945c..afbda7e3fd04 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -527,7 +527,7 @@  static void nft_rbtree_activate(const struct net *net,
 {
 	struct nft_rbtree_elem *rbe = elem->priv;
 
-	nft_set_elem_change_active(net, set, &rbe->ext);
+	nft_clear(net, &rbe->ext);
 }
 
 static bool nft_rbtree_flush(const struct net *net,
@@ -596,8 +596,6 @@  static void nft_rbtree_walk(const struct nft_ctx *ctx,
 
 		if (iter->count < iter->skip)
 			goto cont;
-		if (!nft_set_elem_active(&rbe->ext, iter->genmask))
-			goto cont;
 
 		elem.priv = rbe;