netfilter: nf_tables: use-after-free in failing rule with bound set

If a rule that has already a bound anonymous set fails to be added, the
preparation phase releases the rule and the bound set. However, the
transaction object from the abort path still has a reference to the set
object that is stale, leading to a use-after-free when checking for the
set->bound field. Add a new field to the transaction that specifies if
the set is bound, so the abort path can skip releasing it since the rule
command owns it and it takes care of releasing it. After this update,
the set->bound field is removed.

[   24.649883] Unable to handle kernel paging request at virtual address 0000000000040434
[   24.657858] Mem abort info:
[   24.660686]   ESR = 0x96000004
[   24.663769]   Exception class = DABT (current EL), IL = 32 bits
[   24.669725]   SET = 0, FnV = 0
[   24.672804]   EA = 0, S1PTW = 0
[   24.675975] Data abort info:
[   24.678880]   ISV = 0, ISS = 0x00000004
[   24.682743]   CM = 0, WnR = 0
[   24.685723] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000428952000
[   24.692207] [0000000000040434] pgd=0000000000000000
[   24.697119] Internal error: Oops: 96000004 [#1] SMP
[...]
[   24.889414] Call trace:
[   24.891870]  __nf_tables_abort+0x3f0/0x7a0
[   24.895984]  nf_tables_abort+0x20/0x40
[   24.899750]  nfnetlink_rcv_batch+0x17c/0x588
[   24.904037]  nfnetlink_rcv+0x13c/0x190
[   24.907803]  netlink_unicast+0x18c/0x208
[   24.911742]  netlink_sendmsg+0x1b0/0x350
[   24.915682]  sock_sendmsg+0x4c/0x68
[   24.919185]  ___sys_sendmsg+0x288/0x2c8
[   24.923037]  __sys_sendmsg+0x7c/0xd0
[   24.926628]  __arm64_sys_sendmsg+0x2c/0x38
[   24.930744]  el0_svc_common.constprop.0+0x94/0x158
[   24.935556]  el0_svc_handler+0x34/0x90
[   24.939322]  el0_svc+0x8/0xc
[   24.942216] Code: 37280300 f9404023 91014262 aa1703e0 (f9401863)
[   24.948336] ---[ end trace cebbb9dcbed3b56f ]---

Fixes: f6ac85858976 ("netfilter: nf_tables: unbind set in rule from commit path")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 9b624566b82d3028cd5210a183308e8571ade2e5..475d6f28ca677a8b40c106fa08af86971226000e 100644 (file)
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -421,8 +421,7 @@ struct nft_set {
        unsigned char                   *udata;
        /* runtime data below here */
        const struct nft_set_ops        *ops ____cacheline_aligned;
-       u16                             flags:13,
-                                       bound:1,
+       u16                             flags:14,
                                        genmask:2;
        u8                              klen;
        u8                              dlen;
@@ -1348,12 +1347,15 @@ struct nft_trans_rule {
 struct nft_trans_set {
        struct nft_set                  *set;
        u32                             set_id;
+       bool                            bound;
 };
 
 #define nft_trans_set(trans)   \
        (((struct nft_trans_set *)trans->data)->set)
 #define nft_trans_set_id(trans)        \
        (((struct nft_trans_set *)trans->data)->set_id)
+#define nft_trans_set_bound(trans)     \
+       (((struct nft_trans_set *)trans->data)->bound)
 
 struct nft_trans_chain {
        bool                            update;
@@ -1384,12 +1386,15 @@ struct nft_trans_table {
 struct nft_trans_elem {
        struct nft_set                  *set;
        struct nft_set_elem             elem;
+       bool                            bound;
 };
 
 #define nft_trans_elem_set(trans)      \
        (((struct nft_trans_elem *)trans->data)->set)
 #define nft_trans_elem(trans)  \
        (((struct nft_trans_elem *)trans->data)->elem)
+#define nft_trans_elem_set_bound(trans)        \
+       (((struct nft_trans_elem *)trans->data)->bound)
 
 struct nft_trans_obj {
        struct nft_object               *obj;

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 605a7cfe7ca79ef316fa091bd913fd3827e61deb..88abbddf896740a1d7dadd2d40b82c623d2273ca 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -138,9 +138,14 @@ static void nft_set_trans_bind(const struct nft_ctx *ctx, struct nft_set *set)
                return;
 
        list_for_each_entry_reverse(trans, &net->nft.commit_list, list) {
-               if (trans->msg_type == NFT_MSG_NEWSET &&
-                   nft_trans_set(trans) == set) {
-                       set->bound = true;
+               switch (trans->msg_type) {
+               case NFT_MSG_NEWSET:
+                       if (nft_trans_set(trans) == set)
+                               nft_trans_set_bound(trans) = true;
+                       break;
+               case NFT_MSG_NEWSETELEM:
+                       if (nft_trans_elem_set(trans) == set)
+                               nft_trans_elem_set_bound(trans) = true;
                        break;
                }
        }
@@ -6906,7 +6911,7 @@ static int __nf_tables_abort(struct net *net)
                        break;
                case NFT_MSG_NEWSET:
                        trans->ctx.table->use--;
-                       if (nft_trans_set(trans)->bound) {
+                       if (nft_trans_set_bound(trans)) {
                                nft_trans_destroy(trans);
                                break;
                        }
@@ -6918,7 +6923,7 @@ static int __nf_tables_abort(struct net *net)
                        nft_trans_destroy(trans);
                        break;
                case NFT_MSG_NEWSETELEM:
-                       if (nft_trans_elem_set(trans)->bound) {
+                       if (nft_trans_elem_set_bound(trans)) {
                                nft_trans_destroy(trans);
                                break;
                        }