target/linux/generic/backport-4.19/345-v4.16-netfilter-nf_flow_offload-fix-use-after-free-and-a-r.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Wed, 7 Feb 2018 09:23:25 +0100
   3 Subject: [PATCH] netfilter: nf_flow_offload: fix use-after-free and a resource
   4  leak
   5
   6 flow_offload_del frees the flow, so all associated resource must be
   7 freed before.
   8
   9 Since the ct entry in struct flow_offload_entry was allocated by
  10 flow_offload_alloc, it should be freed by flow_offload_free to take care
  11 of the error handling path when flow_offload_add fails.
  12
  13 While at it, make flow_offload_del static, since it should never be
  14 called directly, only from the gc step
  15
  16 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  17 ---
  18
  19 --- a/include/net/netfilter/nf_flow_table.h
  20 +++ b/include/net/netfilter/nf_flow_table.h
  21 @@ -90,7 +90,6 @@ struct flow_offload *flow_offload_alloc(
  22  void flow_offload_free(struct flow_offload *flow);
  23
  24  int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow);
  25 -void flow_offload_del(struct nf_flowtable *flow_table, struct flow_offload *flow);
  26  struct flow_offload_tuple_rhash *flow_offload_lookup(struct nf_flowtable *flow_table,
  27                                                      struct flow_offload_tuple *tuple);
  28  int nf_flow_table_iterate(struct nf_flowtable *flow_table,
  29 --- a/net/netfilter/nf_flow_table.c
  30 +++ b/net/netfilter/nf_flow_table.c
  31 @@ -125,7 +125,9 @@ void flow_offload_free(struct flow_offlo
  32         dst_release(flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_cache);
  33         dst_release(flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_cache);
  34         e = container_of(flow, struct flow_offload_entry, flow);
  35 -       kfree(e);
  36 +       nf_ct_delete(e->ct, 0, 0);
  37 +       nf_ct_put(e->ct);
  38 +       kfree_rcu(e, rcu_head);
  39  }
  40  EXPORT_SYMBOL_GPL(flow_offload_free);
  41
  42 @@ -149,11 +151,9 @@ int flow_offload_add(struct nf_flowtable
  43  }
  44  EXPORT_SYMBOL_GPL(flow_offload_add);
  45
  46 -void flow_offload_del(struct nf_flowtable *flow_table,
  47 -                     struct flow_offload *flow)
  48 +static void flow_offload_del(struct nf_flowtable *flow_table,
  49 +                            struct flow_offload *flow)
  50  {
  51 -       struct flow_offload_entry *e;
  52 -
  53         rhashtable_remove_fast(&flow_table->rhashtable,
  54                                &flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].node,
  55                                *flow_table->type->params);
  56 @@ -161,10 +161,8 @@ void flow_offload_del(struct nf_flowtabl
  57                                &flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].node,
  58                                *flow_table->type->params);
  59
  60 -       e = container_of(flow, struct flow_offload_entry, flow);
  61 -       kfree_rcu(e, rcu_head);
  62 +       flow_offload_free(flow);
  63  }
  64 -EXPORT_SYMBOL_GPL(flow_offload_del);
  65
  66  struct flow_offload_tuple_rhash *
  67  flow_offload_lookup(struct nf_flowtable *flow_table,
  68 @@ -175,15 +173,6 @@ flow_offload_lookup(struct nf_flowtable
  69  }
  70  EXPORT_SYMBOL_GPL(flow_offload_lookup);
  71
  72 -static void nf_flow_release_ct(const struct flow_offload *flow)
  73 -{
  74 -       struct flow_offload_entry *e;
  75 -
  76 -       e = container_of(flow, struct flow_offload_entry, flow);
  77 -       nf_ct_delete(e->ct, 0, 0);
  78 -       nf_ct_put(e->ct);
  79 -}
  80 -
  81  int nf_flow_table_iterate(struct nf_flowtable *flow_table,
  82                           void (*iter)(struct flow_offload *flow, void *data),
  83                           void *data)
  84 @@ -259,10 +248,8 @@ static int nf_flow_offload_gc_step(struc
  85                 flow = container_of(tuplehash, struct flow_offload, tuplehash[0]);
  86
  87                 if (nf_flow_has_expired(flow) ||
  88 -                   nf_flow_is_dying(flow)) {
  89 +                   nf_flow_is_dying(flow))
  90                         flow_offload_del(flow_table, flow);
  91 -                       nf_flow_release_ct(flow);
  92 -               }
  93         }
  94  out:
  95         rhashtable_walk_stop(&hti);