target/linux/generic/backport-5.4/370-netfilter-nf_flow_table-fix-offloaded-connection-tim.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Wed, 13 Jun 2018 12:33:39 +0200
   3 Subject: [PATCH] netfilter: nf_flow_table: fix offloaded connection timeout
   4  corner case
   5
   6 The full teardown of offloaded flows is deferred to a gc work item,
   7 however processing of packets by netfilter needs to happen immediately
   8 after a teardown is requested, because the conntrack state needs to be
   9 fixed up.
  10
  11 Since the IPS_OFFLOAD_BIT is still kept until the teardown is complete,
  12 the netfilter conntrack gc can accidentally bump the timeout of a
  13 connection where offload was just stopped, causing a conntrack entry
  14 leak.
  15
  16 Fix this by moving the conntrack timeout bumping from conntrack core to
  17 the nf_flow_offload and add a check to prevent bogus timeout bumps.
  18
  19 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  20 ---
  21
  22 --- a/net/netfilter/nf_conntrack_core.c
  23 +++ b/net/netfilter/nf_conntrack_core.c
  24 @@ -1178,18 +1178,6 @@ static bool gc_worker_can_early_drop(con
  25         return false;
  26  }
  27
  28 -#define        DAY     (86400 * HZ)
  29 -
  30 -/* Set an arbitrary timeout large enough not to ever expire, this save
  31 - * us a check for the IPS_OFFLOAD_BIT from the packet path via
  32 - * nf_ct_is_expired().
  33 - */
  34 -static void nf_ct_offload_timeout(struct nf_conn *ct)
  35 -{
  36 -       if (nf_ct_expires(ct) < DAY / 2)
  37 -               ct->timeout = nfct_time_stamp + DAY;
  38 -}
  39 -
  40  static void gc_worker(struct work_struct *work)
  41  {
  42         unsigned int min_interval = max(HZ / GC_MAX_BUCKETS_DIV, 1u);
  43 @@ -1226,10 +1214,8 @@ static void gc_worker(struct work_struct
  44                         tmp = nf_ct_tuplehash_to_ctrack(h);
  45
  46                         scanned++;
  47 -                       if (test_bit(IPS_OFFLOAD_BIT, &tmp->status)) {
  48 -                               nf_ct_offload_timeout(tmp);
  49 +                       if (test_bit(IPS_OFFLOAD_BIT, &tmp->status))
  50                                 continue;
  51 -                       }
  52
  53                         if (nf_ct_is_expired(tmp)) {
  54                                 nf_ct_gc_expired(tmp);
  55 --- a/net/netfilter/nf_flow_table_core.c
  56 +++ b/net/netfilter/nf_flow_table_core.c
  57 @@ -183,10 +183,29 @@ static const struct rhashtable_params nf
  58         .automatic_shrinking    = true,
  59  };
  60
  61 +#define        DAY     (86400 * HZ)
  62 +
  63 +/* Set an arbitrary timeout large enough not to ever expire, this save
  64 + * us a check for the IPS_OFFLOAD_BIT from the packet path via
  65 + * nf_ct_is_expired().
  66 + */
  67 +static void nf_ct_offload_timeout(struct flow_offload *flow)
  68 +{
  69 +       struct flow_offload_entry *entry;
  70 +       struct nf_conn *ct;
  71 +
  72 +       entry = container_of(flow, struct flow_offload_entry, flow);
  73 +       ct = entry->ct;
  74 +
  75 +       if (nf_ct_expires(ct) < DAY / 2)
  76 +               ct->timeout = nfct_time_stamp + DAY;
  77 +}
  78 +
  79  int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow)
  80  {
  81         int err;
  82
  83 +       nf_ct_offload_timeout(flow);
  84         flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
  85
  86         err = rhashtable_insert_fast(&flow_table->rhashtable,
  87 @@ -317,6 +336,8 @@ static int nf_flow_offload_gc_step(struc
  88         rhashtable_walk_start(&hti);
  89
  90         while ((tuplehash = rhashtable_walk_next(&hti))) {
  91 +               bool teardown;
  92 +
  93                 if (IS_ERR(tuplehash)) {
  94                         err = PTR_ERR(tuplehash);
  95                         if (err != -EAGAIN)
  96 @@ -329,9 +350,13 @@ static int nf_flow_offload_gc_step(struc
  97
  98                 flow = container_of(tuplehash, struct flow_offload, tuplehash[0]);
  99
 100 -               if (nf_flow_has_expired(flow) ||
 101 -                   (flow->flags & (FLOW_OFFLOAD_DYING |
 102 -                                   FLOW_OFFLOAD_TEARDOWN)))
 103 +               teardown = flow->flags & (FLOW_OFFLOAD_DYING |
 104 +                                         FLOW_OFFLOAD_TEARDOWN);
 105 +
 106 +               if (!teardown)
 107 +                       nf_ct_offload_timeout(flow);
 108 +
 109 +               if (nf_flow_has_expired(flow) || teardown)
 110                         flow_offload_del(flow_table, flow);
 111         }
 112  out: