Steffen Klassert | 9fdc488 | 2011-03-08 00:08:32 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * xfrm_replay.c - xfrm replay detection, derived from xfrm_state.c. |
| 3 | */ |
| 4 | |
| 5 | #include <net/xfrm.h> |
| 6 | |
| 7 | static void xfrm_replay_notify(struct xfrm_state *x, int event) |
| 8 | { |
| 9 | struct km_event c; |
| 10 | /* we send notify messages in case |
| 11 | * 1. we updated on of the sequence numbers, and the seqno difference |
| 12 | * is at least x->replay_maxdiff, in this case we also update the |
| 13 | * timeout of our timer function |
| 14 | * 2. if x->replay_maxage has elapsed since last update, |
| 15 | * and there were changes |
| 16 | * |
| 17 | * The state structure must be locked! |
| 18 | */ |
| 19 | |
| 20 | switch (event) { |
| 21 | case XFRM_REPLAY_UPDATE: |
| 22 | if (x->replay_maxdiff && |
| 23 | (x->replay.seq - x->preplay.seq < x->replay_maxdiff) && |
| 24 | (x->replay.oseq - x->preplay.oseq < x->replay_maxdiff)) { |
| 25 | if (x->xflags & XFRM_TIME_DEFER) |
| 26 | event = XFRM_REPLAY_TIMEOUT; |
| 27 | else |
| 28 | return; |
| 29 | } |
| 30 | |
| 31 | break; |
| 32 | |
| 33 | case XFRM_REPLAY_TIMEOUT: |
| 34 | if (memcmp(&x->replay, &x->preplay, |
| 35 | sizeof(struct xfrm_replay_state)) == 0) { |
| 36 | x->xflags |= XFRM_TIME_DEFER; |
| 37 | return; |
| 38 | } |
| 39 | |
| 40 | break; |
| 41 | } |
| 42 | |
| 43 | memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state)); |
| 44 | c.event = XFRM_MSG_NEWAE; |
| 45 | c.data.aevent = event; |
| 46 | km_state_notify(x, &c); |
| 47 | |
| 48 | if (x->replay_maxage && |
| 49 | !mod_timer(&x->rtimer, jiffies + x->replay_maxage)) |
| 50 | x->xflags &= ~XFRM_TIME_DEFER; |
| 51 | } |
| 52 | |
| 53 | static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb) |
| 54 | { |
| 55 | int err = 0; |
| 56 | struct net *net = xs_net(x); |
| 57 | |
| 58 | if (x->type->flags & XFRM_TYPE_REPLAY_PROT) { |
| 59 | XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq; |
| 60 | if (unlikely(x->replay.oseq == 0)) { |
| 61 | x->replay.oseq--; |
| 62 | xfrm_audit_state_replay_overflow(x, skb); |
| 63 | err = -EOVERFLOW; |
| 64 | |
| 65 | return err; |
| 66 | } |
| 67 | if (xfrm_aevent_is_on(net)) |
| 68 | x->repl->notify(x, XFRM_REPLAY_UPDATE); |
| 69 | } |
| 70 | |
| 71 | return err; |
| 72 | } |
| 73 | |
| 74 | static int xfrm_replay_check(struct xfrm_state *x, |
| 75 | struct sk_buff *skb, __be32 net_seq) |
| 76 | { |
| 77 | u32 diff; |
| 78 | u32 seq = ntohl(net_seq); |
| 79 | |
| 80 | if (unlikely(seq == 0)) |
| 81 | goto err; |
| 82 | |
| 83 | if (likely(seq > x->replay.seq)) |
| 84 | return 0; |
| 85 | |
| 86 | diff = x->replay.seq - seq; |
| 87 | if (diff >= min_t(unsigned int, x->props.replay_window, |
| 88 | sizeof(x->replay.bitmap) * 8)) { |
| 89 | x->stats.replay_window++; |
| 90 | goto err; |
| 91 | } |
| 92 | |
| 93 | if (x->replay.bitmap & (1U << diff)) { |
| 94 | x->stats.replay++; |
| 95 | goto err; |
| 96 | } |
| 97 | return 0; |
| 98 | |
| 99 | err: |
| 100 | xfrm_audit_state_replay(x, skb, net_seq); |
| 101 | return -EINVAL; |
| 102 | } |
| 103 | |
| 104 | static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq) |
| 105 | { |
| 106 | u32 diff; |
| 107 | u32 seq = ntohl(net_seq); |
| 108 | |
| 109 | if (!x->props.replay_window) |
| 110 | return; |
| 111 | |
| 112 | if (seq > x->replay.seq) { |
| 113 | diff = seq - x->replay.seq; |
| 114 | if (diff < x->props.replay_window) |
| 115 | x->replay.bitmap = ((x->replay.bitmap) << diff) | 1; |
| 116 | else |
| 117 | x->replay.bitmap = 1; |
| 118 | x->replay.seq = seq; |
| 119 | } else { |
| 120 | diff = x->replay.seq - seq; |
| 121 | x->replay.bitmap |= (1U << diff); |
| 122 | } |
| 123 | |
| 124 | if (xfrm_aevent_is_on(xs_net(x))) |
| 125 | xfrm_replay_notify(x, XFRM_REPLAY_UPDATE); |
| 126 | } |
| 127 | |
| 128 | static struct xfrm_replay xfrm_replay_legacy = { |
| 129 | .advance = xfrm_replay_advance, |
| 130 | .check = xfrm_replay_check, |
| 131 | .notify = xfrm_replay_notify, |
| 132 | .overflow = xfrm_replay_overflow, |
| 133 | }; |
| 134 | |
| 135 | int xfrm_init_replay(struct xfrm_state *x) |
| 136 | { |
| 137 | x->repl = &xfrm_replay_legacy; |
| 138 | |
| 139 | return 0; |
| 140 | } |
| 141 | EXPORT_SYMBOL(xfrm_init_replay); |