[XFRM]: RFC4303 compliant auditing

This patch adds a number of new IPsec audit events to meet the auditing
requirements of RFC4303.  This includes audit hooks for the following events:

 * Could not find a valid SA [sections 2.1, 3.4.2]
   . xfrm_audit_state_notfound()
   . xfrm_audit_state_notfound_simple()

 * Sequence number overflow [section 3.3.3]
   . xfrm_audit_state_replay_overflow()

 * Replayed packet [section 3.4.3]
   . xfrm_audit_state_replay()

 * Integrity check failure [sections 3.4.4.1, 3.4.4.2]
   . xfrm_audit_state_icvfail()

While RFC4304 deals only with ESP most of the changes in this patch apply to
IPsec in general, i.e. both AH and ESP.  The one case, integrity check
failure, where ESP specific code had to be modified the same was done to the
AH code for the sake of consistency.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 147 insertions, 25 deletions

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 493243fc5fe5..1b250f33ad5b 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -147,6 +147,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
                 x = xfrm_state_lookup(daddr, spi, nexthdr, family);
                 if (x == NULL) {
                         XFRM_INC_STATS(LINUX_MIB_XFRMINNOSTATES);
+                        xfrm_audit_state_notfound(skb, family, spi, seq);
                         goto drop;
                 }
 
@@ -163,7 +164,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
                         goto drop_unlock;
                 }
 
-                if (x->props.replay_window && xfrm_replay_check(x, seq)) {
+                if (x->props.replay_window && xfrm_replay_check(x, skb, seq)) {
                         XFRM_INC_STATS(LINUX_MIB_XFRMINSEQOUTOFWINDOW);
                         goto drop_unlock;
                 }
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 867484a046af..09514449fe8a 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -57,6 +57,8 @@ static int xfrm_output_one(struct sk_buff *skb, int err)
 
                 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
                         XFRM_SKB_CB(skb)->seq = ++x->replay.oseq;
+                        if (unlikely(x->replay.oseq == 0))
+                                xfrm_audit_state_replay_overflow(x, skb);
                         if (xfrm_aevent_is_on())
                                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
                 }
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index abc3e39b115b..280f8ded975c 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2407,12 +2407,11 @@ void xfrm_audit_policy_add(struct xfrm_policy *xp, int result,
 {
         struct audit_buffer *audit_buf;
 
-        if (audit_enabled == 0)
-                return;
-        audit_buf = xfrm_audit_start(auid, secid);
+        audit_buf = xfrm_audit_start("SPD-add");
         if (audit_buf == NULL)
                 return;
-        audit_log_format(audit_buf, " op=SPD-add res=%u", result);
+        xfrm_audit_helper_usrinfo(auid, secid, audit_buf);
+        audit_log_format(audit_buf, " res=%u", result);
         xfrm_audit_common_policyinfo(xp, audit_buf);
         audit_log_end(audit_buf);
 }
@@ -2423,12 +2422,11 @@ void xfrm_audit_policy_delete(struct xfrm_policy *xp, int result,
 {
         struct audit_buffer *audit_buf;
 
-        if (audit_enabled == 0)
-                return;
-        audit_buf = xfrm_audit_start(auid, secid);
+        audit_buf = xfrm_audit_start("SPD-delete");
         if (audit_buf == NULL)
                 return;
-        audit_log_format(audit_buf, " op=SPD-delete res=%u", result);
+        xfrm_audit_helper_usrinfo(auid, secid, audit_buf);
+        audit_log_format(audit_buf, " res=%u", result);
         xfrm_audit_common_policyinfo(xp, audit_buf);
         audit_log_end(audit_buf);
 }
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 9e57378c51df..6bf876c866df 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -61,6 +61,13 @@ static unsigned int xfrm_state_genid;
 static struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family);
 static void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo);
 
+#ifdef CONFIG_AUDITSYSCALL
+static void xfrm_audit_state_replay(struct xfrm_state *x,
+                                    struct sk_buff *skb, __be32 net_seq);
+#else
+#define xfrm_audit_state_replay(x, s, sq)       do { ; } while (0)
+#endif /* CONFIG_AUDITSYSCALL */
+
 static inline unsigned int xfrm_dst_hash(xfrm_address_t *daddr,
                                          xfrm_address_t *saddr,
                                          u32 reqid,
@@ -1609,13 +1616,14 @@ static void xfrm_replay_timer_handler(unsigned long data)
         spin_unlock(&x->lock);
 }
 
-int xfrm_replay_check(struct xfrm_state *x, __be32 net_seq)
+int xfrm_replay_check(struct xfrm_state *x,
+                      struct sk_buff *skb, __be32 net_seq)
 {
         u32 diff;
         u32 seq = ntohl(net_seq);
 
         if (unlikely(seq == 0))
-                return -EINVAL;
+                goto err;
 
         if (likely(seq > x->replay.seq))
                 return 0;
@@ -1624,14 +1632,18 @@ int xfrm_replay_check(struct xfrm_state *x, __be32 net_seq)
         if (diff >= min_t(unsigned int, x->props.replay_window,
                           sizeof(x->replay.bitmap) * 8)) {
                 x->stats.replay_window++;
-                return -EINVAL;
+                goto err;
         }
 
         if (x->replay.bitmap & (1U << diff)) {
                 x->stats.replay++;
-                return -EINVAL;
+                goto err;
         }
         return 0;
+
+err:
+        xfrm_audit_state_replay(x, skb, net_seq);
+        return -EINVAL;
 }
 EXPORT_SYMBOL(xfrm_replay_check);
 
@@ -1996,8 +2008,8 @@ void __init xfrm_state_init(void)
 }
 
 #ifdef CONFIG_AUDITSYSCALL
-static inline void xfrm_audit_common_stateinfo(struct xfrm_state *x,
-                                               struct audit_buffer *audit_buf)
+static inline void xfrm_audit_helper_sainfo(struct xfrm_state *x,
+                                            struct audit_buffer *audit_buf)
 {
         struct xfrm_sec_ctx *ctx = x->security;
         u32 spi = ntohl(x->id.spi);
@@ -2024,18 +2036,45 @@ static inline void xfrm_audit_common_stateinfo(struct xfrm_state *x,
         audit_log_format(audit_buf, " spi=%u(0x%x)", spi, spi);
 }
 
+static inline void xfrm_audit_helper_pktinfo(struct sk_buff *skb, u16 family,
+                                             struct audit_buffer *audit_buf)
+{
+        struct iphdr *iph4;
+        struct ipv6hdr *iph6;
+
+        switch (family) {
+        case AF_INET:
+                iph4 = ip_hdr(skb);
+                audit_log_format(audit_buf,
+                                 " src=" NIPQUAD_FMT " dst=" NIPQUAD_FMT,
+                                 NIPQUAD(iph4->saddr),
+                                 NIPQUAD(iph4->daddr));
+                break;
+        case AF_INET6:
+                iph6 = ipv6_hdr(skb);
+                audit_log_format(audit_buf,
+                                 " src=" NIP6_FMT " dst=" NIP6_FMT
+                                 " flowlbl=0x%x%x%x",
+                                 NIP6(iph6->saddr),
+                                 NIP6(iph6->daddr),
+                                 iph6->flow_lbl[0] & 0x0f,
+                                 iph6->flow_lbl[1],
+                                 iph6->flow_lbl[2]);
+                break;
+        }
+}
+
 void xfrm_audit_state_add(struct xfrm_state *x, int result,
                           u32 auid, u32 secid)
 {
         struct audit_buffer *audit_buf;
 
-        if (audit_enabled == 0)
-                return;
-        audit_buf = xfrm_audit_start(auid, secid);
+        audit_buf = xfrm_audit_start("SAD-add");
         if (audit_buf == NULL)
                 return;
-        audit_log_format(audit_buf, " op=SAD-add res=%u", result);
-        xfrm_audit_common_stateinfo(x, audit_buf);
+        xfrm_audit_helper_usrinfo(auid, secid, audit_buf);
+        xfrm_audit_helper_sainfo(x, audit_buf);
+        audit_log_format(audit_buf, " res=%u", result);
         audit_log_end(audit_buf);
 }
 EXPORT_SYMBOL_GPL(xfrm_audit_state_add);
@@ -2045,14 +2084,96 @@ void xfrm_audit_state_delete(struct xfrm_state *x, int result,
 {
         struct audit_buffer *audit_buf;
 
-        if (audit_enabled == 0)
-                return;
-        audit_buf = xfrm_audit_start(auid, secid);
+        audit_buf = xfrm_audit_start("SAD-delete");
         if (audit_buf == NULL)
                 return;
-        audit_log_format(audit_buf, " op=SAD-delete res=%u", result);
-        xfrm_audit_common_stateinfo(x, audit_buf);
+        xfrm_audit_helper_usrinfo(auid, secid, audit_buf);
+        xfrm_audit_helper_sainfo(x, audit_buf);
+        audit_log_format(audit_buf, " res=%u", result);
         audit_log_end(audit_buf);
 }
 EXPORT_SYMBOL_GPL(xfrm_audit_state_delete);
+
+void xfrm_audit_state_replay_overflow(struct xfrm_state *x,
+                                      struct sk_buff *skb)
+{
+        struct audit_buffer *audit_buf;
+        u32 spi;
+
+        audit_buf = xfrm_audit_start("SA-replay-overflow");
+        if (audit_buf == NULL)
+                return;
+        xfrm_audit_helper_pktinfo(skb, x->props.family, audit_buf);
+        /* don't record the sequence number because it's inherent in this kind
+         * of audit message */
+        spi = ntohl(x->id.spi);
+        audit_log_format(audit_buf, " spi=%u(0x%x)", spi, spi);
+        audit_log_end(audit_buf);
+}
+EXPORT_SYMBOL_GPL(xfrm_audit_state_replay_overflow);
+
+static void xfrm_audit_state_replay(struct xfrm_state *x,
+                             struct sk_buff *skb, __be32 net_seq)
+{
+        struct audit_buffer *audit_buf;
+        u32 spi;
+
+        audit_buf = xfrm_audit_start("SA-replayed-pkt");
+        if (audit_buf == NULL)
+                return;
+        xfrm_audit_helper_pktinfo(skb, x->props.family, audit_buf);
+        spi = ntohl(x->id.spi);
+        audit_log_format(audit_buf, " spi=%u(0x%x) seqno=%u",
+                         spi, spi, ntohl(net_seq));
+        audit_log_end(audit_buf);
+}
+
+void xfrm_audit_state_notfound_simple(struct sk_buff *skb, u16 family)
+{
+        struct audit_buffer *audit_buf;
+
+        audit_buf = xfrm_audit_start("SA-notfound");
+        if (audit_buf == NULL)
+                return;
+        xfrm_audit_helper_pktinfo(skb, family, audit_buf);
+        audit_log_end(audit_buf);
+}
+EXPORT_SYMBOL_GPL(xfrm_audit_state_notfound_simple);
+
+void xfrm_audit_state_notfound(struct sk_buff *skb, u16 family,
+                               __be32 net_spi, __be32 net_seq)
+{
+        struct audit_buffer *audit_buf;
+        u32 spi;
+
+        audit_buf = xfrm_audit_start("SA-notfound");
+        if (audit_buf == NULL)
+                return;
+        xfrm_audit_helper_pktinfo(skb, family, audit_buf);
+        spi = ntohl(net_spi);
+        audit_log_format(audit_buf, " spi=%u(0x%x) seqno=%u",
+                         spi, spi, ntohl(net_seq));
+        audit_log_end(audit_buf);
+}
+EXPORT_SYMBOL_GPL(xfrm_audit_state_notfound);
+
+void xfrm_audit_state_icvfail(struct xfrm_state *x,
+                              struct sk_buff *skb, u8 proto)
+{
+        struct audit_buffer *audit_buf;
+        __be32 net_spi;
+        __be32 net_seq;
+
+        audit_buf = xfrm_audit_start("SA-icv-failure");
+        if (audit_buf == NULL)
+                return;
+        xfrm_audit_helper_pktinfo(skb, x->props.family, audit_buf);
+        if (xfrm_parse_spi(skb, proto, &net_spi, &net_seq) == 0) {
+                u32 spi = ntohl(net_spi);
+                audit_log_format(audit_buf, " spi=%u(0x%x) seqno=%u",
+                                 spi, spi, ntohl(net_seq));
+        }
+        audit_log_end(audit_buf);
+}
+EXPORT_SYMBOL_GPL(xfrm_audit_state_icvfail);
 #endif /* CONFIG_AUDITSYSCALL */