[NETFILTER]: nf_{conntrack,nat}_proto_tcp: constify and annotate TCP modules

Constify a few data tables use const qualifiers on variables where
possible in the nf_*_proto_tcp sources.

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 26 insertions, 22 deletions

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index bda78a286e2b..90b3e7f5df5f 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -216,7 +216,7 @@ static inline void nf_ct_refresh(struct nf_conn *ct,
 
 /* These are for NAT.  Icky. */
 /* Update TCP window tracking data when NAT mangles the packet */
-extern void nf_conntrack_tcp_update(struct sk_buff *skb,
+extern void nf_conntrack_tcp_update(const struct sk_buff *skb,
                                     unsigned int dataoff,
                                     struct nf_conn *ct,
                                     int dir);
diff --git a/net/ipv4/netfilter/nf_nat_proto_tcp.c b/net/ipv4/netfilter/nf_nat_proto_tcp.c
index da23e9fbe679..ffd5d1589eca 100644
--- a/net/ipv4/netfilter/nf_nat_proto_tcp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_tcp.c
@@ -93,7 +93,7 @@ tcp_manip_pkt(struct sk_buff *skb,
               const struct nf_conntrack_tuple *tuple,
               enum nf_nat_manip_type maniptype)
 {
-        struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
+        const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
         struct tcphdr *hdr;
         unsigned int hdroff = iphdroff + iph->ihl*4;
         __be32 oldip, newip;
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 9807af677a56..3e0cccae5636 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -46,7 +46,7 @@ static int nf_ct_tcp_max_retrans __read_mostly = 3;
   /* FIXME: Examine ipfilter's timeouts and conntrack transitions more
      closely.  They're more complex. --RR */
 
-static const char *tcp_conntrack_names[] = {
+static const char *const tcp_conntrack_names[] = {
         "NONE",
         "SYN_SENT",
         "SYN_RECV",
@@ -261,7 +261,8 @@ static int tcp_pkt_to_tuple(const struct sk_buff *skb,
                             unsigned int dataoff,
                             struct nf_conntrack_tuple *tuple)
 {
-        struct tcphdr _hdr, *hp;
+        const struct tcphdr *hp;
+        struct tcphdr _hdr;
 
         /* Actually only need first 8 bytes. */
         hp = skb_header_pointer(skb, dataoff, 8, &_hdr);
@@ -343,7 +344,7 @@ static unsigned int get_conntrack_index(const struct tcphdr *tcph)
 static inline __u32 segment_seq_plus_len(__u32 seq,
                                          size_t len,
                                          unsigned int dataoff,
-                                         struct tcphdr *tcph)
+                                         const struct tcphdr *tcph)
 {
         /* XXX Should I use payload length field in IP/IPv6 header ?
          * - YK */
@@ -362,11 +363,11 @@ static inline __u32 segment_seq_plus_len(__u32 seq,
  */
 static void tcp_options(const struct sk_buff *skb,
                         unsigned int dataoff,
-                        struct tcphdr *tcph,
+                        const struct tcphdr *tcph,
                         struct ip_ct_tcp_state *state)
 {
         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
-        unsigned char *ptr;
+        const unsigned char *ptr;
         int length = (tcph->doff*4) - sizeof(struct tcphdr);
 
         if (!length)
@@ -417,10 +418,10 @@ static void tcp_options(const struct sk_buff *skb,
 }
 
 static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
-                     struct tcphdr *tcph, __u32 *sack)
+                     const struct tcphdr *tcph, __u32 *sack)
 {
         unsigned char buff[(15 * 4) - sizeof(struct tcphdr)];
-        unsigned char *ptr;
+        const unsigned char *ptr;
         int length = (tcph->doff*4) - sizeof(struct tcphdr);
         __u32 tmp;
 
@@ -477,18 +478,18 @@ static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
         }
 }
 
-static int tcp_in_window(struct nf_conn *ct,
+static int tcp_in_window(const struct nf_conn *ct,
                          struct ip_ct_tcp *state,
                          enum ip_conntrack_dir dir,
                          unsigned int index,
                          const struct sk_buff *skb,
                          unsigned int dataoff,
-                         struct tcphdr *tcph,
+                         const struct tcphdr *tcph,
                          int pf)
 {
         struct ip_ct_tcp_state *sender = &state->seen[dir];
         struct ip_ct_tcp_state *receiver = &state->seen[!dir];
-        struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
+        const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
         __u32 seq, ack, sack, end, win, swin;
         int res;
 
@@ -686,14 +687,14 @@ static int tcp_in_window(struct nf_conn *ct,
 #ifdef CONFIG_NF_NAT_NEEDED
 /* Update sender->td_end after NAT successfully mangled the packet */
 /* Caller must linearize skb at tcp header. */
-void nf_conntrack_tcp_update(struct sk_buff *skb,
+void nf_conntrack_tcp_update(const struct sk_buff *skb,
                              unsigned int dataoff,
                              struct nf_conn *ct,
                              int dir)
 {
-        struct tcphdr *tcph = (void *)skb->data + dataoff;
-        struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[dir];
-        struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[!dir];
+        const struct tcphdr *tcph = (const void *)skb->data + dataoff;
+        const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[dir];
+        const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[!dir];
         __u32 end;
 
         end = segment_seq_plus_len(ntohl(tcph->seq), skb->len, dataoff, tcph);
@@ -726,7 +727,7 @@ EXPORT_SYMBOL_GPL(nf_conntrack_tcp_update);
 #define TH_CWR  0x80
 
 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
-static u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG) + 1] =
+static const u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG) + 1] =
 {
         [TH_SYN]                        = 1,
         [TH_SYN|TH_URG]                 = 1,
@@ -746,7 +747,8 @@ static int tcp_error(struct sk_buff *skb,
                      int pf,
                      unsigned int hooknum)
 {
-        struct tcphdr _tcph, *th;
+        const struct tcphdr *th;
+        struct tcphdr _tcph;
         unsigned int tcplen = skb->len - dataoff;
         u_int8_t tcpflags;
 
@@ -803,7 +805,8 @@ static int tcp_packet(struct nf_conn *ct,
         struct nf_conntrack_tuple *tuple;
         enum tcp_conntrack new_state, old_state;
         enum ip_conntrack_dir dir;
-        struct tcphdr *th, _tcph;
+        const struct tcphdr *th;
+        struct tcphdr _tcph;
         unsigned long timeout;
         unsigned int index;
 
@@ -964,9 +967,10 @@ static int tcp_new(struct nf_conn *ct,
                    unsigned int dataoff)
 {
         enum tcp_conntrack new_state;
-        struct tcphdr *th, _tcph;
-        struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
-        struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
+        const struct tcphdr *th;
+        struct tcphdr _tcph;
+        const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
+        const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];
 
         th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
         BUG_ON(th == NULL);