netfilter: xtables: add const qualifiers

This should make it easier to remove redundant arguments later.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

2 files changed, 88 insertions, 69 deletions

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 2303dc92a277..4db5c1ece0f9 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -233,7 +233,14 @@ arpt_error(struct sk_buff *skb, const struct xt_target_param *par)
         return NF_DROP;
 }
 
-static inline struct arpt_entry *get_entry(void *base, unsigned int offset)
+static inline const struct arpt_entry_target *
+arpt_get_target_c(const struct arpt_entry *e)
+{
+        return arpt_get_target((struct arpt_entry *)e);
+}
+
+static inline struct arpt_entry *
+get_entry(const void *base, unsigned int offset)
 {
         return (struct arpt_entry *)(base + offset);
 }
@@ -280,7 +287,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
 
         arp = arp_hdr(skb);
         do {
-                struct arpt_entry_target *t;
+                const struct arpt_entry_target *t;
                 int hdr_len;
 
                 if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
@@ -292,7 +299,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
                         (2 * skb->dev->addr_len);
                 ADD_COUNTER(e->counters, hdr_len, 1);
 
-                t = arpt_get_target(e);
+                t = arpt_get_target_c(e);
 
                 /* Standard target? */
                 if (!t->u.kernel.target->target) {
@@ -358,7 +365,7 @@ static inline bool unconditional(const struct arpt_arp *arp)
 /* Figures out from what hook each rule can be called: returns 0 if
  * there are loops.  Puts hook bitmask in comefrom.
  */
-static int mark_source_chains(struct xt_table_info *newinfo,
+static int mark_source_chains(const struct xt_table_info *newinfo,
                               unsigned int valid_hooks, void *entry0)
 {
         unsigned int hook;
@@ -379,7 +386,7 @@ static int mark_source_chains(struct xt_table_info *newinfo,
 
                 for (;;) {
                         const struct arpt_standard_target *t
-                                = (void *)arpt_get_target(e);
+                                = (void *)arpt_get_target_c(e);
                         int visited = e->comefrom & (1 << hook);
 
                         if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
@@ -463,7 +470,7 @@ static int mark_source_chains(struct xt_table_info *newinfo,
         return 1;
 }
 
-static inline int check_entry(struct arpt_entry *e, const char *name)
+static inline int check_entry(const struct arpt_entry *e, const char *name)
 {
         const struct arpt_entry_target *t;
 
@@ -475,7 +482,7 @@ static inline int check_entry(struct arpt_entry *e, const char *name)
         if (e->target_offset + sizeof(struct arpt_entry_target) > e->next_offset)
                 return -EINVAL;
 
-        t = arpt_get_target(e);
+        t = arpt_get_target_c(e);
         if (e->target_offset + t->u.target_size > e->next_offset)
                 return -EINVAL;
 
@@ -540,14 +547,14 @@ out:
         return ret;
 }
 
-static bool check_underflow(struct arpt_entry *e)
+static bool check_underflow(const struct arpt_entry *e)
 {
         const struct arpt_entry_target *t;
         unsigned int verdict;
 
         if (!unconditional(&e->arp))
                 return false;
-        t = arpt_get_target(e);
+        t = arpt_get_target_c(e);
         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
                 return false;
         verdict = ((struct arpt_standard_target *)t)->verdict;
@@ -557,8 +564,8 @@ static bool check_underflow(struct arpt_entry *e)
 
 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
                                              struct xt_table_info *newinfo,
-                                             unsigned char *base,
-                                             unsigned char *limit,
+                                             const unsigned char *base,
+                                             const unsigned char *limit,
                                              const unsigned int *hook_entries,
                                              const unsigned int *underflows,
                                              unsigned int valid_hooks,
@@ -768,11 +775,11 @@ static void get_counters(const struct xt_table_info *t,
         local_bh_enable();
 }
 
-static struct xt_counters *alloc_counters(struct xt_table *table)
+static struct xt_counters *alloc_counters(const struct xt_table *table)
 {
         unsigned int countersize;
         struct xt_counters *counters;
-        struct xt_table_info *private = table->private;
+        const struct xt_table_info *private = table->private;
 
         /* We need atomic snapshot of counters: rest doesn't change
          * (other than comefrom, which userspace doesn't care
@@ -790,11 +797,11 @@ static struct xt_counters *alloc_counters(struct xt_table *table)
 }
 
 static int copy_entries_to_user(unsigned int total_size,
-                                struct xt_table *table,
+                                const struct xt_table *table,
                                 void __user *userptr)
 {
         unsigned int off, num;
-        struct arpt_entry *e;
+        const struct arpt_entry *e;
         struct xt_counters *counters;
         struct xt_table_info *private = table->private;
         int ret = 0;
@@ -814,7 +821,7 @@ static int copy_entries_to_user(unsigned int total_size,
         /* FIXME: use iterator macros --RR */
         /* ... then go back and fix counters and names */
         for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
-                struct arpt_entry_target *t;
+                const struct arpt_entry_target *t;
 
                 e = (struct arpt_entry *)(loc_cpu_entry + off);
                 if (copy_to_user(userptr + off
@@ -825,7 +832,7 @@ static int copy_entries_to_user(unsigned int total_size,
                         goto free_counters;
                 }
 
-                t = arpt_get_target(e);
+                t = arpt_get_target_c(e);
                 if (copy_to_user(userptr + off + e->target_offset
                                  + offsetof(struct arpt_entry_target,
                                             u.user.name),
@@ -860,18 +867,18 @@ static int compat_standard_to_user(void __user *dst, const void *src)
         return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 }
 
-static int compat_calc_entry(struct arpt_entry *e,
+static int compat_calc_entry(const struct arpt_entry *e,
                              const struct xt_table_info *info,
-                             void *base, struct xt_table_info *newinfo)
+                             const void *base, struct xt_table_info *newinfo)
 {
-        struct arpt_entry_target *t;
+        const struct arpt_entry_target *t;
         unsigned int entry_offset;
         int off, i, ret;
 
         off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
         entry_offset = (void *)e - base;
 
-        t = arpt_get_target(e);
+        t = arpt_get_target_c(e);
         off += xt_compat_target_offset(t->u.kernel.target);
         newinfo->size -= off;
         ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
@@ -907,7 +914,8 @@ static int compat_table_info(const struct xt_table_info *info,
 }
 #endif
 
-static int get_info(struct net *net, void __user *user, int *len, int compat)
+static int get_info(struct net *net, void __user *user,
+                    const int *len, int compat)
 {
         char name[ARPT_TABLE_MAXNAMELEN];
         struct xt_table *t;
@@ -966,7 +974,7 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
 }
 
 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
-                       int *len)
+                       const int *len)
 {
         int ret;
         struct arpt_get_entries get;
@@ -1080,7 +1088,8 @@ static int __do_replace(struct net *net, const char *name,
         return ret;
 }
 
-static int do_replace(struct net *net, void __user *user, unsigned int len)
+static int do_replace(struct net *net, const void __user *user,
+                      unsigned int len)
 {
         int ret;
         struct arpt_replace tmp;
@@ -1140,8 +1149,8 @@ add_counter_to_entry(struct arpt_entry *e,
         return 0;
 }
 
-static int do_add_counters(struct net *net, void __user *user, unsigned int len,
-                           int compat)
+static int do_add_counters(struct net *net, const void __user *user,
+                           unsigned int len, int compat)
 {
         unsigned int i, curcpu;
         struct xt_counters_info tmp;
@@ -1245,10 +1254,10 @@ static inline int
 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
                                   struct xt_table_info *newinfo,
                                   unsigned int *size,
-                                  unsigned char *base,
-                                  unsigned char *limit,
-                                  unsigned int *hook_entries,
-                                  unsigned int *underflows,
+                                  const unsigned char *base,
+                                  const unsigned char *limit,
+                                  const unsigned int *hook_entries,
+                                  const unsigned int *underflows,
                                   unsigned int *i,
                                   const char *name)
 {
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 2a4f745ce36e..e94c18bdfc68 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -176,7 +176,7 @@ ipt_error(struct sk_buff *skb, const struct xt_target_param *par)
 
 /* Performance critical - called for every packet */
 static inline bool
-do_match(struct ipt_entry_match *m, const struct sk_buff *skb,
+do_match(const struct ipt_entry_match *m, const struct sk_buff *skb,
          struct xt_match_param *par)
 {
         par->match     = m->u.kernel.match;
@@ -191,7 +191,7 @@ do_match(struct ipt_entry_match *m, const struct sk_buff *skb,
 
 /* Performance critical */
 static inline struct ipt_entry *
-get_entry(void *base, unsigned int offset)
+get_entry(const void *base, unsigned int offset)
 {
         return (struct ipt_entry *)(base + offset);
 }
@@ -206,6 +206,13 @@ static inline bool unconditional(const struct ipt_ip *ip)
 #undef FWINV
 }
 
+/* for const-correctness */
+static inline const struct ipt_entry_target *
+ipt_get_target_c(const struct ipt_entry *e)
+{
+        return ipt_get_target((struct ipt_entry *)e);
+}
+
 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 static const char *const hooknames[] = {
@@ -240,11 +247,11 @@ static struct nf_loginfo trace_loginfo = {
 
 /* Mildly perf critical (only if packet tracing is on) */
 static inline int
-get_chainname_rulenum(struct ipt_entry *s, struct ipt_entry *e,
+get_chainname_rulenum(const struct ipt_entry *s, const struct ipt_entry *e,
                       const char *hookname, const char **chainname,
                       const char **comment, unsigned int *rulenum)
 {
-        struct ipt_standard_target *t = (void *)ipt_get_target(s);
+        const struct ipt_standard_target *t = (void *)ipt_get_target_c(s);
 
         if (strcmp(t->target.u.kernel.target->name, IPT_ERROR_TARGET) == 0) {
                 /* Head of user chain: ERROR target with chainname */
@@ -270,15 +277,15 @@ get_chainname_rulenum(struct ipt_entry *s, struct ipt_entry *e,
         return 0;
 }
 
-static void trace_packet(struct sk_buff *skb,
+static void trace_packet(const struct sk_buff *skb,
                          unsigned int hook,
                          const struct net_device *in,
                          const struct net_device *out,
                          const char *tablename,
-                         struct xt_table_info *private,
-                         struct ipt_entry *e)
+                         const struct xt_table_info *private,
+                         const struct ipt_entry *e)
 {
-        void *table_base;
+        const void *table_base;
         const struct ipt_entry *root;
         const char *hookname, *chainname, *comment;
         unsigned int rulenum = 0;
@@ -322,9 +329,9 @@ ipt_do_table(struct sk_buff *skb,
         /* Initializing verdict to NF_DROP keeps gcc happy. */
         unsigned int verdict = NF_DROP;
         const char *indev, *outdev;
-        void *table_base;
+        const void *table_base;
         struct ipt_entry *e, *back;
-        struct xt_table_info *private;
+        const struct xt_table_info *private;
         struct xt_match_param mtpar;
         struct xt_target_param tgpar;
 
@@ -357,7 +364,7 @@ ipt_do_table(struct sk_buff *skb,
         back = get_entry(table_base, private->underflow[hook]);
 
         do {
-                struct ipt_entry_target *t;
+                const struct ipt_entry_target *t;
 
                 IP_NF_ASSERT(e);
                 IP_NF_ASSERT(back);
@@ -450,7 +457,7 @@ ipt_do_table(struct sk_buff *skb,
 /* Figures out from what hook each rule can be called: returns 0 if
    there are loops.  Puts hook bitmask in comefrom. */
 static int
-mark_source_chains(struct xt_table_info *newinfo,
+mark_source_chains(const struct xt_table_info *newinfo,
                    unsigned int valid_hooks, void *entry0)
 {
         unsigned int hook;
@@ -468,8 +475,8 @@ mark_source_chains(struct xt_table_info *newinfo,
                 e->counters.pcnt = pos;
 
                 for (;;) {
-                        struct ipt_standard_target *t
-                                = (void *)ipt_get_target(e);
+                        const struct ipt_standard_target *t
+                                = (void *)ipt_get_target_c(e);
                         int visited = e->comefrom & (1 << hook);
 
                         if (e->comefrom & (1 << NF_INET_NUMHOOKS)) {
@@ -578,9 +585,9 @@ cleanup_match(struct ipt_entry_match *m, struct net *net, unsigned int *i)
 }
 
 static int
-check_entry(struct ipt_entry *e, const char *name)
+check_entry(const struct ipt_entry *e, const char *name)
 {
-        struct ipt_entry_target *t;
+        const struct ipt_entry_target *t;
 
         if (!ip_checkentry(&e->ip)) {
                 duprintf("ip_tables: ip check failed %p %s.\n", e, name);
@@ -591,7 +598,7 @@ check_entry(struct ipt_entry *e, const char *name)
             e->next_offset)
                 return -EINVAL;
 
-        t = ipt_get_target(e);
+        t = ipt_get_target_c(e);
         if (e->target_offset + t->u.target_size > e->next_offset)
                 return -EINVAL;
 
@@ -718,14 +725,14 @@ find_check_entry(struct ipt_entry *e, struct net *net, const char *name,
         return ret;
 }
 
-static bool check_underflow(struct ipt_entry *e)
+static bool check_underflow(const struct ipt_entry *e)
 {
         const struct ipt_entry_target *t;
         unsigned int verdict;
 
         if (!unconditional(&e->ip))
                 return false;
-        t = ipt_get_target(e);
+        t = ipt_get_target_c(e);
         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
                 return false;
         verdict = ((struct ipt_standard_target *)t)->verdict;
@@ -736,8 +743,8 @@ static bool check_underflow(struct ipt_entry *e)
 static int
 check_entry_size_and_hooks(struct ipt_entry *e,
                            struct xt_table_info *newinfo,
-                           unsigned char *base,
-                           unsigned char *limit,
+                           const unsigned char *base,
+                           const unsigned char *limit,
                            const unsigned int *hook_entries,
                            const unsigned int *underflows,
                            unsigned int valid_hooks,
@@ -952,11 +959,11 @@ get_counters(const struct xt_table_info *t,
         local_bh_enable();
 }
 
-static struct xt_counters * alloc_counters(struct xt_table *table)
+static struct xt_counters *alloc_counters(const struct xt_table *table)
 {
         unsigned int countersize;
         struct xt_counters *counters;
-        struct xt_table_info *private = table->private;
+        const struct xt_table_info *private = table->private;
 
         /* We need atomic snapshot of counters: rest doesn't change
            (other than comefrom, which userspace doesn't care
@@ -974,11 +981,11 @@ static struct xt_counters * alloc_counters(struct xt_table *table)
 
 static int
 copy_entries_to_user(unsigned int total_size,
-                     struct xt_table *table,
+                     const struct xt_table *table,
                      void __user *userptr)
 {
         unsigned int off, num;
-        struct ipt_entry *e;
+        const struct ipt_entry *e;
         struct xt_counters *counters;
         const struct xt_table_info *private = table->private;
         int ret = 0;
@@ -1030,7 +1037,7 @@ copy_entries_to_user(unsigned int total_size,
                         }
                 }
 
-                t = ipt_get_target(e);
+                t = ipt_get_target_c(e);
                 if (copy_to_user(userptr + off + e->target_offset
                                  + offsetof(struct ipt_entry_target,
                                             u.user.name),
@@ -1066,24 +1073,24 @@ static int compat_standard_to_user(void __user *dst, const void *src)
 }
 
 static inline int
-compat_calc_match(struct ipt_entry_match *m, int *size)
+compat_calc_match(const struct ipt_entry_match *m, int *size)
 {
         *size += xt_compat_match_offset(m->u.kernel.match);
         return 0;
 }
 
-static int compat_calc_entry(struct ipt_entry *e,
+static int compat_calc_entry(const struct ipt_entry *e,
                              const struct xt_table_info *info,
-                             void *base, struct xt_table_info *newinfo)
+                             const void *base, struct xt_table_info *newinfo)
 {
-        struct ipt_entry_target *t;
+        const struct ipt_entry_target *t;
         unsigned int entry_offset;
         int off, i, ret;
 
         off = sizeof(struct ipt_entry) - sizeof(struct compat_ipt_entry);
         entry_offset = (void *)e - base;
         IPT_MATCH_ITERATE(e, compat_calc_match, &off);
-        t = ipt_get_target(e);
+        t = ipt_get_target_c(e);
         off += xt_compat_target_offset(t->u.kernel.target);
         newinfo->size -= off;
         ret = xt_compat_add_offset(AF_INET, entry_offset, off);
@@ -1119,7 +1126,8 @@ static int compat_table_info(const struct xt_table_info *info,
 }
 #endif
 
-static int get_info(struct net *net, void __user *user, int *len, int compat)
+static int get_info(struct net *net, void __user *user,
+                    const int *len, int compat)
 {
         char name[IPT_TABLE_MAXNAMELEN];
         struct xt_table *t;
@@ -1179,7 +1187,8 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
 }
 
 static int
-get_entries(struct net *net, struct ipt_get_entries __user *uptr, int *len)
+get_entries(struct net *net, struct ipt_get_entries __user *uptr,
+            const int *len)
 {
         int ret;
         struct ipt_get_entries get;
@@ -1289,7 +1298,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 }
 
 static int
-do_replace(struct net *net, void __user *user, unsigned int len)
+do_replace(struct net *net, const void __user *user, unsigned int len)
 {
         int ret;
         struct ipt_replace tmp;
@@ -1350,7 +1359,8 @@ add_counter_to_entry(struct ipt_entry *e,
 }
 
 static int
-do_add_counters(struct net *net, void __user *user, unsigned int len, int compat)
+do_add_counters(struct net *net, const void __user *user,
+                unsigned int len, int compat)
 {
         unsigned int i, curcpu;
         struct xt_counters_info tmp;
@@ -1546,10 +1556,10 @@ static int
 check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
                                   struct xt_table_info *newinfo,
                                   unsigned int *size,
-                                  unsigned char *base,
-                                  unsigned char *limit,
-                                  unsigned int *hook_entries,
-                                  unsigned int *underflows,
+                                  const unsigned char *base,
+                                  const unsigned char *limit,
+                                  const unsigned int *hook_entries,
+                                  const unsigned int *underflows,
                                   unsigned int *i,
                                   const char *name)
 {