ebtables: use match, target and data copy_to_user helpers

Convert ebtables to copying entries, matches and targets one by one.

The solution is analogous to that of generic xt_(match|target)_to_user
helpers, but is applied to different structs.

Convert existing helpers ebt_make_XXXname helpers that overwrite
fields of an already copy_to_user'd struct with ebt_XXX_to_user
helpers that copy all relevant fields of the struct from scratch.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 537e3d5..79b6991 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1346,56 +1346,72 @@ static int update_counters(struct net *net, const void __user *user,
                                hlp.num_counters, user, len);
 }
 
-static inline int ebt_make_matchname(const struct ebt_entry_match *m,
-                                    const char *base, char __user *ubase)
+static inline int ebt_obj_to_user(char __user *um, const char *_name,
+                                 const char *data, int entrysize,
+                                 int usersize, int datasize)
 {
-       char __user *hlp = ubase + ((char *)m - base);
-       char name[EBT_FUNCTION_MAXNAMELEN] = {};
+       char name[EBT_FUNCTION_MAXNAMELEN] = {0};
 
        /* ebtables expects 32 bytes long names but xt_match names are 29 bytes
         * long. Copy 29 bytes and fill remaining bytes with zeroes.
         */
-       strlcpy(name, m->u.match->name, sizeof(name));
-       if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
+       strlcpy(name, _name, sizeof(name));
+       if (copy_to_user(um, name, EBT_FUNCTION_MAXNAMELEN) ||
+           put_user(datasize, (int __user *)(um + EBT_FUNCTION_MAXNAMELEN)) ||
+           xt_data_to_user(um + entrysize, data, usersize, datasize))
                return -EFAULT;
+
        return 0;
 }
 
-static inline int ebt_make_watchername(const struct ebt_entry_watcher *w,
-                                      const char *base, char __user *ubase)
+static inline int ebt_match_to_user(const struct ebt_entry_match *m,
+                                   const char *base, char __user *ubase)
 {
-       char __user *hlp = ubase + ((char *)w - base);
-       char name[EBT_FUNCTION_MAXNAMELEN] = {};
+       return ebt_obj_to_user(ubase + ((char *)m - base),
+                              m->u.match->name, m->data, sizeof(*m),
+                              m->u.match->usersize, m->match_size);
+}
 
-       strlcpy(name, w->u.watcher->name, sizeof(name));
-       if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
-               return -EFAULT;
-       return 0;
+static inline int ebt_watcher_to_user(const struct ebt_entry_watcher *w,
+                                     const char *base, char __user *ubase)
+{
+       return ebt_obj_to_user(ubase + ((char *)w - base),
+                              w->u.watcher->name, w->data, sizeof(*w),
+                              w->u.watcher->usersize, w->watcher_size);
 }
 
-static inline int ebt_make_names(struct ebt_entry *e, const char *base,
-                                char __user *ubase)
+static inline int ebt_entry_to_user(struct ebt_entry *e, const char *base,
+                                   char __user *ubase)
 {
        int ret;
        char __user *hlp;
        const struct ebt_entry_target *t;
-       char name[EBT_FUNCTION_MAXNAMELEN] = {};
 
-       if (e->bitmask == 0)
+       if (e->bitmask == 0) {
+               /* special case !EBT_ENTRY_OR_ENTRIES */
+               if (copy_to_user(ubase + ((char *)e - base), e,
+                                sizeof(struct ebt_entries)))
+                       return -EFAULT;
                return 0;
+       }
+
+       if (copy_to_user(ubase + ((char *)e - base), e, sizeof(*e)))
+               return -EFAULT;
 
        hlp = ubase + (((char *)e + e->target_offset) - base);
        t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);
 
-       ret = EBT_MATCH_ITERATE(e, ebt_make_matchname, base, ubase);
+       ret = EBT_MATCH_ITERATE(e, ebt_match_to_user, base, ubase);
        if (ret != 0)
                return ret;
-       ret = EBT_WATCHER_ITERATE(e, ebt_make_watchername, base, ubase);
+       ret = EBT_WATCHER_ITERATE(e, ebt_watcher_to_user, base, ubase);
        if (ret != 0)
                return ret;
-       strlcpy(name, t->u.target->name, sizeof(name));
-       if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
-               return -EFAULT;
+       ret = ebt_obj_to_user(hlp, t->u.target->name, t->data, sizeof(*t),
+                             t->u.target->usersize, t->target_size);
+       if (ret != 0)
+               return ret;
+
        return 0;
 }
 
@@ -1475,13 +1491,9 @@ static int copy_everything_to_user(struct ebt_table *t, void __user *user,
        if (ret)
                return ret;
 
-       if (copy_to_user(tmp.entries, entries, entries_size)) {
-               BUGPRINT("Couldn't copy entries to userspace\n");
-               return -EFAULT;
-       }
        /* set the match/watcher/target names right */
        return EBT_ENTRY_ITERATE(entries, entries_size,
-          ebt_make_names, entries, tmp.entries);
+          ebt_entry_to_user, entries, tmp.entries);
 }
 
 static int do_ebt_set_ctl(struct sock *sk,
@@ -1630,8 +1642,10 @@ static int compat_match_to_user(struct ebt_entry_match *m, void __user **dstptr,
        if (match->compat_to_user) {
                if (match->compat_to_user(cm->data, m->data))
                        return -EFAULT;
-       } else if (copy_to_user(cm->data, m->data, msize))
+       } else {
+               if (xt_data_to_user(cm->data, m->data, match->usersize, msize))
                        return -EFAULT;
+       }
 
        *size -= ebt_compat_entry_padsize() + off;
        *dstptr = cm->data;
@@ -1657,8 +1671,10 @@ static int compat_target_to_user(struct ebt_entry_target *t,
        if (target->compat_to_user) {
                if (target->compat_to_user(cm->data, t->data))
                        return -EFAULT;
-       } else if (copy_to_user(cm->data, t->data, tsize))
-               return -EFAULT;
+       } else {
+               if (xt_data_to_user(cm->data, t->data, target->usersize, tsize))
+                       return -EFAULT;
+       }
 
        *size -= ebt_compat_entry_padsize() + off;
        *dstptr = cm->data;