netfilter: x_tables: introduce and use xt_copy_counters_from_user

[firefly-linux-kernel-4.4.55.git] / net / netfilter / x_tables.c

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 08c9e312bd78a41f8e86ade29c0fe87cd3f3d592..25391fb255162204b197895647f9c2f3c6d96507 100644 (file)
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -751,6 +751,80 @@ int xt_check_target(struct xt_tgchk_param *par,
 }
 EXPORT_SYMBOL_GPL(xt_check_target);
 
+/**
+ * xt_copy_counters_from_user - copy counters and metadata from userspace
+ *
+ * @user: src pointer to userspace memory
+ * @len: alleged size of userspace memory
+ * @info: where to store the xt_counters_info metadata
+ * @compat: true if we setsockopt call is done by 32bit task on 64bit kernel
+ *
+ * Copies counter meta data from @user and stores it in @info.
+ *
+ * vmallocs memory to hold the counters, then copies the counter data
+ * from @user to the new memory and returns a pointer to it.
+ *
+ * If @compat is true, @info gets converted automatically to the 64bit
+ * representation.
+ *
+ * The metadata associated with the counters is stored in @info.
+ *
+ * Return: returns pointer that caller has to test via IS_ERR().
+ * If IS_ERR is false, caller has to vfree the pointer.
+ */
+void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
+                                struct xt_counters_info *info, bool compat)
+{
+       void *mem;
+       u64 size;
+
+#ifdef CONFIG_COMPAT
+       if (compat) {
+               /* structures only differ in size due to alignment */
+               struct compat_xt_counters_info compat_tmp;
+
+               if (len <= sizeof(compat_tmp))
+                       return ERR_PTR(-EINVAL);
+
+               len -= sizeof(compat_tmp);
+               if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0)
+                       return ERR_PTR(-EFAULT);
+
+               strlcpy(info->name, compat_tmp.name, sizeof(info->name));
+               info->num_counters = compat_tmp.num_counters;
+               user += sizeof(compat_tmp);
+       } else
+#endif
+       {
+               if (len <= sizeof(*info))
+                       return ERR_PTR(-EINVAL);
+
+               len -= sizeof(*info);
+               if (copy_from_user(info, user, sizeof(*info)) != 0)
+                       return ERR_PTR(-EFAULT);
+
+               info->name[sizeof(info->name) - 1] = '\0';
+               user += sizeof(*info);
+       }
+
+       size = sizeof(struct xt_counters);
+       size *= info->num_counters;
+
+       if (size != (u64)len)
+               return ERR_PTR(-EINVAL);
+
+       mem = vmalloc(len);
+       if (!mem)
+               return ERR_PTR(-ENOMEM);
+
+       if (copy_from_user(mem, user, len) == 0)
+               return mem;
+
+       vfree(mem);
+       return ERR_PTR(-EFAULT);
+}
+EXPORT_SYMBOL_GPL(xt_copy_counters_from_user);
+
 #ifdef CONFIG_COMPAT
 int xt_compat_target_offset(const struct xt_target *target)
 {