xt_ACCOUNT: make counters 64-bit wide

The Smoothwall Express traffic stats collector (traffiClogger) does
not handle counter rollovers well and does not perform read&flush.
(Yes, the code is somewhat aged.) To change it to perform read&flush
is non-trivial. Then, it occurred to me that it might be easier to
change ipt_ACCOUNT in xtables-addons to use 64-bit counters,
considering it was designed around single kernel pages.

The following submission counts to at least 100 GB, produces no
obvious kernel gripes, and adjacent counters do not seem to interfere
with each other. Yes, it uses more memory, but RAM costs much less
than bugs that grown out of complex software.

The theory:

  - Use two kernel pages for the counters for each group of 256
    addresses.
  - Change counters to 64-bit.
  - Change to __get_free_pages/free_pages, using order=2
    (two consecutive pages), and zero both pages.
  - Change "%u" to "%llu" as needed.
  - Everything else pretty much stays the same.

I also changed tmpbuf to two pages (Justin Case's idea), but I
do not know if that's really necessary.

extensions/ACCOUNT/iptaccount.c

@@ -200,11 +200,11 @@ int main(int argc, char *argv[])
 			while ((entry = ipt_ACCOUNT_get_next_entry(&ctx)) != NULL)
 			{
 				if (doCSV)
-					printf("%s;%u;%u;%u;%u\n",
+					printf("%s;%llu;%llu;%llu;%llu\n",
 					       addr_to_dotted(entry->ip), entry->src_packets, entry->src_bytes,
 					       entry->dst_packets, entry->dst_bytes);
 				else
-					printf("IP: %s SRC packets: %u bytes: %u DST packets: %u bytes: %u\n",
+					printf("IP: %s SRC packets: %llu bytes: %llu DST packets: %llu bytes: %llu\n",
 					       addr_to_dotted(entry->ip), entry->src_packets, entry->src_bytes,
 					       entry->dst_packets, entry->dst_bytes);
 			}

extensions/ACCOUNT/xt_ACCOUNT.c

@@ -73,13 +73,13 @@ struct ipt_acc_handle {
 };
 
 /* Used for every IP entry
-   Size is 16 bytes so that 256 (class C network) * 16
-   fits in one kernel (zero) page */
+   Size is 32 bytes so that 256 (class C network) * 16
+   fits in a double kernel (zero) page (two consecutive kernel pages)*/
 struct ipt_acc_ip {
-	uint32_t src_packets;
-	uint32_t src_bytes;
-	uint32_t dst_packets;
-	uint32_t dst_bytes;
+	uint64_t src_packets;
+	uint64_t src_bytes;
+	uint64_t dst_packets;
+	uint64_t dst_bytes;
 };
 
 /*
@@ -109,14 +109,14 @@ static DEFINE_SPINLOCK(ipt_acc_lock);
 /* Mutex (semaphore) used for manipulating userspace handles/snapshot data */
 static struct semaphore ipt_acc_userspace_mutex;
 
-/* Allocates a page and clears it */
+/* Allocates a page pair and clears it */
 static void *ipt_acc_zalloc_page(void)
 {
 	// Don't use get_zeroed_page until it's fixed in the kernel.
 	// get_zeroed_page(GFP_ATOMIC)
-	void *mem = (void *)__get_free_page(GFP_ATOMIC);
+	void *mem = (void *)__get_free_pages(GFP_ATOMIC, 2);
 	if (mem) {
-		memset (mem, 0, PAGE_SIZE);
+		memset(mem, 0,  2 *PAGE_SIZE);
 	}
 
 	return mem;
@@ -131,7 +131,7 @@ static void ipt_acc_data_free(void *data, uint8_t depth)
 
 	/* Free for 8 bit network */
 	if (depth == 0) {
-		free_page((unsigned long)data);
+		free_pages((unsigned long)data, 2);
 		return;
 	}
 
@@ -144,7 +144,7 @@ static void ipt_acc_data_free(void *data, uint8_t depth)
 				free_page((unsigned long)mask_16->mask_24[b]);
 			}
 		}
-		free_page((unsigned long)data);
+		free_pages((unsigned long)data, 2);
 		return;
 	}
 
@@ -164,7 +164,7 @@ static void ipt_acc_data_free(void *data, uint8_t depth)
 				free_page((unsigned long)mask_16);
 			}
 		}
-		free_page((unsigned long)data);
+		free_pages((unsigned long)data, 2);
 		return;
 	}
 
@@ -538,7 +538,7 @@ ipt_acc_target(struct sk_buff *skb, const struct xt_action_param *par)
 
 /*
 	Functions dealing with "handles":
-	Handles are snapshots of a accounting state.
+	Handles are snapshots of an accounting state.
 
 	read snapshots are only for debugging the code
 	and are very expensive concerning speed/memory
@@ -1120,7 +1120,7 @@ static int __init account_tg_init(void)
 		ACCOUNT_MAX_HANDLES * sizeof(struct ipt_acc_handle));
 
 	/* Allocate one page as temporary storage */
-	if ((ipt_acc_tmpbuf = (void*)__get_free_page(GFP_KERNEL)) == NULL) {
+	if ((ipt_acc_tmpbuf = (void *)__get_free_pages(GFP_KERNEL, 2)) == NULL) {
 		printk("ACCOUNT: Out of memory for temporary buffer page\n");
 		goto error_cleanup;
 	}
@@ -1142,7 +1142,7 @@ error_cleanup:
 	if (ipt_acc_handles)
 		kfree(ipt_acc_handles);
 	if (ipt_acc_tmpbuf)
-		free_page((unsigned long)ipt_acc_tmpbuf);
+		free_pages((unsigned long)ipt_acc_tmpbuf, 2);
 
 	return -EINVAL;
 }
@@ -1155,7 +1155,7 @@ static void __exit account_tg_exit(void)
 
 	kfree(ipt_acc_tables);
 	kfree(ipt_acc_handles);
-	free_page((unsigned long)ipt_acc_tmpbuf);
+	free_pages((unsigned long)ipt_acc_tmpbuf, 2);
 }
 
 module_init(account_tg_init);

extensions/ACCOUNT/xt_ACCOUNT.h

@@ -60,10 +60,10 @@ struct ipt_acc_handle_sockopt {
 */
 struct ipt_acc_handle_ip {
 	__be32 ip;
-	uint32_t src_packets;
-	uint32_t src_bytes;
-	uint32_t dst_packets;
-	uint32_t dst_bytes;
+	uint64_t src_packets;
+	uint64_t src_bytes;
+	uint64_t dst_packets;
+	uint64_t dst_bytes;
 };
 
 #endif /* _IPT_ACCOUNT_H */