1 files changed, 54 insertions, 21 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index dd6d46015058..e9cb27061c12 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1810,6 +1810,29 @@ static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
 	return CIPSO_V4_HDR_LEN + ret_val;
 }
 
+static int cipso_v4_get_actual_opt_len(const unsigned char *data, int len)
+{
+	int iter = 0, optlen = 0;
+
+	/* determining the new total option length is tricky because of
+	 * the padding necessary, the only thing i can think to do at
+	 * this point is walk the options one-by-one, skipping the
+	 * padding at the end to determine the actual option size and
+	 * from there we can determine the new total option length
+	 */
+	while (iter < len) {
+		if (data[iter] == IPOPT_END) {
+			break;
+		} else if (data[iter] == IPOPT_NOP) {
+			iter++;
+		} else {
+			iter += data[iter + 1];
+			optlen = iter;
+		}
+	}
+	return optlen;
+}
+
 /**
  * cipso_v4_sock_setattr - Add a CIPSO option to a socket
  * @sk: the socket
@@ -1986,7 +2009,6 @@ static int cipso_v4_delopt(struct ip_options_rcu __rcu **opt_ptr)
 		u8 cipso_len;
 		u8 cipso_off;
 		unsigned char *cipso_ptr;
-		int iter;
 		int optlen_new;
 
 		cipso_off = opt->opt.cipso - sizeof(struct iphdr);
@@ -2006,19 +2028,8 @@ static int cipso_v4_delopt(struct ip_options_rcu __rcu **opt_ptr)
 		memmove(cipso_ptr, cipso_ptr + cipso_len,
 			opt->opt.optlen - cipso_off - cipso_len);
 
-		/* determining the new total option length is tricky because of
-		 * the padding necessary, the only thing i can think to do at
-		 * this point is walk the options one-by-one, skipping the
-		 * padding at the end to determine the actual option size and
-		 * from there we can determine the new total option length */
-		iter = 0;
-		optlen_new = 0;
-		while (iter < opt->opt.optlen)
-			if (opt->opt.__data[iter] != IPOPT_NOP) {
-				iter += opt->opt.__data[iter + 1];
-				optlen_new = iter;
-			} else
-				iter++;
+		optlen_new = cipso_v4_get_actual_opt_len(opt->opt.__data,
+							 opt->opt.optlen);
 		hdr_delta = opt->opt.optlen;
 		opt->opt.optlen = (optlen_new + 3) & ~3;
 		hdr_delta -= opt->opt.optlen;
@@ -2238,7 +2249,8 @@ int cipso_v4_skbuff_setattr(struct sk_buff *skb,
  */
 int cipso_v4_skbuff_delattr(struct sk_buff *skb)
 {
-	int ret_val;
+	int ret_val, cipso_len, hdr_len_actual, new_hdr_len_actual, new_hdr_len,
+	    hdr_len_delta;
 	struct iphdr *iph;
 	struct ip_options *opt = &IPCB(skb)->opt;
 	unsigned char *cipso_ptr;
@@ -2251,16 +2263,37 @@ int cipso_v4_skbuff_delattr(struct sk_buff *skb)
 	if (ret_val < 0)
 		return ret_val;
 
-	/* the easiest thing to do is just replace the cipso option with noop
-	 * options since we don't change the size of the packet, although we
-	 * still need to recalculate the checksum */
-
 	iph = ip_hdr(skb);
 	cipso_ptr = (unsigned char *)iph + opt->cipso;
-	memset(cipso_ptr, IPOPT_NOOP, cipso_ptr[1]);
+	cipso_len = cipso_ptr[1];
+
+	hdr_len_actual = sizeof(struct iphdr) +
+			 cipso_v4_get_actual_opt_len((unsigned char *)(iph + 1),
+						     opt->optlen);
+	new_hdr_len_actual = hdr_len_actual - cipso_len;
+	new_hdr_len = (new_hdr_len_actual + 3) & ~3;
+	hdr_len_delta = (iph->ihl << 2) - new_hdr_len;
+
+	/* 1. shift any options after CIPSO to the left */
+	memmove(cipso_ptr, cipso_ptr + cipso_len,
+		new_hdr_len_actual - opt->cipso);
+	/* 2. move the whole IP header to its new place */
+	memmove((unsigned char *)iph + hdr_len_delta, iph, new_hdr_len_actual);
+	/* 3. adjust the skb layout */
+	skb_pull(skb, hdr_len_delta);
+	skb_reset_network_header(skb);
+	iph = ip_hdr(skb);
+	/* 4. re-fill new padding with IPOPT_END (may now be longer) */
+	memset((unsigned char *)iph + new_hdr_len_actual, IPOPT_END,
+	       new_hdr_len - new_hdr_len_actual);
+
+	opt->optlen -= hdr_len_delta;
 	opt->cipso = 0;
 	opt->is_changed = 1;
-
+	if (hdr_len_delta != 0) {
+		iph->ihl = new_hdr_len >> 2;
+		iph_set_totlen(iph, skb->len);
+	}
 	ip_send_check(iph);
 
 	return 0;