Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 645 insertions, 0 deletions

diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
new file mode 100644
index 000000000..09d745112
--- /dev/null
+++ b/net/ipv4/ip_options.c
@@ -0,0 +1,645 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		The options processing module for ip.c
+ *
+ * Authors:	A.N.Kuznetsov
+ *
+ */
+
+#define pr_fmt(fmt) "IPv4: " fmt
+
+#include <linux/capability.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/unaligned.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/icmp.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/route.h>
+#include <net/cipso_ipv4.h>
+#include <net/ip_fib.h>
+
+/*
+ * Write options to IP header, record destination address to
+ * source route option, address of outgoing interface
+ * (we should already know it, so that this  function is allowed be
+ * called only after routing decision) and timestamp,
+ * if we originate this datagram.
+ *
+ * daddr is real destination address, next hop is recorded in IP header.
+ * saddr is address of outgoing interface.
+ */
+
+void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
+		      __be32 daddr, struct rtable *rt)
+{
+	unsigned char *iph = skb_network_header(skb);
+
+	memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
+	memcpy(iph + sizeof(struct iphdr), opt->__data, opt->optlen);
+	opt = &(IPCB(skb)->opt);
+
+	if (opt->srr)
+		memcpy(iph + opt->srr + iph[opt->srr + 1] - 4, &daddr, 4);
+
+	if (opt->rr_needaddr)
+		ip_rt_get_source(iph + opt->rr + iph[opt->rr + 2] - 5, skb, rt);
+	if (opt->ts_needaddr)
+		ip_rt_get_source(iph + opt->ts + iph[opt->ts + 2] - 9, skb, rt);
+	if (opt->ts_needtime) {
+		__be32 midtime;
+
+		midtime = inet_current_timestamp();
+		memcpy(iph + opt->ts + iph[opt->ts + 2] - 5, &midtime, 4);
+	}
+}
+
+/*
+ * Provided (sopt, skb) points to received options,
+ * build in dopt compiled option set appropriate for answering.
+ * i.e. invert SRR option, copy anothers,
+ * and grab room in RR/TS options.
+ *
+ * NOTE: dopt cannot point to skb.
+ */
+
+int __ip_options_echo(struct net *net, struct ip_options *dopt,
+		      struct sk_buff *skb, const struct ip_options *sopt)
+{
+	unsigned char *sptr, *dptr;
+	int soffset, doffset;
+	int	optlen;
+
+	memset(dopt, 0, sizeof(struct ip_options));
+
+	if (sopt->optlen == 0)
+		return 0;
+
+	sptr = skb_network_header(skb);
+	dptr = dopt->__data;
+
+	if (sopt->rr) {
+		optlen  = sptr[sopt->rr+1];
+		soffset = sptr[sopt->rr+2];
+		dopt->rr = dopt->optlen + sizeof(struct iphdr);
+		memcpy(dptr, sptr+sopt->rr, optlen);
+		if (sopt->rr_needaddr && soffset <= optlen) {
+			if (soffset + 3 > optlen)
+				return -EINVAL;
+			dptr[2] = soffset + 4;
+			dopt->rr_needaddr = 1;
+		}
+		dptr += optlen;
+		dopt->optlen += optlen;
+	}
+	if (sopt->ts) {
+		optlen = sptr[sopt->ts+1];
+		soffset = sptr[sopt->ts+2];
+		dopt->ts = dopt->optlen + sizeof(struct iphdr);
+		memcpy(dptr, sptr+sopt->ts, optlen);
+		if (soffset <= optlen) {
+			if (sopt->ts_needaddr) {
+				if (soffset + 3 > optlen)
+					return -EINVAL;
+				dopt->ts_needaddr = 1;
+				soffset += 4;
+			}
+			if (sopt->ts_needtime) {
+				if (soffset + 3 > optlen)
+					return -EINVAL;
+				if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
+					dopt->ts_needtime = 1;
+					soffset += 4;
+				} else {
+					dopt->ts_needtime = 0;
+
+					if (soffset + 7 <= optlen) {
+						__be32 addr;
+
+						memcpy(&addr, dptr+soffset-1, 4);
+						if (inet_addr_type(net, addr) != RTN_UNICAST) {
+							dopt->ts_needtime = 1;
+							soffset += 8;
+						}
+					}
+				}
+			}
+			dptr[2] = soffset;
+		}
+		dptr += optlen;
+		dopt->optlen += optlen;
+	}
+	if (sopt->srr) {
+		unsigned char *start = sptr+sopt->srr;
+		__be32 faddr;
+
+		optlen  = start[1];
+		soffset = start[2];
+		doffset = 0;
+		if (soffset > optlen)
+			soffset = optlen + 1;
+		soffset -= 4;
+		if (soffset > 3) {
+			memcpy(&faddr, &start[soffset-1], 4);
+			for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4)
+				memcpy(&dptr[doffset-1], &start[soffset-1], 4);
+			/*
+			 * RFC1812 requires to fix illegal source routes.
+			 */
+			if (memcmp(&ip_hdr(skb)->saddr,
+				   &start[soffset + 3], 4) == 0)
+				doffset -= 4;
+		}
+		if (doffset > 3) {
+			dopt->faddr = faddr;
+			dptr[0] = start[0];
+			dptr[1] = doffset+3;
+			dptr[2] = 4;
+			dptr += doffset+3;
+			dopt->srr = dopt->optlen + sizeof(struct iphdr);
+			dopt->optlen += doffset+3;
+			dopt->is_strictroute = sopt->is_strictroute;
+		}
+	}
+	if (sopt->cipso) {
+		optlen  = sptr[sopt->cipso+1];
+		dopt->cipso = dopt->optlen+sizeof(struct iphdr);
+		memcpy(dptr, sptr+sopt->cipso, optlen);
+		dptr += optlen;
+		dopt->optlen += optlen;
+	}
+	while (dopt->optlen & 3) {
+		*dptr++ = IPOPT_END;
+		dopt->optlen++;
+	}
+	return 0;
+}
+
+/*
+ *	Options "fragmenting", just fill options not
+ *	allowed in fragments with NOOPs.
+ *	Simple and stupid 8), but the most efficient way.
+ */
+
+void ip_options_fragment(struct sk_buff *skb)
+{
+	unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
+	struct ip_options *opt = &(IPCB(skb)->opt);
+	int  l = opt->optlen;
+	int  optlen;
+
+	while (l > 0) {
+		switch (*optptr) {
+		case IPOPT_END:
+			return;
+		case IPOPT_NOOP:
+			l--;
+			optptr++;
+			continue;
+		}
+		optlen = optptr[1];
+		if (optlen < 2 || optlen > l)
+		  return;
+		if (!IPOPT_COPIED(*optptr))
+			memset(optptr, IPOPT_NOOP, optlen);
+		l -= optlen;
+		optptr += optlen;
+	}
+	opt->ts = 0;
+	opt->rr = 0;
+	opt->rr_needaddr = 0;
+	opt->ts_needaddr = 0;
+	opt->ts_needtime = 0;
+}
+
+/* helper used by ip_options_compile() to call fib_compute_spec_dst()
+ * at most one time.
+ */
+static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
+{
+	if (*spec_dst == htonl(INADDR_ANY))
+		*spec_dst = fib_compute_spec_dst(skb);
+}
+
+/*
+ * Verify options and fill pointers in struct options.
+ * Caller should clear *opt, and set opt->data.
+ * If opt == NULL, then skb->data should point to IP header.
+ */
+
+int __ip_options_compile(struct net *net,
+			 struct ip_options *opt, struct sk_buff *skb,
+			 __be32 *info)
+{
+	__be32 spec_dst = htonl(INADDR_ANY);
+	unsigned char *pp_ptr = NULL;
+	struct rtable *rt = NULL;
+	unsigned char *optptr;
+	unsigned char *iph;
+	int optlen, l;
+
+	if (skb) {
+		rt = skb_rtable(skb);
+		optptr = (unsigned char *)&(ip_hdr(skb)[1]);
+	} else
+		optptr = opt->__data;
+	iph = optptr - sizeof(struct iphdr);
+
+	for (l = opt->optlen; l > 0; ) {
+		switch (*optptr) {
+		case IPOPT_END:
+			for (optptr++, l--; l > 0; optptr++, l--) {
+				if (*optptr != IPOPT_END) {
+					*optptr = IPOPT_END;
+					opt->is_changed = 1;
+				}
+			}
+			goto eol;
+		case IPOPT_NOOP:
+			l--;
+			optptr++;
+			continue;
+		}
+		if (unlikely(l < 2)) {
+			pp_ptr = optptr;
+			goto error;
+		}
+		optlen = optptr[1];
+		if (optlen < 2 || optlen > l) {
+			pp_ptr = optptr;
+			goto error;
+		}
+		switch (*optptr) {
+		case IPOPT_SSRR:
+		case IPOPT_LSRR:
+			if (optlen < 3) {
+				pp_ptr = optptr + 1;
+				goto error;
+			}
+			if (optptr[2] < 4) {
+				pp_ptr = optptr + 2;
+				goto error;
+			}
+			/* NB: cf RFC-1812 5.2.4.1 */
+			if (opt->srr) {
+				pp_ptr = optptr;
+				goto error;
+			}
+			if (!skb) {
+				if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
+					pp_ptr = optptr + 1;
+					goto error;
+				}
+				memcpy(&opt->faddr, &optptr[3], 4);
+				if (optlen > 7)
+					memmove(&optptr[3], &optptr[7], optlen-7);
+			}
+			opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
+			opt->srr = optptr - iph;
+			break;
+		case IPOPT_RR:
+			if (opt->rr) {
+				pp_ptr = optptr;
+				goto error;
+			}
+			if (optlen < 3) {
+				pp_ptr = optptr + 1;
+				goto error;
+			}
+			if (optptr[2] < 4) {
+				pp_ptr = optptr + 2;
+				goto error;
+			}
+			if (optptr[2] <= optlen) {
+				if (optptr[2]+3 > optlen) {
+					pp_ptr = optptr + 2;
+					goto error;
+				}
+				if (rt) {
+					spec_dst_fill(&spec_dst, skb);
+					memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
+					opt->is_changed = 1;
+				}
+				optptr[2] += 4;
+				opt->rr_needaddr = 1;
+			}
+			opt->rr = optptr - iph;
+			break;
+		case IPOPT_TIMESTAMP:
+			if (opt->ts) {
+				pp_ptr = optptr;
+				goto error;
+			}
+			if (optlen < 4) {
+				pp_ptr = optptr + 1;
+				goto error;
+			}
+			if (optptr[2] < 5) {
+				pp_ptr = optptr + 2;
+				goto error;
+			}
+			if (optptr[2] <= optlen) {
+				unsigned char *timeptr = NULL;
+				if (optptr[2]+3 > optlen) {
+					pp_ptr = optptr + 2;
+					goto error;
+				}
+				switch (optptr[3]&0xF) {
+				case IPOPT_TS_TSONLY:
+					if (skb)
+						timeptr = &optptr[optptr[2]-1];
+					opt->ts_needtime = 1;
+					optptr[2] += 4;
+					break;
+				case IPOPT_TS_TSANDADDR:
+					if (optptr[2]+7 > optlen) {
+						pp_ptr = optptr + 2;
+						goto error;
+					}
+					if (rt)  {
+						spec_dst_fill(&spec_dst, skb);
+						memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
+						timeptr = &optptr[optptr[2]+3];
+					}
+					opt->ts_needaddr = 1;
+					opt->ts_needtime = 1;
+					optptr[2] += 8;
+					break;
+				case IPOPT_TS_PRESPEC:
+					if (optptr[2]+7 > optlen) {
+						pp_ptr = optptr + 2;
+						goto error;
+					}
+					{
+						__be32 addr;
+						memcpy(&addr, &optptr[optptr[2]-1], 4);
+						if (inet_addr_type(net, addr) == RTN_UNICAST)
+							break;
+						if (skb)
+							timeptr = &optptr[optptr[2]+3];
+					}
+					opt->ts_needtime = 1;
+					optptr[2] += 8;
+					break;
+				default:
+					if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
+						pp_ptr = optptr + 3;
+						goto error;
+					}
+					break;
+				}
+				if (timeptr) {
+					__be32 midtime;
+
+					midtime = inet_current_timestamp();
+					memcpy(timeptr, &midtime, 4);
+					opt->is_changed = 1;
+				}
+			} else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {
+				unsigned int overflow = optptr[3]>>4;
+				if (overflow == 15) {
+					pp_ptr = optptr + 3;
+					goto error;
+				}
+				if (skb) {
+					optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
+					opt->is_changed = 1;
+				}
+			}
+			opt->ts = optptr - iph;
+			break;
+		case IPOPT_RA:
+			if (optlen < 4) {
+				pp_ptr = optptr + 1;
+				goto error;
+			}
+			if (optptr[2] == 0 && optptr[3] == 0)
+				opt->router_alert = optptr - iph;
+			break;
+		case IPOPT_CIPSO:
+			if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) {
+				pp_ptr = optptr;
+				goto error;
+			}
+			opt->cipso = optptr - iph;
+			if (cipso_v4_validate(skb, &optptr)) {
+				pp_ptr = optptr;
+				goto error;
+			}
+			break;
+		case IPOPT_SEC:
+		case IPOPT_SID:
+		default:
+			if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
+				pp_ptr = optptr;
+				goto error;
+			}
+			break;
+		}
+		l -= optlen;
+		optptr += optlen;
+	}
+
+eol:
+	if (!pp_ptr)
+		return 0;
+
+error:
+	if (info)
+		*info = htonl((pp_ptr-iph)<<24);
+	return -EINVAL;
+}
+EXPORT_SYMBOL(__ip_options_compile);
+
+int ip_options_compile(struct net *net,
+		       struct ip_options *opt, struct sk_buff *skb)
+{
+	int ret;
+	__be32 info;
+
+	ret = __ip_options_compile(net, opt, skb, &info);
+	if (ret != 0 && skb)
+		icmp_send(skb, ICMP_PARAMETERPROB, 0, info);
+	return ret;
+}
+EXPORT_SYMBOL(ip_options_compile);
+
+/*
+ *	Undo all the changes done by ip_options_compile().
+ */
+
+void ip_options_undo(struct ip_options *opt)
+{
+	if (opt->srr) {
+		unsigned char *optptr = opt->__data + opt->srr - sizeof(struct iphdr);
+
+		memmove(optptr + 7, optptr + 3, optptr[1] - 7);
+		memcpy(optptr + 3, &opt->faddr, 4);
+	}
+	if (opt->rr_needaddr) {
+		unsigned char *optptr = opt->__data + opt->rr - sizeof(struct iphdr);
+
+		optptr[2] -= 4;
+		memset(&optptr[optptr[2] - 1], 0, 4);
+	}
+	if (opt->ts) {
+		unsigned char *optptr = opt->__data + opt->ts - sizeof(struct iphdr);
+
+		if (opt->ts_needtime) {
+			optptr[2] -= 4;
+			memset(&optptr[optptr[2] - 1], 0, 4);
+			if ((optptr[3] & 0xF) == IPOPT_TS_PRESPEC)
+				optptr[2] -= 4;
+		}
+		if (opt->ts_needaddr) {
+			optptr[2] -= 4;
+			memset(&optptr[optptr[2] - 1], 0, 4);
+		}
+	}
+}
+
+int ip_options_get(struct net *net, struct ip_options_rcu **optp,
+		   sockptr_t data, int optlen)
+{
+	struct ip_options_rcu *opt;
+
+	opt = kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
+		       GFP_KERNEL);
+	if (!opt)
+		return -ENOMEM;
+	if (optlen && copy_from_sockptr(opt->opt.__data, data, optlen)) {
+		kfree(opt);
+		return -EFAULT;
+	}
+
+	while (optlen & 3)
+		opt->opt.__data[optlen++] = IPOPT_END;
+	opt->opt.optlen = optlen;
+	if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
+		kfree(opt);
+		return -EINVAL;
+	}
+	if (opt->opt.srr && !ns_capable(net->user_ns, CAP_NET_RAW)) {
+		kfree(opt);
+		return -EPERM;
+	}
+	kfree(*optp);
+	*optp = opt;
+	return 0;
+}
+
+void ip_forward_options(struct sk_buff *skb)
+{
+	struct   ip_options *opt	= &(IPCB(skb)->opt);
+	unsigned char *optptr;
+	struct rtable *rt = skb_rtable(skb);
+	unsigned char *raw = skb_network_header(skb);
+
+	if (opt->rr_needaddr) {
+		optptr = (unsigned char *)raw + opt->rr;
+		ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
+		opt->is_changed = 1;
+	}
+	if (opt->srr_is_hit) {
+		int srrptr, srrspace;
+
+		optptr = raw + opt->srr;
+
+		for ( srrptr = optptr[2], srrspace = optptr[1];
+		     srrptr <= srrspace;
+		     srrptr += 4
+		     ) {
+			if (srrptr + 3 > srrspace)
+				break;
+			if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
+				break;
+		}
+		if (srrptr + 3 <= srrspace) {
+			opt->is_changed = 1;
+			ip_hdr(skb)->daddr = opt->nexthop;
+			ip_rt_get_source(&optptr[srrptr-1], skb, rt);
+			optptr[2] = srrptr+4;
+		} else {
+			net_crit_ratelimited("%s(): Argh! Destination lost!\n",
+					     __func__);
+		}
+		if (opt->ts_needaddr) {
+			optptr = raw + opt->ts;
+			ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
+			opt->is_changed = 1;
+		}
+	}
+	if (opt->is_changed) {
+		opt->is_changed = 0;
+		ip_send_check(ip_hdr(skb));
+	}
+}
+
+int ip_options_rcv_srr(struct sk_buff *skb, struct net_device *dev)
+{
+	struct ip_options *opt = &(IPCB(skb)->opt);
+	int srrspace, srrptr;
+	__be32 nexthop;
+	struct iphdr *iph = ip_hdr(skb);
+	unsigned char *optptr = skb_network_header(skb) + opt->srr;
+	struct rtable *rt = skb_rtable(skb);
+	struct rtable *rt2;
+	unsigned long orefdst;
+	int err;
+
+	if (!rt)
+		return 0;
+
+	if (skb->pkt_type != PACKET_HOST)
+		return -EINVAL;
+	if (rt->rt_type == RTN_UNICAST) {
+		if (!opt->is_strictroute)
+			return 0;
+		icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
+		return -EINVAL;
+	}
+	if (rt->rt_type != RTN_LOCAL)
+		return -EINVAL;
+
+	for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
+		if (srrptr + 3 > srrspace) {
+			icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
+			return -EINVAL;
+		}
+		memcpy(&nexthop, &optptr[srrptr-1], 4);
+
+		orefdst = skb_dstref_steal(skb);
+		err = ip_route_input(skb, nexthop, iph->saddr, ip4h_dscp(iph),
+				     dev) ? -EINVAL : 0;
+		rt2 = skb_rtable(skb);
+		if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
+			skb_dst_drop(skb);
+			skb_dstref_restore(skb, orefdst);
+			return -EINVAL;
+		}
+		refdst_drop(orefdst);
+		if (rt2->rt_type != RTN_LOCAL)
+			break;
+		/* Superfast 8) loopback forward */
+		iph->daddr = nexthop;
+		opt->is_changed = 1;
+	}
+	if (srrptr <= srrspace) {
+		opt->srr_is_hit = 1;
+		opt->nexthop = nexthop;
+		opt->is_changed = 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(ip_options_rcv_srr);