Restore netstat -M functionality for most statistics on core dumps. In

general, when support was added to netstat for fetching data using sysctl,
no provision was left for fetching equivalent data from a core dump, and
in fact, netstat would _always_ fetch data from the live kernel using
sysctl even when -M was specified resulting in the user believing they
were getting data from coredumps when they actually weren't.  Some specific
changes:
- Add a global 'live' variable that is true if netstat is running against
  the live kernel and false if -M has been specified.
- Stop abusing the sysctl flag in the protocol tables to hold the protocol
  number.  Instead, the protocol is now its own field in the tables, and
  it is passed as a separate parameter to the PCB and stat routines rather
  than overloading the KVM offset parameter.
- Don't run PCB or stats functions who don't have a namelist offset if we
  are being run against a crash dump (!live).
- For the inet and unix PCB routines, we generate the same buffer from KVM
  that the sysctl usually generates complete with the header and trailer.
- Don't run bpf stats for !live (before it would just silently always run
  live).
- kread() no longer trashes memory when opening the buffer if there is an
  error on open and the passed in buffer is smaller than _POSIX2_LINE_MAX.
- The multicast routing code doesn't fallback to kvm on live kernels if
  the sysctl fails.  Keeping this made the code rather hairy, and netstat
  is already tied to the kernel ABI anyway (even when using sysctl's since
  things like xinpcb contain an inpcb) so any kernels this is run against
  that have the multicast routing stuff should have the sysctls.
- Don't try to dig around in the kernel linker in the netgraph PCB routine
  for core dumps.

Other notes:
- sctp's PCB routine only works on live kernels, it looked rather
  complicated to generate all the same stuff via KVM.  Someone can always
  add it later if desired though.
- Fix the ipsec removal bug where N_xxx for IPSEC stats weren't renumbered.
- Use sysctlbyname() everywhere rather than hardcoded mib values.

MFC after:	1 week
Approved by:	re (rwatson)

1 files changed, 133 insertions, 19 deletions

diff --git a/usr.bin/netstat/unix.c b/usr.bin/netstat/unix.c
index be70d5b..03bef85 100644
--- a/usr.bin/netstat/unix.c
+++ b/usr.bin/netstat/unix.c
@@ -61,6 +61,7 @@ __FBSDID("$FreeBSD$");
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <strings.h>
 #include <kvm.h>
 #include "netstat.h"
 
@@ -69,35 +70,148 @@ static	void unixdomainpr (struct xunpcb *, struct xsocket *);
 static	const char *const socktype[] =
     { "#0", "stream", "dgram", "raw", "rdm", "seqpacket" };
 
-void
-unixpr(void)
+static int
+pcblist_sysctl(int type, char **bufp)
 {
 	char 	*buf;
-	int	type;
 	size_t	len;
-	struct	xsocket *so;
-	struct	xunpgen *xug, *oxug;
-	struct	xunpcb *xunp;
 	char mibvar[sizeof "net.local.seqpacket.pcblist"];
 
-	for (type = SOCK_STREAM; type <= SOCK_SEQPACKET; type++) {
-		sprintf(mibvar, "net.local.%s.pcblist", socktype[type]);
+	sprintf(mibvar, "net.local.%s.pcblist", socktype[type]);
+
+	len = 0;
+	if (sysctlbyname(mibvar, 0, &len, 0, 0) < 0) {
+		if (errno != ENOENT)
+			warn("sysctl: %s", mibvar);
+		return (-1);
+	}
+	if ((buf = malloc(len)) == 0) {
+		warnx("malloc %lu bytes", (u_long)len);
+		return (-2);
+	}
+	if (sysctlbyname(mibvar, buf, &len, 0, 0) < 0) {
+		warn("sysctl: %s", mibvar);
+		free(buf);
+		return (-2);
+	}
+	*bufp = buf;
+	return (0);
+}
+
+static int
+pcblist_kvm(u_long count_off, u_long gencnt_off, u_long head_off, char **bufp)
+{
+	struct unp_head head;
+	struct unpcb *unp, unp_conn;
+	u_char sun_len;
+	struct socket so;
+	struct xunpgen xug;
+	struct xunpcb xu;
+	unp_gen_t unp_gencnt;
+	u_int	unp_count;
+	char 	*buf, *p;
+	size_t	len;
+
+	if (count_off == 0 || gencnt_off == 0)
+		return (-2);
+	if (head_off == 0)
+		return (-1);
+	kread(count_off, &unp_count, sizeof(unp_count));
+	len = 2 * sizeof(xug) + (unp_count + unp_count / 8) * sizeof(xu);
+	if ((buf = malloc(len)) == 0) {
+		warnx("malloc %lu bytes", (u_long)len);
+		return (-2);
+	}
+	p = buf;
+
+#define COPYOUT(obj, size) do {						\
+	if (len < (size)) {						\
+		warnx("buffer size exceeded");				\
+		goto fail;						\
+	}								\
+	bcopy((obj), p, (size));					\
+	len -= (size);							\
+	p += (size);							\
+} while (0)
+
+#define KREAD(off, buf, len) do {					\
+	if (kread((uintptr_t)(off), (buf), (len)) != 0)			\
+		goto fail;						\
+} while (0)
+
+	/* Write out header. */
+	kread(gencnt_off, &unp_gencnt, sizeof(unp_gencnt));
+	xug.xug_len = sizeof xug;
+	xug.xug_count = unp_count;
+	xug.xug_gen = unp_gencnt;
+	xug.xug_sogen = 0;
+	COPYOUT(&xug, sizeof xug);
 
-		len = 0;
-		if (sysctlbyname(mibvar, 0, &len, 0, 0) < 0) {
-			if (errno != ENOENT)
-				warn("sysctl: %s", mibvar);
+	/* Walk the PCB list. */
+	xu.xu_len = sizeof xu;
+	KREAD(head_off, &head, sizeof(head));
+	LIST_FOREACH(unp, &head, unp_link) {
+		xu.xu_unpp = unp;
+		KREAD(unp, &xu.xu_unp, sizeof (*unp));
+		unp = &xu.xu_unp;
+
+		if (unp->unp_gencnt > unp_gencnt)
 			continue;
+		if (unp->unp_addr != NULL) {
+			KREAD(unp->unp_addr, &sun_len, sizeof(sun_len));
+			KREAD(unp->unp_addr, &xu.xu_addr, sun_len);
 		}
-		if ((buf = malloc(len)) == 0) {
-			warnx("malloc %lu bytes", (u_long)len);
-			return;
+		if (unp->unp_conn != NULL) {
+			KREAD(unp->unp_conn, &unp_conn, sizeof(unp_conn));
+			if (unp_conn.unp_addr != NULL) {
+				KREAD(unp_conn.unp_addr, &sun_len,
+				    sizeof(sun_len));
+				KREAD(unp_conn.unp_addr, &xu.xu_caddr, sun_len);
+			}
 		}
-		if (sysctlbyname(mibvar, buf, &len, 0, 0) < 0) {
-			warn("sysctl: %s", mibvar);
-			free(buf);
+		KREAD(unp->unp_socket, &so, sizeof(so));
+		if (sotoxsocket(&so, &xu.xu_socket) != 0)
+			goto fail;
+		COPYOUT(&xu, sizeof(xu));
+	}
+
+	/* Reread the counts and write the footer. */
+	kread(count_off, &unp_count, sizeof(unp_count));
+	kread(gencnt_off, &unp_gencnt, sizeof(unp_gencnt));
+	xug.xug_count = unp_count;
+	xug.xug_gen = unp_gencnt;
+	COPYOUT(&xug, sizeof xug);
+
+	*bufp = buf;
+	return (0);
+
+fail:
+	free(buf);
+	return (-1);
+#undef COPYOUT
+#undef KREAD
+}
+
+void
+unixpr(u_long count_off, u_long gencnt_off, u_long dhead_off, u_long shead_off)
+{
+	char 	*buf;
+	int	ret, type;
+	struct	xsocket *so;
+	struct	xunpgen *xug, *oxug;
+	struct	xunpcb *xunp;
+
+	for (type = SOCK_STREAM; type <= SOCK_SEQPACKET; type++) {
+		if (live)
+			ret = pcblist_sysctl(type, &buf);
+		else
+			ret = pcblist_kvm(count_off, gencnt_off,
+			    type == SOCK_STREAM ? shead_off :
+			    (type == SOCK_DGRAM ? dhead_off : 0), &buf);
+		if (ret == -1)
+			continue;
+		if (ret < 0)
 			return;
-		}
 
 		oxug = xug = (struct xunpgen *)buf;
 		for (xug = (struct xunpgen *)((char *)xug + xug->xug_len);