Adapt libkvm_getswapinfo() to make use of recently committed vm and swap
sysctls exporting swap information. When running on a live kernel, the sysctl's will now be used instead of kvm_read, allowing consumers of this interface to run without privilege (setgid kmem). Retain the ability to run on coredumps, or on a kernel using kmem if explicitly pointed at one. A side effect of this change is that kvm_getswapinfo() is faster now in the general case. If the SWIF_DUMP_TREE flag is given (pstat -ss does this), the radix tree walker, which still uses kvm_read in any case, is invoked, and therefore does require privilege. Submitted by: Thomas Moestl <tmoestl@gmx.net> Reviewed by: freebsd-audit
This commit is contained in:
parent
edfa785a8e
commit
ae3a37ad44
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=72950
@ -1,5 +1,6 @@
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/*
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* Copyright (c) 1999, Matthew Dillon. All Rights Reserved.
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* Copyright (c) 2001, Thomas Moestl
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided under the terms of the BSD
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@ -22,6 +23,7 @@ static const char rcsid[] =
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#include <sys/stat.h>
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#include <sys/conf.h>
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#include <sys/blist.h>
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#include <sys/sysctl.h>
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#include <err.h>
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#include <fcntl.h>
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@ -32,6 +34,9 @@ static const char rcsid[] =
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <limits.h>
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#include "kvm_private.h"
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static struct nlist kvm_swap_nl[] = {
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{ "_swapblist" }, /* new radix swap list */
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@ -48,11 +53,19 @@ static struct nlist kvm_swap_nl[] = {
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static int kvm_swap_nl_cached = 0;
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static int nswdev;
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static int unswdev;
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static int unswdev; /* number of found swap dev's */
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static int dmmax;
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static void getswapinfo_radix(kvm_t *kd, struct kvm_swap *swap_ary,
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int swap_max, int flags);
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static int kvm_getswapinfo2(kvm_t *kd, struct kvm_swap *swap_ary,
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int swap_max, int flags);
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static int kvm_getswapinfo_kvm(kvm_t *, struct kvm_swap *, int, int);
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static int kvm_getswapinfo_sysctl(kvm_t *, struct kvm_swap *, int, int);
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static int nlist_init(kvm_t *);
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static int getsysctl(kvm_t *, char *, void *, int);
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static int getsysctl2(kvm_t *, char *, char *, char *, int, void *, int);
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#define SVAR(var) __STRING(var) /* to force expansion */
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#define KGET(idx, var) \
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@ -74,6 +87,17 @@ static void getswapinfo_radix(kvm_t *kd, struct kvm_swap *swap_ary,
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return (0); \
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}
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#define GETSWDEVNAME(dev, str, flags) \
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if (dev == NODEV) { \
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strlcpy(str, "[NFS swap]", sizeof(str)); \
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} else { \
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snprintf( \
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str, sizeof(str),"%s%s", \
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((flags & SWIF_DEV_PREFIX) ? _PATH_DEV : ""), \
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devname(dev, S_IFCHR) \
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); \
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}
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int
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kvm_getswapinfo(
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kvm_t *kd,
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@ -81,7 +105,10 @@ kvm_getswapinfo(
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int swap_max,
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int flags
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) {
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int ti = 0;
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int rv;
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#ifdef DEBUG_SWAPINFO
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int i;
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#endif
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/*
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* clear cache
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@ -91,52 +118,69 @@ kvm_getswapinfo(
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return(0);
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}
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rv = kvm_getswapinfo2(kd, swap_ary, swap_max, flags);
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/* This is only called when the tree shall be dumped. It needs kvm. */
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if (flags & SWIF_DUMP_TREE) {
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#ifdef DEBUG_SWAPINFO
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/*
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* sanity check: Sizes must be equal - used field must be
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* 0 after this. Fill it with total-used before, where
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* getswapinfo_radix will subtrat total-used.
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* This will of course only work if there is no swap activity
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* while we are working, so this code is normally not active.
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*/
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for (i = 0; i < unswdev; i++) {
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swap_ary[i].ksw_used = swap_ary[i].ksw_total -
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swap_ary[i].ksw_used;
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}
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#endif
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getswapinfo_radix(kd, swap_ary, swap_max, flags);
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#ifdef DEBUG_SWAPINFO
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for (i = 0; i < unswdev; i++) {
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if (swap_ary[i].ksw_used != 0) {
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fprintf(stderr, "kvm_getswapinfo: swap size "
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"mismatch (%d blocks)!\n",
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swap_ary[i].ksw_used
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);
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}
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}
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/* This is fast enough now, so just do it again. */
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rv = kvm_getswapinfo2(kd, swap_ary, swap_max, flags);
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#endif
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}
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return rv;
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}
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static int
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kvm_getswapinfo2(
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kvm_t *kd,
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struct kvm_swap *swap_ary,
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int swap_max,
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int flags
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) {
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if (ISALIVE(kd)) {
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return kvm_getswapinfo_sysctl(kd, swap_ary, swap_max, flags);
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} else {
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return kvm_getswapinfo_kvm(kd, swap_ary, swap_max, flags);
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}
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}
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int
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kvm_getswapinfo_kvm(
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kvm_t *kd,
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struct kvm_swap *swap_ary,
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int swap_max,
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int flags
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) {
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int ti = 0;
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/*
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* namelist
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*/
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if (kvm_swap_nl_cached == 0) {
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struct swdevt *sw;
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if (kvm_nlist(kd, kvm_swap_nl) < 0)
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return(-1);
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/*
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* required entries
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*/
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if (
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kvm_swap_nl[NL_SWDEVT].n_value == 0 ||
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kvm_swap_nl[NL_NSWDEV].n_value == 0 ||
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kvm_swap_nl[NL_DMMAX].n_value == 0 ||
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kvm_swap_nl[NL_SWAPBLIST].n_type == 0
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) {
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return(-1);
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}
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/*
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* get globals, type of swap
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*/
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KGET(NL_NSWDEV, nswdev);
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KGET(NL_DMMAX, dmmax);
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/*
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* figure out how many actual swap devices are enabled
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*/
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KGET(NL_SWDEVT, sw);
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for (unswdev = nswdev - 1; unswdev >= 0; --unswdev) {
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struct swdevt swinfo;
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KGET2(&sw[unswdev], &swinfo, sizeof(swinfo), "swinfo");
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if (swinfo.sw_nblks)
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break;
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}
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++unswdev;
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kvm_swap_nl_cached = 1;
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}
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if (!nlist_init(kd))
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return (-1);
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{
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struct swdevt *sw;
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@ -174,33 +218,19 @@ kvm_getswapinfo(
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if (i < ti) {
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swap_ary[i].ksw_total = ttl;
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swap_ary[i].ksw_used = ttl;
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swap_ary[i].ksw_used = swinfo.sw_used;
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swap_ary[i].ksw_flags = swinfo.sw_flags;
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if (swinfo.sw_dev == NODEV) {
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snprintf(
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swap_ary[i].ksw_devname,
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sizeof(swap_ary[i].ksw_devname),
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"%s",
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"[NFS swap]"
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);
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} else {
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snprintf(
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swap_ary[i].ksw_devname,
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sizeof(swap_ary[i].ksw_devname),
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"%s%s",
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((flags & SWIF_DEV_PREFIX) ? _PATH_DEV : ""),
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devname(swinfo.sw_dev, S_IFCHR)
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);
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}
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GETSWDEVNAME(swinfo.sw_dev,
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swap_ary[i].ksw_devname, flags
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);
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}
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if (ti >= 0) {
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swap_ary[ti].ksw_total += ttl;
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swap_ary[ti].ksw_used += ttl;
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swap_ary[ti].ksw_used += swinfo.sw_used;
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}
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}
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}
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getswapinfo_radix(kd, swap_ary, swap_max, flags);
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return(ti);
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}
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@ -226,7 +256,9 @@ scanradix(
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int flags
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) {
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blmeta_t meta;
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#ifdef DEBUG_SWAPINFO
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int ti = (unswdev >= swap_max) ? swap_max - 1 : unswdev;
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#endif
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KGET2(scan, &meta, sizeof(meta), "blmeta_t");
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@ -248,7 +280,9 @@ scanradix(
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/*
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* Leaf bitmap
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*/
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#ifdef DEBUG_SWAPINFO
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int i;
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#endif
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if (flags & SWIF_DUMP_TREE) {
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printf("%*.*s(0x%06x,%d) Bitmap %08x big=%d\n",
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@ -260,6 +294,7 @@ scanradix(
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);
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}
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#ifdef DEBUG_SWAPINFO
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/*
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* If not all allocated, count.
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*/
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@ -280,6 +315,7 @@ scanradix(
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}
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}
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}
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#endif
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} else if (meta.u.bmu_avail == radix) {
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/*
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* Meta node if all free
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@ -291,6 +327,7 @@ scanradix(
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radix
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);
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}
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#ifdef DEBUG_SWAPINFO
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/*
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* Note: both dmmax and radix are powers of 2. However, dmmax
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* may be larger then radix so use a smaller increment if
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@ -312,6 +349,7 @@ scanradix(
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swap_ary[ti].ksw_used -= tinc;
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}
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}
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#endif
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} else if (meta.u.bmu_avail == 0) {
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/*
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* Meta node if all used
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@ -378,6 +416,11 @@ getswapinfo_radix(kvm_t *kd, struct kvm_swap *swap_ary, int swap_max, int flags)
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struct blist *swapblist = NULL;
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struct blist blcopy = { 0 };
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if (!nlist_init(kd)) {
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fprintf(stderr, "radix tree: nlist_init failed!\n");
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return;
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}
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KGET(NL_SWAPBLIST, swapblist);
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if (swapblist == NULL) {
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@ -412,3 +455,154 @@ getswapinfo_radix(kvm_t *kd, struct kvm_swap *swap_ary, int swap_max, int flags)
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flags
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);
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}
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#define GETSYSCTL(kd, name, var) \
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getsysctl(kd, name, &(var), sizeof(var))
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#define GETSYSCTL2(kd, pref, suff, buf, var) \
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getsysctl2(kd, pref, suff, buf, sizeof(buf), &(var), \
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sizeof(var))
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int
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kvm_getswapinfo_sysctl(
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kvm_t *kd,
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struct kvm_swap *swap_ary,
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int swap_max,
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int flags
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) {
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int ti = 0;
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udev_t dev;
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char node[15];
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char buf[20];
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int used, ttl, i;
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if (!GETSYSCTL(kd, "vm.nswapdev", unswdev))
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return -1;
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ti = unswdev;
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if (ti >= swap_max)
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ti = swap_max - 1;
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if (ti >= 0)
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bzero(swap_ary, sizeof(struct kvm_swap) * (ti + 1));
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if (!GETSYSCTL(kd, "vm.dmmax", dmmax))
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return -1;
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for (i = 0; i < unswdev; ++i) {
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if (snprintf(node, sizeof(node), "vm.swapdev%d.", i) >=
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sizeof(node)) {
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_kvm_err(kd, kd->program, "XXX: node buffer too small");
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return -1;
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}
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if (!GETSYSCTL2(kd, node, "nblks", buf, ttl))
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return -1;
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if (!GETSYSCTL2(kd, node, "used", buf, used))
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return -1;
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ttl -= dmmax;
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if (i < ti) {
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if (!GETSYSCTL2(kd, node, "dev", buf, dev))
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return -1;
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if (!GETSYSCTL2(kd, node, "flags", buf,
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swap_ary[i].ksw_flags))
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return -1;
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swap_ary[i].ksw_total = ttl;
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swap_ary[i].ksw_used = used;
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GETSWDEVNAME(dev, swap_ary[i].ksw_devname, flags);
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}
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if (ti >= 0) {
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swap_ary[ti].ksw_total += ttl;
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swap_ary[ti].ksw_used += used;
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}
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}
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return(ti);
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}
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static int
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nlist_init (
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kvm_t *kd
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) {
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struct swdevt *sw;
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if (kvm_swap_nl_cached)
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return (1);
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if (kvm_nlist(kd, kvm_swap_nl) < 0)
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return (0);
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/*
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* required entries
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*/
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if (
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kvm_swap_nl[NL_SWDEVT].n_value == 0 ||
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kvm_swap_nl[NL_NSWDEV].n_value == 0 ||
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kvm_swap_nl[NL_DMMAX].n_value == 0 ||
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kvm_swap_nl[NL_SWAPBLIST].n_type == 0
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) {
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return (0);
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}
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/*
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* get globals, type of swap
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*/
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KGET(NL_NSWDEV, nswdev);
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KGET(NL_DMMAX, dmmax);
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/*
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* figure out how many actual swap devices are enabled
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*/
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KGET(NL_SWDEVT, sw);
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for (unswdev = nswdev - 1; unswdev >= 0; --unswdev) {
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struct swdevt swinfo;
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KGET2(&sw[unswdev], &swinfo, sizeof(swinfo), "swinfo");
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if (swinfo.sw_nblks)
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break;
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}
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++unswdev;
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kvm_swap_nl_cached = 1;
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return (1);
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}
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static int
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getsysctl (
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kvm_t *kd,
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char *name,
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void *ptr,
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int len
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) {
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int nlen = len;
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if (sysctlbyname(name, ptr, &nlen, NULL, 0) == -1) {
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_kvm_err(kd, kd->program, "cannot read sysctl %s", name);
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return (0);
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}
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if (nlen != len) {
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_kvm_err(kd, kd->program, "sysctl %s has unexpected size", name);
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return (0);
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}
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return (1);
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}
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static int
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getsysctl2 (
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kvm_t *kd,
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char *pref,
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char *suff,
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char *buf,
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int buflen,
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void *ptr,
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int len
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) {
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if (strlcpy(buf, pref, buflen) >= buflen) {
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_kvm_err(kd, kd->program, "getsysctl2: string buffer too small");
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return (0);
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}
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if (strlcat(buf, suff, buflen) >= buflen) {
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_kvm_err(kd, kd->program, "getsysctl2: string buffer too small");
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return (0);
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}
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return getsysctl(kd, buf, ptr, len);
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}
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