Use new KERN_MSGBUF sysctl if running on a live kernel, and remove
setgid kmem bit from executable.
This commit is contained in:
simonb
parent
00d1b6b147
commit
a7d9e1f93d
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@ -1,4 +1,4 @@
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/* $NetBSD: dmesg.c,v 1.16 1998/07/05 08:56:54 mrg Exp $ */
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/* $NetBSD: dmesg.c,v 1.17 2000/06/16 00:20:23 simonb Exp $ */
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/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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@ -42,11 +42,13 @@ __COPYRIGHT("@(#) Copyright (c) 1991, 1993\n\
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#if 0
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static char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93";
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#else
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__RCSID("$NetBSD: dmesg.c,v 1.16 1998/07/05 08:56:54 mrg Exp $");
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__RCSID("$NetBSD: dmesg.c,v 1.17 2000/06/16 00:20:23 simonb Exp $");
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#endif
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#endif /* not lint */
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#include <sys/param.h>
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#include <sys/msgbuf.h>
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#include <sys/sysctl.h>
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#include <err.h>
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#include <fcntl.h>
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@ -54,7 +56,9 @@ __RCSID("$NetBSD: dmesg.c,v 1.16 1998/07/05 08:56:54 mrg Exp $");
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#include <limits.h>
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#include <nlist.h>
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#include <stdio.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <vis.h>
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@ -76,11 +80,9 @@ main(argc, argv)
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int argc;
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char *argv[];
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{
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struct kern_msgbuf cur;
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int ch, newl, skip, i;
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char *p;
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struct kern_msgbuf *bufp, cur;
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char *memf, *nlistf, *bufdata;
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kvm_t *kd;
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char *p, *memf, *nlistf, *bufdata;
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char buf[5];
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memf = nlistf = NULL;
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@ -99,38 +101,60 @@ main(argc, argv)
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argc -= optind;
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argv += optind;
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/*
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* Discard setgid privileges if not the running kernel so that bad
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* guys can't print interesting stuff from kernel memory.
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*/
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if (memf != NULL || nlistf != NULL)
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setgid(getgid());
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if (memf == NULL && nlistf == NULL) {
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size_t size;
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int mib[2];
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/* Read in message buffer header and data, and do sanity checks. */
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if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg")) == NULL)
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exit (1);
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setgid(getgid()); /* do now anyway */
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if (kvm_nlist(kd, nl) == -1)
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errx(1, "kvm_nlist: %s", kvm_geterr(kd));
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if (nl[X_MSGBUF].n_type == 0)
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errx(1, "%s: msgbufp not found", nlistf ? nlistf : "namelist");
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if (KREAD(nl[X_MSGBUF].n_value, bufp))
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errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd),
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nl[X_MSGBUF].n_value);
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if (KREAD((long)bufp, cur))
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errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd),
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(unsigned long)bufp);
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if (cur.msg_magic != MSG_MAGIC)
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errx(1, "magic number incorrect");
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bufdata = malloc(cur.msg_bufs);
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if (bufdata == NULL)
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errx(1, "couldn't allocate space for buffer data");
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if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata,
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cur.msg_bufs) != cur.msg_bufs)
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errx(1, "kvm_read: %s", kvm_geterr(kd));
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kvm_close(kd);
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if (cur.msg_bufx >= cur.msg_bufs)
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cur.msg_bufx = 0;
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mib[0] = CTL_KERN;
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mib[1] = KERN_MSGBUF;
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if (sysctl(mib, 2, NULL, &size, NULL, 0) == -1)
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errx(1, "can't get size of msgbuf");
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if ((bufdata = malloc(size)) == NULL)
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err(1, "couldn't allocate space for buffer data");
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if (sysctl(mib, 2, bufdata, &size, NULL, 0) == -1)
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err(1, "can't get msgbuf");
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/* make a dummy struct msgbuf for the display logic */
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cur.msg_bufx = cur.msg_bufs = size;
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} else {
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kvm_t *kd;
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struct kern_msgbuf *bufp;
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/*
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* Read in message buffer header and data, and do sanity
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* checks.
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*/
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kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
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if (kd == NULL)
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exit (1);
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if (kvm_nlist(kd, nl) == -1)
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errx(1, "kvm_nlist: %s", kvm_geterr(kd));
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if (nl[X_MSGBUF].n_type == 0)
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errx(1, "%s: msgbufp not found", nlistf ? nlistf :
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"namelist");
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if (KREAD(nl[X_MSGBUF].n_value, bufp))
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errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd),
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nl[X_MSGBUF].n_value);
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if (kvm_read(kd, (long)bufp, &cur,
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offsetof(struct kern_msgbuf, msg_bufc)) !=
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offsetof(struct kern_msgbuf, msg_bufc))
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errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd),
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(unsigned long)bufp);
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if (cur.msg_magic != MSG_MAGIC)
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errx(1, "magic number incorrect");
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bufdata = malloc(cur.msg_bufs);
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if (bufdata == NULL)
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errx(1, "couldn't allocate space for buffer data");
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if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata,
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cur.msg_bufs) != cur.msg_bufs)
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errx(1, "kvm_read: %s", kvm_geterr(kd));
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kvm_close(kd);
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if (cur.msg_bufx >= cur.msg_bufs)
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cur.msg_bufx = 0;
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}
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/*
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* The message buffer is circular; start at the write pointer
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