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Pick up kernel variables/constants using sysctl rather than through /dev/mem

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Use /dev/null for opening the kvm library, we don't need access to /dev/mem
anymore.

ps can now run without the setgid(kmem) bit.  If it does it will not be
able to show argv/envp for another uid's processes unless you are root.
This commit is contained in:
Poul-Henning Kamp 1998-06-30 21:34:14 +00:00
parent 35e6b695d6
commit 85082fc3c3
2 changed files with 17 additions and 80 deletions
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83
bin/ps/nlist.c
View File

@ -31,93 +31,24 @@
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)nlist.c 8.4 (Berkeley) 4/2/94";
#endif
static const char rcsid[] =
"$Id$";
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/resource.h>
#include <err.h>
#include <errno.h>
#include <kvm.h>
#include <nlist.h>
#include <stdio.h>
#include <string.h>
#include "ps.h"
struct nlist psnl[] = {
{"_fscale"},
#define X_FSCALE 0
{"_ccpu"},
#define X_CCPU 1
{"_avail_start"},
#define X_AVAILSTART 2
{"_avail_end"},
#define X_AVAILEND 3
{NULL}
};
fixpt_t ccpu; /* kernel _ccpu variable */
int nlistread; /* if nlist already read. */
int mempages; /* number of pages of phys. memory */
int fscale; /* kernel _fscale variable */
extern kvm_t *kd;
#define kread(x, v) \
kvm_read(kd, psnl[x].n_value, (char *)&v, sizeof v) != sizeof(v)
int
donlist()
{
int rval;
int tmp;
rval = 0;
nlistread = 1;
if (kvm_nlist(kd, psnl)) {
nlisterr(psnl);
eval = 1;
if (sysctlbyname("kern.ccpu", &ccpu, sizeof ccpu, 0, 0) < 0)
return (1);
}
if (kread(X_FSCALE, fscale)) {
warnx("fscale: %s", kvm_geterr(kd));
eval = rval = 1;
}
if (kread(X_AVAILEND, mempages)) {
warnx("avail_start: %s", kvm_geterr(kd));
eval = rval = 1;
}
if (kread(X_AVAILSTART, tmp)) {
warnx("avail_end: %s", kvm_geterr(kd));
eval = rval = 1;
}
mempages -= tmp;
mempages /= PAGE_SIZE;
if (kread(X_CCPU, ccpu)) {
warnx("ccpu: %s", kvm_geterr(kd));
eval = rval = 1;
}
return (rval);
}
void
nlisterr(nl)
struct nlist nl[];
{
int i;
(void)fprintf(stderr, "ps: nlist: can't find following symbols:");
for (i = 0; nl[i].n_name != NULL; i++)
if (nl[i].n_value == 0)
(void)fprintf(stderr, " %s", nl[i].n_name);
(void)fprintf(stderr, "\n");
if (sysctlbyname("kern.fscale", &fscale, sizeof fscale, 0, 0) < 0)
return (1);
if (sysctlbyname("hw.availpages", &mempages, sizeof mempages, 0, 0) < 0)
return (1);
nlistread = 1;
return (0);
}

14
bin/ps/ps.c
View File

@ -42,7 +42,7 @@ static char const copyright[] =
static char sccsid[] = "@(#)ps.c 8.4 (Berkeley) 4/2/94";
#endif
static const char rcsid[] =
"$Id$";
"$Id: ps.c,v 1.24 1998/05/15 06:29:17 charnier Exp $";
#endif /* not lint */
#include <sys/param.h>
@ -121,7 +121,7 @@ main(argc, argv)
dev_t ttydev;
pid_t pid;
uid_t uid;
int all, ch, flag, i, fmt, lineno, nentries;
int all, ch, flag, i, fmt, lineno, nentries, dropgid;
int prtheader, wflag, what, xflg;
char *nlistf, *memf, *swapf, errbuf[_POSIX2_LINE_MAX];
@ -142,7 +142,8 @@ main(argc, argv)
pid = -1;
uid = (uid_t) -1;
ttydev = NODEV;
memf = nlistf = swapf = NULL;
dropgid = 0;
memf = nlistf = swapf = _PATH_DEVNULL;
while ((ch = getopt(argc, argv,
#if defined(LAZY_PS)
"aCcefghjLlM:mN:O:o:p:rSTt:U:uvW:wx")) != -1)
@ -182,12 +183,14 @@ main(argc, argv)
break;
case 'M':
memf = optarg;
dropgid = 1;
break;
case 'm':
sortby = SORTMEM;
break;
case 'N':
nlistf = optarg;
dropgid = 1;
break;
case 'O':
parsefmt(o1);
@ -260,6 +263,7 @@ main(argc, argv)
break;
case 'W':
swapf = optarg;
dropgid = 1;
break;
case 'w':
if (wflag)
@ -293,8 +297,10 @@ main(argc, argv)
* Discard setgid privileges if not the running kernel so that bad
* guys can't print interesting stuff from kernel memory.
*/
if (nlistf != NULL || memf != NULL || swapf != NULL)
if (dropgid) {
setgid(getgid());
setuid(getuid());
}
kd = kvm_openfiles(nlistf, memf, swapf, O_RDONLY, errbuf);
if (kd == 0)