Pick up kernel variables/constants using sysctl rather than through /dev/mem
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:
parent
35e6b695d6
commit
85082fc3c3
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=37317
@ -31,93 +31,24 @@
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* SUCH DAMAGE.
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*/
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)nlist.c 8.4 (Berkeley) 4/2/94";
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#endif
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static const char rcsid[] =
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"$Id$";
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#endif /* not lint */
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#include <sys/param.h>
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#include <sys/time.h>
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#include <sys/proc.h>
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#include <sys/resource.h>
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#include <err.h>
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#include <errno.h>
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#include <kvm.h>
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#include <nlist.h>
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#include <stdio.h>
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#include <string.h>
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#include "ps.h"
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struct nlist psnl[] = {
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{"_fscale"},
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#define X_FSCALE 0
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{"_ccpu"},
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#define X_CCPU 1
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{"_avail_start"},
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#define X_AVAILSTART 2
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{"_avail_end"},
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#define X_AVAILEND 3
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{NULL}
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};
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fixpt_t ccpu; /* kernel _ccpu variable */
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int nlistread; /* if nlist already read. */
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int mempages; /* number of pages of phys. memory */
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int fscale; /* kernel _fscale variable */
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extern kvm_t *kd;
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#define kread(x, v) \
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kvm_read(kd, psnl[x].n_value, (char *)&v, sizeof v) != sizeof(v)
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int
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donlist()
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{
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int rval;
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int tmp;
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rval = 0;
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nlistread = 1;
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if (kvm_nlist(kd, psnl)) {
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nlisterr(psnl);
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eval = 1;
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if (sysctlbyname("kern.ccpu", &ccpu, sizeof ccpu, 0, 0) < 0)
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return (1);
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}
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if (kread(X_FSCALE, fscale)) {
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warnx("fscale: %s", kvm_geterr(kd));
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eval = rval = 1;
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}
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if (kread(X_AVAILEND, mempages)) {
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warnx("avail_start: %s", kvm_geterr(kd));
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eval = rval = 1;
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}
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if (kread(X_AVAILSTART, tmp)) {
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warnx("avail_end: %s", kvm_geterr(kd));
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eval = rval = 1;
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}
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mempages -= tmp;
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mempages /= PAGE_SIZE;
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if (kread(X_CCPU, ccpu)) {
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warnx("ccpu: %s", kvm_geterr(kd));
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eval = rval = 1;
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}
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return (rval);
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}
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void
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nlisterr(nl)
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struct nlist nl[];
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{
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int i;
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(void)fprintf(stderr, "ps: nlist: can't find following symbols:");
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for (i = 0; nl[i].n_name != NULL; i++)
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if (nl[i].n_value == 0)
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(void)fprintf(stderr, " %s", nl[i].n_name);
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(void)fprintf(stderr, "\n");
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if (sysctlbyname("kern.fscale", &fscale, sizeof fscale, 0, 0) < 0)
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return (1);
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if (sysctlbyname("hw.availpages", &mempages, sizeof mempages, 0, 0) < 0)
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return (1);
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nlistread = 1;
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return (0);
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}
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14
bin/ps/ps.c
14
bin/ps/ps.c
@ -42,7 +42,7 @@ static char const copyright[] =
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static char sccsid[] = "@(#)ps.c 8.4 (Berkeley) 4/2/94";
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#endif
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static const char rcsid[] =
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"$Id$";
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"$Id: ps.c,v 1.24 1998/05/15 06:29:17 charnier Exp $";
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#endif /* not lint */
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#include <sys/param.h>
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@ -121,7 +121,7 @@ main(argc, argv)
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dev_t ttydev;
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pid_t pid;
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uid_t uid;
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int all, ch, flag, i, fmt, lineno, nentries;
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int all, ch, flag, i, fmt, lineno, nentries, dropgid;
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int prtheader, wflag, what, xflg;
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char *nlistf, *memf, *swapf, errbuf[_POSIX2_LINE_MAX];
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@ -142,7 +142,8 @@ main(argc, argv)
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pid = -1;
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uid = (uid_t) -1;
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ttydev = NODEV;
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memf = nlistf = swapf = NULL;
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dropgid = 0;
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memf = nlistf = swapf = _PATH_DEVNULL;
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while ((ch = getopt(argc, argv,
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#if defined(LAZY_PS)
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"aCcefghjLlM:mN:O:o:p:rSTt:U:uvW:wx")) != -1)
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@ -182,12 +183,14 @@ main(argc, argv)
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break;
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case 'M':
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memf = optarg;
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dropgid = 1;
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break;
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case 'm':
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sortby = SORTMEM;
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break;
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case 'N':
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nlistf = optarg;
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dropgid = 1;
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break;
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case 'O':
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parsefmt(o1);
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@ -260,6 +263,7 @@ main(argc, argv)
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break;
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case 'W':
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swapf = optarg;
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dropgid = 1;
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break;
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case 'w':
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if (wflag)
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@ -293,8 +297,10 @@ main(argc, argv)
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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 (nlistf != NULL || memf != NULL || swapf != NULL)
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if (dropgid) {
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setgid(getgid());
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setuid(getuid());
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}
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kd = kvm_openfiles(nlistf, memf, swapf, O_RDONLY, errbuf);
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if (kd == 0)
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