Date: Tue, 10 Jun 1997 23:54:19 +0200 (CEST) From: Luigi Rizzo <luigi@iet.unipi.it> To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: bin/3837: new feature for rtprio Message-ID: <199706102154.XAA01012@prova.iet.unipi.it> Resent-Message-ID: <199706102200.PAA06327@hub.freebsd.org>
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>Number: 3837
>Category: bin
>Synopsis: new feature for rtprio
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Tue Jun 10 15:00:01 PDT 1997
>Last-Modified:
>Originator: Luigi Rizzo
>Organization:
Dip. Ing. Informazione Univ. Pisa
>Release: FreeBSD 2.2.1-RELEASE i386
>Environment:
>Description:
This patch allows users listed in /etc/rtprio.conf to set
realtime priorities for processes. Useful to let non-root
users burn CDs. I also include the small manpage change.
>How-To-Repeat:
>Fix:
--- rtprio.1.orig Fri Mar 7 08:45:39 1997
+++ rtprio.1 Tue Jun 10 23:47:26 1997
@@ -107,8 +107,15 @@
.Ar Pid
of 0 means "the current process".
.Pp
-Only root is allowed to set realtime priorities. Non-root processes may
+Only root or users listed in
+.Ar /etc/rtprio.conf
+are
+allowed to set realtime priorities. Non-allowed processes may
set idle priority levels for the current process only.
+.Pp
+.Ar /etc/rtprio.conf
+must be be a regular file owned by root and not writable by other users.
+It contains one username per line, starting at the beginning of the line.
.Sh RETURN VALUE
If
.Nm rtprio
--- rtprio.c.orig Sun Oct 2 05:48:21 1994
+++ rtprio.c Tue Jun 10 23:43:07 1997
@@ -46,6 +46,77 @@
static void usage();
+/*
+ * this module checks which modules are allowed to set rtpriority.
+ * Allowed users are listed in /etc/rtprio.conf, which must not be
+ * writable by others than root. One user per line, starting at
+ * the beginning.
+ *
+ */
+
+#include <syslog.h>
+#include <pwd.h>
+#include <sys/stat.h>
+
+#define _PATH_RTPRIOCONF "/etc/rtprio.conf"
+
+int
+allowed_user()
+{
+ FILE *fp;
+ char line[BUFSIZ];
+ int lineno = 0 ;
+ int end ;
+ uid_t uid;
+ struct passwd *pw;
+ struct stat sb;
+
+ uid = getuid() ;
+ if (uid == 0)
+ return 1; /* root is always allowed */
+
+ if (stat(_PATH_RTPRIOCONF, &sb))
+ return 0;
+
+ /*
+ * the access control file must be a regular file, owned by
+ * root and not writable by others
+ *
+ */
+ if ( (sb.st_uid != 0) || ( (sb.st_mode & S_IFMT) != S_IFREG) ||
+ ( (sb.st_mode & (S_IWGRP | S_IWOTH)) != 0 ) ) {
+ syslog(LOG_ERR, "%s: bad permissions, ignoring it",
+ _PATH_RTPRIOCONF);
+ return 0 ;
+ }
+ /* should check that _PATH_RTPRIOCONF is only writable by root. */
+
+ if (fp = fopen(_PATH_RTPRIOCONF, "r")) {
+ while (fgets(line, sizeof(line), fp)) {
+ lineno++;
+ if (line[end = strlen(line) - 1] != '\n') {
+ syslog(LOG_ERR, "%s: line %d: missing newline or line too long",
+ _PATH_RTPRIOCONF, lineno);
+ continue;
+ }
+ while (end > 0 && isspace(line[end - 1]))
+ end--;
+ line[end] = 0;
+ if (line[0] == 0)
+ continue;
+ pw = getpwnam(line) ;
+ if ( pw && pw->pw_uid == uid ) {
+ fclose(fp);
+ return 1 ;
+ }
+ }
+ fclose(fp);
+ }
+ syslog(LOG_ERR, "%s: userid %d not allowed",
+ _PATH_RTPRIOCONF, uid);
+ return 0 ;
+}
+
int
main(argc, argv)
int argc;
@@ -55,6 +126,7 @@
int proc = 0;
struct rtprio rtp;
+ seteuid( getuid() ); /* drop privileges immediately */
/* find basename */
if ((p = rindex(argv[0], '/')) == NULL)
p = argv[0];
@@ -113,10 +185,13 @@
if (argv[2][0] == '-')
proc = -atoi(argv[2]);
+ if (allowed_user())
+ seteuid(0); /* raise privilege */
if (rtprio(RTP_SET, proc, &rtp) != 0) {
perror(argv[0]);
exit (1);
}
+ seteuid(getuid()); /* lower privilege again */
if (proc == 0) {
execvp(argv[2], &argv[2]);
>Audit-Trail:
>Unformatted:
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