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path: root/main/sysklogd/sysklogd-1.4.2-caen-owl-klogd-drop-root.diff
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http://cvsweb.openwall.com/cgi/cvsweb.cgi/~checkout~/Owl/packages/sysklogd/sysklogd-1.4.2-caen-owl-klogd-drop-root.diff?rev=1.2;content-type=text%2Fplain
diff -upk.orig sysklogd-1.4.2.orig/klogd.8 sysklogd-1.4.2/klogd.8
--- sysklogd-1.4.2.orig/klogd.8	2005-03-11 16:12:09 +0000
+++ sysklogd-1.4.2/klogd.8	2005-08-18 14:37:47 +0000
@@ -18,6 +19,12 @@ klogd \- Kernel Log Daemon
 .RB [ " \-f "
 .I fname
 ]
+.RB [ " \-u "
+.I username
+]
+.RB [ " \-j "
+.I chroot_dir
+]
 .RB [ " \-iI " ]
 .RB [ " \-n " ]
 .RB [ " \-o " ]
@@ -53,6 +60,20 @@ stderr.
 .BI "\-f " file
 Log messages to the specified filename rather than to the syslog facility.
 .TP
+.BI "\-u " username
+Tells klogd to become the specified user and drop root privileges before
+starting logging.
+.TP
+.BI "\-j " chroot_dir
+Tells klogd to
+.BR chroot (2)
+into this directory after initializing.
+This option is only valid if the \-u option is also used to run klogd
+without root privileges.
+Note that the use of this option will prevent \-i and \-I from working
+unless you set up the chroot directory in such a way that klogd can still
+read the kernel module symbols.
+.TP
 .BI "\-i \-I"
 Signal the currently executing klogd daemon.  Both of these switches control
 the loading/reloading of symbol information.  The \-i switch signals the
diff -upk.orig sysklogd-1.4.2.orig/klogd.c sysklogd-1.4.2/klogd.c
--- sysklogd-1.4.2.orig/klogd.c	2005-08-18 12:29:52 +0000
+++ sysklogd-1.4.2/klogd.c	2005-08-18 14:37:47 +0000
@@ -261,6 +261,8 @@
 #include <stdarg.h>
 #include <paths.h>
 #include <stdlib.h>
+#include <pwd.h>
+#include <grp.h>
 #include "klogd.h"
 #include "ksyms.h"
 #ifndef TESTING
@@ -315,6 +317,9 @@ static enum LOGSRC {none, proc, kernel} 
 int debugging = 0;
 int symbols_twice = 0;
 
+char *server_user = NULL;
+char *chroot_dir = NULL;
+int log_flags = 0;
 
 /* Function prototypes. */
 extern int ksyslog(int type, char *buf, int len);
@@ -535,8 +540,9 @@ static enum LOGSRC GetKernelLogSrc(void)
 	 * First do a stat to determine whether or not the proc based
 	 * file system is available to get kernel messages from.
 	 */
-	if ( use_syscall ||
-	    ((stat(_PATH_KLOG, &sb) < 0) && (errno == ENOENT)) )
+	if (!server_user &&
+	    (use_syscall ||
+	    ((stat(_PATH_KLOG, &sb) < 0) && (errno == ENOENT))))
 	{
 	  	/* Initialize kernel logging. */
 	  	ksyslog(1, NULL, 0);
@@ -983,6 +989,27 @@ static void LogProcLine(void)
 }
 
 
+static int drop_root(void)
+{
+	struct passwd *pw;
+
+	if (!(pw = getpwnam(server_user))) return -1;
+
+	if (!pw->pw_uid) return -1;
+
+	if (chroot_dir) {
+		if (chdir(chroot_dir)) return -1;
+		if (chroot(".")) return -1;
+	}
+
+	if (setgroups(0, NULL)) return -1;
+	if (setgid(pw->pw_gid)) return -1;
+	if (setuid(pw->pw_uid)) return -1;
+
+	return 0;
+}
+
+
 int main(argc, argv)
 
 	int argc;
@@ -1000,7 +1027,7 @@ int main(argc, argv)
 	chdir ("/");
 #endif
 	/* Parse the command-line. */
-	while ((ch = getopt(argc, argv, "c:df:iIk:nopsvx2")) != EOF)
+	while ((ch = getopt(argc, argv, "c:df:u:j:iIk:nopsvx2")) != EOF)
 		switch((char)ch)
 		{
 		    case '2':		/* Print lines with symbols twice. */
@@ -1022,6 +1049,10 @@ int main(argc, argv)
 		    case 'I':
 			SignalDaemon(SIGUSR2);
 			return(0);
+		    case 'j':		/* chroot 'j'ail */
+			chroot_dir = optarg;
+			log_flags |= LOG_NDELAY;
+			break;
 		    case 'k':		/* Kernel symbol file. */
 			symfile = optarg;
 			break;
@@ -1037,6 +1068,9 @@ int main(argc, argv)
 		    case 's':		/* Use syscall interface. */
 			use_syscall = 1;
 			break;
+		    case 'u':		/* Run as this user */
+			server_user = optarg;
+			break;
 		    case 'v':
 			printf("klogd %s.%s\n", VERSION, PATCHLEVEL);
 			exit (1);
@@ -1045,6 +1079,10 @@ int main(argc, argv)
 			break;
 		}
 
+	if (chroot_dir && !server_user) {
+		fputs("'-j' is only valid with '-u'\n", stderr);
+		exit(1);
+	}
 
 	/* Set console logging level. */
 	if ( log_level != (char *) 0 )
@@ -1158,7 +1196,7 @@ int main(argc, argv)
 		}
 	}
 	else
-		openlog("kernel", 0, LOG_KERN);
+		openlog("kernel", log_flags, LOG_KERN);
 
 
 	/* Handle one-shot logging. */
@@ -1191,6 +1229,11 @@ int main(argc, argv)
 		}
 	}
 
+	if (server_user && drop_root()) {
+		syslog(LOG_ALERT, "klogd: failed to drop root");
+		Terminate();
+	}
+
         /* The main loop. */
 	while (1)
 	{