Re: [patch] udev-selinux: restores file security context and sets mode in matchpathcon

[Luke Kenneth Casson Leighton <lkcl@lkcl.net>]

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duh!

On Wed, Aug 04, 2004 at 11:33:07AM +0200, Hannes Reinecke wrote:
> Luke Kenneth Casson Leighton wrote:
> >okay, updated.
> >
> >this is an experimental patch.
> >
> [ .. ]
> >the reason for using this patch is because of speed:
> >if matchpathcon is used in the same process, the lookups etc.
> >are cached.
> >
> >a reason for _not_ using this patch is for a udev in initrd
> >where the smaller klibc is used.  it would be necessary to add
> >rexeg to klibc and to compile a special libselinux1 with it.
> >
> >if you do not intend to put udev into an initrd, this patch is
> >perfectly acceptable for use.
> >
> >l.
> So where is it then?
> 
> Cheers,
> 
> Hannes
> -- 
> Dr. Hannes Reinecke			hare@suse.de
> SuSE Linux AG				S390 & zSeries
> Maxfeldstra?e 5				+49 911 74053 688
> 90409 N?rnberg				http://www.suse.de

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-- 
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--- udev-add.c.orig	2004-07-09 18:59:09.000000000 +0100
+++ udev-add.c	2004-08-03 16:21:59.000000000 +0100
@@ -50,6 +50,10 @@
 
 #define LOCAL_USER "$local"
 
+#ifdef WITH_SELINUX
+#include <selinux/selinux.h>
+#endif
+
 /* 
  * Right now the major/minor of a device is stored in a file called
  * "dev" in sysfs.
@@ -92,7 +96,31 @@
 			break;
 		*pos = 0x00;
 		if (stat(p, &stats)) {
+#ifdef WITH_SELINUX
+			int seretval = 0;
+			security_context_t scontext;
+		   if (is_selinux_enabled() > 0)
+		   {
+				seretval = matchpathcon(p, S_IFDIR, &scontext);
+				if (seretval < 0) {
+					dbg("matchpathcon(%s) failed\n", p);
+				} else {
+					seretval=setfscreatecon(scontext);
+					if (seretval < 0)
+						dbg("setfiles %s failed with error '%s'",
+					p, strerror(errno));
+				}
+			}
+#endif
 			retval = mkdir(p, 0755);
+#ifdef WITH_SELINUX
+			if (is_selinux_enabled() > 0)
+			{
+			   /* after mkdir, free the context */
+				freecon(scontext);
+			}
+#endif
+									
 			if (retval != 0) {
 				dbg("mkdir(%s) failed with error '%s'",
 				    p, strerror(errno));
@@ -109,6 +137,10 @@
 {
 	struct stat stats;
 	int retval = 0;
+	int seretval = 0;
+#ifdef WITH_SELINUX
+	security_context_t scontext;
+#endif
 
 	if (stat(file, &stats) != 0)
 		goto create;
@@ -117,6 +149,24 @@
 	if (((stats.st_mode & S_IFMT) == S_IFBLK || (stats.st_mode & S_IFMT) == S_IFCHR) &&
 	    (stats.st_rdev == makedev(major, minor))) {
 		dbg("preserve file '%s', cause it has correct dev_t", file);
+#ifdef WITH_SELINUX
+		/* lkcl: maybe someone would like to do the same thing with se/linux
+		 * security contexts (check they are the same) but hey, not me!
+		 */
+	   if (is_selinux_enabled() > 0)
+	   {
+			retval = matchpathcon(file, mode, &scontext);
+			if (retval < 0) {
+				dbg("matchpathcon(%s) failed\n", file);
+			} else {
+				retval=setfilecon(scontext, file);
+				if (retval < 0)
+					dbg("setfiles %s failed with error '%s'",
+				file, strerror(errno));
+				freecon(scontext);
+			}
+		}
+#endif
 		goto perms;
 	}
 
@@ -126,6 +176,21 @@
 		dbg("already present file '%s' unlinked", file);
 
 create:
+#ifdef WITH_SELINUX
+   if (is_selinux_enabled() > 0)
+   {
+		seretval = matchpathcon(file, mode, &scontext);
+		if (seretval < 0) {
+			dbg("matchpathcon(%s) failed\n", file);
+		} else {
+			retval=setfscreatecon(scontext);
+			if (retval < 0)
+				dbg("setfiles %s failed with error '%s'",
+			file, strerror(errno));
+		}
+	}
+#endif
+						    
 	retval = mknod(file, mode, makedev(major, minor));
 	if (retval != 0) {
 		dbg("mknod(%s, %#o, %u, %u) failed with error '%s'",
@@ -133,6 +198,15 @@
 		goto exit;
 	}
 
+#ifdef WITH_SELINUX
+   if (is_selinux_enabled() > 0)
+   {
+	   /* after mknod, free the context */
+		if (seretval == 0)
+			freecon(scontext);
+	}
+#endif
+						    
 perms:
 	dbg("chmod(%s, %#o)", file, mode);
 	if (chmod(file, mode) != 0) {
@@ -150,7 +224,11 @@
 	}
 
 exit:
+#ifdef WITH_SELINUX
+	return retval < 0 ? retval : seretval;
+#else
 	return retval;
+#endif
 }
 
 /* get the local logged in user */
@@ -304,10 +382,36 @@
 
 		dbg("symlink(%s, %s)", linktarget, filename);
 		if (!fake) {
+#ifdef WITH_SELINUX
+			int seretval = 0;
+			security_context_t scontext;
+		   if (is_selinux_enabled() > 0)
+		   {
+				seretval = matchpathcon(filename, S_IFLNK, &scontext);
+				if (seretval < 0) {
+					dbg("matchpathcon(%s) failed\n", filename);
+				} else {
+					seretval=setfscreatecon(scontext);
+					if (seretval < 0)
+						dbg("setfiles %s failed with error '%s'",
+					filename, strerror(errno));
+				}
+			}
+#endif
+									
+
 			unlink(filename);
 			if (symlink(linktarget, filename) != 0)
 				dbg("symlink(%s, %s) failed with error '%s'",
 				    linktarget, filename, strerror(errno));
+#ifdef WITH_SELINUX
+		   if (is_selinux_enabled() > 0)
+		   {
+			   /* after symlink, free the context */
+				freecon(scontext);
+			}
+#endif
+									
 		}
 	}
 
@@ -403,6 +507,11 @@
 	char *pos;
 	int retval;
 
+#ifdef WITH_SELINUX
+	int seretval;
+	security_context_t prev_scontext;
+#endif
+
 	memset(&dev, 0x00, sizeof(dev));
 
 	dev.type = get_device_type(path, subsystem);
@@ -438,6 +547,23 @@
 
 	dbg("name='%s'", dev.name);
 
+#ifdef WITH_SELINUX
+	/* record the present security context, for file-creation
+	 * restoration creation purposes.
+	 *
+	 * we're going to assume that between now and the time that
+	 * this context is restored that the only filecreation of any
+	 * kind to occur will be mknod, symlink and mkdirs.
+	 */
+
+	if (is_selinux_enabled() > 0)
+	{
+		seretval = getfscreatecon(&prev_scontext);
+		if (seretval < 0) {
+			dbg("getfscreatecon failed\n");
+		}
+	}
+#endif
 	switch (dev.type) {
 	case 'b':
 	case 'c':
@@ -474,6 +600,16 @@
 		break;
 	}
 
+#ifdef WITH_SELINUX
+	if (is_selinux_enabled() > 0)
+	{
+	   /* reset the file create context to its former glory */
+		if (seretval == 0)
+			seretval=setfscreatecon(prev_scontext);
+		freecon(prev_scontext);
+	}
+#endif
+
 exit:
 	sysfs_close_class_device(class_dev);
 
--- Makefile.orig	2004-08-02 22:23:58.000000000 +0100
+++ Makefile	2004-08-02 22:24:01.000000000 +0100
@@ -25,6 +25,8 @@
 # Leave this set to `false' for production use.
 DEBUG = true
 
+# Set this to compile with Security-Enhanced Linux support.
+WITH_SELINUX = true
 
 ROOT =		udev
 DAEMON =	udevd
@@ -39,6 +41,7 @@
 LOCAL_CFG_DIR =	etc/udev
 HOTPLUG_EXEC =	$(ROOT)
 
+
 DESTDIR =
 
 KERNEL_DIR = /lib/modules/${shell uname -r}/build
@@ -172,6 +175,13 @@
 
 CFLAGS += -I$(PWD)/libsysfs
 
+ifeq ($(strip $(WITH_SELINUX)),true)
+	LIB_OBJS +=	\
+			-lselinux
+	CFLAGS += \
+		-DWITH_SELINUX
+endif
+
 all: $(ROOT) $(SENDER) $(DAEMON) $(INFO) $(TESTER) $(STARTER)
 	@extras="$(EXTRAS)" ; for target in $$extras ; do \
 		echo $$target ; \