- new

[packages/util-linux.git] / util-linux-mount-context.patch

- mount does not translate SELIinux context options though libselinux
- Need man page entry for -o context= mount option
- Can't mount with additional contexts

--- util-linux-2.13-pre6/mount/Makefile.am.context	2005-09-12 22:41:11.000000000 +0200
+++ util-linux-2.13-pre6/mount/Makefile.am	2006-11-01 11:31:46.000000000 +0100
@@ -37,6 +37,9 @@
 man_MANS += pivot_root.8
 endif
 
+if HAVE_SELINUX
+mount_LDADD += -lselinux
+endif
 
 swapon.c: swapargs.h
 
--- util-linux-2.13-pre6/mount/mount.c.context	2006-11-01 11:31:46.000000000 +0100
+++ util-linux-2.13-pre6/mount/mount.c	2006-11-01 11:36:17.000000000 +0100
@@ -21,6 +21,11 @@
 #include <sys/wait.h>
 #include <sys/mount.h>
 
+#ifdef HAVE_LIBSELINUX
+#include <selinux/selinux.h>
+#include <selinux/context.h>
+#endif
+
 #include "mount_blkid.h"
 #include "mount_constants.h"
 #include "sundries.h"
@@ -255,13 +260,79 @@
 		free((void *) s);
 }
 
+#ifdef HAVE_LIBSELINUX
+/* strip quotes from a "string"
+ * Warning: This function modify the "str" argument.
+ */
+static char *
+strip_quotes(char *str)
+{
+	char *end = NULL;
+
+	if (*str != '"') 
+		return str;
+	
+	end = strrchr(str, '"');
+	if (end == NULL || end == str) 
+		die (EX_USAGE, _("mount: improperly quoted option string '%s'"), str);
+
+	*end = '\0';
+	return str+1;
+}
+
+/* translates SELinux context from human to raw format and 
+ * appends it to the mount extra options.
+ *
+ * returns -1 on error and 0 on success 
+ */
+static int
+append_context(const char *optname, char *optdata, char *extra_opts, int *len)
+{
+	security_context_t raw = NULL;
+	char *data = NULL;
+	char *buf = NULL;
+	int bufsz;
+	
+	if (!is_selinux_enabled())
+		/* ignore the option if we running without selinux */
+		return 0;
+
+	if (optdata==NULL || *optdata=='\0' || optname==NULL)
+		return -1;
+	
+	/* TODO: use strip_quotes() for all mount options? */
+	data = *optdata =='"' ? strip_quotes(optdata) : optdata;
+	
+	if (selinux_trans_to_raw_context(
+			(security_context_t) data, &raw)==-1 ||
+			raw==NULL) 
+		return -1;
+	
+	if (verbose)
+		printf(_("mount: translated %s '%s' to '%s'\n"), 
+				optname, data, (char *) raw);
+        
+	bufsz = strlen(optname) + strlen(raw) + 4;	/* 4 is \0, '=' and 2x '"' */ 
+	buf = xmalloc(bufsz);
+
+	snprintf(buf, bufsz, "%s=\"%s\"", optname, (char *) raw);
+	freecon(raw);
+	
+	if ((*len -= bufsz-1) > 0)
+		strcat(extra_opts, buf);
+	
+	my_free(buf);
+	return 0;
+}
+#endif
+
 /*
  * Look for OPT in opt_map table and return mask value.
  * If OPT isn't found, tack it onto extra_opts (which is non-NULL).
  * For the options uid= and gid= replace user or group name by its value.
  */
 static inline void
-parse_opt(const char *opt, int *mask, char *extra_opts, int len) {
+parse_opt(char *opt, int *mask, char *extra_opts, int len) {
 	const struct opt_map *om;
 
 	for (om = opt_map; om->opt != NULL; om++)
@@ -313,7 +384,20 @@
 			return;
 		}
 	}
-
+#ifdef HAVE_LIBSELINUX
+	if (strncmp(opt, "context=", 8)==0 && *(opt+8)) {
+		if (append_context("context", opt+8, extra_opts, &len)==0)
+			return;
+	}
+	if (strncmp(opt, "fscontext=", 10)==0 && *(opt+10)) {
+		if (append_context("fscontext", opt+10, extra_opts, &len)==0)
+			return;
+	}
+	if (strncmp(opt, "defcontext=", 11)==0 && *(opt+11)) {
+		if (append_context("defcontext", opt+11, extra_opts, &len)==0)
+			return;
+	}
+#endif
 	if ((len -= strlen(opt)) > 0)
 		strcat(extra_opts, opt);
 }
@@ -329,16 +413,29 @@
 
 	if (options != NULL) {
 		char *opts = xstrdup(options);
-		char *opt;
-		int len = strlen(opts) + 20;
+		int len = strlen(opts) + 256;
+		int open_quote = 0;
+		char *opt, *p;
 
 		*extra_opts = xmalloc(len); 
 		**extra_opts = '\0';
 
-		for (opt = strtok(opts, ","); opt; opt = strtok(NULL, ","))
-			if (!parse_string_opt(opt))
-				parse_opt(opt, flags, *extra_opts, len);
-
+		for (p=opts, opt=NULL; p && *p; p++) {
+			if (!opt)
+				opt = p;		/* begin of the option item */
+			if (*p == '"') 
+				open_quote ^= 1;	/* reverse the status */
+			if (open_quote)
+				continue;		/* still in quoted block */
+			if (*p == ',')
+				*p = '\0';		/* terminate the option item */
+			/* end of option item or last item */
+			if (*p == '\0' || *(p+1) == '\0') {
+				if (!parse_string_opt(opt))
+					parse_opt(opt, flags, *extra_opts, len);
+				opt = NULL;
+			}
+		} 
 		free(opts);
 	}
 
--- util-linux-2.13-pre6/mount/mount.8.context	2006-11-01 11:31:46.000000000 +0100
+++ util-linux-2.13-pre6/mount/mount.8	2006-11-01 11:31:46.000000000 +0100
@@ -660,6 +660,50 @@
 .BR noexec ", " nosuid ", and " nodev
 (unless overridden by subsequent options, as in the option line
 .BR users,exec,dev,suid ).
+.TP
+\fBcontext=\fP\fIcontext\fP, \fBfscontext=\fP\fIcontext\fP and \fBdefcontext=\fP\fIcontext\fP
+The 
+.BR context= 
+option is useful when mounting filesystems that do not support
+extended attributes, such as a floppy or hard disk formatted with VFAT, or
+systems that are not normally running under SELinux, such as an ext3 formatted
+disk from a non-SELinux workstation. You can also use
+.BR context= 
+on filesystems you do not trust, such as a floppy. It also helps in compatibility with
+xattr-supporting filesystems on earlier 2.4.<x> kernel versions. Even where
+xattrs are supported, you can save time not having to label every file by
+assigning the entire disk one security context.
+
+A commonly used option for removable media is 
+.BR context=system_u:object_r:removable_t .
+
+Two other options are 
+.BR fscontext= 
+and 
+.BR defcontext= ,
+both of which are mutually exclusive of the context option. This means you
+can use fscontext and defcontext with each other, but neither can be used with
+context.
+
+The 
+.BR fscontext= 
+option works for all filesystems, regardless of their xattr
+support. The fscontext option sets the overarching filesystem label to a
+specific security context. This filesystem label is separate from the
+individual labels on the files. It represents the entire filesystem for
+certain kinds of permission checks, such as during mount or file creation.
+Individual file labels are still obtained from the xattrs on the files
+themselves. The context option actually sets the aggregate context that
+fscontext provides, in addition to supplying the same label for individual
+files.
+
+You can set the default security context for unlabeled files using 
+.BR defcontext=
+option. This overrides the value set for unlabeled files in the policy and requires a
+file system that supports xattr labeling. 
+
+For more details see 
+.BR selinux (8)
 .RE
 .TP
 .B \-\-bind