util-linux/util-linux-2.13-mount-context.patch

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This patch adds to the mount man page docs about context, fscontext and
defcontext mount options and translate context options from human to raw
selinux context format. -- 03/30/2006 Karel Zak <kzak@redhat.com>
--- util-linux-2.13-pre7/mount/mount.8.cxt 2006-03-30 17:15:06.000000000 +0200
+++ util-linux-2.13-pre7/mount/mount.8 2006-03-30 17:15:06.000000000 +0200
@@ -661,6 +661,50 @@
.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
--- util-linux-2.13-pre7/mount/mount.c.cxt 2006-03-30 17:15:06.000000000 +0200
+++ util-linux-2.13-pre7/mount/mount.c 2006-03-30 20:16:57.000000000 +0200
@@ -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"
@@ -255,6 +260,49 @@
free((void *) s);
}
+#ifdef HAVE_LIBSELINUX
+/* 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, const char *optdata, char *extra_opts, int *len)
+{
+ security_context_t raw = 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;
+
+ if (selinux_trans_to_raw_context(
+ (security_context_t) optdata, &raw)==-1 ||
+ raw==NULL)
+ return -1;
+
+ if (verbose)
+ printf(_("mount: translated %s '%s' to '%s'\n"),
+ optname, optdata, (char *) raw);
+
+ bufsz = strlen(optname) + strlen(raw) + 2; /* 2 is \0 and '=' */
+ 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).
@@ -313,7 +361,20 @@
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);
}
@@ -330,7 +391,7 @@
if (options != NULL) {
char *opts = xstrdup(options);
char *opt;
- int len = strlen(opts) + 20;
+ int len = strlen(opts) + 256;
*extra_opts = xmalloc(len);
**extra_opts = '\0';