openssh/openssh-4.5p1-mls.patch

--- openssh-4.5p1/openbsd-compat/port-linux.c.mls	2007-01-16 22:13:32.000000000 +0100
+++ openssh-4.5p1/openbsd-compat/port-linux.c	2007-03-20 10:07:39.000000000 +0100
@@ -33,12 +33,23 @@
 #include "key.h"
 #include "hostfile.h"
 #include "auth.h"
+#include "xmalloc.h"
 
 #include <selinux/selinux.h>
 #include <selinux/flask.h>
+#include <selinux/context.h>
 #include <selinux/get_context_list.h>
+#include <selinux/get_default_type.h>
+#include <selinux/av_permissions.h>
+
+#ifdef HAVE_LINUX_AUDIT
+#include <libaudit.h>
+#include <unistd.h>
+#endif
 
 extern Authctxt *the_authctxt;
+extern int inetd_flag;
+extern int rexeced_flag;
 
 /* Wrapper around is_selinux_enabled() to log its return value once only */
 static int
@@ -54,17 +65,173 @@
 	return (enabled);
 }
 
+/* Send audit message */
+static int
+send_audit_message(int success, security_context_t default_context,
+		       security_context_t selected_context)
+{
+	int rc=0;
+#ifdef HAVE_LINUX_AUDIT
+	char *msg = NULL;
+	int audit_fd = audit_open();
+	security_context_t default_raw=NULL;
+	security_context_t selected_raw=NULL;
+	rc = -1;
+	if (audit_fd < 0) {
+		if (errno == EINVAL || errno == EPROTONOSUPPORT ||
+                                        errno == EAFNOSUPPORT)
+                        return 0; /* No audit support in kernel */
+		error("Error connecting to audit system.");
+		return rc;
+	}
+	if (selinux_trans_to_raw_context(default_context, &default_raw) < 0) {
+		error("Error translating default context.");
+		goto out;
+	}
+	if (selinux_trans_to_raw_context(selected_context, &selected_raw) < 0) {
+		error("Error translating selected context.");
+		goto out;
+	}
+	if (asprintf(&msg, "sshd: default-context=%s selected-context=%s",
+		     default_context ? default_raw : "?",
+		     selected_context ? selected_raw : "?") < 0) {
+		error("Error allocating memory.");
+		goto out;
+	}
+	if (audit_log_user_message(audit_fd, AUDIT_USER_ROLE_CHANGE,
+				   msg, NULL, NULL, NULL, success) <= 0) {
+		error("Error sending audit message.");
+		goto out;
+	}
+	rc = 0;
+      out:
+	free(msg);
+	freecon(default_raw);
+	freecon(selected_raw);
+	close(audit_fd);
+#endif
+	return rc;
+}
+
+static int
+mls_range_allowed(security_context_t src, security_context_t dst)
+{
+	struct av_decision avd;
+	int retval;
+	unsigned int bit = CONTEXT__CONTAINS;
+
+	debug("%s: src:%s dst:%s", __func__, src, dst);
+	retval = security_compute_av(src, dst, SECCLASS_CONTEXT, bit, &avd);
+	if (retval || ((bit & avd.allowed) != bit))
+		return 0;
+
+	return 1;
+}
+
+static int
+get_user_context(const char *sename, const char *role, const char *lvl,
+	security_context_t *sc) {
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+	if (get_default_context_with_level(sename, lvl, NULL, sc) != 0) {
+	        /* User may have requested a level completely outside of his 
+	           allowed range. We get a context just for auditing as the
+	           range check below will certainly fail for default context. */
+#endif
+		if (get_default_context(sename, NULL, sc) != 0) {
+			*sc = NULL;
+			return -1;
+		}
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+	}
+#endif
+	if (role != NULL && role[0]) {
+		context_t con;
+		char *type=NULL;
+		if (get_default_type(role, &type) != 0) {
+			error("get_default_type: failed to get default type for '%s'",
+				role);
+			goto out;
+		}
+		con = context_new(*sc);
+		if (!con) {
+			goto out;
+		}
+		context_role_set(con, role);
+		context_type_set(con, type);
+		freecon(*sc);
+		*sc = strdup(context_str(con));
+		context_free(con);
+		if (!*sc) 
+			return -1;
+	}
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+	if (lvl != NULL && lvl[0]) {
+		/* verify that the requested range is obtained */
+		context_t con;
+		security_context_t obtained_raw;
+		security_context_t requested_raw;
+		con = context_new(*sc);
+		if (!con) {
+			goto out;
+		}
+		context_range_set(con, lvl);
+		if (selinux_trans_to_raw_context(*sc, &obtained_raw) < 0) {
+			context_free(con);
+			goto out;
+		}
+		if (selinux_trans_to_raw_context(context_str(con), &requested_raw) < 0) {
+			freecon(obtained_raw);
+			context_free(con);
+			goto out;
+		}
+
+		debug("get_user_context: obtained context '%s' requested context '%s'",
+			obtained_raw, requested_raw);
+		if (strcmp(obtained_raw, requested_raw)) {
+			/* set the context to the real requested one but fail */
+			freecon(requested_raw);
+			freecon(obtained_raw);
+			freecon(*sc);
+			*sc = strdup(context_str(con));
+			context_free(con);
+			return -1;
+		}
+		freecon(requested_raw);
+		freecon(obtained_raw);
+		context_free(con);
+	}
+#endif
+	return 0;
+      out:
+        freecon(*sc);
+        *sc = NULL;
+        return -1;
+}
+
 /* Return the default security context for the given username */
-static security_context_t
-ssh_selinux_getctxbyname(char *pwname)
+static int
+ssh_selinux_getctxbyname(char *pwname,
+	security_context_t *default_sc, security_context_t *user_sc)
 {
-	security_context_t sc = NULL;
 	char *sename, *lvl;
+	const char *reqlvl = NULL;
 	char *role = NULL;
-	int r = 0;
+	int r = -1;
+	context_t con = NULL;
+
+	*default_sc = NULL;
+	*user_sc = NULL;
+	if (the_authctxt) {
+		if (the_authctxt->role != NULL) {
+			char *slash;
+			role = xstrdup(the_authctxt->role);
+			if ((slash = strchr(role, '/')) != NULL) {
+				*slash = '\0';
+				reqlvl = slash + 1;
+			}
+		}
+	}
 
-	if (the_authctxt) 
-		role=the_authctxt->role;
 #ifdef HAVE_GETSEUSERBYNAME
 	if ((r=getseuserbyname(pwname, &sename, &lvl)) != 0) {
 		sename = NULL;
@@ -72,37 +239,63 @@
 	}
 #else
 	sename = pwname;
-	lvl = NULL;
+	lvl = "";
 #endif
 
 	if (r == 0) {
 #ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
-		if (role != NULL && role[0])
-			r = get_default_context_with_rolelevel(sename, role, lvl, NULL, &sc);
-		else
-			r = get_default_context_with_level(sename, lvl, NULL, &sc);
+		r = get_default_context_with_level(sename, lvl, NULL, default_sc);
 #else
-		if (role != NULL && role[0])
-			r = get_default_context_with_role(sename, role, NULL, &sc);
-		else
-			r = get_default_context(sename, NULL, &sc);
+		r = get_default_context(sename, NULL, default_sc);
 #endif
 	}
 
-	if (r != 0) {
-		switch (security_getenforce()) {
-		case -1:
-			fatal("%s: ssh_selinux_getctxbyname: "
-			    "security_getenforce() failed", __func__);
-		case 0:
-			error("%s: Failed to get default SELinux security "
-			    "context for %s", __func__, pwname);
-		default:
-			fatal("%s: Failed to get default SELinux security "
-			    "context for %s (in enforcing mode)",
-			    __func__, pwname);
+	if (r == 0) {
+		/* If launched from xinetd, we must use current level */
+		if (inetd_flag && !rexeced_flag) {
+			security_context_t sshdsc=NULL;
+
+			if (getcon_raw(&sshdsc) < 0)
+				fatal("failed to allocate security context");
+
+			if ((con=context_new(sshdsc)) == NULL)
+				fatal("failed to allocate selinux context");
+			reqlvl = context_range_get(con);
+			freecon(sshdsc);
+			if (reqlvl !=NULL && lvl != NULL && strcmp(reqlvl, lvl) == 0)
+			    /* we actually don't change level */
+			    reqlvl = "";
+
+			debug("%s: current connection level '%s'", __func__, reqlvl);
+		}
+		
+		if ((reqlvl != NULL && reqlvl[0]) || (role != NULL && role[0])) {
+			r = get_user_context(sename, role, reqlvl, user_sc);
+		
+			if (r == 0 && reqlvl != NULL && reqlvl[0]) {
+				security_context_t default_level_sc = *default_sc;
+				if (role != NULL && role[0]) {
+					if (get_user_context(sename, role, lvl, &default_level_sc) < 0)
+						default_level_sc = *default_sc;
+				}
+				/* verify that the requested range is contained in the user range */
+				if (mls_range_allowed(default_level_sc, *user_sc)) {
+					logit("permit MLS level %s (user range %s)", reqlvl, lvl);
+				} else {
+					r = -1;
+					error("deny MLS level %s (user range %s)", reqlvl, lvl);
+				}
+				if (default_level_sc != *default_sc)
+					freecon(default_level_sc);
+			}
+		} else {
+			*user_sc = *default_sc;
 		}
 	}
+	if (r != 0) {
+		error("%s: Failed to get default SELinux security "
+		    "context for %s", __func__, pwname);
+	}
 
 #ifdef HAVE_GETSEUSERBYNAME
 	if (sename != NULL)
@@ -110,14 +303,20 @@
 	if (lvl != NULL)
 		xfree(lvl);
 #endif
+	if (role != NULL)
+		xfree(role);
+	if (con)
+		context_free(con);
 
-	return (sc);
+	return (r);
 }
 
 /* Set the execution context to the default for the specified user */
 void
 ssh_selinux_setup_exec_context(char *pwname)
 {
+	int r = 0;
+	security_context_t default_ctx = NULL;
 	security_context_t user_ctx = NULL;
 
 	if (!ssh_selinux_enabled())
@@ -125,21 +324,39 @@
 
 	debug3("%s: setting execution context", __func__);
 
-	user_ctx = ssh_selinux_getctxbyname(pwname);
-	if (setexeccon(user_ctx) != 0) {
+	r = ssh_selinux_getctxbyname(pwname, &default_ctx, &user_ctx);
+	if (r >= 0) {
+		r = setexeccon(user_ctx);
+		if (r < 0) {
+			error("%s: Failed to set SELinux execution context %s for %s",
+			    __func__, user_ctx, pwname);
+		}
+	}
+	if (user_ctx == NULL) {
+		user_ctx = default_ctx;
+	}
+	if (r < 0 || user_ctx != default_ctx) {
+		/* audit just the case when user changed a role or there was
+		   a failure */
+		send_audit_message(r >= 0, default_ctx, user_ctx);
+	}
+	if (r < 0) {
 		switch (security_getenforce()) {
 		case -1:
 			fatal("%s: security_getenforce() failed", __func__);
 		case 0:
-			error("%s: Failed to set SELinux execution "
-			    "context for %s", __func__, pwname);
+			error("%s: SELinux failure. Continuing in permissive mode.",
+			    __func__);
+			break;
 		default:
-			fatal("%s: Failed to set SELinux execution context "
-			    "for %s (in enforcing mode)", __func__, pwname);
+			fatal("%s: SELinux failure. Aborting connection.",
+			    __func__);
 		}
 	}
-	if (user_ctx != NULL)
+	if (user_ctx != NULL && user_ctx != default_ctx)
 		freecon(user_ctx);
+	if (default_ctx != NULL)
+		freecon(default_ctx);
 
 	debug3("%s: done", __func__);
 }
@@ -157,7 +374,10 @@
 
 	debug3("%s: setting TTY context on %s", __func__, tty);
 
-	user_ctx = ssh_selinux_getctxbyname(pwname);
+	if (getexeccon(&user_ctx) < 0) {
+		error("%s: getexeccon: %s", __func__, strerror(errno));
+		goto out;
+	}
 
 	/* XXX: should these calls fatal() upon failure in enforcing mode? */
 
--- openssh-4.5p1/sshd.c.mls	2007-01-16 22:13:32.000000000 +0100
+++ openssh-4.5p1/sshd.c	2007-01-16 22:13:32.000000000 +0100
@@ -1833,6 +1833,9 @@
 		restore_uid();
 	}
 #endif
+#ifdef WITH_SELINUX
+	ssh_selinux_setup_exec_context(authctxt->pw->pw_name);
+#endif
 #ifdef USE_PAM
 	if (options.use_pam) {
 		do_pam_setcred(1);
--- openssh-4.5p1/misc.c.mls	2006-08-05 04:39:40.000000000 +0200
+++ openssh-4.5p1/misc.c	2007-01-16 22:13:32.000000000 +0100
@@ -418,6 +418,7 @@
 colon(char *cp)
 {
 	int flag = 0;
+	int start = 1;
 
 	if (*cp == ':')		/* Leading colon is part of file name. */
 		return (0);
@@ -431,8 +432,13 @@
 			return (cp+1);
 		if (*cp == ':' && !flag)
 			return (cp);
-		if (*cp == '/')
-			return (0);
+		if (start) {
+		/* Slash on beginning or after dots only denotes file name. */
+			if (*cp == '/')
+				return (0);
+			if (*cp != '.')
+				start = 0;
+		}
 	}
 	return (0);
 }
--- openssh-4.5p1/session.c.mls	2007-01-16 22:13:32.000000000 +0100
+++ openssh-4.5p1/session.c	2007-01-16 22:13:32.000000000 +0100
@@ -1347,10 +1347,6 @@
 #endif
 	if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
 		fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
-
-#ifdef WITH_SELINUX
-	ssh_selinux_setup_exec_context(pw->pw_name);
-#endif
 }
 
 static void