- (djm) [Makefile.in configure.ac session.c sshpty.c]

   [contrib/redhat/sshd.init openbsd-compat/Makefile.in]
   [openbsd-compat/openbsd-compat.h openbsd-compat/port-linux.c]
   [openbsd-compat/port-linux.h] Add support for SELinux, setting
   the execution and TTY contexts. based on patch from Daniel Walsh,
   bz #880; ok dtucker@

1 files changed, 165 insertions, 0 deletions

diff --git a/openbsd-compat/port-linux.c b/openbsd-compat/port-linux.c
new file mode 100644
index 000000000..54ec2910e
--- /dev/null
+++ b/openbsd-compat/port-linux.c
@@ -0,0 +1,165 @@
+/* $Id: port-linux.c,v 1.1 2006/04/22 11:26:08 djm Exp $ */
+
+/*
+ * Copyright (c) 2005 Daniel Walsh <dwalsh@redhat.com>
+ * Copyright (c) 2006 Damien Miller <djm@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Linux-specific portability code - just SELinux support at present
+ */
+
+#include "includes.h"
+
+#ifdef WITH_SELINUX
+#include "log.h"
+#include "port-linux.h"
+
+#include <selinux/selinux.h>
+#include <selinux/flask.h>
+#include <selinux/get_context_list.h>
+
+/* Wrapper around is_selinux_enabled() to log its return value once only */
+static int
+ssh_selinux_enabled(void)
+{
+        static int enabled = -1;
+
+        if (enabled == -1) {
+                enabled = is_selinux_enabled();
+                debug("SELinux support %s", enabled ? "enabled" : "disabled");
+        }
+
+        return (enabled);
+}
+
+/* Return the default security context for the given username */
+static security_context_t
+ssh_selinux_getctxbyname(char *pwname)
+{
+        security_context_t sc;
+        char *sename = NULL, *lvl = NULL;
+        int r;
+
+#ifdef HAVE_GETSEUSERBYNAME
+        if (getseuserbyname(pwname, &sename, &lvl) != 0)
+                return NULL;
+#else
+        sename = pwname;
+        lvl = NULL;
+#endif
+
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+        r = get_default_context_with_level(sename, lvl, NULL, &sc);
+#else
+        r = get_default_context(sename, NULL, &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);
+                }
+        }
+
+#ifdef HAVE_GETSEUSERBYNAME
+        if (sename != NULL)
+                xfree(sename);
+        if (lvl != NULL)
+                xfree(lvl);
+#endif
+
+        return (sc);
+}
+
+/* Set the execution context to the default for the specified user */
+void
+ssh_selinux_setup_exec_context(char *pwname)
+{
+        security_context_t user_ctx = NULL;
+
+        if (!ssh_selinux_enabled())
+                return;
+
+        debug3("%s: setting execution context", __func__);
+
+        user_ctx = ssh_selinux_getctxbyname(pwname);
+        if (setexeccon(user_ctx) != 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);
+                default:
+                        fatal("%s: Failed to set SELinux execution context "
+                            "for %s (in enforcing mode)", __func__, pwname);
+                }
+        }
+        if (user_ctx != NULL)
+                freecon(user_ctx);
+
+        debug3("%s: done", __func__);
+}
+
+/* Set the TTY context for the specified user */
+void
+ssh_selinux_setup_pty(char *pwname, const char *tty)
+{
+        security_context_t new_tty_ctx = NULL;
+        security_context_t user_ctx = NULL;
+        security_context_t old_tty_ctx = NULL;
+
+        if (!ssh_selinux_enabled())
+                return;
+
+        debug3("%s: setting TTY context on %s", __func__, tty);
+
+        user_ctx = ssh_selinux_getctxbyname(pwname);
+
+        /* XXX: should these calls fatal() upon failure in enforcing mode? */
+
+        if (getfilecon(tty, &old_tty_ctx) == -1) {
+                error("%s: getfilecon: %s", __func__, strerror(errno));
+                goto out;
+        }
+
+        if (security_compute_relabel(user_ctx, old_tty_ctx,
+            SECCLASS_CHR_FILE, &new_tty_ctx) != 0) {
+                error("%s: security_compute_relabel: %s",
+                    __func__, strerror(errno));
+                goto out;
+        }
+
+        if (setfilecon(tty, new_tty_ctx) != 0)
+                error("%s: setfilecon: %s", __func__, strerror(errno));
+ out:
+        if (new_tty_ctx != NULL)
+                freecon(new_tty_ctx);
+        if (old_tty_ctx != NULL)
+                freecon(old_tty_ctx);
+        if (user_ctx != NULL)
+                freecon(user_ctx);
+        debug3("%s: done", __func__);
+}
+#endif /* WITH_SELINUX */