--- /dev/null
+/*
+ * Copyright (c) 2009-2010 Todd C. Miller <Todd.Miller@courtesan.com>
+ * Copyright (c) 2008 Dan Walsh <dwalsh@redhat.com>
+ *
+ * Borrowed heavily from newrole source code
+ * Authors:
+ * Anthony Colatrella
+ * Tim Fraser
+ * Steve Grubb <sgrubb@redhat.com>
+ * Darrel Goeddel <DGoeddel@trustedcs.com>
+ * Michael Thompson <mcthomps@us.ibm.com>
+ * Dan Walsh <dwalsh@redhat.com>
+ *
+ * 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.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+
+#include <selinux/flask.h> /* for SECCLASS_CHR_FILE */
+#include <selinux/selinux.h> /* for is_selinux_enabled() */
+#include <selinux/context.h> /* for context-mangling functions */
+#include <selinux/get_default_type.h>
+#include <selinux/get_context_list.h>
+
+#ifdef HAVE_LINUX_AUDIT
+# include <libaudit.h>
+#endif
+
+#include "sudo.h"
+#include "sudo_exec.h"
+
+static struct selinux_state {
+ security_context_t old_context;
+ security_context_t new_context;
+ security_context_t tty_context;
+ security_context_t new_tty_context;
+ const char *ttyn;
+ int ttyfd;
+ int enforcing;
+} se_state;
+
+#ifdef HAVE_LINUX_AUDIT
+static int
+audit_role_change(const security_context_t old_context,
+ const security_context_t new_context, const char *ttyn)
+{
+ int au_fd, rc = -1;
+ char *message;
+ debug_decl(audit_role_change, SUDO_DEBUG_SELINUX)
+
+ au_fd = audit_open();
+ if (au_fd == -1) {
+ /* Kernel may not have audit support. */
+ if (errno != EINVAL && errno != EPROTONOSUPPORT && errno != EAFNOSUPPORT
+)
+ error(1, _("unable to open audit system"));
+ } else {
+ /* audit role change using the same format as newrole(1) */
+ easprintf(&message, "newrole: old-context=%s new-context=%s",
+ old_context, new_context);
+ rc = audit_log_user_message(au_fd, AUDIT_USER_ROLE_CHANGE,
+ message, NULL, NULL, ttyn, 1);
+ if (rc <= 0)
+ warning(_("unable to send audit message"));
+ efree(message);
+ close(au_fd);
+ }
+
+ debug_return_int(rc);
+}
+#endif
+
+/*
+ * This function attempts to revert the relabeling done to the tty.
+ * fd - referencing the opened ttyn
+ * ttyn - name of tty to restore
+ *
+ * Returns zero on success, non-zero otherwise
+ */
+int
+selinux_restore_tty(void)
+{
+ int retval = 0;
+ security_context_t chk_tty_context = NULL;
+ debug_decl(selinux_restore_tty, SUDO_DEBUG_SELINUX)
+
+ if (se_state.ttyfd == -1 || se_state.new_tty_context == NULL)
+ goto skip_relabel;
+
+ /* Verify that the tty still has the context set by sudo. */
+ if ((retval = fgetfilecon(se_state.ttyfd, &chk_tty_context)) < 0) {
+ warning(_("unable to fgetfilecon %s"), se_state.ttyn);
+ goto skip_relabel;
+ }
+
+ if ((retval = strcmp(chk_tty_context, se_state.new_tty_context))) {
+ warningx(_("%s changed labels"), se_state.ttyn);
+ goto skip_relabel;
+ }
+
+ if ((retval = fsetfilecon(se_state.ttyfd, se_state.tty_context)) < 0)
+ warning(_("unable to restore context for %s"), se_state.ttyn);
+
+skip_relabel:
+ if (se_state.ttyfd != -1) {
+ close(se_state.ttyfd);
+ se_state.ttyfd = -1;
+ }
+ if (chk_tty_context != NULL) {
+ freecon(chk_tty_context);
+ chk_tty_context = NULL;
+ }
+ debug_return_int(retval);
+}
+
+/*
+ * This function attempts to relabel the tty. If this function fails, then
+ * the contexts are free'd and -1 is returned. On success, 0 is returned
+ * and tty_context and new_tty_context are set.
+ *
+ * This function will not fail if it can not relabel the tty when selinux is
+ * in permissive mode.
+ */
+static int
+relabel_tty(const char *ttyn, int ptyfd)
+{
+ security_context_t tty_con = NULL;
+ security_context_t new_tty_con = NULL;
+ int fd;
+ debug_decl(relabel_tty, SUDO_DEBUG_SELINUX)
+
+ se_state.ttyfd = ptyfd;
+
+ /* It is perfectly legal to have no tty. */
+ if (ptyfd == -1 && ttyn == NULL)
+ debug_return_int(0);
+
+ /* If sudo is not allocating a pty for the command, open current tty. */
+ if (ptyfd == -1) {
+ se_state.ttyfd = open(ttyn, O_RDWR|O_NONBLOCK);
+ if (se_state.ttyfd == -1) {
+ warning(_("unable to open %s, not relabeling tty"), ttyn);
+ if (se_state.enforcing)
+ goto bad;
+ }
+ (void)fcntl(se_state.ttyfd, F_SETFL,
+ fcntl(se_state.ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
+ }
+
+ if (fgetfilecon(se_state.ttyfd, &tty_con) < 0) {
+ warning(_("unable to get current tty context, not relabeling tty"));
+ if (se_state.enforcing)
+ goto bad;
+ }
+
+ if (tty_con && (security_compute_relabel(se_state.new_context, tty_con,
+ SECCLASS_CHR_FILE, &new_tty_con) < 0)) {
+ warning(_("unable to get new tty context, not relabeling tty"));
+ if (se_state.enforcing)
+ goto bad;
+ }
+
+ if (new_tty_con != NULL) {
+ if (fsetfilecon(se_state.ttyfd, new_tty_con) < 0) {
+ warning(_("unable to set new tty context"));
+ if (se_state.enforcing)
+ goto bad;
+ }
+ }
+
+ if (ptyfd != -1) {
+ /* Reopen pty that was relabeled, std{in,out,err} are reset later. */
+ se_state.ttyfd = open(ttyn, O_RDWR|O_NOCTTY, 0);
+ if (se_state.ttyfd == -1) {
+ warning(_("unable to open %s"), ttyn);
+ if (se_state.enforcing)
+ goto bad;
+ }
+ if (dup2(se_state.ttyfd, ptyfd) == -1) {
+ warning("dup2");
+ goto bad;
+ }
+ } else {
+ /* Re-open tty to get new label and reset std{in,out,err} */
+ close(se_state.ttyfd);
+ se_state.ttyfd = open(ttyn, O_RDWR|O_NONBLOCK);
+ if (se_state.ttyfd == -1) {
+ warning(_("unable to open %s"), ttyn);
+ goto bad;
+ }
+ (void)fcntl(se_state.ttyfd, F_SETFL,
+ fcntl(se_state.ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
+ for (fd = STDIN_FILENO; fd <= STDERR_FILENO; fd++) {
+ if (isatty(fd) && dup2(se_state.ttyfd, fd) == -1) {
+ warning("dup2");
+ goto bad;
+ }
+ }
+ }
+ /* Retain se_state.ttyfd so we can restore label when command finishes. */
+ (void)fcntl(se_state.ttyfd, F_SETFD, FD_CLOEXEC);
+
+ se_state.ttyn = ttyn;
+ se_state.tty_context = tty_con;
+ se_state.new_tty_context = new_tty_con;
+ debug_return_int(0);
+
+bad:
+ if (se_state.ttyfd != -1 && se_state.ttyfd != ptyfd) {
+ close(se_state.ttyfd);
+ se_state.ttyfd = -1;
+ }
+ freecon(tty_con);
+ debug_return_int(-1);
+}
+
+/*
+ * Returns a new security context based on the old context and the
+ * specified role and type.
+ */
+security_context_t
+get_exec_context(security_context_t old_context, const char *role, const char *type)
+{
+ security_context_t new_context = NULL;
+ context_t context = NULL;
+ char *typebuf = NULL;
+ debug_decl(get_exec_context, SUDO_DEBUG_SELINUX)
+
+ /* We must have a role, the type is optional (we can use the default). */
+ if (!role) {
+ warningx(_("you must specify a role for type %s"), type);
+ errno = EINVAL;
+ goto bad;
+ }
+ if (!type) {
+ if (get_default_type(role, &typebuf)) {
+ warningx(_("unable to get default type for role %s"), role);
+ errno = EINVAL;
+ goto bad;
+ }
+ type = typebuf;
+ }
+
+ /*
+ * Expand old_context into a context_t so that we extract and modify
+ * its components easily.
+ */
+ context = context_new(old_context);
+
+ /*
+ * Replace the role and type in "context" with the role and
+ * type we will be running the command as.
+ */
+ if (context_role_set(context, role)) {
+ warning(_("failed to set new role %s"), role);
+ goto bad;
+ }
+ if (context_type_set(context, type)) {
+ warning(_("failed to set new type %s"), type);
+ goto bad;
+ }
+
+ /*
+ * Convert "context" back into a string and verify it.
+ */
+ new_context = estrdup(context_str(context));
+ if (security_check_context(new_context) < 0) {
+ warningx(_("%s is not a valid context"), new_context);
+ errno = EINVAL;
+ goto bad;
+ }
+
+#ifdef DEBUG
+ warningx("Your new context is %s", new_context);
+#endif
+
+ context_free(context);
+ debug_return_ptr(new_context);
+
+bad:
+ efree(typebuf);
+ context_free(context);
+ freecon(new_context);
+ debug_return_ptr(NULL);
+}
+
+/*
+ * Set the exec and tty contexts in preparation for fork/exec.
+ * Must run as root, before the uid change.
+ * If ptyfd is not -1, it indicates we are running
+ * in a pty and do not need to reset std{in,out,err}.
+ * Returns 0 on success and -1 on failure.
+ */
+int
+selinux_setup(const char *role, const char *type, const char *ttyn,
+ int ptyfd)
+{
+ int rval = -1;
+ debug_decl(selinux_setup, SUDO_DEBUG_SELINUX)
+
+ /* Store the caller's SID in old_context. */
+ if (getprevcon(&se_state.old_context)) {
+ warning(_("failed to get old_context"));
+ goto done;
+ }
+
+ se_state.enforcing = security_getenforce();
+ if (se_state.enforcing < 0) {
+ warning(_("unable to determine enforcing mode."));
+ goto done;
+ }
+
+#ifdef DEBUG
+ warningx("your old context was %s", se_state.old_context);
+#endif
+ se_state.new_context = get_exec_context(se_state.old_context, role, type);
+ if (!se_state.new_context)
+ goto done;
+
+ if (relabel_tty(ttyn, ptyfd) < 0) {
+ warning(_("unable to setup tty context for %s"), se_state.new_context);
+ goto done;
+ }
+
+#ifdef DEBUG
+ if (se_state.ttyfd != -1) {
+ warningx("your old tty context is %s", se_state.tty_context);
+ warningx("your new tty context is %s", se_state.new_tty_context);
+ }
+#endif
+
+#ifdef HAVE_LINUX_AUDIT
+ audit_role_change(se_state.old_context, se_state.new_context,
+ se_state.ttyn);
+#endif
+
+ rval = 0;
+
+done:
+ debug_return_int(rval);
+}
+
+void
+selinux_execve(const char *path, char *const argv[], char *const envp[],
+ int noexec)
+{
+ char **nargv;
+ int argc, serrno;
+ debug_decl(selinux_execve, SUDO_DEBUG_SELINUX)
+
+ if (setexeccon(se_state.new_context)) {
+ warning(_("unable to set exec context to %s"), se_state.new_context);
+ if (se_state.enforcing)
+ debug_return;
+ }
+
+#ifdef HAVE_SETKEYCREATECON
+ if (setkeycreatecon(se_state.new_context)) {
+ warning(_("unable to set key creation context to %s"), se_state.new_context);
+ if (se_state.enforcing)
+ debug_return;
+ }
+#endif /* HAVE_SETKEYCREATECON */
+
+ /*
+ * Build new argv with sesh as argv[0].
+ * If argv[0] ends in -noexec, sesh will disable execute
+ * for the command it runs.
+ */
+ for (argc = 0; argv[argc] != NULL; argc++)
+ continue;
+ nargv = emalloc2(argc + 2, sizeof(char *));
+ if (noexec)
+ nargv[0] = *argv[0] == '-' ? "-sesh-noexec" : "sesh-noexec";
+ else
+ nargv[0] = *argv[0] == '-' ? "-sesh" : "sesh";
+ nargv[1] = (char *)path;
+ memcpy(&nargv[2], &argv[1], argc * sizeof(char *)); /* copies NULL */
+
+ /* sesh will handle noexec for us. */
+ sudo_execve(_PATH_SUDO_SESH, nargv, envp, 0);
+ serrno = errno;
+ free(nargv);
+ errno = serrno;
+ debug_return;
+}
projects / debian / sudo / blobdiff