Fix sudoedit when running with SELinux RBAC mode.

We can't use run_command() to run sesh, that will use the sudo event
loop (and might run it in a pty!).
There's no need to relabel the tty when copying files.
Get the path to sesh from sudo.conf.

Currently, for SELinux RBAC, the editor runs with the target user's
security context. This defeats the purpose of sudoedit.  Fixing
that requires passing file descriptors between the main sudo process
(running with the invoking user's security context) and sesh (runnning
with the target user's security context).

src/exec_monitor.c

@@ -606,7 +606,7 @@ exec_monitor(struct command_details *details, sigset_t *oset,
 #ifdef HAVE_SELINUX
     if (ISSET(details->flags, CD_RBAC_ENABLED)) {
         if (selinux_setup(details->selinux_role, details->selinux_type,
-            details->tty, io_fds[SFD_SLAVE]) == -1)
+            details->tty, io_fds[SFD_SLAVE], true) == -1)
             goto bad;
     }
 #endif

src/exec_nopty.c

@@ -379,7 +379,7 @@ exec_nopty(struct command_details *details, struct command_status *cstat)
 #ifdef HAVE_SELINUX
     if (ISSET(details->flags, CD_RBAC_ENABLED)) {
         if (selinux_setup(details->selinux_role, details->selinux_type,
-		details->tty, -1) == -1) {
+		details->tty, -1, true) == -1) {
 	    cstat->type = CMD_ERRNO;
 	    cstat->val = errno;
 	    debug_return;

src/selinux.c

@@ -387,7 +387,7 @@ bad:
  */
 int
 selinux_setup(const char *role, const char *type, const char *ttyn,
-    int ptyfd)
+    int ptyfd, bool label_tty)
 {
     int ret = -1;
     debug_decl(selinux_setup, SUDO_DEBUG_SELINUX);
@@ -416,7 +416,7 @@ selinux_setup(const char *role, const char *type, const char *ttyn,
     sudo_debug_printf(SUDO_DEBUG_INFO, "%s: new context %s", __func__,
 	se_state.new_context);
     
-    if (relabel_tty(ttyn, ptyfd) == -1) {
+    if (label_tty && relabel_tty(ttyn, ptyfd) == -1) {
 	sudo_warn(U_("unable to set tty context to %s"), se_state.new_context);
 	goto done;
     }
@@ -432,6 +432,28 @@ done:
     debug_return_int(ret);
 }
 
+int
+selinux_setcon(void)
+{
+    debug_decl(selinux_setcon, SUDO_DEBUG_SELINUX);
+
+    if (setexeccon(se_state.new_context)) {
+	sudo_warn(U_("unable to set exec context to %s"), se_state.new_context);
+	if (se_state.enforcing)
+	    debug_return_int(-1);
+    }
+
+#ifdef HAVE_SETKEYCREATECON
+    if (setkeycreatecon(se_state.new_context)) {
+	sudo_warn(U_("unable to set key creation context to %s"), se_state.new_context);
+	if (se_state.enforcing)
+	    debug_return_int(-1);
+    }
+#endif /* HAVE_SETKEYCREATECON */
+
+    debug_return_int(0);
+}
+
 void
 selinux_execve(int fd, const char *path, char *const argv[], char *envp[],
     bool noexec)
@@ -448,19 +470,9 @@ selinux_execve(int fd, const char *path, char *const argv[], char *envp[],
 	debug_return;
     }
 
-    if (setexeccon(se_state.new_context)) {
+    /* Set SELinux exec and keycreate contexts. */
-	sudo_warn(U_("unable to set exec context to %s"), se_state.new_context);
+    if (selinux_setcon() == -1)
-	if (se_state.enforcing)
 	debug_return;
-    }
-
-#ifdef HAVE_SETKEYCREATECON
-    if (setkeycreatecon(se_state.new_context)) {
-	sudo_warn(U_("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].

src/sudo.c

@@ -974,10 +974,6 @@ run_command(struct command_details *details)
     case CMD_WSTATUS:
 	/* Command ran, exited or was killed. */
 	status = cstat.val;
-#ifdef HAVE_SELINUX
-	if (ISSET(details->flags, CD_SUDOEDIT_COPY))
-	    break;
-#endif
 	iolog_close(status, 0);
 	policy_close(status, 0);
 	audit_close(SUDO_PLUGIN_WAIT_STATUS, cstat.val);

src/sudo.h

@@ -130,12 +130,11 @@ struct user_details {
 #define CD_USE_PTY		0x001000
 #define CD_SET_UTMP		0x002000
 #define CD_EXEC_BG		0x004000
-#define CD_SUDOEDIT_COPY	0x008000
+#define CD_SUDOEDIT_FOLLOW	0x008000
-#define CD_SUDOEDIT_FOLLOW	0x010000
+#define CD_SUDOEDIT_CHECKDIR	0x010000
-#define CD_SUDOEDIT_CHECKDIR	0x020000
+#define CD_SET_GROUPS		0x020000
-#define CD_SET_GROUPS		0x040000
+#define CD_LOGIN_SHELL		0x040000
-#define CD_LOGIN_SHELL		0x080000
+#define CD_OVERRIDE_UMASK	0x080000
-#define CD_OVERRIDE_UMASK	0x100000
 
 struct preserved_fd {
     TAILQ_ENTRY(preserved_fd) entries;
@@ -242,7 +241,8 @@ int os_init_openbsd(int argc, char *argv[], char *envp[]);
 /* selinux.c */
 int selinux_restore_tty(void);
 int selinux_setup(const char *role, const char *type, const char *ttyn,
-    int ttyfd);
+    int ttyfd, bool label_tty);
+int selinux_setcon(void);
 void selinux_execve(int fd, const char *path, char *const argv[],
     char *envp[], bool noexec);
 

src/sudo_edit.c

@@ -718,6 +718,42 @@ bad:
 }
 
 #ifdef HAVE_SELINUX
+static int
+selinux_run_helper(char *argv[], char *envp[])
+{
+    int status, ret = SESH_ERR_FAILURE;
+    const char *sesh;
+    pid_t child, pid;
+    debug_decl(selinux_run_helper, SUDO_DEBUG_EDIT);
+
+    sesh = sudo_conf_sesh_path();
+    if (sesh == NULL) {
+	sudo_warnx("internal error: sesh path not set");
+	debug_return_int(-1);
+    }
+
+    child = sudo_debug_fork();
+    switch (child) {
+    case -1:
+	sudo_warn(U_("unable to fork"));
+	break;
+    case 0:
+	/* child runs sesh in new context */
+	if (selinux_setcon() == 0)
+	    execve(sesh, argv, envp);
+	_exit(SESH_ERR_FAILURE);
+    default:
+	/* parent waits */
+	do {
+	    pid = waitpid(child, &status, 0);
+	} while (pid == -1 && errno == EINTR);
+
+	ret = WIFSIGNALED(status) ? SESH_ERR_KILLED : WEXITSTATUS(status);
+    }
+
+    debug_return_int(ret);
+}
+
 static int
 selinux_edit_create_tfiles(struct command_details *command_details,
     struct tempfile *tf, char *files[], int nfiles)
@@ -725,22 +761,12 @@ selinux_edit_create_tfiles(struct command_details *command_details,
     char **sesh_args, **sesh_ap;
     int i, rc, sesh_nargs;
     struct stat sb;
-    struct command_details saved_command_details;
     debug_decl(selinux_edit_create_tfiles, SUDO_DEBUG_EDIT);
     
-    /* Prepare selinux stuff (setexeccon) */
-    if (selinux_setup(command_details->selinux_role,
-	command_details->selinux_type, NULL, -1) != 0)
-	debug_return_int(-1);
-
     if (nfiles < 1)
 	debug_return_int(0);
 
     /* Construct common args for sesh */
-    memcpy(&saved_command_details, command_details, sizeof(struct command_details));
-    command_details->command = _PATH_SUDO_SESH;
-    command_details->flags |= CD_SUDOEDIT_COPY;
-    
     sesh_nargs = 4 + (nfiles * 2) + 1;
     sesh_args = sesh_ap = reallocarray(NULL, sesh_nargs, sizeof(char *));
     if (sesh_args == NULL) {
@@ -753,6 +779,7 @@ selinux_edit_create_tfiles(struct command_details *command_details,
 	*sesh_ap++ = "-h";
     *sesh_ap++ = "0";
 
+    /* XXX - temp files should be created with user's context */
     for (i = 0; i < nfiles; i++) {
 	char *tfile, *ofile = files[i];
 	int tfd;
@@ -782,8 +809,7 @@ selinux_edit_create_tfiles(struct command_details *command_details,
     *sesh_ap = NULL;
 
     /* Run sesh -e [-h] 0 <o1> <t1> ... <on> <tn> */
-    command_details->argv = sesh_args;
+    rc = selinux_run_helper(sesh_args, command_details->envp);
-    rc = run_command(command_details);
     switch (rc) {
     case SESH_SUCCESS:
 	break;
@@ -791,15 +817,12 @@ selinux_edit_create_tfiles(struct command_details *command_details,
 	sudo_fatalx(U_("sesh: internal error: odd number of paths"));
     case SESH_ERR_NO_FILES:
 	sudo_fatalx(U_("sesh: unable to create temporary files"));
+    case SESH_ERR_KILLED:
+	sudo_fatalx(U_("sesh: killed by a signal"));
     default:
 	sudo_fatalx(U_("sesh: unknown error %d"), rc);
     }
 
-    /* Restore saved command_details. */
-    command_details->command = saved_command_details.command;
-    command_details->flags = saved_command_details.flags;
-    command_details->argv = saved_command_details.argv;
-    
     /* Chown to user's UID so they can edit the temporary files. */
     for (i = 0; i < nfiles; i++) {
 	if (chown(tf[i].tfile, user_details.uid, user_details.gid) != 0) {
@@ -820,24 +843,14 @@ selinux_edit_copy_tfiles(struct command_details *command_details,
 {
     char **sesh_args, **sesh_ap;
     int i, rc, sesh_nargs, ret = 1;
-    struct command_details saved_command_details;
     struct timespec ts;
     struct stat sb;
     debug_decl(selinux_edit_copy_tfiles, SUDO_DEBUG_EDIT);
     
-    /* Prepare selinux stuff (setexeccon) */
-    if (selinux_setup(command_details->selinux_role,
-	command_details->selinux_type, NULL, -1) != 0)
-	debug_return_int(1);
-
     if (nfiles < 1)
 	debug_return_int(0);
 
     /* Construct common args for sesh */
-    memcpy(&saved_command_details, command_details, sizeof(struct command_details));
-    command_details->command = _PATH_SUDO_SESH;
-    command_details->flags |= CD_SUDOEDIT_COPY;
-    
     sesh_nargs = 3 + (nfiles * 2) + 1;
     sesh_args = sesh_ap = reallocarray(NULL, sesh_nargs, sizeof(char *));
     if (sesh_args == NULL) {
@@ -875,32 +888,29 @@ selinux_edit_copy_tfiles(struct command_details *command_details,
 
     if (sesh_ap - sesh_args > 3) {
 	/* Run sesh -e 1 <t1> <o1> ... <tn> <on> */
-	command_details->argv = sesh_args;
+	rc = selinux_run_helper(sesh_args, command_details->envp);
-	rc = run_command(command_details);
 	switch (rc) {
 	case SESH_SUCCESS:
 	    ret = 0;
 	    break;
 	case SESH_ERR_NO_FILES:
 	    sudo_warnx(U_("unable to copy temporary files back to their original location"));
-	    sudo_warnx(U_("contents of edit session left in %s"), edit_tmpdir);
 	    break;
 	case SESH_ERR_SOME_FILES:
 	    sudo_warnx(U_("unable to copy some of the temporary files back to their original location"));
-	    sudo_warnx(U_("contents of edit session left in %s"), edit_tmpdir);
+	    break;
+	case SESH_ERR_KILLED:
+	    sudo_warnx(U_("sesh: killed by a signal"));
 	    break;
 	default:
 	    sudo_warnx(U_("sesh: unknown error %d"), rc);
 	    break;
 	}
+	if (ret != 0)
+	    sudo_warnx(U_("contents of edit session left in %s"), edit_tmpdir);
     }
     free(sesh_args);
 
-    /* Restore saved command_details. */
-    command_details->command = saved_command_details.command;
-    command_details->flags = saved_command_details.flags;
-    command_details->argv = saved_command_details.argv;
-
     debug_return_int(ret);
 }
 #endif /* HAVE_SELINUX */
@@ -952,6 +962,15 @@ sudo_edit(struct command_details *command_details)
 	goto cleanup;
     }
 
+#ifdef HAVE_SELINUX
+    /* Compute new SELinux security context. */
+    if (ISSET(command_details->flags, CD_RBAC_ENABLED)) {
+	if (selinux_setup(command_details->selinux_role,
+		command_details->selinux_type, NULL, -1, false) != 0)
+	    goto cleanup;
+    }
+#endif
+
     /* Copy editor files to temporaries. */
     tf = calloc(nfiles, sizeof(*tf));
     if (tf == NULL) {
@@ -987,6 +1006,7 @@ sudo_edit(struct command_details *command_details)
     /*
      * Run the editor with the invoking user's creds,
      * keeping track of the time spent in the editor.
+     * XXX - should run editor with user's context
      */
     if (sudo_gettime_real(&times[0]) == -1) {
 	sudo_warn(U_("unable to read the clock"));

src/sudo_exec.h

@@ -73,6 +73,7 @@
  */
 #define SESH_SUCCESS	    0		/* successful operation */
 #define SESH_ERR_FAILURE    1		/* unspecified error */
+#define SESH_ERR_KILLED     2		/* killed by a signal */
 #define SESH_ERR_INVALID    30		/* invalid -e arg value */
 #define SESH_ERR_BAD_PATHS  31		/* odd number of paths */
 #define SESH_ERR_NO_FILES   32		/* copy error, no files copied */