Update the cwd for log_subcmds too.

Fixes a problem for intercept_method=trace when running a relative
command from a different directory than what sudo ws started from.
GitHub issue #194

src/exec_intercept.c

@@ -361,19 +361,19 @@ bad:
  */
 bool
 intercept_check_policy(const char *command, int argc, char **argv, int envc,
-    char **envp, const char *runcwd, void *v)
+    char **envp, const char *runcwd, int *oldcwd, void *v)
 {
     struct intercept_closure *closure = v;
     char **command_info = NULL;
     char **command_info_copy = NULL;
     char **user_env_out = NULL;
     char **run_argv = NULL;
-    bool ret = true;
     int i, rc, saved_dir = -1;
+    bool ret = true;
+    struct stat sb;
     debug_decl(intercept_check_policy, SUDO_DEBUG_EXEC);
 
-    if (ISSET(closure->details->flags, CD_INTERCEPT)) {
-	/* Change to runcwd for the policy check if necessary. */
+    /* Change to runcwd before the policy check if necessary. */
     if (*command != '/') {
 	if (runcwd == NULL || (saved_dir = open(".", O_RDONLY)) == -1 ||
 		chdir(runcwd) == -1) {
@@ -389,6 +389,8 @@ intercept_check_policy(const char *command, int argc, char **argv, int envc,
 		    SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
 		    "unable to chdir for %s", runcwd);
 	    }
+	    if (ISSET(closure->details->flags, CD_INTERCEPT)) {
+		/* Inability to change cwd is fatal in intercept mode. */
 		if (closure->errstr == NULL)
 		    closure->errstr = N_("command rejected by policy");
 		audit_reject(policy_plugin.name, SUDO_POLICY_PLUGIN,
@@ -397,7 +399,19 @@ intercept_check_policy(const char *command, int argc, char **argv, int envc,
 		goto done;
 	    }
 	}
+    }
 
+    /*
+     * Short-circuit the policy check if the command doesn't exist.
+     * Otherwise, both sudo and the shell will report the error.
+     */
+    if (stat(command, &sb) == -1) {
+	closure->errstr = NULL;
+	closure->state = POLICY_REJECT;
+	goto done;
+    }
+
+    if (ISSET(closure->details->flags, CD_INTERCEPT)) {
 	/* We don't currently have a good way to validate the environment. */
 	sudo_debug_set_active_instance(policy_plugin.debug_instance);
 	rc = policy_plugin.u.policy->check_policy(argc, argv, NULL,
@@ -504,6 +518,14 @@ oom:
     closure->errstr = N_("unable to allocate memory");
 
 bad:
+    if (saved_dir != -1) {
+	if (fchdir(saved_dir) == -1) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+		"%s: unable to restore saved cwd", __func__);
+	}
+	close(saved_dir);
+	saved_dir = -1;
+    }
     if (closure->errstr == NULL)
 	closure->errstr = N_("policy plugin error");
     audit_error(policy_plugin.name, SUDO_POLICY_PLUGIN, closure->errstr,
@@ -512,20 +534,13 @@ bad:
     ret = false;
 
 done:
-    if (saved_dir != -1) {
-	if (fchdir(saved_dir) == -1) {
-	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
-		"%s: unable to restore saved cwd", __func__);
-	}
-	close(saved_dir);
-    }
-
     if (command_info_copy != NULL) {
 	for (i = 0; command_info_copy[i] != NULL; i++) {
 	    free(command_info_copy[i]);
 	}
 	free(command_info_copy);
     }
+    *oldcwd = saved_dir;
 
     debug_return_bool(ret);
 }
@@ -536,6 +551,7 @@ intercept_check_policy_req(PolicyCheckRequest *req,
 {
     char **argv = NULL;
     bool ret = false;
+    int oldcwd = -1;
     size_t n;
     debug_decl(intercept_check_policy_req, SUDO_DEBUG_EXEC);
 
@@ -573,9 +589,17 @@ intercept_check_policy_req(PolicyCheckRequest *req,
     argv[n] = NULL;
 
     ret = intercept_check_policy(req->command, req->n_argv, argv, req->n_envp,
-	req->envp, req->cwd, closure);
+	req->envp, req->cwd, &oldcwd, closure);
 
 done:
+    if (oldcwd != -1) {
+	if (fchdir(oldcwd) == -1) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+		"%s: unable to restore saved cwd", __func__);
+	}
+	close(oldcwd);
+    }
+
     free(argv);
 
     debug_return_bool(ret);

src/exec_intercept.h

@@ -50,6 +50,6 @@ struct intercept_closure {
 };
 
 void intercept_closure_reset(struct intercept_closure *closure);
-bool intercept_check_policy(const char *command, int argc, char **argv, int envc, char **envp, const char *runcwd, void *closure);
+bool intercept_check_policy(const char *command, int argc, char **argv, int envc, char **envp, const char *runcwd, int *oldcwd, void *closure);
 
 #endif /* SUDO_EXEC_INTERCEPT_H */

src/exec_ptrace.c

@@ -1697,8 +1697,7 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
     char cwd[PATH_MAX];
     unsigned long msg;
     bool ret = false;
-    struct stat sb;
-    int i;
+    int i, oldcwd = -1;
     debug_decl(ptrace_intercept_execve, SUDO_DEBUG_EXEC);
 
     /* Do not check the policy if we are executing the initial command. */
@@ -1783,16 +1782,6 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
 	goto done;
     }
 
-    /*
-     * Short-circuit the policy check if the command doesn't exist.
-     * Otherwise, both sudo and the shell will report the error.
-     */
-    if (stat(pathname, &sb) == -1) {
-	ptrace_fail_syscall(pid, &regs, errno);
-	ret = true;
-	goto done;
-    }
-
     /* We can only pass the pathname to exececute via argv[0] (plugin API). */
     argv[0] = pathname;
     if (argc == 0) {
@@ -1806,7 +1795,8 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
     sudo_debug_printf(SUDO_DEBUG_INFO, "%s: %d: checking policy for %s",
 	__func__, (int)pid, pathname);
     if (!intercept_check_policy(pathname, argc, argv, envc, envp, cwd,
-	    closure)) {
+	    &oldcwd, closure)) {
+	if (closure->errstr != NULL)
 	    sudo_warnx("%s", U_(closure->errstr));
     }
 
@@ -1939,6 +1929,13 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
     ret = true;
 
 done:
+    if (oldcwd != -1) {
+        if (fchdir(oldcwd) == -1) {
+            sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+                "%s: unable to restore saved cwd", __func__);
+        }
+        close(oldcwd);
+    }
     free(buf);
     intercept_closure_reset(closure);