1 files changed, 143 insertions, 0 deletions

diff --git a/src/jailcheck/access.c b/src/jailcheck/access.c
new file mode 100644
index 000000000..c18d64a82
--- /dev/null
+++ b/src/jailcheck/access.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2014-2021 Firejail Authors
+ *
+ * This file is part of firejail project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+#include "jailcheck.h"
+#include <dirent.h>
+#include <sys/wait.h>
+
+typedef struct {
+        char *tfile;
+        char *tdir;
+} TestDir;
+
+#define MAX_TEST_FILES 16
+TestDir td[MAX_TEST_FILES];
+static int files_cnt = 0;
+
+void access_setup(const char *directory) {
+        // I am root!
+        assert(directory);
+        assert(user_home_dir);
+
+        if (files_cnt >= MAX_TEST_FILES) {
+                fprintf(stderr, "Error: maximum number of test directories exceded\n");
+                exit(1);
+        }
+
+        char *fname = strdup(directory);
+        if (!fname)
+                errExit("strdup");
+        if (strncmp(fname, "~/", 2) == 0) {
+                free(fname);
+                if (asprintf(&fname, "%s/%s", user_home_dir, directory + 2) == -1)
+                        errExit("asprintf");
+        }
+
+        char *path = realpath(fname, NULL);
+        free(fname);
+        if (path == NULL) {
+                fprintf(stderr, "Warning: invalid directory %s, skipping...\n", directory);
+                return;
+        }
+
+        // file in home directory
+        if (strncmp(path, user_home_dir, strlen(user_home_dir)) != 0) {
+                fprintf(stderr, "Warning: file %s is not in user home directory, skipping...\n", directory);
+                free(path);
+                return;
+        }
+
+        // try to open the dir as root
+        DIR *dir = opendir(path);
+        if (!dir) {
+                fprintf(stderr, "Warning: directory %s not found, skipping\n", directory);
+                free(path);
+                return;
+        }
+        closedir(dir);
+
+        // create a test file
+        char *test_file;
+        if (asprintf(&test_file, "%s/jailcheck-access-%d", path, getpid()) == -1)
+                errExit("asprintf");
+
+        FILE *fp = fopen(test_file, "w");
+        if (!fp) {
+                printf("Warning: I cannot create test file in directory %s, skipping...\n", directory);
+                return;
+        }
+        fprintf(fp, "this file was created by firetest utility, you can safely delete it\n");
+        fclose(fp);
+        int rv = chown(test_file, user_uid, user_gid);
+        if (rv)
+                errExit("chown");
+
+        char *dname = strdup(directory);
+        if (!dname)
+                errExit("strdup");
+        td[files_cnt].tdir = dname;
+        td[files_cnt].tfile = test_file;
+        files_cnt++;
+}
+
+void access_destroy(void) {
+        // remove test files
+        int i;
+
+        for (i = 0; i < files_cnt; i++) {
+                int rv = unlink(td[i].tfile);
+                (void) rv;
+        }
+        files_cnt = 0;
+}
+
+void access_test(void) {
+        // I am root in sandbox mount namespace
+        assert(user_uid);
+        int i;
+
+        pid_t child = fork();
+        if (child == -1)
+                errExit("fork");
+
+        if (child == 0) { // child
+                // drop privileges
+                if (setgid(user_gid) != 0)
+                        errExit("setgid");
+                if (setuid(user_uid) != 0)
+                        errExit("setuid");
+
+                for (i = 0; i < files_cnt; i++) {
+                        assert(td[i].tfile);
+
+                        // try to open the file for reading
+                        FILE *fp = fopen(td[i].tfile, "r");
+                        if (fp) {
+
+                                printf("   Warning: I can read %s\n", td[i].tdir);
+                                fclose(fp);
+                        }
+                }
+                exit(0);
+        }
+
+        // wait for the child to finish
+        int status;
+        wait(&status);
+}