1 files changed, 205 insertions, 0 deletions

diff --git a/src/firejail/fs_whitelist.c b/src/firejail/fs_whitelist.c
new file mode 100644
index 000000000..fac08705d
--- /dev/null
+++ b/src/firejail/fs_whitelist.c
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2014, 2015 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 "firejail.h"
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <linux/limits.h>
+#include <fnmatch.h>
+#include <glob.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+
+static int mkpath(const char* path, mode_t mode) {
+        assert(path && *path);
+        
+        // work on a copy of the path
+        char *file_path = strdup(path);
+        if (!file_path)
+                errExit("strdup");
+        
+        char* p;
+        for (p=strchr(file_path+1, '/'); p; p=strchr(p+1, '/')) {
+                *p='\0';
+                if (mkdir(file_path, mode)==-1) {
+                        if (errno != EEXIST) {
+                                *p='/';
+                                free(file_path);
+                                return -1;
+                        }
+                }
+                else {
+// TODO: set correct directory mode and properties
+                }                       
+
+                *p='/';
+        }
+        
+        free(file_path);
+        return 0;
+}
+
+static void whitelist_path(const char *path) {
+        assert(path);
+        
+        // fname needs to start with /home/username
+        if (strncmp(path, cfg.homedir, strlen(cfg.homedir))) {
+                fprintf(stderr, "Error: file %s is not in user home directory, exiting...\n", path);
+                exit(1);
+        }
+
+        const char *fname = path + strlen(cfg.homedir);
+        if (*fname == '\0') {
+                fprintf(stderr, "Error: file %s is not in user home directory, exiting...\n", path);
+                exit(1);
+        }
+        
+        char *wfile;
+        if (asprintf(&wfile, "%s/%s", WHITELIST_HOME_DIR, fname) == -1)
+                errExit("asprintf");
+
+        // check if the file exists
+        struct stat s;
+        if (stat(wfile, &s) == 0) {
+                if (arg_debug)
+                        printf("Whitelisting %s\n", path);
+        }
+        else {
+                if (arg_debug) {
+                        fprintf(stderr, "Warning: %s is an invalid file, skipping...\n", path);
+                }
+                return;
+        }
+        
+        // create the path if necessary
+        mkpath(path, 0755);
+
+        // process directory
+        if (S_ISDIR(s.st_mode)) {       
+                // create directory
+                int rv = mkdir(path, 0755);
+                if (rv == -1)
+                        errExit("mkdir");
+                
+        }
+        
+        // process regular file
+        else {
+                // create an empty file
+                FILE *fp = fopen(path, "w");
+                if (!fp) {
+                        fprintf(stderr, "Error: cannot create empty file in home directory\n");
+                        exit(1);
+                }
+                fclose(fp);
+        }
+        
+        // set file properties
+        if (chown(path, s.st_uid, s.st_gid) < 0)
+                errExit("chown");
+        if (chmod(path, s.st_mode) < 0)
+                errExit("chmod");
+
+        // mount
+        if (mount(wfile, path, NULL, MS_BIND|MS_REC, NULL) < 0)
+                errExit("mount bind");
+
+        free(wfile);
+}
+
+
+// whitelist for /home/user directory
+void fs_whitelist(void) {
+        char *homedir = cfg.homedir;
+        assert(homedir);
+        ProfileEntry *entry = cfg.profile;
+        if (!entry)
+                return;
+        
+        // realpath function will fail with ENOENT if the file is not found
+        // we need to expand the path before installing a new, empty home directory
+        while (entry) {
+                // handle only whitelist commands
+                if (strncmp(entry->data, "whitelist ", 10)) {
+                        entry = entry->next;
+                        continue;
+                }
+
+                char *new_name = expand_home(entry->data + 10, cfg.homedir);
+                assert(new_name);
+                char *fname = realpath(new_name, NULL);
+                free(new_name);
+                if (fname) {
+                        // change file name in entry->data
+                        if (strcmp(fname, entry->data + 10) != 0) {
+                                char *newdata;
+                                if (asprintf(&newdata, "whitelist %s", fname) == -1)
+                                        errExit("asprintf");
+                                entry->data = newdata;
+                                if (arg_debug)
+                                        printf("Replaced whitelist path: %s\n", entry->data);
+                        }
+                                                
+                        free(fname);
+                }
+                else {
+                        // file not found, blank the entry in the list
+                        if (arg_debug)
+                                printf("Removed whitelist path: %s\n", entry->data);
+                        *entry->data = '\0';
+                }
+                entry = entry->next;
+        }
+                
+        // create /tmp/firejail/mnt/whome directory
+        fs_build_mnt_dir();
+        int rv = mkdir(WHITELIST_HOME_DIR, S_IRWXU | S_IRWXG | S_IRWXO);
+        if (rv == -1)
+                errExit("mkdir");
+        if (chown(WHITELIST_HOME_DIR, getuid(), getgid()) < 0)
+                errExit("chown");
+        if (chmod(WHITELIST_HOME_DIR, 0755) < 0)
+                errExit("chmod");
+
+        // keep a copy of real home dir in /tmp/firejail/mnt/whome
+        if (mount(cfg.homedir, WHITELIST_HOME_DIR, NULL, MS_BIND|MS_REC, NULL) < 0)
+                errExit("mount bind");
+
+        // start building the new home directory by mounting a tmpfs fielsystem
+         fs_private();
+
+        // go through profile rules again, and interpret whitelist commands
+        entry = cfg.profile;
+        while (entry) {
+                // handle only whitelist commands
+                if (strncmp(entry->data, "whitelist ", 10)) {
+                        entry = entry->next;
+                        continue;
+                }
+
+                whitelist_path(entry->data + 10);
+
+                entry = entry->next;
+        }
+
+        // mask the real home directory, currently mounted on /tmp/firejail/mnt/whome
+        if (mount("tmpfs", WHITELIST_HOME_DIR, "tmpfs", MS_NOSUID | MS_STRICTATIME | MS_REC,  "mode=755,gid=0") < 0)
+                errExit("mount tmpfs");
+}