Merge remote-tracking branch 'tor-gitlab/mr/205'

src/lib/fs/conffile.c

@@ -19,9 +19,11 @@
 #include "lib/fs/path.h"
 #include "lib/log/log.h"
 #include "lib/malloc/malloc.h"
+#include "lib/sandbox/sandbox.h"
 #include "lib/string/printf.h"
 
 #include <stdbool.h>
+#include <errno.h>
 
 static smartlist_t *config_get_file_list(const char *path,
                                          smartlist_t *opened_files);
@@ -52,21 +54,26 @@ config_get_lines_include(const char *string, config_line_t **result,
                               opened_lst, 1, NULL, config_process_include);
 }
 
-/** Returns a list of paths obtained when expading globs in <b>pattern</b>. If
- * <b>pattern</b> has no globs, returns a list with <b>pattern</b> if it is an
- * existing path or NULL otherwise. If <b>opened_files</b> is provided, adds
- * paths opened by glob to it. Returns NULL on failure. */
+/** Return a list of paths obtained when expading globs in <b>pattern</b>.
+ * If <b>pattern</b> has no globs, return a list with <b>pattern</b> in it.
+ * If <b>opened_files</b> is provided, add paths opened by glob to it.
+ * Return NULL on failure. */
 static smartlist_t *
 expand_glob(const char *pattern, smartlist_t *opened_files)
 {
-  smartlist_t *matches = tor_glob(pattern);
-  if (!matches) {
-    return NULL;
+  if (! has_glob(pattern)) {
+    smartlist_t *matches = smartlist_new();
+    smartlist_add_strdup(matches, pattern);
+    return matches;
   }
 
-  // if it is not a glob, return error when the path is missing
-  if (!has_glob(pattern) && smartlist_len(matches) == 0) {
-    smartlist_free(matches);
+  smartlist_t *matches = tor_glob(pattern);
+  if (!matches) {
+    if (errno == EPERM) {
+      log_err(LD_CONFIG, "Sandbox is active, but the configuration pattern "
+              "\"%s\" listed with %%include would access files or folders not "
+              "allowed by it. Cannot proceed.", pattern);
+    }
     return NULL;
   }
 
@@ -107,6 +114,13 @@ config_get_file_list(const char *pattern, smartlist_t *opened_files)
     if (opened_files) {
       smartlist_add_strdup(opened_files, path);
     }
+    if (sandbox_interned_string_is_missing(path)) {
+      log_err(LD_CONFIG, "Sandbox is active, but a new configuration "
+              "file \"%s\" has been listed with %%include. Cannot proceed.",
+              path);
+      error_found = true;
+      break;
+    }
 
     file_status_t file_type = file_status(path);
     if (file_type == FN_FILE) {
@@ -201,6 +215,13 @@ config_process_include(const char *pattern, int recursion_level, int extended,
 
   int rv = -1;
   SMARTLIST_FOREACH_BEGIN(config_files, const char *, config_file) {
+    if (sandbox_interned_string_is_missing(config_file)) {
+      log_err(LD_CONFIG, "Sandbox is active, but a new configuration "
+              "file \"%s\" has been listed with %%include. Cannot proceed.",
+              config_file);
+      goto done;
+    }
+
     log_notice(LD_CONFIG, "Including configuration file \"%s\".", config_file);
     config_line_t *included_config = NULL;
     config_line_t *included_config_last = NULL;

src/lib/fs/path.c

@@ -537,6 +537,10 @@ unglob_win32(const char *pattern, int prev_sep, int next_sep)
 static DIR *
 prot_opendir(const char *name)
 {
+  if (sandbox_interned_string_is_missing(name)) {
+    errno = EPERM;
+    return NULL;
+  }
   return opendir(sandbox_intern_string(name));
 }
 
@@ -544,6 +548,10 @@ prot_opendir(const char *name)
 static int
 prot_stat(const char *pathname, struct stat *buf)
 {
+  if (sandbox_interned_string_is_missing(pathname)) {
+    errno = EPERM;
+    return -1;
+  }
   return stat(sandbox_intern_string(pathname), buf);
 }
 
@@ -551,6 +559,10 @@ prot_stat(const char *pathname, struct stat *buf)
 static int
 prot_lstat(const char *pathname, struct stat *buf)
 {
+  if (sandbox_interned_string_is_missing(pathname)) {
+    errno = EPERM;
+    return -1;
+  }
   return lstat(sandbox_intern_string(pathname), buf);
 }
 /** As closedir, but has the right type for gl_closedir */
@@ -563,7 +575,8 @@ wrap_closedir(void *arg)
 
 /** Return a new list containing the paths that match the pattern
  * <b>pattern</b>. Return NULL on error. On POSIX systems, errno is set by the
- * glob function.
+ * glob function or is set to EPERM if glob tried to access a file not allowed
+ * by the seccomp sandbox.
  */
 struct smartlist_t *
 tor_glob(const char *pattern)

src/lib/sandbox/sandbox.c

@@ -310,6 +310,8 @@ static int filter_nopar_gen[] = {
 #define seccomp_rule_add_4(ctx,act,call,f1,f2,f3,f4)      \
   seccomp_rule_add((ctx),(act),(call),4,(f1),(f2),(f3),(f4))
 
+static const char *sandbox_get_interned_string(const char *str);
+
 /**
  * Function responsible for setting up the rt_sigaction syscall for
  * the seccomp filter sandbox.
@@ -1224,8 +1226,41 @@ static sandbox_filter_func_t filter_func[] = {
     sb_kill
 };
 
+/**
+ * Return the interned (and hopefully sandbox-permitted) string equal
+ * to @a str.
+ *
+ * Return NULL if `str` is NULL, or `str` is not an interned string.
+ **/
 const char *
 sandbox_intern_string(const char *str)
+{
+  const char *interned = sandbox_get_interned_string(str);
+
+  if (sandbox_active && str != NULL && interned == NULL) {
+    log_warn(LD_BUG, "No interned sandbox parameter found for %s", str);
+  }
+
+  return interned ? interned : str;
+}
+
+/**
+ * Return true if the sandbox is running and we are missing an interned string
+ * equal to @a str.
+ */
+bool
+sandbox_interned_string_is_missing(const char *str)
+{
+  return sandbox_active && sandbox_get_interned_string(str) == NULL;
+}
+
+/**
+ * Try to find and return the interned string equal to @a str.
+ *
+ * If there is no such string, return NULL.
+ **/
+static const char *
+sandbox_get_interned_string(const char *str)
 {
   sandbox_cfg_t *elem;
 
@@ -1245,9 +1280,7 @@ sandbox_intern_string(const char *str)
     }
   }
 
-  if (sandbox_active)
-    log_warn(LD_BUG, "No interned sandbox parameter found for %s", str);
-  return str;
+  return NULL;
 }
 
 /* DOCDOC */

src/lib/sandbox/sandbox.h

@@ -104,12 +104,11 @@ typedef struct {
 #endif /* defined(USE_LIBSECCOMP) */
 
 #ifdef USE_LIBSECCOMP
-/** Returns a registered protected string used with the sandbox, given that
- * it matches the parameter.
- */
 const char* sandbox_intern_string(const char *param);
+bool sandbox_interned_string_is_missing(const char *s);
 #else /* !defined(USE_LIBSECCOMP) */
 #define sandbox_intern_string(s) (s)
+#define sandbox_interned_string_is_missing(s) (false)
 #endif /* defined(USE_LIBSECCOMP) */
 
 /** Creates an empty sandbox configuration file.*/