src/temp_permissions_table.c

@@ -38,7 +38,7 @@ unsigned long long get_process_creation_time(pid_t pid) {
   unsigned long long creation_time = 0;
 
   // Construct the path to the process's status file
-  snprintf(path, sizeof(path), "/proc/%d/stat", pid);
+  snprintf(path, sizeof(path), "/proc/%u/stat", pid);
 
   // Open the status file
   fp = fopen(path, "r");
@@ -49,8 +49,8 @@ unsigned long long get_process_creation_time(pid_t pid) {
 
   // Read the creation time (the 22nd field in the stat file)
   for (int i = 1; i < 22; i++) {
-    if (fscanf(fp, "%*s") != 1) {
+    if (fscanf(fp, "%*s") == EOF) {
-      fprintf(stderr, "Error reading process stat file\n");
+      fprintf(stderr, "Error reading process stat file on the number %d\n", i);
       fclose(fp);
       return 0;
     }
@@ -96,17 +96,17 @@ void destroy_temp_permissions_table() {
  * Checks if the process has a temporary access to the file.
  *
  * @param filename: The file that the process is trying to access
- * @pram pi: The process information
+ * @pram pid: PID of the process
  * @return: 0 if access is denied, 1 if access is allowed
  */
-int check_temp_access(const char *filename, struct process_info pi) {
+
+int check_temp_access_noparent(const char *filename, pid_t pid) {
   // TODO: more efficient locking
   pthread_mutex_lock(&temp_permissions_table_lock);
   struct temp_process_permissions *permission_entry =
-      get(&temp_permissions_table, pi.PID);
+      get(&temp_permissions_table, pid);
   if (permission_entry != NULL) {
-    unsigned long long process_creation_time =
+    unsigned long long process_creation_time = get_process_creation_time(pid);
-        get_process_creation_time(pi.PID);
     if (process_creation_time == 0) {
       perror("Could not retrieve process creation time");
       pthread_mutex_unlock(&temp_permissions_table_lock);
@@ -128,6 +128,59 @@ int check_temp_access(const char *filename, struct process_info pi) {
   return 0;
 }
 
+/**
+ * Finds the parent process ID of a given process.
+ *
+ * @param pid: The process ID of the process to find the parent of
+ * @return: The parent process ID, or 0 if the parent process ID could not be
+ * found
+ */
+pid_t get_parent_pid(pid_t pid) {
+  pid_t ppid = 0;
+  char path[256];
+  snprintf(path, sizeof(path), "/proc/%u/status", pid);
+
+  FILE *file = fopen(path, "r");
+  if (file == NULL) {
+    perror("Failed to open /proc/<pid>/status");
+    return 0;
+  }
+
+  char line[256];
+  while (fgets(line, sizeof(line), file)) {
+    if (sscanf(line, "PPid:\t%d", &ppid) == 1) {
+      fclose(file);
+      return ppid;
+    }
+  }
+
+  fclose(file);
+  return 0; // Parent PID not found
+}
+
+/**
+ * Checks if the process or any of it's parents have temporary access to the
+ * file.
+ *
+ * @param filename: The file that the process is trying to access
+ * @pram pi: The process information
+ * @return: 0 if access is denied, 1 if access is allowed
+ * @note: In case one of the parent processes is killed while this function
+ * execution the result is not guranteed to be correct. It should only lead to
+ * false negatives, though.
+ */
+int check_temp_access(const char *filename, struct process_info pi) {
+  pid_t current_pid = pi.PID;
+  while (current_pid != 0) {
+    if (check_temp_access_noparent(filename, current_pid)) {
+      return 1;
+    }
+    current_pid = get_parent_pid(current_pid);
+  }
+
+  return 0;
+}
+
 /**
  * Gives temporary access to the process to the file.
  *
@@ -172,6 +225,7 @@ int give_temp_access(const char *filename, struct process_info pi) {
   push(&new_permission_entry.allowed_files, strdup(filename));
 
   insert(&temp_permissions_table, pi.PID, new_permission_entry);
+  printf("temp_permissions_table size: %ld\n", size(&temp_permissions_table));
 
   pthread_mutex_unlock(&temp_permissions_table_lock);
   return 0;