Merge pull request 'Temp_permission_table' (#5) from Temp_permission_table into main

Reviewed-on: #5

Makefile

@@ -56,7 +56,7 @@ default: $(TARGETS)
 
 .PHONY: clean
 
-icfs: $(BUILD_DIR)/main.o $(BUILD_DIR)/fuse_operations.o $(BUILD_DIR)/sourcefs.o $(BUILD_DIR)/ui-socket.o
+icfs: $(BUILD_DIR)/main.o $(BUILD_DIR)/fuse_operations.o $(BUILD_DIR)/sourcefs.o $(BUILD_DIR)/ui-socket.o $(BUILD_DIR)/temp_permissions_table.o
 	$(CC) $(CFLAGS) $^ $(LDFLAGS) -o $(BUILD_DIR)/icfs
 
 icfs_test: $(BUILD_DIR)/main.o $(BUILD_DIR)/fuse_operations.o $(BUILD_DIR)/sourcefs.o $(BUILD_DIR)/ui-socket.o
@@ -78,5 +78,8 @@ $(BUILD_DIR)/sourcefs.o: $(SOURCES_DIR)/sourcefs.c $(SOURCES_DIR)/sourcefs.h
 $(BUILD_DIR)/ui-socket.o: $(SOURCES_DIR)/ui-socket.c $(SOURCES_DIR)/ui-socket.h
 	$(CC) $(CFLAGS) -c $< $(LDFLAGS) -o $@
 
+$(BUILD_DIR)/temp_permissions_table.o: $(SOURCES_DIR)/temp_permissions_table.c $(SOURCES_DIR)/temp_permissions_table.h
+	$(CC) $(CFLAGS) -c $< $(LDFLAGS) -o $@
+
 clean:
 	rm $(BUILD_DIR)/*.o $(BUILD_DIR)/icfs*

src/main.c

@@ -36,7 +36,7 @@ int main(int argc, char *argv[]) {
     exit(EXIT_FAILURE);
   }
 
-  ret = init_ui_socket("/home/fedir/.icfs-sock");
+  ret = init_ui_socket();
   if (ret != 0) {
     perror("init_ui_socket");
     exit(EXIT_FAILURE);
@@ -45,5 +45,6 @@ int main(int argc, char *argv[]) {
   ret = fuse_main(argc, argv, get_fuse_operations(), NULL);
 
   free(mountpoint);
+  destroy_ui_socket();
   return ret;
 }

src/process_info.h

@@ -0,0 +1,12 @@
+
+#ifndef PROCESS_INFO_H
+#define PROCESS_INFO_H
+
+#include <sys/types.h>
+struct process_info {
+  pid_t PID;
+  const char *name;
+  uid_t UID;
+};
+
+#endif // PROCESS_INFO_H

src/temp_permissions_table.c

@@ -0,0 +1,232 @@
+/*
+  ICFS: Interactively Controlled File System
+  Copyright (C) 2024-2025  Fedir Kovalov
+
+  This program can be distributed under the terms of the GNU GPLv2.
+  See the file LICENSE.
+*/
+
+#include "temp_permissions_table.h"
+#include "cc.h"
+#include "process_info.h"
+#include <pthread.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+struct temp_process_permissions {
+  // yes, this is a correct type for start time in jiffies (see
+  // proc_pid_stat(5))
+  unsigned long long creation_time;
+  vec(char *) allowed_files;
+};
+
+map(pid_t, struct temp_process_permissions) temp_permissions_table;
+pthread_mutex_t temp_permissions_table_lock;
+
+/**
+ * Function to get the process creation time (in jiffies) from the proc
+ * filesystem
+ *
+ * @param pid: The process ID of the process to get the creation time of
+ * @return: The process creation time in jiffies, or 0 on error
+ * @note: although nothing in the documentation says that the creation time is
+ * never really equal to 0, it exceptionally unlikely.
+ */
+unsigned long long get_process_creation_time(pid_t pid) {
+  char path[32];
+  FILE *fp;
+  unsigned long long creation_time = 0;
+
+  // Construct the path to the process's status file
+  snprintf(path, sizeof(path), "/proc/%u/stat", pid);
+
+  // Open the status file
+  fp = fopen(path, "r");
+  if (fp == NULL) {
+    perror("fopen");
+    return 0;
+  }
+
+  // Read the creation time (the 22nd field in the stat file)
+  for (int i = 1; i < 22; i++) {
+    if (fscanf(fp, "%*s") == EOF) {
+      fprintf(stderr, "Error reading process stat file on the number %d\n", i);
+      fclose(fp);
+      return 0;
+    }
+  }
+  if (fscanf(fp, "%llu", &creation_time) != 1) {
+    fprintf(stderr, "Error reading creation time\n");
+    fclose(fp);
+    return 0;
+  }
+
+  // Close the file
+  fclose(fp);
+
+  return creation_time;
+}
+
+/**
+ * Initializes the temporary permissions table.
+ *
+ * @return: 0 on success, -1 on failure (e.g. ENOMEM)
+ */
+int init_temp_permissions_table() {
+  pthread_mutex_init(&temp_permissions_table_lock, PTHREAD_MUTEX_DEFAULT);
+  init(&temp_permissions_table);
+}
+
+/**
+ * Destroys the temporary permissions table.
+ *
+ * @note: the table is guranteed to be destroyed if it is already initialized
+ */
+void destroy_temp_permissions_table() {
+  // free the memory allocated for the table
+  for_each(&temp_permissions_table, entry) {
+    for_each(&entry->allowed_files, allowed_file) { free(*allowed_file); }
+    cleanup(&entry->allowed_files);
+  }
+  cleanup(&temp_permissions_table);
+  pthread_mutex_destroy(&temp_permissions_table_lock);
+}
+
+/**
+ * Checks if the process has a temporary access to the file.
+ *
+ * @param filename: The file that the process is trying to access
+ * @pram pid: PID of the process
+ * @return: 0 if access is denied, 1 if access is allowed
+ */
+
+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, pid);
+  if (permission_entry != NULL) {
+    unsigned long long process_creation_time = get_process_creation_time(pid);
+    if (process_creation_time == 0) {
+      perror("Could not retrieve process creation time");
+      pthread_mutex_unlock(&temp_permissions_table_lock);
+      return 0;
+    }
+
+    if (process_creation_time == permission_entry->creation_time) {
+      // the process is the same as the one that was granted temporary access
+      // to the file
+      for_each(&permission_entry->allowed_files, allowed_file) {
+        if (strncmp(*allowed_file, filename, strlen(filename)) == 0) {
+          pthread_mutex_unlock(&temp_permissions_table_lock);
+          return 1;
+        }
+      }
+    }
+  }
+  pthread_mutex_unlock(&temp_permissions_table_lock);
+  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.
+ *
+ * @param filename: The file that the process is trying to access
+ * @param pi: The process information
+ * @return: 0 on success, -1 on failure (e.g. ENOMEM)
+ */
+int give_temp_access(const char *filename, struct process_info pi) {
+  pthread_mutex_lock(&temp_permissions_table_lock);
+  struct temp_process_permissions *permission_entry =
+      get(&temp_permissions_table, pi.PID);
+
+  if (permission_entry != NULL) {
+
+    unsigned long long process_creation_time =
+        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);
+      return -1;
+    }
+
+    if (process_creation_time == permission_entry->creation_time) {
+      // the process is the same as the one that was granted temporary access
+      // to the file
+      push(&permission_entry->allowed_files, strdup(filename));
+      pthread_mutex_unlock(&temp_permissions_table_lock);
+      return 0;
+    }
+    // we have an entry for the process, but the process is different
+    // delete the entry and create a new one
+    erase(&temp_permissions_table, pi.PID);
+    permission_entry = NULL;
+  }
+
+  // no entry is present
+  // construct the entry
+  struct temp_process_permissions new_permission_entry;
+
+  new_permission_entry.creation_time = get_process_creation_time(pi.PID);
+  init(&new_permission_entry.allowed_files);
+  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;
+}

src/temp_permissions_table.h

@@ -0,0 +1,39 @@
+
+#ifndef TEMP_PERMISSIONS_TABLE_H
+#define TEMP_PERMISSIONS_TABLE_H
+
+#include "process_info.h"
+
+/**
+ * Initializes the temporary permissions table.
+ *
+ * @return: 0 on success, -1 on failure (e.g. ENOMEM)
+ */
+int init_temp_permissions_table();
+
+/**
+ * Destroys the temporary permissions table.
+ *
+ * @note: the table is guranteed to be destroyed if it is already initialized
+ */
+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
+ * @param pi: The process information
+ * @return: 0 if access is denied, 1 if access is allowed
+ */
+int check_temp_access(const char *filename, struct process_info pi);
+
+/**
+ * Gives temporary access to the process to the file.
+ *
+ * @param filename: The file that the process is trying to access
+ * @param pi: The process information
+ * @return: 0 on success, -1 on failure (e.g. ENOMEM)
+ */
+int give_temp_access(const char *filename, struct process_info pi);
+
+#endif // !TEMP_PERMISSIONS_TABLE_H

src/ui-socket.c

@@ -8,7 +8,10 @@
 
 #include <stddef.h>
 #include <sys/types.h>
+#include <time.h>
 #define _GNU_SOURCE
+#include "cc.h"
+#include "temp_permissions_table.h"
 #include "ui-socket.h"
 #include <errno.h>
 #include <pthread.h>
@@ -19,22 +22,26 @@
 #include <sys/un.h>
 #include <unistd.h>
 
-int init_ui_socket(const char *filename) {
+int init_ui_socket() {
   char line[256];
   FILE *fp;
 
+  init_temp_permissions_table();
+
   // Test if Zenity is installed (get version)
   fp = popen("zenity --version", "r");
   if (fp == NULL) {
-    perror("Pipe returned a error");
+    perror("Pipe returned an error");
     return 1;
-  } else {
+  }
+
   while (fgets(line, sizeof(line), fp))
     printf("%s", line);
   pclose(fp);
   return 0;
 }
-}
+
+void destroy_ui_socket() { destroy_temp_permissions_table(); }
 
 /**
  * Asks the user if the process should be allowed to access the file using the
@@ -71,6 +78,7 @@ int ask_access(const char *filename, struct process_info pi) {
   // to manually check the output.
   char buffer[1024];
   while (fgets(buffer, sizeof(buffer), fp)) {
+    printf("%s", buffer);
     if (strcmp(buffer, "Allow this time\n") == 0) {
       pclose(fp);
       return 2;
@@ -86,18 +94,6 @@ int ask_access(const char *filename, struct process_info pi) {
   return 0;
 }
 
-/**
- * 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
- * @return: 0 if access is denied, 1 if access is allowed
- */
-int check_temp_access(const char *filename, struct process_info pi) {
-  perror("Not implemented");
-  return 0;
-}
-
 /**
  * Checks if the process has a permanent access to the file.
  *
@@ -109,12 +105,9 @@ int check_perm_access(const char *filename, struct process_info pi) {
   perror("Not implemented");
   return 0;
 }
-
-void give_temp_access(const char *filename, struct process_info pi) {
-  perror("Not implemented");
-}
-void give_perm_access(const char *filename, struct process_info pi) {
+int give_perm_access(const char *filename, struct process_info pi) {
   perror("Not implemented");
+  return -1;
 }
 
 /**

src/ui-socket.h

@@ -13,17 +13,31 @@
 #ifndef UI_SOCKET_H
 #define UI_SOCKET_H
 
+#include "process_info.h"
 #include <sys/types.h>
 
-struct process_info {
-  pid_t PID;
-  const char *name;
-  uid_t UID;
-};
+/**
+ * Initialize the GUI communication.
+ *
+ * @return: 0 on success, -1 on faliure.
+ */
+int init_ui_socket(void);
 
-// For default socket location, set socket_path = NULL.
-int init_ui_socket(const char *socket_path);
+/**
+ * Close the GUI communication.
+ */
+void destroy_ui_socket(void);
 
+/**
+ * Check access according to:
+ * 1. temporary permission table
+ * 2. permanent permission table
+ * 3. user descision
+ *
+ * @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
+ */
 int interactive_access(const char *filename, struct process_info pi);
 
 #endif // !UI_SOCKET_H