add exerimental deny flag in the tables

For now, perm table does not set the thrid parameter to anything useful

src/perm_permissions_table.c

@@ -7,6 +7,7 @@
 */
 
 #include "perm_permissions_table.h"
+#include "access_t.h"
 #include "process_info.h"
 #include <fcntl.h>
 #include <pthread.h>
@@ -23,9 +24,9 @@
 sqlite3 *perm_database = NULL;
 const char *const table_name = "permissions";
 // one row corresponds to a permission to access one file for one executable
-const int column_count = 2;
+const int column_count = 3;
-const char *const schema[] = {"executable", "filename"};
+const char *const schema[] = {"executable", "filename", "mode"};
-const char *const types[] = {"TEXT", "TEXT"};
+const char *const types[] = {"TEXT", "TEXT", "INTEGER"};
 uid_t ruid, euid, current_pid;
 pthread_mutex_t uid_switch = PTHREAD_MUTEX_INITIALIZER;
 
@@ -69,9 +70,10 @@ static int check_table_col_schema(void *notused, int argc, char **argv,
   }
   int column_num = atoi(argv[0]);
   if (column_num >= column_count) {
-    fprintf(stderr, "Table contains more columns than expected.\n");
+    fprintf(stderr, "Table contains unexpected amount of columns.\n");
     return 1;
   }
+
   if (strcmp(schema[column_num], argv[1]) == 0 &&
       strcmp(types[column_num], argv[2]) == 0) {
     return 0;
@@ -90,8 +92,9 @@ static int set_flag(void *flag, int argc, char **argv, char **colname) {
 
 int create_database_schema() {
   fprintf(stderr, "Creating table 'permissions'.\n");
-  const char *create_query = "CREATE TABLE permissions(executable TEXT NOT "
+  const char *create_query =
-                             "NULL, filename TEXT NOT NULL);";
+      "CREATE TABLE permissions(executable TEXT NOT "
+      "NULL, filename TEXT NOT NULL, mode INTEGER NOT NULL);";
   char *err = NULL;
   int ret = sqlite3_exec(perm_database, create_query, NULL, NULL, &err);
 
@@ -186,37 +189,41 @@ void destroy_perm_permissions_table() { sqlite3_close(perm_database); }
  *
  * @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
+ * @return: access status - ALLOW, DENY or NDEF in case if no information was
+ * found
  */
-int check_perm_access(const char *filename, struct process_info pi) {
+access_t check_perm_access(const char *filename, struct process_info pi) {
-  size_t query_len =
+
-      56 + strlen(table_name) + strlen(filename) + strlen(pi.name);
+  char *query = NULL;
-  const char *query = malloc(query_len);
+  int ret = asprintf(&query,
-  size_t should_be_written = snprintf(
+                     "SELECT * FROM %s WHERE executable = \'%s\' "
-      query, query_len,
+                     "AND filename = \'%s\' AND mode = TRUE;",
-      "SELECT * FROM %s WHERE executable = \'%s\' AND filename = \'%s\';",
+                     table_name, pi.name, filename);
-      table_name, pi.name, filename);
+
-  // -1 for the \0
+  if (ret < 0) {
-  if (should_be_written != query_len - 1) {
+    // If asprintf fails, the contents of query are undefined (see man
-    fprintf(stderr,
+    // asprintf). That does not explicitly rule out that query will be a valid
-            "Unexpected query size while permanent access rule check: "
+    // pointer. But the risk of freeing a non-allocated pointer is too much to
-            "Expected %lu, but snprintf returned %lu. The query: %s\n",
+    // justify preparing for this.
-            query_len, should_be_written, query);
+    fprintf(stderr, "Could not create query on access check");
-    return 0;
+    perror("");
+    return NDEF;
   }
 
   char *sqlite_error = NULL;
   int flag = 0;
-  int ret = sqlite3_exec(perm_database, query, set_flag, &flag, &sqlite_error);
+  ret = sqlite3_exec(perm_database, query, set_flag, &flag, &sqlite_error);
+  free((void *)query);
   if (ret != SQLITE_OK) {
     fprintf(stderr, "SQLite returned an error: %s\n", sqlite_error);
     sqlite3_free(sqlite_error);
-    free(query);
+    return NDEF;
-    return 0;
   }
 
-  free(query);
+  if (flag) {
-  return flag;
+    return ALLOW;
+  }
+  return NDEF;
 }
 
 /**
@@ -227,23 +234,23 @@ int check_perm_access(const char *filename, struct process_info pi) {
  * @return: 0 on success, 1 on failure
  */
 int give_perm_access(const char *filename, struct process_info pi) {
-  size_t query_len =
+  char *query = NULL;
-      30 + strlen(table_name) + strlen(filename) + strlen(pi.name);
+  int ret = asprintf(&query, "INSERT INTO %s VALUES (\'%s\', \'%s\', TRUE);",
-  const char *query = malloc(query_len);
+                     table_name, pi.name, filename);
-  size_t should_be_written =
+
-      snprintf(query, query_len, "INSERT INTO %s VALUES (\'%s\', \'%s\');",
+  if (ret < 0) {
-               table_name, pi.name, filename);
+    // If asprintf fails, the contents of query are undefined (see man
-  // -1 for the \0
+    // asprintf). That does not explicitly rule out that query will be a valid
-  if (should_be_written != query_len - 1) {
+    // pointer. But the risk of freeing a non-allocated pointer is too much to
-    fprintf(stderr,
+    // justify preparing for this.
-            "Unexpected query size while permanent access rule insertion: "
+    fprintf(stderr, "Could not create query on rule insertion");
-            "Expected %lu, but snprintf returned %lu\n",
+    perror("");
-            query_len, should_be_written);
     return 1;
   }
 
   char *sqlite_error = NULL;
-  int ret = sqlite3_exec(perm_database, query, NULL, NULL, &sqlite_error);
+  ret = sqlite3_exec(perm_database, query, NULL, NULL, &sqlite_error);
+  free(query);
   if (ret != SQLITE_OK) {
     fprintf(stderr, "SQLite returned an error: %s\n", sqlite_error);
     sqlite3_free(sqlite_error);
@@ -251,6 +258,5 @@ int give_perm_access(const char *filename, struct process_info pi) {
     return 1;
   }
 
-  free(query);
   return 0;
 }

src/perm_permissions_table.h

@@ -9,6 +9,7 @@
 #ifndef PERM_PERMISSION_TABLE_H
 #define PERM_PERMISSION_TABLE_H
 
+#include "access_t.h"
 #include "process_info.h"
 
 /**
@@ -29,9 +30,10 @@ void destroy_perm_permissions_table();
  *
  * @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
+ * @return: access status - ALLOW, DENY or NDEF in case if no information was
+ * found
  */
-int check_perm_access(const char *filename, struct process_info pi);
+access_t check_perm_access(const char *filename, struct process_info pi);
 
 /**
  * Gives permanent access to the process to the file.

src/temp_permissions_table.c

@@ -7,6 +7,7 @@
 */
 
 #include "temp_permissions_table.h"
+#include "access_t.h"
 #include "cc.h"
 #include "process_info.h"
 #include <pthread.h>
@@ -18,6 +19,7 @@ struct temp_process_permissions {
   // proc_pid_stat(5))
   unsigned long long creation_time;
   vec(char *) allowed_files;
+  vec(char *) denied_files;
 };
 
 map(pid_t, struct temp_process_permissions) temp_permissions_table;
@@ -33,8 +35,8 @@ pthread_mutex_t temp_permissions_table_lock;
  * never really equal to 0, it exceptionally unlikely.
  */
 unsigned long long get_process_creation_time(pid_t pid) {
-  char path[32];
+  char path[256];
-  FILE *fp;
+  FILE *fp = NULL;
   unsigned long long creation_time = 0;
 
   // Construct the path to the process's status file
@@ -72,7 +74,7 @@ unsigned long long get_process_creation_time(pid_t pid) {
  *
  * @return: 0 on success, -1 on failure (e.g. ENOMEM)
  */
-int init_temp_permissions_table() {
+int init_temp_permissions_table(void) {
   pthread_mutex_init(&temp_permissions_table_lock, PTHREAD_MUTEX_DEFAULT);
   init(&temp_permissions_table);
   return 0;
@@ -81,14 +83,21 @@ int init_temp_permissions_table() {
 /**
  * Destroys the temporary permissions table.
  *
- * @note: the table is guranteed to be destroyed if it is already initialized
+ * @note: the table is guranteed to be destroyed if it is already initialized.
+ * It does not indicate any errors whatsoever. If something goes wrong - you are
+ * screwed.
  */
-void destroy_temp_permissions_table() {
+void destroy_temp_permissions_table(void) {
   // 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);
   }
+  for_each(&temp_permissions_table, entry) {
+    for_each(&entry->denied_files, denied_file) { free(*denied_file); }
+    cleanup(&entry->denied_files);
+  }
+
   cleanup(&temp_permissions_table);
   pthread_mutex_destroy(&temp_permissions_table_lock);
 }
@@ -98,10 +107,10 @@ void destroy_temp_permissions_table() {
  *
  * @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
+ * @return: access status - ALLOW, DENY or NDEF in case if no information was
+ * found is avaliable
  */
-
+access_t check_temp_access_noparent(const char *filename, pid_t pid) {
-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 =
@@ -111,22 +120,28 @@ int check_temp_access_noparent(const char *filename, pid_t pid) {
     if (process_creation_time == 0) {
       perror("Could not retrieve process creation time");
       pthread_mutex_unlock(&temp_permissions_table_lock);
-      return 0;
+      return NDEF;
     }
 
     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->denied_files, denied_file) {
+        if (strncmp(*denied_file, filename, strlen(filename)) == 0) {
+          pthread_mutex_unlock(&temp_permissions_table_lock);
+          return DENY;
+        }
+      }
       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;
+          return ALLOW;
         }
       }
     }
   }
   pthread_mutex_unlock(&temp_permissions_table_lock);
-  return 0;
+  return NDEF;
 }
 
 /**
@@ -165,31 +180,36 @@ pid_t get_parent_pid(pid_t pid) {
  *
  * @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
+ * @return: access status - ALLOW, DENY or NDEF in case if no information was
+ * found. Does not return ALLOW_TEMP.
  * @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) {
+access_t 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)) {
+    access_t access = check_temp_access_noparent(filename, current_pid);
-      return 1;
+    if (access != NDEF) {
+      return access;
     }
     current_pid = get_parent_pid(current_pid);
   }
 
-  return 0;
+  return NDEF;
 }
 
 /**
- * Gives temporary access to the process to the file.
+ * Sets temporary access mode of 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)
+ * @param mode: Kind of access rule to be set - SET_DENY to deny access, and
+ * SET_ALLOW to allow access.
+ * @return: 0 on success, -1 on failure.
  */
-int give_temp_access(const char *filename, struct process_info pi) {
+int set_temp_access(const char *filename, struct process_info pi,
+                    set_mode_t mode) {
   pthread_mutex_lock(&temp_permissions_table_lock);
   struct temp_process_permissions *permission_entry =
       get(&temp_permissions_table, pi.PID);
@@ -207,7 +227,13 @@ int give_temp_access(const char *filename, struct process_info pi) {
     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));
+      if (mode == SET_ALLOW) {
+        push(&permission_entry->allowed_files, strdup(filename));
+      }
+      if (mode == SET_DENY) {
+        push(&permission_entry->denied_files, strdup(filename));
+      }
+
       pthread_mutex_unlock(&temp_permissions_table_lock);
       return 0;
     }
@@ -223,7 +249,13 @@ int give_temp_access(const char *filename, struct process_info pi) {
 
   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));
+  init(&new_permission_entry.denied_files);
+  if (mode == SET_ALLOW) {
+    push(&new_permission_entry.allowed_files, strdup(filename));
+  }
+  if (mode == SET_DENY) {
+    push(&new_permission_entry.denied_files, strdup(filename));
+  }
 
   insert(&temp_permissions_table, pi.PID, new_permission_entry);
 

src/temp_permissions_table.h

@@ -2,6 +2,7 @@
 #ifndef TEMP_PERMISSIONS_TABLE_H
 #define TEMP_PERMISSIONS_TABLE_H
 
+#include "access_t.h"
 #include "process_info.h"
 
 /**
@@ -9,31 +10,43 @@
  *
  * @return: 0 on success, -1 on failure (e.g. ENOMEM)
  */
-int init_temp_permissions_table();
+int init_temp_permissions_table(void);
 
 /**
  * Destroys the temporary permissions table.
  *
- * @note: the table is guranteed to be destroyed if it is already initialized
+ * @note: the table is guranteed to be destroyed if it is already initialized.
+ * It does not indicate any errors whatsoever. If something goes wrong - you are
+ * screwed.
  */
-void destroy_temp_permissions_table();
+void destroy_temp_permissions_table(void);
 
 /**
- * Checks if the process has a temporary access to the file.
+ * 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: access status - ALLOW, DENY or NDEF in case if no information was
+ * found. Does not return ALLOW_TEMP.
+ * @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.
+ */
+access_t check_temp_access(const char *filename, struct process_info pi);
+
+typedef enum { SET_DENY, SET_ALLOW } set_mode_t;
+
+/**
+ * Sets temporary access mode of the process 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
+ * @param mode: Kind of access rule to be set - SET_DENY to deny access, and
+ * SET_ALLOW to allow access.
+ * @return: 0 on success, -1 on failure.
  */
-int check_temp_access(const char *filename, struct process_info pi);
+int set_temp_access(const char *filename, struct process_info pi,
-
+                    set_mode_t mode);
-/**
- * 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

@@ -6,6 +6,7 @@
   See the file LICENSE.
 */
 
+#include "access_t.h"
 #include <stddef.h>
 #include <sys/types.h>
 #include <time.h>
@@ -58,10 +59,10 @@ void destroy_ui_socket(void) {
  *
  * @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, 2 if access is
+ * @return: access status - ALLOW, DENY or ALLOW_TEMP
  * allowed for the runtime of the process
  */
-int ask_access(const char *filename, struct process_info proc_info) {
+access_t ask_access(const char *filename, struct process_info proc_info) {
   FILE *fp = NULL;
   size_t command_len =
       139 + sizeof(pid_t) * 8 + strlen(proc_info.name) + strlen(filename);
@@ -78,7 +79,7 @@ int ask_access(const char *filename, struct process_info proc_info) {
 
   if (fp == NULL) {
     perror("Pipe returned a error");
-    return -1;
+    return DENY;
   }
 
   // if the user clicks the "Allow this time" button, `zenity` will only
@@ -89,7 +90,7 @@ int ask_access(const char *filename, struct process_info proc_info) {
     printf("%s", buffer);
     if (strcmp(buffer, ZENITY_TEMP_ALLOW_MESSAGE) == 0) {
       pclose(fp);
-      return 2;
+      return ALLOW_TEMP;
     }
   }
 
@@ -97,10 +98,10 @@ int ask_access(const char *filename, struct process_info proc_info) {
   fprintf(stderr, "zenity returned %d\n", zenity_exit_code);
   // zenity returns 1 on "No" >:(
   if (zenity_exit_code == 0) {
-    return 1;
+    return ALLOW;
   }
 
-  return 0;
+  return DENY;
 }
 
 /**
@@ -117,11 +118,21 @@ int ask_access(const char *filename, struct process_info proc_info) {
 int interactive_access(const char *filename, struct process_info proc_info,
                        int opts) {
 
-  if (check_temp_access(filename, proc_info) ||
+  access_t access = check_temp_access(filename, proc_info);
-      check_perm_access(filename, proc_info)) {
+  if (access == ALLOW) {
-    // access was already granted before
     return 1;
   }
+  if (access == DENY) {
+    return 0;
+  }
+
+  access = check_perm_access(filename, proc_info);
+  if (access == ALLOW) {
+    return 1;
+  }
+  if (access == DENY) {
+    return 0;
+  }
 
   // if noth GRANT_TEMP and GRANT_PERM are selected, then only permanent
   // permissions are granted
@@ -131,23 +142,26 @@ int interactive_access(const char *filename, struct process_info proc_info,
     return 1;
   }
   if (opts & GRANT_TEMP) {
-    give_temp_access(filename, proc_info);
+    set_temp_access(filename, proc_info, SET_ALLOW);
     return 1;
   }
 
-  int user_response = ask_access(filename, proc_info);
+  access_t user_response = ask_access(filename, proc_info);
-  if (user_response == 1) {
+  if (user_response == ALLOW) {
-    // user said "yes"
     give_perm_access(filename, proc_info);
     return 1;
   }
 
-  if (user_response == 2) {
+  if (user_response == ALLOW_TEMP) {
-    // user said "yes, but only this time"
+    set_temp_access(filename, proc_info, SET_ALLOW);
-    give_temp_access(filename, proc_info);
     return 1;
   }
 
-  // otherwise "no"
+  if (user_response == DENY) {
+    set_temp_access(filename, proc_info, SET_DENY);
+    return 0;
+  }
+
+  // deny on unknown options.
   return 0;
 }