setnsfpn.cpp

   1 /* Cydia - iPhone UIKit Front-End for Debian APT
   2  * Copyright (C) 2008-2015  Jay Freeman (saurik)
   3 */
   4
   5 /* GNU General Public License, Version 3 {{{ */
   6 /*
   7  * Cydia is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published
   9  * by the Free Software Foundation, either version 3 of the License,
  10  * or (at your option) any later version.
  11  *
  12  * Cydia is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with Cydia.  If not, see <http://www.gnu.org/licenses/>.
  19 **/
  20 /* }}} */
  21
  22 #include <fcntl.h>
  23 #include <dirent.h>
  24 #include <unistd.h>
  25 #include <stdio.h>
  26 #include <errno.h>
  27 #include <string.h>
  28 #include <sys/stat.h>
  29
  30 #define _syscall(expr) ({ typeof(expr) _value; for (;;) { \
  31     _value = (expr); \
  32     if ((long) _value != -1) \
  33         break; \
  34     if (errno != EINTR) { \
  35         perror(#expr); \
  36         return -1; \
  37     } \
  38 } _value; })
  39
  40 extern "C" int __getdirentries64(int, char *, int, long *);
  41
  42 enum Recurse {
  43     RecurseYes,
  44     RecurseNo,
  45     RecurseMaybe,
  46 };
  47
  48 struct File {
  49     int fd_;
  50
  51     File(int fd);
  52     ~File();
  53
  54     operator int() const;
  55 };
  56
  57 File::File(int fd) :
  58     fd_(fd)
  59 {
  60 }
  61
  62 File::~File() {
  63     close(fd_);
  64 }
  65
  66 File::operator int() const {
  67     return fd_;
  68 }
  69
  70 static int setnsfpn(const char *path, size_t before, Recurse recurse) {
  71     File fd(_syscall(open_dprotected_np(path, O_RDONLY | O_SYMLINK, 0, O_DP_GETRAWENCRYPTED)));
  72
  73     if (recurse == RecurseMaybe) {
  74         struct stat stat;
  75         _syscall(fstat(fd, &stat));
  76         switch (stat.st_mode & S_IFMT) {
  77             case S_IFLNK:
  78                 return 0;
  79             default:
  80                 return -1;
  81
  82             case S_IFDIR:
  83                 recurse = RecurseYes;
  84                 break;
  85             case S_IFREG:
  86                 recurse = RecurseNo;
  87                 break;
  88         }
  89     }
  90
  91     int mode(_syscall(fcntl(fd, F_GETPROTECTIONCLASS)));
  92     if (mode == 4)
  93         return 0;
  94
  95     if (recurse == RecurseYes)
  96         for (long address(0);;) {
  97             char buffer[4096];
  98             int size(_syscall(__getdirentries64(fd, buffer, sizeof(buffer), &address)));
  99             if (size == 0)
 100                 break;
 101
 102             const char *next(buffer), *stop(next + size);
 103             while (next != stop) {
 104                 const dirent *dir(reinterpret_cast<const dirent *>(next));
 105                 const char *name(dir->d_name);
 106                 size_t after(strlen(name));
 107
 108                 if (dir->d_ino == 0);
 109                 else if (after == 1 && name[0] == '.');
 110                 else if (after == 2 && name[0] == '.' && name[1] == '.');
 111                 else {
 112                     size_t both(before + 1 + after);
 113                     char sub[both + 1];
 114                     memcpy(sub, path, before);
 115                     sub[before] = '/';
 116                     memcpy(sub + before + 1, name, after);
 117                     sub[both] = '\0';
 118
 119                     switch (dir->d_type) {
 120                         case DT_LNK:
 121                             break;
 122                         default:
 123                             return -1;
 124
 125                         case DT_DIR:
 126                             if (setnsfpn(sub, both, RecurseYes) != 0)
 127                                 return -1;
 128                             break;
 129                         case DT_REG:
 130                             if (setnsfpn(sub, both, RecurseNo) != 0)
 131                                 return -1;
 132                             break;
 133                     }
 134                 }
 135
 136                 next += dir->d_reclen;
 137             }
 138         }
 139
 140     _syscall(fcntl(fd, F_SETPROTECTIONCLASS, 4));
 141     return 0;
 142 }
 143
 144 int main(int argc, const char *argv[]) {
 145     return setnsfpn(argv[1], strlen(argv[1]), RecurseMaybe);
 146 }