src/xdev.c

   1
   2 #include <stdlib.h>
   3 #include <stdio.h>
   4 #include <dlfcn.h>
   5 #include <unistd.h>
   6 #include <err.h>
   7 #include <errno.h>
   8 #include <string.h>
   9 #include <dirent.h>
  10 #include <sys/stat.h>
  11 #include <ftw.h>
  12
  13 #define TRUE 1
  14 #define FALSE 0
  15 #define MBUF_LENGTH 1024
  16
  17 int xdev_allow(const char *pathname)
  18 {
  19         char realpathname[PATH_MAX];
  20         FILE* proc_mounts = NULL;
  21         char mbuf[MBUF_LENGTH+1];
  22         char* space;
  23         char* mntdev;
  24         char* mntpnt;
  25         char* mntype;
  26         char* mntopt;
  27
  28         warnx("xdev? %s", pathname);
  29
  30         proc_mounts = fopen("/proc/mounts", "r");
  31         if(proc_mounts == NULL)
  32         {
  33                 err(1, "/proc/mounts: open");
  34         }
  35
  36         if(realpath(pathname, realpathname) != NULL)
  37         {
  38                 while(fgets(mbuf, MBUF_LENGTH, proc_mounts) != NULL)
  39                 {
  40                         mntdev = mbuf;
  41                         space = strchr(mbuf, ' ');
  42                         if(space != NULL)
  43                         {
  44                                 *space = 0;
  45                                 mntpnt = space + 1;
  46                                 space = strchr(mntpnt, ' ');
  47                                 if(space != NULL)
  48                                 {
  49                                         *space = 0;
  50                                         mntype = space + 1;
  51                                         space = strchr(mntype, ' ');
  52                                         if(space != NULL)
  53                                         {
  54                                                 *space = 0;
  55                                                 mntopt = space + 1;
  56                                                 space = strchr(mntopt, ' ');
  57                                                 if(space != NULL)
  58                                                 {
  59                                                         *space = 0;
  60                                                         if(strncmp(realpathname, mntpnt, strlen(mntpnt)) == 0)
  61                                                         {
  62                                                                 /* It's a mountpoint, or under a mountpoint */
  63
  64                                                                 /* Deny if it is likely a network device */
  65                                                                 if(strncmp(mntdev, "//", 2) == 0 || strchr(mntdev, ':') != NULL)
  66                                                                         goto deny;
  67
  68                                                                 //TODO XDEV_FSTYPE
  69                                                                 //TODO XDEV_OPTION
  70                                                         }
  71                                                 }
  72                                         }
  73                                 }
  74                         }
  75                 }
  76         }
  77         goto allow;
  78
  79         deny:
  80         fclose(proc_mounts);
  81         errno = ECONNREFUSED;
  82         return FALSE;
  83
  84         allow:
  85         fclose(proc_mounts);
  86         return TRUE;
  87 }
  88
  89
  90 int __lxstat64(int ver, const char *path, struct stat64 *buf)
  91 {
  92         int (*real___lxstat64)(int, const char *, struct stat64 *) = dlsym(RTLD_NEXT, "__lxstat64");
  93         if(xdev_allow(path)) return real___lxstat64(ver, path, buf);
  94         return -1;
  95 }
  96
  97 int __openat_2(int fd, const char *path, int oflag, mode_t mode)
  98 {
  99         int (*real___openat_2)(int, const char*, int, mode_t) = dlsym(RTLD_NEXT, "__openat_2");
 100         if(xdev_allow(path)) return real___openat_2(fd, path, oflag, mode);
 101         return -1;
 102 }
 103
 104 DIR* opendir(const char *pathname)
 105 {
 106         DIR* (*real_opendir)(const char *) = dlsym(RTLD_NEXT, "opendir");
 107         if(xdev_allow(pathname)) return real_opendir(pathname);
 108         return NULL;
 109 }
 110
 111 int xdev_ftw_cb(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf
 112 //  ,int (*real_cb)(const char*, const struct stat*, int, struct FTW*)
 113 )
 114 {
 115 //      if(xdev_allow(fpath)) return real_cb(fpath, sb, typeflag, ftwbuf);
 116 //      return FTW_STOP;
 117         return 0;
 118 }
 119
 120 int nftw64(const char *dirpath,
 121 //  int (*fgv)(const char*, const struct stat*, int, struct FTW*),
 122   __nftw64_func_t fgv,
 123   int nopenfd, int flags)
 124 {
 125         int (*real_nftw64)(const char *, int (*)(const char*, const struct stat*, int, struct FTW*), int, int) = dlsym(RTLD_NEXT, "nftw64");
 126         return real_nftw64(dirpath, xdev_ftw_cb, nopenfd, flags);
 127 }