hw/virtio-9p-local.c

   1 /*
   2  * Virtio 9p Posix callback
   3  *
   4  * Copyright IBM, Corp. 2010
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13 #include "virtio.h"
  14 #include "virtio-9p.h"
  15 #include <pwd.h>
  16 #include <grp.h>
  17
  18 static const char *rpath(FsContext *ctx, const char *path)
  19 {
  20     /* FIXME: so wrong... */
  21     static char buffer[4096];
  22     snprintf(buffer, sizeof(buffer), "%s/%s", ctx->fs_root, path);
  23     return buffer;
  24 }
  25
  26 static int local_lstat(FsContext *ctx, const char *path, struct stat *stbuf)
  27 {
  28     return lstat(rpath(ctx, path), stbuf);
  29 }
  30
  31 static int local_setuid(FsContext *ctx, uid_t uid)
  32 {
  33     struct passwd *pw;
  34     gid_t groups[33];
  35     int ngroups;
  36     static uid_t cur_uid = -1;
  37
  38     if (cur_uid == uid) {
  39         return 0;
  40     }
  41
  42     if (setreuid(0, 0)) {
  43         return -1;
  44     }
  45
  46     pw = getpwuid(uid);
  47     if (pw == NULL) {
  48         return -1;
  49     }
  50
  51     ngroups = 33;
  52     if (getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups) == -1) {
  53         return -1;
  54     }
  55
  56     if (setgroups(ngroups, groups)) {
  57         return -1;
  58     }
  59
  60     if (setregid(-1, pw->pw_gid)) {
  61         return -1;
  62     }
  63
  64     if (setreuid(-1, uid)) {
  65         return -1;
  66     }
  67
  68     cur_uid = uid;
  69
  70     return 0;
  71 }
  72
  73 static ssize_t local_readlink(FsContext *ctx, const char *path,
  74                                 char *buf, size_t bufsz)
  75 {
  76     return readlink(rpath(ctx, path), buf, bufsz);
  77 }
  78
  79 static int local_close(FsContext *ctx, int fd)
  80 {
  81     return close(fd);
  82 }
  83
  84 static int local_closedir(FsContext *ctx, DIR *dir)
  85 {
  86     return closedir(dir);
  87 }
  88
  89 FileOperations local_ops = {
  90     .lstat = local_lstat,
  91     .setuid = local_setuid,
  92     .readlink = local_readlink,
  93     .close = local_close,
  94     .closedir = local_closedir,
  95 };