Re: FHS compliance and UNIX sockets

[Tollef Fog Heen <tollef@add.no>]

* Brian May 

| >>>>> "Tollef" == Tollef Fog Heen <tollef@add.no> writes:
| 
|     Tollef> Putting a tmp directory into /etc/skel and setting TMPDIR
|     Tollef> and TMP to $HOME/tmp might be a start?
| 
|     Tollef> The next step would probably be to search the sources for
|     Tollef> /tmp and replace it with $HOME/tmp wherever possible.
| 
| There is no system in place to automatically delete files on
| $HOME/tmp, nor can you use a faster file system in its place (eg local
| hard-disk where /home is NFS mounted, or something like tmpfs which I
| saw discussed recently on the linux-kernel mailing list).

I don't think my temporary files should be deleted automagically,
since I do store files in ~/tmp myself, which I'd like to remove
myself as well.  Having some tmp reaper do it for me is the wrong
thing.  Others may have different opinions, of course.

| /tmp/user/$USER
| 
| where /tmp/user is owned by root, and a very simply setuid root program
| does (translated to more appropriate language):
| 
| 1. mkdir /tmp/user/$UID
| 2. chown $UID /tmp/user/$UID

You need to chmod as well.  I don't think this small program deserves
a .deb all by itself, so if it could go into wherever applicable
(base-files?) and /etc/profile (and other initialization scripts could
be modified to set $TMP and $TMPDIR to /tmp/user/`id -u`.
Additionally, 

C:

/*
 * mkusertmpdir.c
 * Copyright Tollef Fog Heen, 2001.
 * This program is under GPL, please see http://www.gnu.org/copyleft/gpl.html
 */

#include <unistd.h>
#include <stdio.h>
#include <errno.h>

#include <sys/stat.h>
#include <sys/types.h>

#define SYSUSRTMP "/tmp/user"

int main(int argc, char** argv) {
  int ret;
  char buf[512];
  struct stat statbuf;
  mode_t old_umask;

  ret = lstat(SYSUSRTMP,&statbuf);
  if (ret == -1 && errno != ENOENT) {
    perror("lstat'ing SYSUSRTMP");
    exit(1);
  } else if (ret != -1 && statbuf.st_uid != geteuid()) {
    /* Somebody else than root has grabbed /tmp/user.  Bad, bad, bad. */
    fprintf(stderr,"%s is owned by somebody else than root. " 
	    "Can't create safe tmpdirs\n", SYSUSRTMP);
    exit(2);
  } else if (errno == ENOENT) {
    old_umask = umask(0000);
    if (mkdir(SYSUSRTMP,0711) == -1) {
      perror("mkdir'ing SYSUSRTMP");
      exit(1);
    }
    umask(old_umask);
  }
  if (chown(SYSUSRTMP,0,0) == -1) {
    perror("chown'ing SYSUSRTMP");
    exit(1);
  }

  if (snprintf(buf, 511, "%s/%d",SYSUSRTMP,getuid()) == -1) {
    perror("snprintf");
    exit(1);
  }
  ret = lstat(buf,&statbuf);
  if (ret == -1 && errno != ENOENT) {
    perror("lstat");
    exit(1);
  } else if (ret != -1 && statbuf.st_uid != getuid()) {
    fprintf(stderr,"tmp directory %s owned by someone else than self!\n", buf);
    exit(1);
  } else if (errno == ENOENT) {
    if (mkdir(buf,0700) == -1) {
      perror("mkdir");
      exit(1);
    }
    if (chown(buf,getuid(),getgid()) == -1) {
      perror("chown");
      exit(1);
    }
  }
    exit(0);
}

-- 

Tollef Fog Heen
Unix _IS_ user friendly... It's just selective about who its friends are.