Source Code 1992 March/Source_Code_CD-ROM_Walnut_Creek_March_1992.iso/usenet/compsrcs/unix/volume25/indirpch.4

Text File | 1991-12-13 | 8.4 KB | 305 lines

Subject: v25i031: indir patch - from 2.3 to 2.4
Newsgroups: comp.sources.unix
Approved: [e-mail]

Submitted-By: Maarten Litmaath <[e-mail]>
Posting-Number: Volume 25, Issue 31
Archive-Name: indir.pch2.4

Included is a second minor patch to indir (from version 2.3 to 2.4).
Version 2.3 did not support multiple groups (see getgroups(2)).
The new version has this corrected.  Thanks to John M. Sellens
<[e-mail]> (and Andy at the same site) for
pointing it out.  He also mentioned that the Makefile and the test
script assumed the installer had `.' in his PATH.  This has been
fixed too.  Finally there are a few cosmetic changes to a few files.

To apply the patches below, in the directory containing the sources
of indir 2.3 unpack the shell archive and type:

    patch < indir2.4diffs

Then check the file `README' and the Makefile.  Type `make' to create
the new version of indir in the current directory.

Enjoy.
                Maarten Litmaath @ VU Amsterdam:
                [e-mail], uunet!cs.vu.nl!maart

: This is a shar archive.  Extract with sh, not csh.
: This archive ends with exit, so do not worry about trailing junk.
: --------------------------- cut here --------------------------
PATH=/bin:/usr/bin:/usr/ucb
echo Extracting 'indir2.4diffs'
sed 's/^X//' > 'indir2.4diffs' << '+ END-OF-FILE ''indir2.4diffs'
X*** old/Makefile    Sat Feb  2 07:19:48 1991
X--- Makefile    Sat Feb  2 07:23:38 1991
X***************
X*** 5,11 ****
X  # a few defines for testing purposes; if you test in the current
X  # directory the paths needn't be absolute
X  # the path of indir will be used in #! lines -> max. 32 characters for
X! # #! + name + mandatory option
X  PATH_OF_INDIR    = ./indir
X  TEST_DIRECTORY    = .
X
X--- 5,11 ----
X  # a few defines for testing purposes; if you test in the current
X  # directory the paths needn't be absolute
X  # the path of indir will be used in #! lines -> max. 32 characters for
X! # #! + name + space (or tab) + mandatory option
X  PATH_OF_INDIR    = ./indir
X  TEST_DIRECTORY    = .
X
X***************
X*** 21,32 ****
X          $(CC) -O -o indir $(OBJS)
X
X  exec_ok:
X!         exec_test
X
X  test:        exec_ok
X          test -f tests_made || PATH_OF_INDIR=$(PATH_OF_INDIR) \
X!             TEST_DIRECTORY=$(TEST_DIRECTORY) make_tests
X!         do_tests
X
X  lint:
X          lint $(SRCS)
X--- 21,32 ----
X          $(CC) -O -o indir $(OBJS)
X
X  exec_ok:
X!         ./exec_test
X
X  test:        exec_ok
X          test -f tests_made || PATH_OF_INDIR=$(PATH_OF_INDIR) \
X!             TEST_DIRECTORY=$(TEST_DIRECTORY) ./make_tests
X!         ./do_tests
X
X  lint:
X          lint $(SRCS)
X*** old/do_tests    Sat Feb  2 07:18:58 1991
X--- do_tests    Sat Feb  2 07:23:38 1991
X***************
X*** 1,15 ****
X  #!/bin/sh
X  for i in wrong.* ok.*
X  do
X!     echo '' >&2
X!     echo "$ ls -l $i" >&2
X!     ls -l $i >&2
X!     echo "$ cat $i" >&2
X!     cat $i >&2
X!     echo $
X!     echo -n "-- hit return to run $i: " >&2
X      read x
X!     $i file_argument
X!     echo -n "-- hit return to continue: " >&2
X      read x
X  done
X--- 1,18 ----
X  #!/bin/sh
X+
X  for i in wrong.* ok.*
X  do
X!     echo ''
X!     echo "$ ls -l $i"
X!     ls -l $i
X!     echo "$ cat $i"
X!     cat $i
X!     echo "$ "
X!     echo -n "-- hit return to run $i: "
X      read x
X!     ./$i file_argument
X!     echo -n "-- hit return to continue: "
X      read x
X  done
X+
X+ exit 0
X*** old/indir.c    Sat Feb  2 07:19:48 1991
X--- indir.c    Sat Feb  2 07:23:38 1991
X***************
X*** 1,4 ****
X! static    char    sccsid[] = "@(#)indir.c 2.3 90/03/31 Maarten Litmaath";
X
X  /*
X   * indir.c
X--- 1,5 ----
X! static    char    sccsid[] =
X!     "@(#)indir.c 2.4 91/02/02 Maarten Litmaath @ CS, VU, Amsterdam";
X
X  /*
X   * indir.c
X***************
X*** 145,150 ****
X--- 146,152 ----
X          execvp(Interpreter, Newargv);
X
X      error(E_exec, Prog, Interpreter, File, geterr());
X+     /* NOTREACHED */
X  }
X
X
X***************
X*** 270,276 ****
X  char    *f;
X  {
X      struct    stat    stbuf;
X!     int    xmask, pid;
X      uid_t    uid;
X      gid_t    gid;
X      static    int    status = -1, checked = 0;
X--- 272,278 ----
X  char    *f;
X  {
X      struct    stat    stbuf;
X!     int    xmask, pid, groups_member();
X      uid_t    uid;
X      gid_t    gid;
X      static    int    status = -1, checked = 0;
X***************
X*** 301,308 ****
X      gid = Gid_check ? getgid() : getegid();
X
X      xmask = (Uid == 0) ? (X_USR | X_GRP | X_OTH) :
X!         st->st_uid == uid ? X_USR :
X!         st->st_gid == gid ? X_GRP :
X          X_OTH;
X      /*
X       * Can the invoker really execute the file we're reading from?
X--- 303,311 ----
X      gid = Gid_check ? getgid() : getegid();
X
X      xmask = (Uid == 0) ? (X_USR | X_GRP | X_OTH) :
X!         (st->st_uid == uid) ? X_USR :
X!         (st->st_gid == gid) ? X_GRP :
X!         groups_member(st->st_gid) ? X_GRP :
X          X_OTH;
X      /*
X       * Can the invoker really execute the file we're reading from?
X***************
X*** 330,335 ****
X--- 333,355 ----
X      while (wait(&w) != pid)
X          ;
X      return ok(w) ? status = 0 : -1;
X+ }
X+
X+
X+ static    int    groups_member(gid)
X+ int    gid;
X+ {
X+     register
X+     int    *p, ngroups;
X+     int    groups[NGROUPS];
X+
X+     if ((ngroups = getgroups(NGROUPS, groups)) < 0)
X+         return 0;
X+     p = groups;
X+         while (--ngroups >= 0)
X+         if (*p++ == gid)
X+             return 1;
X+     return 0;
X  }
X
X
X*** old/setuid.txt    Sat Feb  2 07:19:49 1991
X--- setuid.txt    Sat Feb  2 07:23:38 1991
X***************
X*** 1,6 ****
X--- 1,7 ----
X              Setuid Shell Scripts
X              --------------------
X              how to get them safe
X+                  version 1.1
X
X                Maarten Litmaath
X                ([e-mail])
X***************
X*** 42,54 ****
X  Yes, one needs write permission somewhere on the same device, if one's
X  operating system doesn't support symbolic links.
X
X! What about the csh command interpreter? Well, 4.2BSD provides us with a csh
X! which has a NEW option: "-b"! Its goal is to avoid just the thing described
X! above: the mnemonic for `b' is `break'; this option prevents following
X! arguments of an exec of /bin/csh from being interpreted as options...
X! The csh refuses to run a setuid shell script unless the option is present...
X  Scheme:
X!     #!/bin/csh -b
X      ...
X
X      execl("-i", "unimportant", (char *) 0);
X--- 43,54 ----
X  Yes, one needs write permission somewhere on the same device, if one's
X  operating system doesn't support symbolic links.
X
X! What about the bare `-' option present in modern versions of the Bourne
X! shell?  Its goal is to avoid just the thing described above: this option
X! prevents following arguments of an exec of /bin/sh from being interpreted
X! as options...
X  Scheme:
X!     #!/bin/sh -
X      ...
X
X      execl("-i", "unimportant", (char *) 0);
X***************
X*** 58,64 ****
X
X      setuid(0);
X      setgid(0);
X!     execl("/bin/csh", "csh", "-b", "-i", (char *) 0);
X
X  And indeed the contents of the file "-i" are executed!
X  However, there's still another bug hidden, albeit not for long!
X--- 58,64 ----
X
X      setuid(0);
X      setgid(0);
X!     execl("/bin/sh", "sh", "-", "-i", (char *) 0);
X
X  And indeed the contents of the file "-i" are executed!
X  However, there's still another bug hidden, albeit not for long!
X***************
X*** 82,95 ****
X      currently the total length of shell + argument mustn't exceed 32 chars
X      (easily fixed);
X  2)
X!     4.[23]BSD csh is expecting a `-b' flag as the first argument, instead
X!     of the full path (easily fixed);
X  3)
X      the interpreter gets an extra argument;
X  4)
X      the difficulty of maintaining setuid shell scripts increases - if one
X      moves a script, one shouldn't forget to edit it... - editing in turn
X!     could turn off the setuid bits, so one shouldn't forget to chmod(1)
X      the file `back'... - conceptually the solution above isn't `elegant'.
X
X  How does indir(1) tackle the problems? The script to be executed will look
X--- 82,95 ----
X      currently the total length of shell + argument mustn't exceed 32 chars
X      (easily fixed);
X  2)
X!     when executing a setuid script, 4.[23]BSD csh is expecting a `-b' flag
X!     as the first argument, instead of the full path (easily fixed);
X  3)
X      the interpreter gets an extra argument;
X  4)
X      the difficulty of maintaining setuid shell scripts increases - if one
X      moves a script, one shouldn't forget to edit it... - editing in turn
X!     could turn off the setuid bit, so one shouldn't forget to chmod(1)
X      the file `back'... - conceptually the solution above isn't `elegant'.
X
X  How does indir(1) tackle the problems? The script to be executed will look
+ END-OF-FILE indir2.4diffs
chmod 'u=rw,g=r,o=r' 'indir2.4diffs'
set `wc -c 'indir2.4diffs'`
count=$1
case $count in
6805)    :;;
*)    echo 'Bad character count in ''indir2.4diffs' >&2
        echo 'Count should be 6805' >&2
esac
exit 0