mdw@git.distorted.org.uk Git - checkpath/blob - chkpath.1

   1 .\" -*-nroff-*-
   2 .TH chkpath 1 "6 April 1999" "Local tools"
   3 .SH NAME
   4 chkpath \- check a path string for security
   5 .SH SYNOPSIS
   6 .B chkpath
   7 .RB [ \-vqstp ]
   8 .RB [ \-g
   9 .IR group ]
  10 .RI [ path ...]
  11 .SH USAGE
  12 The
  13 .B chkpath
  14 command checks one or more path strings (i.e., lists of directories
  15 separated by colons) for security.  If no path strings are given, the
  16 value of the
  17 .B PATH
  18 environment variable is examined.
  19 .PP
  20 Each directory in turn is broken into its constituent parts and every
  21 step which must be made through the filesystem to reach that directory
  22 from the root is scrutinized for vulnerabilities.  The checks made
  23 against each directory and symbolic link along the way are as follows:
  24 .IP "   1."
  25 No step should be a directory which is world-writable unless its sticky
  26 bit is set, and it's not the final step.
  27 .IP "   2."
  28 No step should be a directory which is group-writable unless its sticky
  29 bit is set, and it's not the final step.  (However, see the
  30 .B \-t
  31 option below.)
  32 .IP "   3."
  33 No step should be a directory owned by another user (other than root).
  34 .IP "   4."
  35 No step should be a symbolic link inside a sticky directory and owned by
  36 another user.
  37 .PP
  38 The author is not aware of any weaknesses in this ruleset.  The
  39 objective is that nobody other than the user and the superuser should be
  40 able to add or change the set of files available within the directories
  41 of the path(s).
  42 .SS Options
  43 The following command line options are available:
  44 .TP
  45 .B "\-h, \-\-help"
  46 Displays a relatively verbose message describing how to use
  47 .BR chkpath .
  48 .TP
  49 .B "\-V, \-\-version"
  50 Displays
  51 .BR chkpath 's
  52 version number.
  53 .TP
  54 .B "\-u, \-\-usage"
  55 Displays a very terse usage summary.
  56 .TP
  57 .B "\-v, \-\-verbose"
  58 Makes
  59 .B chkpath
  60 more verbose about what it's doing.  This option has a cumulative
  61 effect, so put more in for more verbosity.  Note that verbose doesn't
  62 mean the same as interesting.  The default is to report problems with
  63 directories and system errors.
  64 .TP
  65 .B "\-g, \-\-group " group
  66 Consider members of
  67 .I group
  68 to be trustworthy:
  69 .B chkpath
  70 won't warn about a directory being group-writable if its gid matches
  71 .IR group .
  72 The
  73 .I group
  74 may be a group name (looked up in
  75 .BR /etc/group )
  76 or a numeric gid in decimal.
  77 .TP
  78 .B "\-q, \-\-quiet"
  79 Makes
  80 .B chkpath
  81 less verbose about what it's doing.  This option, like
  82 .BR \-v ,
  83 has a cumulative effect.  Each
  84 .B \-q
  85 cancels out a
  86 .B \-v
  87 option.
  88 .TP
  89 .B "\-s, \-\-sticky"
  90 Modifies the ruleset slightly so that any step through the filesystem is
  91 OK, even if world- or group-writable (but not owned by someone else), as
  92 long as the directory's sticky bit is set.  The default is that sticky
  93 directories are considered safe only if they're not the final step.
  94 Turning this option on isn't recommended: if you use a sticky directory
  95 in your path then other people can add malicious commands whose names
  96 are common typos of standard ones.
  97 .TP
  98 .B "\-t, \-\-trust\-group"
  99 Modifies the ruleset slightly so that
 100 .B chkpath
 101 doesn't warn about directories group-owned by groups you're a member
 102 of.  In other words, it trusts your fellow group-members
 103 .IR "in their capacity as group-owners only" :
 104 .B chkpath
 105 will still warn about directories owned by people in your groups.
 106 .TP
 107 .B "\-p, \-\-print"
 108 Writes on standard output a colon-separated list of the directories
 109 which
 110 .B chkpath
 111 considered `safe'.  This can be used to filter out unsafe directories in
 112 an automatic way:
 113 .RS 10
 114 .nf
 115 .ft B
 116 .sp 1
 117 PATH=`chkpath -qqp`
 118 .ft R
 119 .fi
 120 .RE
 121 .SH BUGS
 122 None known.
 123 .SH SEE ALSO
 124 .BR tmpdir (1),
 125 .BR checkpath (3).
 126 .SH AUTHOR
 127 Mark Wooding (mdw@nsict.org).