Re: RFC: changing the "+" in ls -l output to be "." or "+"

[Jim Meyering]

Jim Meyering <address@hidden> wrote:
> I wrote this:
>> [ I'm Cc'ing address@hidden
>>   FYI, this is a continuation of discussion from the SELinux list:
>>   http://marc.info/?t=120645074000003&r=1&w=2
>>   and the debian bug tracking system: http://bugs.debian.org/472590
>>
>>   The problem is that on an SELinux-enabled system, 'ls -l's "+",
>>   the "alternate access method" indicator, is useless, because it
>>   appears on every file:
>>
>>       $ ls -glo /var
>>       total 164
>>       drwxr-xr-x+  3 4096 2008-03-29 08:43 kerberos
>>       drwxr-xr-x+ 39 4096 2008-03-29 08:43 lib
>>       drwxr-xr-x+  2 4096 2008-03-27 17:33 local
>>       drwxrwxr-x+  8 4096 2008-03-31 04:15 lock
>>       drwxr-xr-x+ 20 4096 2008-03-31 09:55 log
>>       lrwxrwxrwx+  1   10 2008-03-28 23:33 mail -> spool/mail
>>       ...
>>
>>   Newer POSIX allows any non-space character as the indicator, and
>>   that's what we're discussing now.
>>   ]
>>
>> Russell Coker <address@hidden> wrote:
>>> On Wednesday 26 March 2008 04:31, Michael Stone <address@hidden> wrote:
>>>> if (acl) then '+'
>>>> else if (selinux) then '.'
>>>
>>> Should there be some special marking of files with both a SE Linux context 
>>> and
>>> an ACL?
>>>
>>> Pity that they didn't choose an "a" to mark an ACL which would then permit
>>> using "A" for ACL + MAC.
>>
>> This is probably as good a time as any to make such a change, though
>> I doubt it will make the cut for the upcoming release.  I'd like to keep
>> it simple (i.e., not try to encode all possible combinations).  If you
>> want to get full details, stat(1) is probably the program to change.
>>
>> I like Michael's suggestion.  Rephrasing it,
>>
>>     if (SELinux, with no other MAC or ACL)
>>       use '.'
>>     else if (any other combination of alternate access methods)
>>       use '+'
>>
>> If someone who already has a copyright assignment on file for coreutils
>> wants to write the patch (including doc update, tests, NEWS, ChangeLog,
>> etc.), please speak up ASAP.  Otherwise I'll do it.
>
> No one spoke up, so here's code, for discussion's sake.
> I've tested it only lightly.
> This change is not slated for the upcoming release.
>
> Here's sample output, running on an SELinux system:
>
>   $ src/ls -ldgo [ac]*
>   -rw-r--r--.  1   42625 2008-04-02 19:31 aclocal.m4
>   drwxr-xr-x.  2    4096 2008-04-02 19:31 autom4te.cache
>   -rw-r--r--.  1    1597 2008-03-21 16:35 cfg.mk
>   -rw-r--r--.  1 1417195 2008-04-02 19:33 config.log
>   -rwxr-xr-x.  1   71225 2008-04-02 19:33 config.status
>   -rwxr-xr-x.  1 1846424 2008-04-02 19:31 configure
>   -rw-r--r--.  1   12014 2008-03-25 23:55 configure.ac

Thanks to a nudge from Ondřej, I've just completed and pushed this:

>From b3677e5e383103bf1764b2c8a9329b1c17934b24 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Wed, 2 Apr 2008 22:26:45 +0200
Subject: [PATCH] ls: use '.' (not +) as SELinux-only alt. access flag in ls -l 
output

* src/ls.c (gobble_file) [long_format]: Map SELinux-only to '.',
any other nonempty combination of MAC and ACL to '+', and all else
to the usual ' '.  Suggested by Michael Stone.
* tests/misc/selinux: Adapt: expect '.', not '+'.
* doc/coreutils.texi (What information is listed): Document this.
* NEWS (Changes in behavior): Mention it.
---
 NEWS               |    6 ++++++
 doc/coreutils.texi |    8 +++++---
 src/ls.c           |   25 +++++++++++++++++++------
 tests/misc/selinux |    4 ++--
 4 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/NEWS b/NEWS
index ab7d5bd..357efc2 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,12 @@ GNU coreutils NEWS                                    -*- 
outline -*-

   stat -f recognizes the Lustre file system type

+** Changes in behavior
+
+  ls -l now marks SELinux-only files with the less obtrusive '.',
+  rather than '+'.  A file with any other combination of MAC and ACL
+  is still marked with a '+'.
+

 * Noteworthy changes in release 7.0 (2008-10-05) [beta]

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 6459870..cbef013 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -6474,9 +6474,11 @@ What information is listed
 space, there is no alternate access method.  When it is a printing
 character, then there is such a method.

-For a file with an extended access control list, a @samp{+} character is
-listed.  Basic access control lists are equivalent to the permissions
-listed, and are not considered an alternate access method.
+GNU @command{ls} uses a @samp{.} character to indicate a file
+with an SELinux security context, but no other alternate access method.
+
+A file with any other combination of alternate access methods
+is marked with a @samp{+} character.

 @item -n
 @itemx --numeric-uid-gid
diff --git a/src/ls.c b/src/ls.c
index e38a5fe..590af7f 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -154,6 +154,12 @@ verify (sizeof filetype_letter - 1 == arg_directory + 1);
     C_LINK, C_SOCK, C_FILE, C_DIR                      \
   }

+enum acl_type
+  {
+    ACL_T_NONE,
+    ACL_T_SELINUX_ONLY,
+    ACL_T_YES
+  };

 struct fileinfo
   {
@@ -182,7 +188,7 @@ struct fileinfo

     /* For long listings, true if the file has an access control list,
        or an SELinux security context.  */
-    bool have_acl;
+    enum acl_type acl_type;
   };

 #define LEN_STR_PAIR(s) sizeof (s) - 1, s
@@ -2689,6 +2695,7 @@ gobble_file (char const *name, enum filetype type, ino_t 
inode,

       if (format == long_format || print_scontext)
        {
+         bool have_selinux = false;
          bool have_acl = false;
          int attr_len = (do_deref
                          ?  getfilecon (absolute_name, &f->scontext)
@@ -2707,7 +2714,7 @@ gobble_file (char const *name, enum filetype type, ino_t 
inode,
            }

          if (err == 0)
-           have_acl = ! STREQ ("unlabeled", f->scontext);
+           have_selinux = ! STREQ ("unlabeled", f->scontext);
          else
            {
              f->scontext = UNKNOWN_SECURITY_CONTEXT;
@@ -2720,15 +2727,19 @@ gobble_file (char const *name, enum filetype type, 
ino_t inode,
                err = 0;
            }

-         if (err == 0 && ! have_acl && format == long_format)
+         if (err == 0 && format == long_format)
            {
              int n = file_has_acl (absolute_name, &f->stat);
              err = (n < 0);
              have_acl = (0 < n);
            }

-         f->have_acl = have_acl;
-         any_has_acl |= have_acl;
+         f->acl_type = (!have_selinux && !have_acl
+                        ? ACL_T_NONE
+                        : (have_selinux && !have_acl
+                           ? ACL_T_SELINUX_ONLY
+                           : ACL_T_YES));
+         any_has_acl |= f->acl_type != ACL_T_NONE;

          if (err)
            error (0, errno, "%s", quotearg_colon (absolute_name));
@@ -3449,7 +3460,9 @@ print_long_format (const struct fileinfo *f)
     }
   if (! any_has_acl)
     modebuf[10] = '\0';
-  else if (f->have_acl)
+  else if (f->acl_type == ACL_T_SELINUX_ONLY)
+    modebuf[10] = '.';
+  else if (f->acl_type == ACL_T_YES)
     modebuf[10] = '+';

   switch (time_type)
diff --git a/tests/misc/selinux b/tests/misc/selinux
index a231fa7..8211c80 100755
--- a/tests/misc/selinux
+++ b/tests/misc/selinux
@@ -34,8 +34,8 @@ for i in d f p; do
   c=`stat --printf %C $i`; test x$c = x$ctx || fail=1
 done

-# ensure that ls -l output includes the "+".
-c=`ls -l f|cut -c11`; test "$c" = + || fail=1
+# ensure that ls -l output includes the ".".
+c=`ls -l f|cut -c11`; test "$c" = . || fail=1

 # Copy each to a new directory and ensure that context is preserved.
 cp -r --preserve=all d f p s1 || fail=1
--
1.6.0.3