[patch] SELinux support (was Re: [patch] Recent findutils test suite failures)

[Miloslav Trmac]

Hi,
I'm taking over findutils package maintenance for Red Hat from Tim
Waugh, and this remained unresolved so far.  An updated patch is attached.

> Date: Fri, 25 Nov 2005 08:42:56 +0000
> From: James Youngman <address@hidden>
> To: Tim Waugh <address@hidden>
> Cc: address@hidden
> Subject: Re: [patch] Recent findutils test suite failures
> 
> On Thu, Nov 24, 2005 at 11:12:19PM +0000, Tim Waugh wrote:
>>2. add support for SELinux.
>>
>>At the moment, it isn't autoconf-ed up, but it would be great if you
>>wanted to take a look.  SELinux is on by default in Fedora Core.
>>
>>http://cvs.fedora.redhat.com/viewcvs/devel/findutils/findutils-selinux.patch?only_with_tag=HEAD&view=markup
> 
> I'd certainly consider it.   However, I have some comments/questions.
> 
> 1. I notice that SELinux-enablement creates two new tests, "-context"
>    and "--context".  I would eliminate "--context", leaving only
>    "-context".  Find predicates aren't GNU-style long options.  Find
>    is confusing enough with options as well as predicates, and so I
>    definitely don't want to further blur that line.
Fixed.

> 
> 2. I see that if you use "find -context" on an SELinux-enabled version
>    of find on a system where SELinux is not enabled, find will
>    immediately perform a fatal exit with an explanatory message.  I
>    won't say that that is definitely the wrong behaviour, but why did
>    you choose not to have -context simply always return false (and
>    perhaps issue one warning message)?
I was told it is not documented that getfilecon () works when SELinux is
disabled.  It currently seems to work correctly, but that is just an
implementation artefact.

> 3. Security contexts are long multi-part strings.  Matching with glob
>    patterns is a reasonable approach.  Nevertheless, does the use of
>    glob patterns to match them reflect practice on other systems?
I don't know what is used in other systems than SELinux; for SELinux
find(1) is the only application I know about that implements matching by
security context.

> 4. I notice that your patch slips in a definition for FNM_CASEFOLD.
>    That looks wrong to me.  gl_FUNC_FNMATCH_GNU should call
>    AC_GNU_SOURCE to ensure that <fnmatch.h> #defines FNM_CASEFOLD for
>    you.  This should be called by gl_INIT.  Is this (a) not working
>    correctly on some of your build systems, (b) not working on any of
>    your build systems, implying a findutils bug, or (c) there for
>    'historical reasons'?
(c).  I have removed it.

> 5. Findutils should probably default to compiling with SELinux support
>    on systems where <selinux/selinux.h> exists or --with-selinux is
>    specifified to configure, and compile without such support
>    otherwise.   
Added.

> 6. Is there a reason you turn off Automake gnits rules checking in the
>    SELinux patch?
Probably an oversight; autoreconf doesn't know about gnits.

> 7. The configure magic for selinux can be fully generic and
>    self-contained I think: we could just have an selinux.m4 file.
>    That would also make it much easier to reuse it.
There's little magic involved :)  Of course moving it to a separate file
is possible.

> 8. Are the DejaGnu test cases for the SELinux patch in another patch
>    file somewhere else?  Perhaps it's in the same patch file as the
>    update to the Texinfo documentation. :) 
I have added some Texinfo documentation.

The test cases belong to the same directory where -user test cases are
stored :)  A regular user building findutils may not be allowed by the
policy to change file labels, and I think it is likely the contexts of
specific files will change as the policy is developed.

Thanks,
        Mirek

diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/configure.in findutils/configure.in
--- findutils-4.2.27/configure.in       2005-12-06 07:53:12.000000000 +0100
+++ findutils/configure.in      2006-01-30 21:10:04.000000000 +0100
@@ -95,6 +95,16 @@
 AC_CHECK_FUNC(getpwnam, [],
 [AC_CHECK_LIB(sun, getpwnam)])
 
+AC_ARG_WITH([selinux],
+           AS_HELP_STRING([--without-selinux], [disable SELinux support]),
+           [:],
+[AC_CHECK_LIB([selinux], [is_selinux_enabled],
+             [with_selinux=yes], [with_selinux=no])])
+if test x$with_selinux != xno; then
+   AC_DEFINE([WITH_SELINUX], [1], [Define to support SELinux])
+   AC_SUBST([LIBSELINUX], [-lselinux])
+fi
+
 dnl Checks for header files.
 AC_HEADER_STDC
 dnl Assume unistd.h is present - coreutils does too.
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/doc/find.texi findutils/doc/find.texi
--- findutils-4.2.27/doc/find.texi      2005-12-05 08:35:33.000000000 +0100
+++ findutils/doc/find.texi     2006-01-30 21:20:10.000000000 +0100
@@ -1091,6 +1091,14 @@
 
 @end deffn
 
address@hidden Test -context pattern
+True if file's SELinux context matches the pattern @var{pattern}.
+The pattern uses shell glob matching.
+
+This predicate is supported only on @code{find} versions compiled with
+SELinux support and only when SELinux is enabled.
address@hidden deffn
+
 @node Contents
 @section Contents
 
@@ -1610,6 +1618,9 @@
 file is a sparse file (that is, it has ``holes'').
 @item %s
 File's size in bytes.
address@hidden %Z
+File's SELinux context, or empty string if the file has no SELinux context
+or this version of find does not support SELinux.
 @end table
 
 @node Location Directives
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/defs.h findutils/find/defs.h
--- findutils-4.2.27/find/defs.h        2005-09-04 19:59:34.000000000 +0200
+++ findutils/find/defs.h       2006-01-30 21:15:38.000000000 +0100
@@ -131,6 +131,10 @@
 #define MODE_RWX       (S_IXUSR | S_IXGRP | S_IXOTH | MODE_RW)
 #define MODE_ALL       (S_ISUID | S_ISGID | S_ISVTX | MODE_RWX)
 
+#ifdef WITH_SELINUX
+#include <selinux/selinux.h>
+#endif
+
 #if 1
 #include <stdbool.h>
 typedef bool boolean;
@@ -320,6 +324,9 @@
     struct dir_id   fileid;    /* samefile */
     mode_t type;               /* type */
     FILE *stream;              /* ls fls fprint0 */
+#ifdef WITH_SELINUX
+    security_context_t scontext; /* scontext */
+#endif
     struct format_val printf_vec; /* printf fprintf fprint  */
   } args;
 
@@ -479,6 +486,9 @@
 boolean pred_used PARAMS((char *pathname, struct stat *stat_buf, struct 
predicate *pred_ptr));
 boolean pred_user PARAMS((char *pathname, struct stat *stat_buf, struct 
predicate *pred_ptr));
 boolean pred_xtype PARAMS((char *pathname, struct stat *stat_buf, struct 
predicate *pred_ptr));
+#ifdef WITH_SELINUX
+boolean pred_context PARAMS((char *pathname, struct stat *stat_buf, struct 
predicate *pred_ptr));
+#endif
 
 
 
@@ -568,6 +578,10 @@
    * can be changed with the positional option, -regextype.
    */
   int regex_options;
+
+#ifdef WITH_SELINUX
+  int (*x_getfilecon) ();
+#endif
 };
 extern struct options options;
 
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/find.c findutils/find/find.c
--- findutils-4.2.27/find/find.c        2005-11-11 08:41:37.000000000 +0100
+++ findutils/find/find.c       2006-01-30 21:15:21.000000000 +0100
@@ -245,6 +245,93 @@
   return lstat(name, p);
 }
 
+#ifdef WITH_SELINUX
+static int
+fallback_getfilecon(const char *name, security_context_t *p, int prev_rv)
+{
+  /* Our original getfilecon() call failed.  Perhaps we can't follow a
+   * symbolic link.  If that might be the problem, lgetfilecon() the link.
+   * Otherwise, admit defeat.
+   */
+  switch (errno)
+    {
+    case ENOENT:
+    case ENOTDIR:
+#ifdef DEBUG_STAT
+      fprintf(stderr, "fallback_getfilecon(): getfilecon(%s) failed; falling 
back on lgetfilecon()\n", name);
+#endif
+      return lgetfilecon(name, p);
+
+    case EACCES:
+    case EIO:
+    case ELOOP:
+    case ENAMETOOLONG:
+#ifdef EOVERFLOW
+    case EOVERFLOW:        /* EOVERFLOW is not #defined on UNICOS. */
+#endif
+    default:
+      return prev_rv;         
+    }
+}
+
+
+/* optionh_getfilecon() implements the getfilecon operation when the
+ * -H option is in effect.
+ *
+ * If the item to be examined is a command-line argument, we follow
+ * symbolic links.  If the getfilecon() call fails on the command-line
+ * item, we fall back on the properties of the symbolic link.
+ *
+ * If the item to be examined is not a command-line argument, we
+ * examine the link itself.
+ */
+int
+optionh_getfilecon(const char *name, security_context_t *p)
+{
+  if (0 == state.curdepth)
+    {
+      /* This file is from the command line; deference the link (if it
+       * is a link).
+       */
+      int rv = getfilecon(name, p);
+      if (0 == rv)
+       return 0;               /* success */
+      else
+       return fallback_getfilecon(name, p, rv);
+    }
+  else
+    {
+      /* Not a file on the command line; do not derefernce the link.
+       */
+      return lgetfilecon(name, p);
+    }
+}
+
+/* optionl_getfilecon() implements the getfilecon operation when the
+ * -L option is in effect.  That option makes us examine the thing the
+ * symbolic link points to, not the symbolic link itself.
+ */
+int
+optionl_getfilecon(const char *name, security_context_t *p)
+{
+  int rv = getfilecon(name, p);
+  if (0 == rv)
+    return 0;                  /* normal case. */
+  else
+    return fallback_getfilecon(name, p, rv);
+}
+
+/* optionp_getfilecon() implements the stat operation when the -P
+ * option is in effect (this is also the default).  That option makes
+ * us examine the symbolic link itself, not the thing it points to.
+ */
+int
+optionp_getfilecon(const char *name, security_context_t *p)
+{
+  return lgetfilecon(name, p);
+}
+#endif /* WITH_SELINUX */
+
 #ifdef DEBUG_STAT
 static uintmax_t stat_count = 0u;
 
@@ -272,11 +359,17 @@
     {
     case SYMLINK_ALWAYS_DEREF:  /* -L */
       options.xstat = optionl_stat;
+#ifdef WITH_SELINUX
+      options.x_getfilecon = optionl_getfilecon;
+#endif
       options.no_leaf_check = true;
       break;
       
     case SYMLINK_NEVER_DEREF:  /* -P (default) */
       options.xstat = optionp_stat;
+#ifdef WITH_SELINUX
+      options.x_getfilecon = optionp_getfilecon;
+#endif
       /* Can't turn no_leaf_check off because the user might have specified 
        * -noleaf anyway
        */
@@ -284,6 +377,9 @@
       
     case SYMLINK_DEREF_ARGSONLY: /* -H */
       options.xstat = optionh_stat;
+#ifdef WITH_SELINUX
+      options.x_getfilecon = optionh_getfilecon;
+#endif
       options.no_leaf_check = true;
     }
 
@@ -1807,7 +1903,7 @@
 static void
 process_dir (char *pathname, char *name, int pathlen, struct stat *statp, char 
*parent)
 {
-  int subdirs_left;            /* Number of unexamined subdirs in PATHNAME. */
+  int subdirs_left=0;          /* Number of unexamined subdirs in PATHNAME. */
   boolean subdirs_unreliable;  /* if true, cannot use dir link count as subdir 
limif (if false, it may STILL be unreliable) */
   int idx;                     /* Which entry are we on? */
   struct stat stat_buf;
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/find.1 findutils/find/find.1
--- findutils-4.2.27/find/find.1        2005-12-05 18:05:02.000000000 +0100
+++ findutils/find/find.1       2006-01-30 21:46:01.000000000 +0100
@@ -483,6 +483,8 @@
 link to a file of type \fIc\fR; if the \-L option has been given, true
 if \fIc\fR is `l'.  In other words, for symbolic links, \-xtype checks
 the type of the file that \-type does not check.
+.IP "\-context \fIpattern\fR"
+(SELinux only) Security context of the file matches glob \fIpattern\fR.
 
 .SS ACTIONS
 .IP "\-delete\fR"
@@ -785,6 +787,8 @@
 File's type (like in ls \-l), U=unknown type (shouldn't happen)
 .IP %Y
 File's type (like %y), plus follow symlinks: L=loop, N=nonexistent
+.IP %Z
+(SELinux only) file's security context.
 .PP
 A `%' character followed by any other character is discarded (but the
 other character is printed).
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/Makefile.am findutils/find/Makefile.am
--- findutils-4.2.27/find/Makefile.am   2005-07-03 18:07:08.000000000 +0200
+++ findutils/find/Makefile.am  2006-01-30 21:46:39.000000000 +0100
@@ -6,7 +6,7 @@
 find_SOURCES = find.c fstype.c parser.c pred.c tree.c util.c version.c
 EXTRA_DIST = defs.h $(man_MANS)
 INCLUDES = -I../gnulib/lib -I$(top_srcdir)/lib -I$(top_srcdir)/gnulib/lib 
-I../intl -DLOCALEDIR=\"$(localedir)\"
-LDADD = ../lib/libfind.a ../gnulib/lib/libgnulib.a @INTLLIBS@
+LDADD = ../lib/libfind.a ../gnulib/lib/libgnulib.a @INTLLIBS@ @LIBSELINUX@
 man_MANS = find.1
 SUBDIRS = testsuite
 
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/parser.c findutils/find/parser.c
--- findutils-4.2.27/find/parser.c      2005-12-04 03:07:52.000000000 +0100
+++ findutils/find/parser.c     2006-01-30 21:14:46.000000000 +0100
@@ -47,6 +47,10 @@
 /* We need <unistd.h> for isatty(). */
 #include <unistd.h> 
 
+#ifdef WITH_SELINUX
+#include <selinux/selinux.h>
+#endif
+
 #if ENABLE_NLS
 # include <libintl.h>
 # define _(Text) gettext (Text)
@@ -147,6 +151,9 @@
 static boolean parse_warn          PARAMS((const struct parser_table*, char 
*argv[], int *arg_ptr));
 static boolean parse_xtype         PARAMS((const struct parser_table*, char 
*argv[], int *arg_ptr));
 static boolean parse_quit          PARAMS((const struct parser_table*, char 
*argv[], int *arg_ptr));
+#ifdef WITH_SELINUX
+static boolean parse_context       PARAMS((const struct parser_table*, char 
*argv[], int *arg_ptr));
+#endif
 
 
 
@@ -217,6 +224,9 @@
   PARSE_TEST       ("cmin",                  cmin),         /* GNU */
   PARSE_TEST       ("cnewer",                cnewer),       /* GNU */
   PARSE_TEST       ("ctime",                 ctime),
+#ifdef WITH_SELINUX
+  PARSE_TEST       ("context",               context),      /* GNU */
+#endif
   PARSE_POSOPT     ("daystart",              daystart),             /* GNU */
   PARSE_ACTION     ("delete",                delete), /* GNU, Mac OS, FreeBSD 
*/
   PARSE_OPTION     ("d",                     d), /* Mac OS X, FreeBSD, NetBSD, 
OpenBSD, but deprecated  in favour of -depth */
@@ -802,8 +812,12 @@
   puts (_("\
       -nouser -nogroup -path PATTERN -perm [+-]MODE -regex PATTERN\n\
       -wholename PATTERN -size N[bcwkMG] -true -type [bcdpflsD] -uid N\n\
-      -used N -user NAME -xtype [bcdpfls]\n"));
+      -used N -user NAME -xtype [bcdpfls]"));
+#ifdef WITH_SELINUX
   puts (_("\
+      -context CONTEXT\n"));
+#endif
+  puts (_("\n\
 actions: -delete -print0 -printf FORMAT -fprintf FILE FORMAT -print \n\
       -fprint0 FILE -fprint FILE -ls -fls FILE -prune -quit\n\
       -exec COMMAND ; -exec COMMAND {} + -ok COMMAND ;\n\
@@ -1716,6 +1730,10 @@
   printf("LEAF_OPTIMISATION ");
   ++features;
 #endif
+#if defined(WITH_SELINUX)
+  printf("SELINUX ");
+  ++features;
+#endif
   if (0 == features)
     {
       /* For the moment, leave this as English in case someone wants
@@ -1727,6 +1745,32 @@
   exit (0);
 }
 
+#ifdef WITH_SELINUX
+static boolean
+parse_context (const struct parser_table* entry, char **argv, int *arg_ptr)
+{
+  struct predicate *our_pred;
+
+  if ((argv == NULL) || (argv[*arg_ptr] == NULL))
+    return false;
+
+  if (is_selinux_enabled() <= 0)
+    {
+      error (1, 0, _("invalid predicate -context: SELinux is not enabled."));
+      return false;
+    }
+  our_pred = insert_primary (entry);
+  our_pred->need_stat = false;
+#ifdef DEBUG
+  our_pred->p_name = find_pred_name (pred_context);
+#endif /*DEBUG*/
+  our_pred->args.scontext = argv[*arg_ptr];
+
+  (*arg_ptr)++;
+  return true;
+}
+#endif /* WITH_SELINUX */
+
 static boolean
 parse_xdev (const struct parser_table* entry, char **argv, int *arg_ptr)
 {
@@ -1964,7 +2008,7 @@
          if (*scan2 == '.')
            for (scan2++; ISDIGIT (*scan2); scan2++)
              /* Do nothing. */ ;
-         if (strchr ("abcdDfFgGhHiklmMnpPstuUyY", *scan2))
+         if (strchr ("abcdDfFgGhHiklmMnpPstuUyYZ", *scan2))
            {
              segmentp = make_segment (segmentp, format, scan2 - format,
                                       (int) *scan2);
@@ -2046,6 +2090,7 @@
     case 'H':                  /* ARGV element file was found under */
     case 'p':                  /* pathname */
     case 'P':                  /* pathname with ARGV element stripped */
+    case 'Z':                  /* SELinux security context */
       *fmt++ = 's';
       break;
 
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/pred.c findutils/find/pred.c
--- findutils-4.2.27/find/pred.c        2005-11-30 07:17:15.000000000 +0100
+++ findutils/find/pred.c       2006-01-30 21:13:18.000000000 +0100
@@ -38,6 +38,10 @@
 #include "buildcmd.h"
 #include "yesno.h"
 
+#ifdef WITH_SELINUX
+#include <selinux/selinux.h>
+#endif /*WITH_SELINUX*/
+
 #if ENABLE_NLS
 # include <libintl.h>
 # define _(Text) gettext (Text)
@@ -215,6 +219,9 @@
   {pred_used, "used    "},
   {pred_user, "user    "},
   {pred_xtype, "xtype   "},
+#ifdef WITH_SELINUX
+  {pred_context, "context"},
+#endif /*WITH_SELINUX*/
   {0, "none    "}
 };
 
@@ -903,6 +910,27 @@
                     mode_to_filetype(stat_buf->st_mode & S_IFMT));
          }
          break;
+       case 'Z':               /* SELinux security context */
+#ifdef WITH_SELINUX
+         {
+           security_context_t scontext;
+           int rv;
+           rv = (*options.x_getfilecon) (state.rel_pathname, &scontext);
+
+           if (rv < 0)
+             {
+               fprintf (stderr, "getfilecon(%s): %s", pathname,
+                        strerror(errno));
+               fflush (stderr);
+             }
+           else
+             {
+               fprintf (fp, segment->text, scontext);
+               freecon (scontext);
+             }
+         }
+#endif /* WITH_SELINUX */
+         break;
        }
     }
   return true;
@@ -1493,6 +1521,33 @@
    */
   return (pred_type (pathname, &sbuf, pred_ptr));
 }
+  
+
+#ifdef WITH_SELINUX
+
+boolean
+pred_context (char *pathname, struct stat *stat_buf,
+             struct predicate *pred_ptr)
+{
+  int rv;
+  security_context_t scontext;
+
+  rv = (*options.x_getfilecon) (state.rel_pathname, &scontext);
+
+  if (rv < 0)
+    {
+      fprintf (stderr, "getfilecon(%s): %s\n", pathname, strerror(errno));
+      fflush (stderr);
+      return false;
+    }
+
+  rv = (fnmatch (pred_ptr->args.scontext, scontext, 0) == 0);
+  freecon (scontext);
+  return rv;
+}
+
+#endif /*WITH_SELINUX*/
+
 
 /*  1) fork to get a child; parent remembers the child pid
     2) child execs the command requested
diff -ur --exclude '*.o' --exclude '*~' --exclude '*.selinux' 
findutils-4.2.27/find/util.c findutils/find/util.c
--- findutils-4.2.27/find/util.c        2005-07-01 23:45:18.000000000 +0200
+++ findutils/find/util.c       2006-01-27 14:38:43.000000000 +0100
@@ -78,6 +78,9 @@
   last_pred->need_stat = true;
   last_pred->need_type = true;
   last_pred->args.str = NULL;
+#ifdef WITH_SELINUX
+  last_pred->args.scontext = NULL;
+#endif
   last_pred->pred_next = NULL;
   last_pred->pred_left = NULL;
   last_pred->pred_right = NULL;