selinux: adjust utils to run restorecon with -Z

cp, mv, install, mkdir, mkfifo, mknod are adjusted so that:
 -Z no longer accepts an argument.
 -Z or --context without an argument do not warn without SELinux.
 --context with an argument will warn without SELinux.

* src/local.mk: Reference the new selinux module where required.
* src/system.h: Make the argument to --context optional.
* src/mkdir.c: Likewise.  Also handle the SMACK case for --context.
Note we currently silently ignore -Z with SMACK.
* src/mkfifo.c: Likewise.
* src/mknod.c: Likewise.
* src/install.c: Likewise.  Note install(1) by default already
set the context for target files to their system default,
albeit with an older method.  Use the -Z option to select between
the old and new context restoration behavior, and document
the differences and details for how context restoration
is done in new and old methods, with a view disabling the
old method entirely in future.
* src/cp.c: Make the argument to --context optional.
Note -Z implies --no-preserve=context.  I.E. -Z overrides
that aspect of -a no matter what order specified.
(struct cp_options): Document the context handling options.
(main): Check/adjust option combinations after all
options are processed, to both simplify processing
and to make handling independent of order of options
on the command line.  Also improve the diagnostics
from a failed call to setfscreatecon().
(set_process_security_ctx): A new function,
refactored to set the default context from the source file,
or with the type adjusted as per the system default for
the destination path.
(set_file_security_ctx): A new function refactored to
set the security context of an existing file, either based on
the process context or the default system context for a path.
(copy_internal): Use the refactored functions to simplify
error handling and consistently fail or warn as needed.
(copy_reg): Likewise.
(copy_internal): With --preserve=context, also copy
context from non regular files.  Note for directories this may
impact the copying of subsequent files to that directory?
(copy_attr): If we're handling SELinux explicitly,
then exclude to avoid the redudant copy with --preserve=context,
and the problematic copy with -Z.  Note SELinux attribute exclusion
also now honors cp -a --no-preserve=context.  Note there was a
very small window over 10 years ago, where attr_copy_file was
available, while attr_copy_check_permissions was not, so we
don't bother adding an explicit m4 check for the latter function.
* src/mv.c: Support --context, but don't allow specifying an argument.
* src/chcon.c: Adjust a comment to be specific to SELinux.
* src/runcon.c: Likewise.
* src/copy.c: Honor the context settings to "restorecon" as appropriate.
* src/copy.h: Add a new setting to select "restorecon" functionality.
* tests/mkdir/selinux.sh: s/-Z/--context=/
* tests/cp/cp-a-selinux.sh: Augment this test with cases
testing basic -Z functionality, and also test the various
invalid option combinations and option precedence.
* tests/mkdir/restorecon.sh: Add a new test for the
more involved mkdir -Z handling, since the directory changing
and non existent directories need to be specially handled.
Also check the similar but simpler handling of -Z by mk{nod,fifo}.
* tests/local.mk: Reference the new test.
* doc/coreutils.texi (cp invocation): Update as per interface changes.
(mv invocation): Likewise.
(install invocation): Likewise.
(mkfifo invocation): Likewise.
(mknod invocation): Likewise.
(mkdir invocation): Likewise.
* NEWS: Mention the new feature and change in behavior.

1 files changed, 53 insertions, 11 deletions

diff --git a/src/cp.c b/src/cp.c
index 78c0a0402..59d659d03 100644
--- a/src/cp.c
+++ b/src/cp.c
@@ -141,6 +141,7 @@ static struct option const long_opts[] =
   {"target-directory", required_argument, NULL, 't'},
   {"update", no_argument, NULL, 'u'},
   {"verbose", no_argument, NULL, 'v'},
+  {GETOPT_SELINUX_CONTEXT_OPTION_DECL},
   {GETOPT_HELP_OPTION_DECL},
   {GETOPT_VERSION_OPTION_DECL},
   {NULL, 0, NULL, 0}
@@ -228,6 +229,10 @@ Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.\n\
   -v, --verbose                explain what is being done\n\
   -x, --one-file-system        stay on this file system\n\
 "), stdout);
+      fputs (_("\
+  -Z, --context[=CTX]          set SELinux security context of destination\n\
+                                 file to default type, or to CTX if specified\n\
+"), stdout);
       fputs (HELP_OPTION_DESCRIPTION, stdout);
       fputs (VERSION_OPTION_DESCRIPTION, stdout);
       fputs (_("\
@@ -782,8 +787,9 @@ cp_option_init (struct cp_options *x)
   x->preserve_mode = false;
   x->preserve_timestamps = false;
   x->explicit_no_preserve_mode = false;
-  x->preserve_security_context = false;
-  x->require_preserve_context = false;
+  x->preserve_security_context = false; /* -a or --preserve=context.  */
+  x->require_preserve_context = false;  /* --preserve=context.  */
+  x->set_security_context = false;      /* -Z, set sys default context. */
   x->preserve_xattr = false;
   x->reduce_diagnostics = false;
   x->require_preserve_xattr = false;
@@ -876,8 +882,8 @@ decode_preserve_arg (char const *arg, struct cp_options *x, bool on_off)
           break;
 
         case PRESERVE_CONTEXT:
-          x->preserve_security_context = on_off;
           x->require_preserve_context = on_off;
+          x->preserve_security_context = on_off;
           break;
 
         case PRESERVE_XATTR:
@@ -918,6 +924,7 @@ main (int argc, char **argv)
   bool copy_contents = false;
   char *target_directory = NULL;
   bool no_target_directory = false;
+  security_context_t scontext = NULL;
 
   initialize_main (&argc, &argv);
   set_program_name (argv[0]);
@@ -934,7 +941,7 @@ main (int argc, char **argv)
      we'll actually use backup_suffix_string.  */
   backup_suffix_string = getenv ("SIMPLE_BACKUP_SUFFIX");
 
-  while ((c = getopt_long (argc, argv, "abdfHilLnprst:uvxPRS:T",
+  while ((c = getopt_long (argc, argv, "abdfHilLnprst:uvxPRS:TZ",
                            long_opts, NULL))
          != -1)
     {
@@ -1092,6 +1099,24 @@ main (int argc, char **argv)
           x.one_file_system = true;
           break;
 
+
+        case 'Z':
+          /* politely decline if we're not on a selinux-enabled kernel.  */
+          if (selinux_enabled)
+            {
+              if (optarg)
+                scontext = optarg;
+              else
+                x.set_security_context = true;
+            }
+          else if (optarg)
+            {
+              error (0, 0,
+                     _("warning: ignoring --context; "
+                       "it requires an SELinux-enabled kernel"));
+            }
+          break;
+
         case 'S':
           make_backups = true;
           backup_suffix_string = optarg;
@@ -1150,13 +1175,30 @@ main (int argc, char **argv)
   if (x.unlink_dest_after_failed_open && (x.hard_link || x.symbolic_link))
     x.unlink_dest_before_opening = true;
 
-  if (x.preserve_security_context)
-    {
-      if (!selinux_enabled)
-        error (EXIT_FAILURE, 0,
-               _("cannot preserve security context "
-                 "without an SELinux-enabled kernel"));
-    }
+  /* Ensure -Z overrides -a.  */
+  if ((x.set_security_context || scontext)
+      && ! x.require_preserve_context)
+    x.preserve_security_context = false;
+
+  if (x.preserve_security_context && (x.set_security_context || scontext))
+    error (EXIT_FAILURE, 0,
+           _("cannot set target context and preserve it"));
+
+  if (x.require_preserve_context && ! selinux_enabled)
+    error (EXIT_FAILURE, 0,
+           _("cannot preserve security context "
+             "without an SELinux-enabled kernel"));
+
+  /* FIXME: This handles new files.  But what about existing files?
+     I.E. if updating a tree, new files would have the specified context,
+     but shouldn't existing files be updated for consistency like this?
+       if (scontext)
+         restorecon (dst_path, 0, true);
+   */
+  if (scontext && setfscreatecon (optarg) < 0)
+    error (EXIT_FAILURE, errno,
+           _("failed to set default file creation context to %s"),
+           quote (optarg));
 
 #if !USE_XATTR
   if (x.require_preserve_xattr)