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, 75 insertions, 11 deletions

diff --git a/src/mkdir.c b/src/mkdir.c
index efd318497..25b1da5e7 100644
--- a/src/mkdir.c
+++ b/src/mkdir.c
@@ -29,6 +29,7 @@
 #include "prog-fprintf.h"
 #include "quote.h"
 #include "savewd.h"
+#include "selinux.h"
 #include "smack.h"
 
 /* The official name of this program (e.g., no 'g' prefix).  */
@@ -65,8 +66,8 @@ Create the DIRECTORY(ies), if they do not already exist.\n\
   -m, --mode=MODE   set file mode (as in chmod), not a=rwx - umask\n\
   -p, --parents     no error if existing, make parent directories as needed\n\
   -v, --verbose     print a message for each created directory\n\
-  -Z, --context=CTX  set the SELinux security context of each created\n\
-                      directory to CTX\n\
+  -Z, --context[=CTX]  set the SELinux security context of each created\n\
+                         directory to default type or to CTX if specified\n\
 "), stdout);
       fputs (HELP_OPTION_DESCRIPTION, stdout);
       fputs (VERSION_OPTION_DESCRIPTION, stdout);
@@ -91,6 +92,9 @@ struct mkdir_options
   /* File mode bits affected by MODE.  */
   mode_t mode_bits;
 
+  /* Set the SELinux File Context.  */
+  bool set_security_context;
+
   /* If not null, format to use when reporting newly made directories.  */
   char const *created_directory_format;
 };
@@ -113,12 +117,16 @@ static int
 make_ancestor (char const *dir, char const *component, void *options)
 {
   struct mkdir_options const *o = options;
-  int r;
+
+  if (o->set_security_context && defaultcon (dir, S_IFDIR) < 0)
+    error (0, errno, _("failed to set default creation context for %s"),
+           quote (dir));
+
   mode_t user_wx = S_IWUSR | S_IXUSR;
   bool self_denying_umask = (o->umask_value & user_wx) != 0;
   if (self_denying_umask)
     umask (o->umask_value & ~user_wx);
-  r = mkdir (component, S_IRWXUGO);
+  int r = mkdir (component, S_IRWXUGO);
   if (self_denying_umask)
     {
       int mkdir_errno = errno;
@@ -138,11 +146,46 @@ static int
 process_dir (char *dir, struct savewd *wd, void *options)
 {
   struct mkdir_options const *o = options;
-  return (make_dir_parents (dir, wd, o->make_ancestor_function, options,
-                            o->mode, announce_mkdir,
-                            o->mode_bits, (uid_t) -1, (gid_t) -1, true)
-          ? EXIT_SUCCESS
-          : EXIT_FAILURE);
+  bool set_defaultcon = false;
+
+  /* If possible set context before DIR created.  */
+  if (o->set_security_context)
+    {
+      if (! o->make_ancestor_function)
+        set_defaultcon = true;
+      else
+        {
+          char *pdir = dir_name (dir);
+          struct stat st;
+          if (STREQ (pdir, ".")
+              || (stat (pdir, &st) == 0 && S_ISDIR (st.st_mode)))
+            set_defaultcon = true;
+          free (pdir);
+        }
+      if (set_defaultcon && defaultcon (dir, S_IFDIR) < 0)
+        error (0, errno, _("failed to set default creation context for %s"),
+               quote (dir));
+    }
+
+  int ret = (make_dir_parents (dir, wd, o->make_ancestor_function, options,
+                               o->mode, announce_mkdir,
+                               o->mode_bits, (uid_t) -1, (gid_t) -1, true)
+             ? EXIT_SUCCESS
+             : EXIT_FAILURE);
+
+  /* FIXME: Due to the current structure of make_dir_parents()
+     we don't have the facility to call defaultcon() before the
+     final component of DIR is created.  So for now, create the
+     final component with the context from previous component
+     and here we set the context for the final component. */
+  if (ret == EXIT_SUCCESS && o->set_security_context && ! set_defaultcon)
+    {
+      if (restorecon (last_component (dir), false, false) < 0)
+        error (0, errno, _("failed to set restore context for %s"),
+               quote (dir));
+    }
+
+  return ret;
 }
 
 int
@@ -157,6 +200,7 @@ main (int argc, char **argv)
   options.mode = S_IRWXUGO;
   options.mode_bits = 0;
   options.created_directory_format = NULL;
+  options.set_security_context = false;
 
   initialize_main (&argc, &argv);
   set_program_name (argv[0]);
@@ -166,7 +210,7 @@ main (int argc, char **argv)
 
   atexit (close_stdout);
 
-  while ((optc = getopt_long (argc, argv, "pm:vZ:", longopts, NULL)) != -1)
+  while ((optc = getopt_long (argc, argv, "pm:vZ", longopts, NULL)) != -1)
     {
       switch (optc)
         {
@@ -180,7 +224,24 @@ main (int argc, char **argv)
           options.created_directory_format = _("created directory %s");
           break;
         case 'Z':
-          scontext = optarg;
+          if (is_smack_enabled ())
+            {
+              /* We don't yet support -Z to restore context with SMACK.  */
+              scontext = optarg;
+            }
+          else if (is_selinux_enabled () > 0)
+            {
+              if (optarg)
+                scontext = optarg;
+              else
+                options.set_security_context = true;
+            }
+          else if (optarg)
+            {
+              error (0, 0,
+                     _("warning: ignoring --context; "
+                       "it requires an SELinux/SMACK-enabled kernel"));
+            }
           break;
         case_GETOPT_HELP_CHAR;
         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
@@ -195,6 +256,9 @@ main (int argc, char **argv)
       usage (EXIT_FAILURE);
     }
 
+  /* FIXME: This assumes mkdir() is done in the same process.
+     If that's not always the case we would need to call this
+     like we do when options.set_security_context == true.  */
   if (scontext)
     {
       int ret = 0;