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, 34 insertions, 30 deletions

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 7a5023101..c3237304d 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -8467,6 +8467,24 @@ Skip subdirectories that are on different file systems from the one that
 the copy started on.
 However, mount point directories @emph{are} copied.
 
+@macro optContext
+@item -Z
+@itemx --context[=@var{context}]
+@opindex -Z
+@opindex --context
+@cindex SELinux, setting/restoring security context
+@cindex security context
+Without a specified @var{context}, adjust the SELinux security context according
+to the system default type for destination files, similarly to the
+@command{restorecon} command.
+The long form of this option with a specific context specified,
+will set the context for newly created files only.
+With a specified context, if SELinux is disabled, a warning is issued.
+@end macro
+@optContext
+This option is mutually exclusive with the @option{--preserve=context}
+option, and overrides the @option{--preserve=all} and @option{-a} options.
+
 @end table
 
 @exitstatus
@@ -9110,15 +9128,9 @@ Program used to strip binaries.
 @opindex --verbose
 Print the name of each file before copying it.
 
-@item -Z @var{context}
-@itemx --context=@var{context}
-@opindex -Z
-@opindex --context
-@cindex SELinux
-@cindex security context
-Set the default SELinux security context to be used for any
-created files and directories.  If SELinux is disabled then
-print a warning and ignore the option.
+@optContext
+This option is mutually exclusive with the @option{--preserve-context} option.
+
 
 @end table
 
@@ -9251,6 +9263,16 @@ Print the name of each file before moving it.
 
 @optNoTargetDirectory
 
+@item -Z
+@itemx --context
+@opindex -Z
+@opindex --context
+@cindex SELinux, restoring security context
+@cindex security context
+This option functions similarly to the @command{restorecon} command,
+by adjusting the SELinux security context according
+to the system default type for destination files.
+
 @end table
 
 @exitstatus
@@ -10066,13 +10088,7 @@ newly-created parent directories are inherited.
 Print a message for each created directory.  This is most useful with
 @option{--parents}.
 
-@item -Z @var{context}
-@itemx --context=@var{context}
-@opindex -Z
-@opindex --context
-@cindex SELinux
-@cindex security context
-Set the default SELinux security context to be used for created directories.
+@optContext
 
 @end table
 
@@ -10113,13 +10129,7 @@ Set the mode of created FIFOs to @var{mode}, which is symbolic as in
 for the point of departure.  @var{mode} should specify only file
 permission bits.  @xref{File permissions}.
 
-@item -Z @var{context}
-@itemx --context=@var{context}
-@opindex -Z
-@opindex --context
-@cindex SELinux
-@cindex security context
-Set the default SELinux security context to be used for created FIFOs.
+@optContext
 
 @end table
 
@@ -10196,13 +10206,7 @@ Set the mode of created files to @var{mode}, which is symbolic as in
 @var{mode} should specify only file permission bits.
 @xref{File permissions}.
 
-@item -Z @var{context}
-@itemx --context=@var{context}
-@opindex -Z
-@opindex --context
-@cindex SELinux
-@cindex security context
-Set the default SELinux security context to be used for created files.
+@optContext
 
 @end table