Add fcntl sealing interfaces from Linux 3.17 to bits/fcntl-linux.h.

While reviewing Linux 4.13 for glibc header changes needed, I noticed
that bits/fcntl-linux.h was missing F_ADD_SEALS etc. from Linux 3.17.

I didn't find any discussion indicating this omission is deliberate.
Now, these interfaces can only be used with file descriptors created
with memfd_create, and we don't have a memfd_create wrapper in glibc
(a patch was submitted in October 2014, albeit without documentation /
tests, and discussions continued over the next few months, but without
consensus on whether to add the interface - and we still lack any
general consensus on syscall wrappers), but I don't think that's a
reason to exclude the constants from bits/fcntl-linux.h (especially as
the header does not look compatible with simultaneously including
linux/fcntl.h).

(Some of those 2014/2015 discussions raised concerns about difficulty
using the memfd_create / sealing interface, but those seem to me more
like a question of whether it should be part of the OS-independent GNU
API - in my view, even fairly specialized syscalls ought to have
wrappers added to glibc if not obsolescent, but there may be cases
where we only want to include them in the Linux-specific API and
anything in the OS-independent GNU API should be different - rather
than being relevant to whether constants for use with fcntl should
appear in headers.)

	* sysdeps/unix/sysv/linux/bits/fcntl-linux.h [__USE_GNU]
	(F_ADD_SEALS): New macro.
	[__USE_GNU] (F_GET_SEALS): Likewise.
	[__USE_GNU] (F_SEAL_SEAL): Likewise.
	[__USE_GNU] (F_SEAL_SHRINK): Likewise.
	[__USE_GNU] (F_SEAL_GROW): Likewise.
	[__USE_GNU] (F_SEAL_WRITE): Likewise.

1 files changed, 10 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
index 0cd0a5d731..fc65fc2e4a 100644
--- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
+++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
@@ -202,6 +202,8 @@
 # define F_NOTIFY	1026	/* Request notifications on a directory.  */
 # define F_SETPIPE_SZ	1031	/* Set pipe page size array.  */
 # define F_GETPIPE_SZ	1032	/* Set pipe page size array.  */
+# define F_ADD_SEALS	1033	/* Add seals to file.  */
+# define F_GET_SEALS	1034	/* Get seals for file.  */
 #endif
 #ifdef __USE_XOPEN2K8
 # define F_DUPFD_CLOEXEC 1030	/* Duplicate file descriptor with
@@ -271,6 +273,14 @@ struct f_owner_ex
   };
 #endif
 
+#ifdef __USE_GNU
+/* Types of seals.  */
+# define F_SEAL_SEAL	0x0001	/* Prevent further seals from being set.  */
+# define F_SEAL_SHRINK	0x0002	/* Prevent file from shrinking.  */
+# define F_SEAL_GROW	0x0004	/* Prevent file from growing.  */
+# define F_SEAL_WRITE	0x0008	/* Prevent writes.  */
+#endif
+
 /* Define some more compatibility macros to be backward compatible with
    BSD systems which did not managed to hide these kernel macros.  */
 #ifdef	__USE_MISC