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.

diff --git a/ChangeLog b/ChangeLog
index 4f4635f..dca63fe 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2017-09-08  Joseph Myers  <joseph@codesourcery.com>
+
+       * 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.
+
 2017-09-08  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
        * posix/glob_internal.h (GLOBPAT_NONE, GLOBPAT_SPECIAL)

diff --git a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
index 0cd0a5d..fc65fc2 100644 (file)
--- 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