Revert r240931, as the previous comment was actually in sync with POSIX.

I have to note that POSIX is simply stupid in how it describes O_EXEC/fexecve
and friends. Yes, not only inconsistent, but stupid.

In the open(2) description, O_RDONLY flag is described as:

	O_RDONLY	Open for reading only.

Taken from:

	http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html

Note "for reading only". Not "for reading or executing"!

In the fexecve(2) description you can find:

	The fexecve() function shall fail if:

	[EBADF]
		The fd argument is not a valid file descriptor open for executing.

Taken from:

	http://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html

As you can see the function shall fail if the file was not open with O_EXEC!

And yet, if you look closer you can find this mess in the exec.html:

	Since execute permission is checked by fexecve(), the file description
	fd need not have been opened with the O_EXEC flag.

Yes, O_EXEC flag doesn't have to be specified after all. You can open a file
with O_RDONLY and you still be able to fexecve(2) it.

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 20a9b81..90f7311b 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -441,10 +441,10 @@ interpret:
 	} else {
 		AUDIT_ARG_FD(args->fd);
 		/*
-		 * Some might argue that CAP_MMAP should also be required here;
-		 * such arguments will be entertained.
+		 * Some might argue that CAP_READ and/or CAP_MMAP should also
+		 * be required here; such arguments will be entertained.
 		 *
-		 * Descriptors opened only with O_EXEC are allowed.
+		 * Descriptors opened only with O_EXEC or O_RDONLY are allowed.
 		 */
 		error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp);
 		if (error)