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

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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.
This commit is contained in:
Pawel Jakub Dawidek 2012-09-27 16:43:23 +00:00
parent 7a2275046d
commit c8e781f6e0
1 changed files with 3 additions and 3 deletions
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6
sys/kern/kern_exec.c
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@ -441,10 +441,10 @@ do_execve(td, args, mac_p)
} 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)