Author: pjd
Date: Thu Sep 27 16:43:23 2012
New Revision: 241000
URL: http://svn.freebsd.org/changeset/base/241000
Log:
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.
Modified:
head/sys/kern/kern_exec.c
Modified: head/sys/kern/kern_exec.c
==============================================================================
--- head/sys/kern/kern_exec.c Thu Sep 27 15:45:24 2012 (r240999)
+++ head/sys/kern/kern_exec.c Thu Sep 27 16:43:23 2012 (r241000)
@@ -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)
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