cvs commit: src/sys/kern imgact_elf.c vfs_lookup.c vfs_syscalls.c

[John Baldwin]

On Thursday 15 September 2005 11:03 am, Christian S.J. Peron wrote:
> csjp        2005-09-15 15:03:48 UTC
>
>   FreeBSD src repository
>
>   Modified files:
>     sys/kern             imgact_elf.c vfs_lookup.c vfs_syscalls.c
>   Log:
>   Improve the MP safeness associated with the creation of symbolic
>   links and the execution of ELF binaries. Two problems were found:
>
>   1) The link path wasn't tagged as being MP safe and thus was not properly
>      protected.
>   2) The ELF interpreter vnode wasnt being locked in namei(9) and thus was
>      insufficiently protected.
>
>   This commit makes the following changes:
>
>   -Sets the MPSAFE flag in NDINIT for symbolic link paths
>   -Sets the MPSAFE flag in NDINIT and introduce a vfslocked variable which
>    will be used to instruct VFS_UNLOCK_GIANT to unlock Giant if it has been
>    picked up.
>   -Drop in an assertion into vfs_lookup which ensures that if the MPSAFE
>    flag is NOT set, that we have picked up giant. If not panic (if WITNESS
>    compiled into the kernel). This should help us find conditions where
> vnode operations are in-sufficiently protected.
>
>   This is a RELENG_6 candidate.
>
>   Discussed with: jeff
>   MFC after:      4 days

Why not just use mtx_assert() to do locking assertions?

	if (!(cnp->cn_flags & MPSAFE))
		mtx_assert(&Giant, MA_OWNED);

Also, note that assertions only depend on INVARIANTS, not on WITNESS.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org