[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 10 Oct 2022 12:54:12 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Alexei Starovoitov' <alexei.starovoitov@...il.com>,
Paul Moore <paul@...l-moore.com>
CC: Martin KaFai Lau <martin.lau@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Network Development <netdev@...r.kernel.org>,
LSM List <linux-security-module@...r.kernel.org>,
"selinux@...r.kernel.org" <selinux@...r.kernel.org>
Subject: RE: SO_PEERSEC protections in sk_getsockopt()?
From: Alexei Starovoitov
> Sent: 07 October 2022 22:55
....
> Not easy at all.
> There is only way place in the whole kernel that does:
> return sk_getsockopt(sk, SOL_SOCKET, optname,
> KERNEL_SOCKPTR(optval),
> KERNEL_SOCKPTR(optlen));
Until I add change my out of tree driver to work with
the new code.
(Although it actually needs to do a getsockopt into SCTP.)
I didn't spot the change to sk_getsockopt() going though.
But KERNEL_SOCKPTR() is really the wrong function/type
for the length.
It would be much safer to have a struct with two members,
one an __user pointer and one a kernel pointer both to
socklen_t.
It isn't really ideal for the buffer pointer either.
That started as a single field (assuming the caller
has verified the user/kernel status), then the is_kernel
field was added for architectures where user/kernel
addresses use the same values.
Then a horrid bug (forgotten where) forced the is_kernel
field be used everywhere.
Again a structure with two pointers would be much safer.
Indeed the length could likely be included as well.
That would even give scope for a short user buffer being
copied into kernel memory while letting code that needs
a long buffer (or ignores the length) still directly
access userspace.
I can't remember, but something makes me think that a lot
of the 'not checking the length' setsockopt calls were in
decnet - which has now been deleted.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
Powered by blists - more mailing lists