Merge branch 'get-rid-of-the-address_space-override-in-setsockopt-v2'

Christoph Hellwig says:

====================
get rid of the address_space override in setsockopt v2

setsockopt is the last place in architecture-independ code that still
uses set_fs to force the uaccess routines to operate on kernel pointers.

This series adds a new sockptr_t type that can contained either a kernel
or user pointer, and which has accessors that do the right thing, and
then uses it for setsockopt, starting by refactoring some low-level
helpers and moving them over to it before finally doing the main
setsockopt method.

Note that apparently the eBPF selftests do not even cover this path, so
the series has been tested with a testing patch that always copies the
data first and passes a kernel pointer.  This is something that works for
most common sockopts (and is something that the ePBF support relies on),
but unfortunately in various corner cases we either don't use the passed
in length, or in one case actually copy data back from setsockopt, or in
case of bpfilter straight out do not work with kernel pointers at all.

Against net-next/master.

Changes since v1:
 - check that users don't pass in kernel addresses
 - more bpfilter cleanups
 - cosmetic mptcp tweak
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 7 deletions

diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c
index 9063c6767d34..94f18d2352d0 100644
--- a/net/ipv4/bpfilter/sockopt.c
+++ b/net/ipv4/bpfilter/sockopt.c
@@ -21,8 +21,7 @@ void bpfilter_umh_cleanup(struct umd_info *info)
 }
 EXPORT_SYMBOL_GPL(bpfilter_umh_cleanup);
 
-static int bpfilter_mbox_request(struct sock *sk, int optname,
-				 char __user *optval,
+static int bpfilter_mbox_request(struct sock *sk, int optname, sockptr_t optval,
 				 unsigned int optlen, bool is_set)
 {
 	int err;
@@ -52,20 +51,23 @@ out:
 	return err;
 }
 
-int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval,
+int bpfilter_ip_set_sockopt(struct sock *sk, int optname, sockptr_t optval,
 			    unsigned int optlen)
 {
 	return bpfilter_mbox_request(sk, optname, optval, optlen, true);
 }
 
-int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval,
-			    int __user *optlen)
+int bpfilter_ip_get_sockopt(struct sock *sk, int optname,
+			    char __user *user_optval, int __user *optlen)
 {
-	int len;
+	sockptr_t optval;
+	int err, len;
 
 	if (get_user(len, optlen))
 		return -EFAULT;
-
+	err = init_user_sockptr(&optval, user_optval);
+	if (err)
+		return err;
 	return bpfilter_mbox_request(sk, optname, optval, len, false);
 }