BMC/Intel-BMC/linux.git/net/netlink/genetlink.c, branch dev

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-01-28T00:59:56+00:00

Conflicts: arch/arm/boot/dts/imx6sx-sdb.dts net/sched/cls_bpf.c Two simple sets of overlapping changes. Signed-off-by: David S. Miller

netlink: make nlmsg_end() and genlmsg_end() void

2015-01-18T06:03:45+00:00

Contrary to common expectations for an "int" return, these functions return only a positive value -- if used correctly they cannot even return 0 because the message header will necessarily be in the skb. This makes the very common pattern of if (genlmsg_end(...) < 0) { ... } be a whole bunch of dead code. Many places also simply do return nlmsg_end(...); and the caller is expected to deal with it. This also commonly (at least for me) causes errors, because it is very common to write if (my_function(...)) /* error condition */ and if my_function() does "return nlmsg_end()" this is of course wrong. Additionally, there's not a single place in the kernel that actually needs the message length returned, and if anyone needs it later then it'll be very easy to just use skb->len there. Remove this, and make the functions void. This removes a bunch of dead code as described above. The patch adds lines because I did - return nlmsg_end(...); + nlmsg_end(...); + return 0; I could have preserved all the function's return values by returning skb->len, but instead I've audited all the places calling the affected functions and found that none cared. A few places actually compared the return value with <= 0 in dump functionality, but that could just be changed to < 0 with no change in behaviour, so I opted for the more efficient version. One instance of the error I've made numerous times now is also present in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't check for <0 or <=0 and thus broke out of the loop every single time. I've preserved this since it will (I think) have caused the messages to userspace to be formatted differently with just a single message for every SKB returned to userspace. It's possible that this isn't needed for the tools that actually use this, but I don't even know what they are so couldn't test that changing this behaviour would be acceptable. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

genetlink: synchronize socket closing and family removal

2015-01-16T22:04:25+00:00

In addition to the problem Jeff Layton reported, I looked at the code and reproduced the same warning by subscribing and removing the genl family with a socket still open. This is a fairly tricky race which originates in the fact that generic netlink allows the family to go away while sockets are still open - unlike regular netlink which has a module refcount for every open socket so in general this cannot be triggered. Trying to resolve this issue by the obvious locking isn't possible as it will result in deadlocks between unregistration and group unbind notification (which incidentally lockdep doesn't find due to the home grown locking in the netlink table.) To really resolve this, introduce a "closing socket" reference counter (for generic netlink only, as it's the only affected family) in the core netlink code and use that in generic netlink to wait for all the sockets that are being closed at the same time as a generic netlink family is removed. This fixes the race that when a socket is closed, it will should call the unbind, but if the family is removed at the same time the unbind will not find it, leading to the warning. The real problem though is that in this case the unbind could actually find a new family that is registered to have a multicast group with the same ID, and call its mcast_unbind() leading to confusing. Also remove the warning since it would still trigger, but is now no longer a problem. This also moves the code in af_netlink.c to before unreferencing the module to avoid having the same problem in the normal non-genl case. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

genetlink: disallow subscribing to unknown mcast groups

2015-01-16T22:04:24+00:00

Jeff Layton reported that he could trigger the multicast unbind warning in generic netlink using trinity. I originally thought it was a race condition between unregistering the generic netlink family and closing the socket, but there's a far simpler explanation: genetlink currently allows subscribing to groups that don't (yet) exist, and the warning is triggered when unsubscribing again while the group still doesn't exist. Originally, I had a warning in the subscribe case and accepted it out of userspace API concerns, but the warning was of course wrong and removed later. However, I now think that allowing userspace to subscribe to groups that don't exist is wrong and could possibly become a security problem: Consider a (new) genetlink family implementing a permission check in the mcast_bind() function similar to the like the audit code does today; it would be possible to bypass the permission check by guessing the ID and subscribing to the group it exists. This is only possible in case a family like that would be dynamically loaded, but it doesn't seem like a huge stretch, for example wireless may be loaded when you plug in a USB device. To avoid this reject such subscription attempts. If this ends up causing userspace issues we may need to add a workaround in af_netlink to deny such requests but not return an error. Reported-by: Jeff Layton Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

genetlink: A genl_bind() to an out-of-range multicast group should not WARN().

2014-12-29T21:31:49+00:00

Users can request to bind to arbitrary multicast groups, so warning when the requested group number is out of range is not appropriate. And with the warning removed, and the 'err' variable properly given an initial value, we can remove 'found' altogether. Reported-by: Sedat Dilek Signed-off-by: David S. Miller

netlink/genetlink: pass network namespace to bind/unbind

2014-12-27T08:07:50+00:00

Netlink families can exist in multiple namespaces, and for the most part multicast subscriptions are per network namespace. Thus it only makes sense to have bind/unbind notifications per network namespace. To achieve this, pass the network namespace of a given client socket to the bind/unbind functions. Also do this in generic netlink, and there also make sure that any bind for multicast groups that only exist in init_net is rejected. This isn't really a problem if it is accepted since a client in a different namespace will never receive any notifications from such a group, but it can confuse the family if not rejected (it's also possible to silently (without telling the family) accept it, but it would also have to be ignored on unbind so families that take any kind of action on bind/unbind won't do unnecessary work for invalid clients like that. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

genetlink: pass multicast bind/unbind to families

2014-12-27T07:20:23+00:00

In order to make the newly fixed multicast bind/unbind functionality in generic netlink, pass them down to the appropriate family. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

genetlink: remove superfluous assignment

2014-06-02T17:36:18+00:00

the local variable ops and n_ops were just read out from family, and not changed, hence no need to assign back. Validation functions should operate on const parameters and not change anything. Signed-off-by: Cheng Renquan Signed-off-by: David S. Miller

net: Use netlink_ns_capable to verify the permisions of netlink messages

2014-04-24T17:44:54+00:00

It is possible by passing a netlink socket to a more privileged executable and then to fool that executable into writing to the socket data that happens to be valid netlink message to do something that privileged executable did not intend to do. To keep this from happening replace bare capable and ns_capable calls with netlink_capable, netlink_net_calls and netlink_ns_capable calls. Which act the same as the previous calls except they verify that the opener of the socket had the desired permissions as well. Reported-by: Andy Lutomirski Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jesse/openvswitch

2014-01-07T00:48:38+00:00

Jesse Gross says: ==================== [GIT net-next] Open vSwitch Open vSwitch changes for net-next/3.14. Highlights are: * Performance improvements in the mechanism to get packets to userspace using memory mapped netlink and skb zero copy where appropriate. * Per-cpu flow stats in situations where flows are likely to be shared across CPUs. Standard flow stats are used in other situations to save memory and allocation time. * A handful of code cleanups and rationalization. ==================== Signed-off-by: David S. Miller