From e1ee3673a83cc02b6b5e43c9e647d8dd5e1c4e26 Mon Sep 17 00:00:00 2001 From: Pablo Neira Date: Mon, 29 Jul 2013 12:30:04 +0200 Subject: [PATCH] genetlink: fix usage of NLM_F_EXCL or NLM_F_REPLACE Currently, it is not possible to use neither NLM_F_EXCL nor NLM_F_REPLACE from genetlink. This is due to this checking in genl_family_rcv_msg: if (nlh->nlmsg_flags & NLM_F_DUMP) NLM_F_DUMP is NLM_F_MATCH|NLM_F_ROOT. Thus, if NLM_F_EXCL or NLM_F_REPLACE flag is set, genetlink believes that you're requesting a dump and it calls the .dumpit callback. The solution that I propose is to refine this checking to make it stricter: if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) And given the combination NLM_F_REPLACE and NLM_F_EXCL does not make sense to me, it removes the ambiguity. There was a patch that tried to fix this some time ago (0ab03c2 netlink: test for all flags of the NLM_F_DUMP composite) but it tried to resolve this ambiguity in *all* existing netlink subsystems, not only genetlink. That patch was reverted since it broke iproute2, which is using NLM_F_ROOT to request the dump of the routing cache. Signed-off-by: Pablo Neira Ayuso Signed-off-by: David S. Miller --- net/netlink/genetlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index 1076fe16b122..512718adb0d5 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -571,7 +571,7 @@ static int genl_family_rcv_msg(struct genl_family *family, !capable(CAP_NET_ADMIN)) return -EPERM; - if (nlh->nlmsg_flags & NLM_F_DUMP) { + if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) { struct netlink_dump_control c = { .dump = ops->dumpit, .done = ops->done,