Message ID | 1420455986-5800-2-git-send-email-pablo@netfilter.org |
---|---|
State | Changes Requested |
Delegated to: | Pablo Neira |
Headers | show |
On 05.01, Pablo Neira Ayuso wrote: > Relax the checking that was introduced in 97840cb ("netfilter: > nfnetlink: fix insufficient validation in nfnetlink_bind") when the > subscription bitmask is used. Existing userspace code code may request > to listen to all of the existing netlink groups by setting an all to one > subscription group bitmask. Netlink already validates subscription via > setsockopt() for us. What is the point of doing this? I don't think its particulary reasonable to subscribe to ~0 unless you're implementing some kind of monitor. We also don't know whether a bitmask or an invalid group number was used, so the comment below is at least misleading. And, unrelated, but since it went in via netfilter asking anyway, why is the group number signed? That doesn't make any sense, it is treated as unsigned everywhere else. > diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c > index c6619d4..5082d81 100644 > --- a/net/netfilter/nfnetlink.c > +++ b/net/netfilter/nfnetlink.c > @@ -469,8 +469,11 @@ static int nfnetlink_bind(int group) > const struct nfnetlink_subsystem *ss; > int type; > > + /* No strict check for groups when subscription bitmask is used, group > + * binding via setsockopt() already rejects this from netlink. > + */ > if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) > - return -EINVAL; > + return 0; > > type = nfnl_group2type[group]; > > -- > 1.7.10.4 > -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Jan 05, 2015 at 11:22:35AM +0000, Patrick McHardy wrote: > On 05.01, Pablo Neira Ayuso wrote: > > Relax the checking that was introduced in 97840cb ("netfilter: > > nfnetlink: fix insufficient validation in nfnetlink_bind") when the > > subscription bitmask is used. Existing userspace code code may request > > to listen to all of the existing netlink groups by setting an all to one > > subscription group bitmask. Netlink already validates subscription via > > setsockopt() for us. > > What is the point of doing this? I don't think its particulary > reasonable to subscribe to ~0 unless you're implementing some kind of > monitor. This is how we've been supporting this since the beginning. So userspace applications could subscribe to ~0 and don't care if the group exists or not. After the recent change, those will break. None of the userspace netfilter codebase actually need this, but other third party application will break when binding if they were using ~0 for monitoring. > We also don't know whether a bitmask or an invalid group number was > used, so the comment below is at least misleading. > > And, unrelated, but since it went in via netfilter asking anyway, why > is the group number signed? That doesn't make any sense, it is treated > as unsigned everywhere else. That should be changed, yes. > > diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c > > index c6619d4..5082d81 100644 > > --- a/net/netfilter/nfnetlink.c > > +++ b/net/netfilter/nfnetlink.c > > @@ -469,8 +469,11 @@ static int nfnetlink_bind(int group) > > const struct nfnetlink_subsystem *ss; > > int type; > > > > + /* No strict check for groups when subscription bitmask is used, group > > + * binding via setsockopt() already rejects this from netlink. > > + */ > > if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) > > - return -EINVAL; > > + return 0; > > > > type = nfnl_group2type[group]; > > > > -- > > 1.7.10.4 > > -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05.01, Pablo Neira Ayuso wrote: > On Mon, Jan 05, 2015 at 11:22:35AM +0000, Patrick McHardy wrote: > > On 05.01, Pablo Neira Ayuso wrote: > > > Relax the checking that was introduced in 97840cb ("netfilter: > > > nfnetlink: fix insufficient validation in nfnetlink_bind") when the > > > subscription bitmask is used. Existing userspace code code may request > > > to listen to all of the existing netlink groups by setting an all to one > > > subscription group bitmask. Netlink already validates subscription via > > > setsockopt() for us. > > > > What is the point of doing this? I don't think its particulary > > reasonable to subscribe to ~0 unless you're implementing some kind of > > monitor. > > This is how we've been supporting this since the beginning. So > userspace applications could subscribe to ~0 and don't care if the > group exists or not. > > After the recent change, those will break. None of the userspace > netfilter codebase actually need this, but other third party > application will break when binding if they were using ~0 for > monitoring. > > > We also don't know whether a bitmask or an invalid group number was > > used, so the comment below is at least misleading. > > > > And, unrelated, but since it went in via netfilter asking anyway, why > > is the group number signed? That doesn't make any sense, it is treated > > as unsigned everywhere else. > > That should be changed, yes. Assuming you mean both the signedness and the comment, that seems fine. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index c6619d4..5082d81 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -469,8 +469,11 @@ static int nfnetlink_bind(int group) const struct nfnetlink_subsystem *ss; int type; + /* No strict check for groups when subscription bitmask is used, group + * binding via setsockopt() already rejects this from netlink. + */ if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) - return -EINVAL; + return 0; type = nfnl_group2type[group];
Relax the checking that was introduced in 97840cb ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") when the subscription bitmask is used. Existing userspace code code may request to listen to all of the existing netlink groups by setting an all to one subscription group bitmask. Netlink already validates subscription via setsockopt() for us. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> --- net/netfilter/nfnetlink.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)