| Message ID | fc61912d585ccf3999c3cba5e481c1920af17ca6.1589961603.git.sd@queasysnail.net |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] net: don't return invalid table id error when we fall back to PF_UNSPEC | expand |
On 5/20/20 3:15 AM, Sabrina Dubroca wrote: > In case we can't find a ->dumpit callback for the requested > (family,type) pair, we fall back to (PF_UNSPEC,type). In effect, we're > in the same situation as if userspace had requested a PF_UNSPEC > dump. For RTM_GETROUTE, that handler is rtnl_dump_all, which calls all > the registered RTM_GETROUTE handlers. ... > Instead, this patch removes dump_all_families and updates the > RTM_GETROUTE handlers to check if the family that is being dumped is > their own. When it's not, which covers both the intentional PF_UNSPEC > dumps (as dump_all_families did) and the fallback case, ignore the > missing table id error. > > Fixes: cb167893f41e ("net: Plumb support for filtering ipv4 and ipv6 multicast route dumps") > Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> > --- > include/net/ip_fib.h | 1 - > net/ipv4/fib_frontend.c | 3 +-- > net/ipv4/ipmr.c | 2 +- > net/ipv6/ip6_fib.c | 2 +- > net/ipv6/ip6mr.c | 2 +- > 5 files changed, 4 insertions(+), 6 deletions(-) > Thanks for the detailed analysis and commit message. Reviewed-by: David Ahern <dsahern@gmail.com>
From: Sabrina Dubroca <sd@queasysnail.net> Date: Wed, 20 May 2020 11:15:46 +0200 > In case we can't find a ->dumpit callback for the requested > (family,type) pair, we fall back to (PF_UNSPEC,type). In effect, we're > in the same situation as if userspace had requested a PF_UNSPEC > dump. For RTM_GETROUTE, that handler is rtnl_dump_all, which calls all > the registered RTM_GETROUTE handlers. > > The requested table id may or may not exist for all of those > families. commit ae677bbb4441 ("net: Don't return invalid table id > error when dumping all families") fixed the problem when userspace > explicitly requests a PF_UNSPEC dump, but missed the fallback case. > > For example, when we pass ipv6.disable=1 to a kernel with > CONFIG_IP_MROUTE=y and CONFIG_IP_MROUTE_MULTIPLE_TABLES=y, > the (PF_INET6, RTM_GETROUTE) handler isn't registered, so we end up in > rtnl_dump_all, and listing IPv6 routes will unexpectedly print: > > # ip -6 r > Error: ipv4: MR table does not exist. > Dump terminated > > commit ae677bbb4441 introduced the dump_all_families variable, which > gets set when userspace requests a PF_UNSPEC dump. However, we can't > simply set the family to PF_UNSPEC in rtnetlink_rcv_msg in the > fallback case to get dump_all_families == true, because some messages > types (for example RTM_GETRULE and RTM_GETNEIGH) only register the > PF_UNSPEC handler and use the family to filter in the kernel what is > dumped to userspace. We would then export more entries, that userspace > would have to filter. iproute does that, but other programs may not. > > Instead, this patch removes dump_all_families and updates the > RTM_GETROUTE handlers to check if the family that is being dumped is > their own. When it's not, which covers both the intentional PF_UNSPEC > dumps (as dump_all_families did) and the fallback case, ignore the > missing table id error. > > Fixes: cb167893f41e ("net: Plumb support for filtering ipv4 and ipv6 multicast route dumps") > Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Applied and queued up for -stable, thank you.
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index 59e0d4e99f94..b219a8fe0950 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -257,7 +257,6 @@ struct fib_dump_filter { u32 table_id; /* filter_set is an optimization that an entry is set */ bool filter_set; - bool dump_all_families; bool dump_routes; bool dump_exceptions; unsigned char protocol; diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 213be9c050ad..1bf9da3a75f9 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -918,7 +918,6 @@ int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh, else filter->dump_exceptions = false; - filter->dump_all_families = (rtm->rtm_family == AF_UNSPEC); filter->flags = rtm->rtm_flags; filter->protocol = rtm->rtm_protocol; filter->rt_type = rtm->rtm_type; @@ -990,7 +989,7 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) if (filter.table_id) { tb = fib_get_table(net, filter.table_id); if (!tb) { - if (filter.dump_all_families) + if (rtnl_msg_family(cb->nlh) != PF_INET) return skb->len; NL_SET_ERR_MSG(cb->extack, "ipv4: FIB table does not exist"); diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index 5c218db2dede..b2363b82b48d 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -2613,7 +2613,7 @@ static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb) mrt = ipmr_get_table(sock_net(skb->sk), filter.table_id); if (!mrt) { - if (filter.dump_all_families) + if (rtnl_msg_family(cb->nlh) != RTNL_FAMILY_IPMR) return skb->len; NL_SET_ERR_MSG(cb->extack, "ipv4: MR table does not exist"); diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 46ed56719476..20314895509c 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -664,7 +664,7 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) if (arg.filter.table_id) { tb = fib6_get_table(net, arg.filter.table_id); if (!tb) { - if (arg.filter.dump_all_families) + if (rtnl_msg_family(cb->nlh) != PF_INET6) goto out; NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist"); diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index 1e223e26f079..1f4d20e97c07 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -2503,7 +2503,7 @@ static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb) mrt = ip6mr_get_table(sock_net(skb->sk), filter.table_id); if (!mrt) { - if (filter.dump_all_families) + if (rtnl_msg_family(cb->nlh) != RTNL_FAMILY_IP6MR) return skb->len; NL_SET_ERR_MSG_MOD(cb->extack, "MR table does not exist");
In case we can't find a ->dumpit callback for the requested (family,type) pair, we fall back to (PF_UNSPEC,type). In effect, we're in the same situation as if userspace had requested a PF_UNSPEC dump. For RTM_GETROUTE, that handler is rtnl_dump_all, which calls all the registered RTM_GETROUTE handlers. The requested table id may or may not exist for all of those families. commit ae677bbb4441 ("net: Don't return invalid table id error when dumping all families") fixed the problem when userspace explicitly requests a PF_UNSPEC dump, but missed the fallback case. For example, when we pass ipv6.disable=1 to a kernel with CONFIG_IP_MROUTE=y and CONFIG_IP_MROUTE_MULTIPLE_TABLES=y, the (PF_INET6, RTM_GETROUTE) handler isn't registered, so we end up in rtnl_dump_all, and listing IPv6 routes will unexpectedly print: # ip -6 r Error: ipv4: MR table does not exist. Dump terminated commit ae677bbb4441 introduced the dump_all_families variable, which gets set when userspace requests a PF_UNSPEC dump. However, we can't simply set the family to PF_UNSPEC in rtnetlink_rcv_msg in the fallback case to get dump_all_families == true, because some messages types (for example RTM_GETRULE and RTM_GETNEIGH) only register the PF_UNSPEC handler and use the family to filter in the kernel what is dumped to userspace. We would then export more entries, that userspace would have to filter. iproute does that, but other programs may not. Instead, this patch removes dump_all_families and updates the RTM_GETROUTE handlers to check if the family that is being dumped is their own. When it's not, which covers both the intentional PF_UNSPEC dumps (as dump_all_families did) and the fallback case, ignore the missing table id error. Fixes: cb167893f41e ("net: Plumb support for filtering ipv4 and ipv6 multicast route dumps") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> --- include/net/ip_fib.h | 1 - net/ipv4/fib_frontend.c | 3 +-- net/ipv4/ipmr.c | 2 +- net/ipv6/ip6_fib.c | 2 +- net/ipv6/ip6mr.c | 2 +- 5 files changed, 4 insertions(+), 6 deletions(-)