[PATCH net-next 0/2] ip6mr: implement RTM_GETROUTE for single entry

[PATCH net-next 0/2] ip6mr: implement RTM_GETROUTE for single entry

[David Lamparter]

The IPv6 multicast routing code implements RTM_GETROUTE, but only for a
dump request.  Retrieving a single MFC entry is not currently possible
via netlink.

While most of the data here can also be retrieved with SIOCGETSGCNT_IN6,
the lastused / RTA_EXPIRES is not included in the ioctl result (and we
need it in FRR.)

=> Implement single-entry RTM_GETROUTE by copying and adapting the IPv4
code.

Tested against FRRouting's (work-in-progress) IPv6 PIM implementation.

Cheers,


-David

[PATCH 1/2] ipv6: make rtm_ipv6_policy available

[David Lamparter]

... so ip6mr.c can use it too (as it is in IPv4.)

Signed-off-by: David Lamparter <equinox@diac24.net>
---

1:1 analog to IPv4, where rtm_ipv4_policy is exposed for pretty exactly
the same thing.  IPv6 just got away with not using this across file
boundaries so far.

---
 include/net/ip6_fib.h | 1 +
 net/ipv6/route.c      | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 6268963d9599..a12fedea97de 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -483,6 +483,7 @@ void rt6_get_prefsrc(const struct rt6_info *rt, struct in6_addr *addr)
 	rcu_read_unlock();
 }
 
+extern const struct nla_policy rtm_ipv6_policy[];
 int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 		 struct fib6_config *cfg, gfp_t gfp_flags,
 		 struct netlink_ext_ack *extack);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1d6f75eef4bd..26c7b31abe96 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4964,7 +4964,7 @@ void rt6_mtu_change(struct net_device *dev, unsigned int mtu)
 	fib6_clean_all(dev_net(dev), rt6_mtu_change_route, &arg);
 }
 
-static const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
+const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
 	[RTA_UNSPEC]		= { .strict_start_type = RTA_DPORT + 1 },
 	[RTA_GATEWAY]           = { .len = sizeof(struct in6_addr) },
 	[RTA_PREFSRC]		= { .len = sizeof(struct in6_addr) },
-- 
2.36.1

[PATCH 2/2] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

The IPv6 multicast routing code previously implemented only the dump
variant of RTM_GETROUTE.  Implement single MFC item retrieval by copying
and adapting the respective IPv4 code.

Tested against FRRouting's IPv6 PIM stack.

Signed-off-by: David Lamparter <equinox@diac24.net>
---

Pretty much copypasted from IPv4.

---
 net/ipv6/ip6mr.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 118 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ec6e1509fc7c..a10bed171417 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -95,6 +95,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
 static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
 			      int cmd);
 static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack);
 static int ip6mr_rtm_dumproute(struct sk_buff *skb,
 			       struct netlink_callback *cb);
 static void mroute_clean_tables(struct mr_table *mrt, int flags);
@@ -1390,7 +1392,7 @@ int __init ip6_mr_init(void)
 	}
 #endif
 	err = rtnl_register_module(THIS_MODULE, RTNL_FAMILY_IP6MR, RTM_GETROUTE,
-				   NULL, ip6mr_rtm_dumproute, 0);
+				   ip6mr_rtm_getroute, ip6mr_rtm_dumproute, 0);
 	if (err == 0)
 		return 0;
 
@@ -2510,6 +2512,121 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
 	rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
 }
 
+static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
+					const struct nlmsghdr *nlh,
+					struct nlattr **tb,
+					struct netlink_ext_ack *extack)
+{
+	struct rtmsg *rtm;
+	int i, err;
+
+	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
+		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
+		return -EINVAL;
+	}
+
+	if (!netlink_strict_get_check(skb))
+		return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
+					      rtm_ipv6_policy, extack);
+
+	rtm = nlmsg_data(nlh);
+	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
+	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
+	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
+	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
+		NL_SET_ERR_MSG(extack, "ipv6: Invalid values in header for multicast route get request");
+		return -EINVAL;
+	}
+
+	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
+					    rtm_ipv6_policy, extack);
+	if (err)
+		return err;
+
+	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+		NL_SET_ERR_MSG(extack, "ipv6: rtm_src_len and rtm_dst_len must be 128 for IPv6");
+		return -EINVAL;
+	}
+
+	for (i = 0; i <= RTA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case RTA_SRC:
+		case RTA_DST:
+		case RTA_TABLE:
+			break;
+		default:
+			NL_SET_ERR_MSG(extack, "ipv6: Unsupported attribute in multicast route get request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct nlattr *tb[RTA_MAX + 1];
+	struct sk_buff *skb = NULL;
+	struct mfc6_cache *cache;
+	struct mr_table *mrt;
+	struct in6_addr src = {}, grp = {};
+	u32 tableid;
+	int err;
+
+	err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
+	if (err < 0)
+		goto errout;
+
+	if (tb[RTA_SRC])
+		src = nla_get_in6_addr(tb[RTA_SRC]);
+	if (tb[RTA_DST])
+		grp = nla_get_in6_addr(tb[RTA_DST]);
+	tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
+
+	mrt = ip6mr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
+	if (!mrt) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR table does not exist");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	/* entries are added/deleted only under RTNL */
+	rcu_read_lock();
+	cache = ip6mr_cache_find(mrt, &src, &grp);
+	rcu_read_unlock();
+	if (!cache) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR cache entry not found");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
+	if (!skb) {
+		err = -ENOBUFS;
+		goto errout_free;
+	}
+
+	err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
+				nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
+	if (err < 0)
+		goto errout_free;
+
+	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout:
+	return err;
+
+errout_free:
+	kfree_skb(skb);
+	goto errout;
+}
+
 static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nlmsghdr *nlh = cb->nlh;
-- 
2.36.1

Re: [PATCH net-next 0/2] ip6mr: implement RTM_GETROUTE for single entry

[Jakub Kicinski]

On Thu, 30 Jun 2022 15:30:49 +0200 David Lamparter wrote:
> The IPv6 multicast routing code implements RTM_GETROUTE, but only for a
> dump request.  Retrieving a single MFC entry is not currently possible
> via netlink.
> 
> While most of the data here can also be retrieved with SIOCGETSGCNT_IN6,
> the lastused / RTA_EXPIRES is not included in the ioctl result (and we
> need it in FRR.)
> 
> => Implement single-entry RTM_GETROUTE by copying and adapting the IPv4  
> code.
> 
> Tested against FRRouting's (work-in-progress) IPv6 PIM implementation.

You must CC maintainers (./scripts/get_maintainer.pl). With the patch
volume on netdev and constant trouble with gmail the chances of people
missing a submission are just too high. Please repost.

[PATCH resend net-next 0/2] ip6mr: implement RTM_GETROUTE for single entry

[David Lamparter]

[resend with a slightly random pick of Cc:s - apologies if I ended up
choosing poorly]

The IPv6 multicast routing code implements RTM_GETROUTE, but only for a
dump request.  Retrieving a single MFC entry is not currently possible
via netlink.

While most of the data here can also be retrieved with SIOCGETSGCNT_IN6,
the lastused / RTA_EXPIRES is not included in the ioctl result (and we
need it in FRR.)

=> Implement single-entry RTM_GETROUTE by copying and adapting the IPv4
code.

Tested against FRRouting's (work-in-progress) IPv6 PIM implementation.

Cheers,


-David

[PATCH net-next 1/2] ipv6: make rtm_ipv6_policy available

[David Lamparter]

... so ip6mr.c can use it too (as it is in IPv4.)

Signed-off-by: David Lamparter <equinox@diac24.net>
---

1:1 analog to IPv4, where rtm_ipv4_policy is exposed for pretty exactly
the same thing.  IPv6 just got away with not using this across file
boundaries so far.

---
 include/net/ip6_fib.h | 1 +
 net/ipv6/route.c      | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 6268963d9599..a12fedea97de 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -483,6 +483,7 @@ void rt6_get_prefsrc(const struct rt6_info *rt, struct in6_addr *addr)
 	rcu_read_unlock();
 }
 
+extern const struct nla_policy rtm_ipv6_policy[];
 int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 		 struct fib6_config *cfg, gfp_t gfp_flags,
 		 struct netlink_ext_ack *extack);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1d6f75eef4bd..26c7b31abe96 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4964,7 +4964,7 @@ void rt6_mtu_change(struct net_device *dev, unsigned int mtu)
 	fib6_clean_all(dev_net(dev), rt6_mtu_change_route, &arg);
 }
 
-static const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
+const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
 	[RTA_UNSPEC]		= { .strict_start_type = RTA_DPORT + 1 },
 	[RTA_GATEWAY]           = { .len = sizeof(struct in6_addr) },
 	[RTA_PREFSRC]		= { .len = sizeof(struct in6_addr) },
-- 
2.36.1

[PATCH net-next 2/2] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

The IPv6 multicast routing code previously implemented only the dump
variant of RTM_GETROUTE.  Implement single MFC item retrieval by copying
and adapting the respective IPv4 code.

Tested against FRRouting's IPv6 PIM stack.

Signed-off-by: David Lamparter <equinox@diac24.net>
---

Pretty much copypasted from IPv4.

---
 net/ipv6/ip6mr.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 118 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ec6e1509fc7c..a10bed171417 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -95,6 +95,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
 static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
 			      int cmd);
 static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack);
 static int ip6mr_rtm_dumproute(struct sk_buff *skb,
 			       struct netlink_callback *cb);
 static void mroute_clean_tables(struct mr_table *mrt, int flags);
@@ -1390,7 +1392,7 @@ int __init ip6_mr_init(void)
 	}
 #endif
 	err = rtnl_register_module(THIS_MODULE, RTNL_FAMILY_IP6MR, RTM_GETROUTE,
-				   NULL, ip6mr_rtm_dumproute, 0);
+				   ip6mr_rtm_getroute, ip6mr_rtm_dumproute, 0);
 	if (err == 0)
 		return 0;
 
@@ -2510,6 +2512,121 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
 	rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
 }
 
+static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
+					const struct nlmsghdr *nlh,
+					struct nlattr **tb,
+					struct netlink_ext_ack *extack)
+{
+	struct rtmsg *rtm;
+	int i, err;
+
+	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
+		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
+		return -EINVAL;
+	}
+
+	if (!netlink_strict_get_check(skb))
+		return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
+					      rtm_ipv6_policy, extack);
+
+	rtm = nlmsg_data(nlh);
+	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
+	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
+	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
+	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
+		NL_SET_ERR_MSG(extack, "ipv6: Invalid values in header for multicast route get request");
+		return -EINVAL;
+	}
+
+	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
+					    rtm_ipv6_policy, extack);
+	if (err)
+		return err;
+
+	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+		NL_SET_ERR_MSG(extack, "ipv6: rtm_src_len and rtm_dst_len must be 128 for IPv6");
+		return -EINVAL;
+	}
+
+	for (i = 0; i <= RTA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case RTA_SRC:
+		case RTA_DST:
+		case RTA_TABLE:
+			break;
+		default:
+			NL_SET_ERR_MSG(extack, "ipv6: Unsupported attribute in multicast route get request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct nlattr *tb[RTA_MAX + 1];
+	struct sk_buff *skb = NULL;
+	struct mfc6_cache *cache;
+	struct mr_table *mrt;
+	struct in6_addr src = {}, grp = {};
+	u32 tableid;
+	int err;
+
+	err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
+	if (err < 0)
+		goto errout;
+
+	if (tb[RTA_SRC])
+		src = nla_get_in6_addr(tb[RTA_SRC]);
+	if (tb[RTA_DST])
+		grp = nla_get_in6_addr(tb[RTA_DST]);
+	tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
+
+	mrt = ip6mr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
+	if (!mrt) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR table does not exist");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	/* entries are added/deleted only under RTNL */
+	rcu_read_lock();
+	cache = ip6mr_cache_find(mrt, &src, &grp);
+	rcu_read_unlock();
+	if (!cache) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR cache entry not found");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
+	if (!skb) {
+		err = -ENOBUFS;
+		goto errout_free;
+	}
+
+	err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
+				nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
+	if (err < 0)
+		goto errout_free;
+
+	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout:
+	return err;
+
+errout_free:
+	kfree_skb(skb);
+	goto errout;
+}
+
 static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nlmsghdr *nlh = cb->nlh;
-- 
2.36.1

Re: [PATCH net-next 2/2] net: ip6mr: add RTM_GETROUTE netlink op

[David Ahern]

On 7/1/22 1:58 AM, David Lamparter wrote:
> @@ -2510,6 +2512,121 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
>  	rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
>  }
>  
> +static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
> +					const struct nlmsghdr *nlh,
> +					struct nlattr **tb,
> +					struct netlink_ext_ack *extack)
> +{
> +	struct rtmsg *rtm;
> +	int i, err;
> +
> +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
> +		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
> +		return -EINVAL;
> +	}
> +
> +	if (!netlink_strict_get_check(skb))
> +		return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
> +					      rtm_ipv6_policy, extack);

Since this is new code, it always operates in strict mode.

> +
> +	rtm = nlmsg_data(nlh);
> +	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
> +	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
> +	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
> +	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
> +		NL_SET_ERR_MSG(extack, "ipv6: Invalid values in header for multicast route get request");
> +		return -EINVAL;
> +	}
> +
> +	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
> +					    rtm_ipv6_policy, extack);

nlmsg_parse here.

Re: [PATCH net-next 2/2] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

On Sun, Jul 03, 2022 at 01:07:33PM -0600, David Ahern wrote:
> On 7/1/22 1:58 AM, David Lamparter wrote:
[...]
> > +	if (!netlink_strict_get_check(skb))
> > +		return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
> > +					      rtm_ipv6_policy, extack);
>
> Since this is new code, it always operates in strict mode.
>
[...]
> > +	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
> > +					    rtm_ipv6_policy, extack);
>
> nlmsg_parse here.

Thanks for the feedback!  I've fixed the code, am currently retesting,
and will post a v2 shortly.


-David / equi

[PATCH net-next v2] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

The IPv6 multicast routing code previously implemented only the dump
variant of RTM_GETROUTE.  Implement single MFC item retrieval by copying
and adapting the respective IPv4 code.

Tested against FRRouting's IPv6 PIM stack.

Signed-off-by: David Lamparter <equinox@diac24.net>
Cc: David Ahern <dsahern@kernel.org>
---

v2: changeover to strict netlink attribute parsing.  Doing so actually
exposed a bunch of other issues, first and foremost that rtm_ipv6_policy
does not have RTA_SRC or RTA_DST.  This made reusing that policy rather
pointless so I changed it to use a separate rtm_ipv6_mr_policy.

Thanks again dsahern@ for the feedback on the previous version!

---
 net/ipv6/ip6mr.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 127 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ec6e1509fc7c..95dc366a2d9b 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -95,6 +95,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
 static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
 			      int cmd);
 static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack);
 static int ip6mr_rtm_dumproute(struct sk_buff *skb,
 			       struct netlink_callback *cb);
 static void mroute_clean_tables(struct mr_table *mrt, int flags);
@@ -1390,7 +1392,7 @@ int __init ip6_mr_init(void)
 	}
 #endif
 	err = rtnl_register_module(THIS_MODULE, RTNL_FAMILY_IP6MR, RTM_GETROUTE,
-				   NULL, ip6mr_rtm_dumproute, 0);
+				   ip6mr_rtm_getroute, ip6mr_rtm_dumproute, 0);
 	if (err == 0)
 		return 0;
 
@@ -2510,6 +2512,130 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
 	rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
 }
 
+const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
+	[RTA_UNSPEC]		= { .strict_start_type = RTA_UNSPEC },
+	[RTA_SRC]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+	[RTA_DST]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+	[RTA_TABLE]		= { .type = NLA_U32 },
+};
+
+static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
+					const struct nlmsghdr *nlh,
+					struct nlattr **tb,
+					struct netlink_ext_ack *extack)
+{
+	struct rtmsg *rtm;
+	int i, err;
+
+	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
+		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
+		return -EINVAL;
+	}
+
+	rtm = nlmsg_data(nlh);
+	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
+	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
+	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
+	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
+		NL_SET_ERR_MSG(extack,
+			       "ipv6: Invalid values in header for multicast route get request");
+		return -EINVAL;
+	}
+
+	err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_mr_policy,
+			  extack);
+	if (err)
+		return err;
+
+	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+		NL_SET_ERR_MSG(extack, "ipv6: rtm_src_len and rtm_dst_len must be 128 for IPv6");
+		return -EINVAL;
+	}
+
+	/* rtm_ipv6_mr_policy does not list other attributes right now, but
+	 * future changes may reuse rtm_ipv6_mr_policy with adding further
+	 * attrs.  Enforce the subset.
+	 */
+	for (i = 0; i <= RTA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case RTA_SRC:
+		case RTA_DST:
+		case RTA_TABLE:
+			break;
+		default:
+			NL_SET_ERR_MSG_ATTR(extack, tb[i],
+					    "ipv6: Unsupported attribute in multicast route get request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct nlattr *tb[RTA_MAX + 1];
+	struct sk_buff *skb = NULL;
+	struct mfc6_cache *cache;
+	struct mr_table *mrt;
+	struct in6_addr src = {}, grp = {};
+	u32 tableid;
+	int err;
+
+	err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
+	if (err < 0)
+		goto errout;
+
+	if (tb[RTA_SRC])
+		src = nla_get_in6_addr(tb[RTA_SRC]);
+	if (tb[RTA_DST])
+		grp = nla_get_in6_addr(tb[RTA_DST]);
+	tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
+
+	mrt = ip6mr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
+	if (!mrt) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR table does not exist");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	/* entries are added/deleted only under RTNL */
+	rcu_read_lock();
+	cache = ip6mr_cache_find(mrt, &src, &grp);
+	rcu_read_unlock();
+	if (!cache) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR cache entry not found");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
+	if (!skb) {
+		err = -ENOBUFS;
+		goto errout_free;
+	}
+
+	err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
+				nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
+	if (err < 0)
+		goto errout_free;
+
+	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout:
+	return err;
+
+errout_free:
+	kfree_skb(skb);
+	goto errout;
+}
+
 static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nlmsghdr *nlh = cb->nlh;
-- 
2.36.1

Re: [PATCH net-next v2] net: ip6mr: add RTM_GETROUTE netlink op

[Nikolay Aleksandrov]

On 04/07/2022 12:58, David Lamparter wrote:
> The IPv6 multicast routing code previously implemented only the dump
> variant of RTM_GETROUTE.  Implement single MFC item retrieval by copying
> and adapting the respective IPv4 code.
> 
> Tested against FRRouting's IPv6 PIM stack.
> 
> Signed-off-by: David Lamparter <equinox@diac24.net>
> Cc: David Ahern <dsahern@kernel.org>
> ---
> 
> v2: changeover to strict netlink attribute parsing.  Doing so actually
> exposed a bunch of other issues, first and foremost that rtm_ipv6_policy
> does not have RTA_SRC or RTA_DST.  This made reusing that policy rather
> pointless so I changed it to use a separate rtm_ipv6_mr_policy.
> 
> Thanks again dsahern@ for the feedback on the previous version!
> 
> ---
>  net/ipv6/ip6mr.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 127 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
> index ec6e1509fc7c..95dc366a2d9b 100644
> --- a/net/ipv6/ip6mr.c
> +++ b/net/ipv6/ip6mr.c
> @@ -95,6 +95,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
>  static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
>  			      int cmd);
>  static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
> +static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
> +			      struct netlink_ext_ack *extack);
>  static int ip6mr_rtm_dumproute(struct sk_buff *skb,
>  			       struct netlink_callback *cb);
>  static void mroute_clean_tables(struct mr_table *mrt, int flags);
> @@ -1390,7 +1392,7 @@ int __init ip6_mr_init(void)
>  	}
>  #endif
>  	err = rtnl_register_module(THIS_MODULE, RTNL_FAMILY_IP6MR, RTM_GETROUTE,
> -				   NULL, ip6mr_rtm_dumproute, 0);
> +				   ip6mr_rtm_getroute, ip6mr_rtm_dumproute, 0);
>  	if (err == 0)
>  		return 0;
>  
> @@ -2510,6 +2512,130 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
>  	rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
>  }
>  
> +const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
> +	[RTA_UNSPEC]		= { .strict_start_type = RTA_UNSPEC },

I don't think you need to add RTA_UNSPEC, nlmsg_parse() would reject it due to NL_VALIDATE_STRICT

> +	[RTA_SRC]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
> +	[RTA_DST]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
> +	[RTA_TABLE]		= { .type = NLA_U32 },
> +};
> +
> +static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
> +					const struct nlmsghdr *nlh,
> +					struct nlattr **tb,
> +					struct netlink_ext_ack *extack)
> +{
> +	struct rtmsg *rtm;
> +	int i, err;
> +
> +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
> +		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
> +		return -EINVAL;
> +	}

I think you can drop this check if you...

> +
> +	rtm = nlmsg_data(nlh);
> +	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
> +	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
> +	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
> +	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
> +		NL_SET_ERR_MSG(extack,
> +			       "ipv6: Invalid values in header for multicast route get request");
> +		return -EINVAL;
> +	}

...move these after nlmsg_parse() because it already does the hdrlen check for you

> +
> +	err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_mr_policy,
> +			  extack);
> +	if (err)
> +		return err;
> +
> +	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
> +	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
> +		NL_SET_ERR_MSG(extack, "ipv6: rtm_src_len and rtm_dst_len must be 128 for IPv6");
> +		return -EINVAL;
> +	}
> +
> +	/* rtm_ipv6_mr_policy does not list other attributes right now, but
> +	 * future changes may reuse rtm_ipv6_mr_policy with adding further
> +	 * attrs.  Enforce the subset.
> +	 */
> +	for (i = 0; i <= RTA_MAX; i++) {
> +		if (!tb[i])
> +			continue;
> +
> +		switch (i) {
> +		case RTA_SRC:
> +		case RTA_DST:
> +		case RTA_TABLE:
> +			break;
> +		default:
> +			NL_SET_ERR_MSG_ATTR(extack, tb[i],
> +					    "ipv6: Unsupported attribute in multicast route get request");
> +			return -EINVAL;
> +		}
> +	}

I think you can skip this loop as well, nlmsg_parse() shouldn't allow attributes that
don't have policy defined when policy is provided (i.e. they should show up as NLA_UNSPEC
and you should get "Error: Unknown attribute type.").

> +
> +	return 0;
> +}
> +
> +static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
> +			      struct netlink_ext_ack *extack)
> +{
> +	struct net *net = sock_net(in_skb->sk);
> +	struct nlattr *tb[RTA_MAX + 1];
> +	struct sk_buff *skb = NULL;
> +	struct mfc6_cache *cache;
> +	struct mr_table *mrt;
> +	struct in6_addr src = {}, grp = {};

reverse xmas tree order

> +	u32 tableid;
> +	int err;
> +
> +	err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
> +	if (err < 0)
> +		goto errout;
> +
> +	if (tb[RTA_SRC])
> +		src = nla_get_in6_addr(tb[RTA_SRC]);
> +	if (tb[RTA_DST])
> +		grp = nla_get_in6_addr(tb[RTA_DST]);
> +	tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
> +
> +	mrt = ip6mr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
> +	if (!mrt) {
> +		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR table does not exist");
> +		err = -ENOENT;
> +		goto errout_free;
> +	}
> +
> +	/* entries are added/deleted only under RTNL */
> +	rcu_read_lock();
> +	cache = ip6mr_cache_find(mrt, &src, &grp);
> +	rcu_read_unlock();
> +	if (!cache) {
> +		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR cache entry not found");
> +		err = -ENOENT;
> +		goto errout_free;
> +	}
> +
> +	skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
> +	if (!skb) {
> +		err = -ENOBUFS;
> +		goto errout_free;
> +	}
> +
> +	err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
> +				nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
> +	if (err < 0)
> +		goto errout_free;
> +
> +	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
> +
> +errout:
> +	return err;
> +
> +errout_free:
> +	kfree_skb(skb);
> +	goto errout;
> +}
> +
>  static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
>  {
>  	const struct nlmsghdr *nlh = cb->nlh;

Re: [PATCH net-next v2] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

On Mon, Jul 04, 2022 at 01:22:36PM +0300, Nikolay Aleksandrov wrote:
> On 04/07/2022 12:58, David Lamparter wrote:
> > +const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
> > +	[RTA_UNSPEC]		= { .strict_start_type = RTA_UNSPEC },
> 
> I don't think you need to add RTA_UNSPEC, nlmsg_parse() would reject
> it due to NL_VALIDATE_STRICT

Will remove it.

> > +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
> > +		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
> > +		return -EINVAL;
> > +	}
> 
> I think you can drop this check if you...
> 
> > +
> > +	rtm = nlmsg_data(nlh);
> > +	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
> > +	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
> > +	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
> > +	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
> > +		NL_SET_ERR_MSG(extack,
> > +			       "ipv6: Invalid values in header for multicast route get request");
> > +		return -EINVAL;
> > +	}
> 
> ...move these after nlmsg_parse() because it already does the hdrlen
> check for you

Indeed it does.  Moving it down.

[...]
> > +	/* rtm_ipv6_mr_policy does not list other attributes right now, but
> > +	 * future changes may reuse rtm_ipv6_mr_policy with adding further
> > +	 * attrs.  Enforce the subset.
> > +	 */
> > +	for (i = 0; i <= RTA_MAX; i++) {
> > +		if (!tb[i])
> > +			continue;
> > +
> > +		switch (i) {
> > +		case RTA_SRC:
> > +		case RTA_DST:
> > +		case RTA_TABLE:
> > +			break;
> > +		default:
> > +			NL_SET_ERR_MSG_ATTR(extack, tb[i],
> > +					    "ipv6: Unsupported attribute in multicast route get request");
> > +			return -EINVAL;
> > +		}
> > +	}
> 
> I think you can skip this loop as well, nlmsg_parse() shouldn't allow attributes that
> don't have policy defined when policy is provided (i.e. they should show up as NLA_UNSPEC
> and you should get "Error: Unknown attribute type.").

I left it in with the comment above:

> > +	/* rtm_ipv6_mr_policy does not list other attributes right now, but
> > +	 * future changes may reuse rtm_ipv6_mr_policy with adding further
> > +	 * attrs.  Enforce the subset.
> > +	 */

... to try and avoid silently starting to accept more attributes if/when
future patches add other netlink operations reusing the same policy but
with adding new attributes.

But I don't feel particularly about this - shall I remove it?  (just
confirming with the rationale above)

> > +	struct net *net = sock_net(in_skb->sk);
> > +	struct nlattr *tb[RTA_MAX + 1];
> > +	struct sk_buff *skb = NULL;
> > +	struct mfc6_cache *cache;
> > +	struct mr_table *mrt;
> > +	struct in6_addr src = {}, grp = {};
> 
> reverse xmas tree order

Ah.  Wasn't aware of that coding style aspect.  Fixing.

Thanks for the review!


-David/equi

Re: [PATCH net-next v2] net: ip6mr: add RTM_GETROUTE netlink op

[Nikolay Aleksandrov]

On 04/07/2022 13:38, David Lamparter wrote:
> On Mon, Jul 04, 2022 at 01:22:36PM +0300, Nikolay Aleksandrov wrote:
>> On 04/07/2022 12:58, David Lamparter wrote:
>>> +const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
>>> +	[RTA_UNSPEC]		= { .strict_start_type = RTA_UNSPEC },
>>
>> I don't think you need to add RTA_UNSPEC, nlmsg_parse() would reject
>> it due to NL_VALIDATE_STRICT
> 
> Will remove it.
> 
>>> +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
>>> +		NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
>>> +		return -EINVAL;
>>> +	}
>>
>> I think you can drop this check if you...
>>
>>> +
>>> +	rtm = nlmsg_data(nlh);
>>> +	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
>>> +	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
>>> +	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
>>> +	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
>>> +		NL_SET_ERR_MSG(extack,
>>> +			       "ipv6: Invalid values in header for multicast route get request");
>>> +		return -EINVAL;
>>> +	}
>>
>> ...move these after nlmsg_parse() because it already does the hdrlen
>> check for you
> 
> Indeed it does.  Moving it down.
> 
> [...]
>>> +	/* rtm_ipv6_mr_policy does not list other attributes right now, but
>>> +	 * future changes may reuse rtm_ipv6_mr_policy with adding further
>>> +	 * attrs.  Enforce the subset.
>>> +	 */
>>> +	for (i = 0; i <= RTA_MAX; i++) {
>>> +		if (!tb[i])
>>> +			continue;
>>> +
>>> +		switch (i) {
>>> +		case RTA_SRC:
>>> +		case RTA_DST:
>>> +		case RTA_TABLE:
>>> +			break;
>>> +		default:
>>> +			NL_SET_ERR_MSG_ATTR(extack, tb[i],
>>> +					    "ipv6: Unsupported attribute in multicast route get request");
>>> +			return -EINVAL;
>>> +		}
>>> +	}
>>
>> I think you can skip this loop as well, nlmsg_parse() shouldn't allow attributes that
>> don't have policy defined when policy is provided (i.e. they should show up as NLA_UNSPEC
>> and you should get "Error: Unknown attribute type.").
> 
> I left it in with the comment above:
> 
>>> +	/* rtm_ipv6_mr_policy does not list other attributes right now, but
>>> +	 * future changes may reuse rtm_ipv6_mr_policy with adding further
>>> +	 * attrs.  Enforce the subset.
>>> +	 */
> 
> ... to try and avoid silently starting to accept more attributes if/when
> future patches add other netlink operations reusing the same policy but
> with adding new attributes.
> 

They really should be using policies specific to their actions with only the allowed
attributes. Re-using this policy is ok only if those match, otherwise it's a bug IMO.

> But I don't feel particularly about this - shall I remove it?  (just
> confirming with the rationale above)
> 

I don't have a preference either, IMO if anyone re-uses this policy without making
sure the same attributes and types are needed is adding buggy code. Actually the thing
that I like about keeping the loop is the more specific error message, let's see what
others think.

>>> +	struct net *net = sock_net(in_skb->sk);
>>> +	struct nlattr *tb[RTA_MAX + 1];
>>> +	struct sk_buff *skb = NULL;
>>> +	struct mfc6_cache *cache;
>>> +	struct mr_table *mrt;
>>> +	struct in6_addr src = {}, grp = {};
>>
>> reverse xmas tree order
> 
> Ah.  Wasn't aware of that coding style aspect.  Fixing.
> 
> Thanks for the review!
> 
> 
> -David/equi

[PATCH net-next v3] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

The IPv6 multicast routing code previously implemented only the dump
variant of RTM_GETROUTE.  Implement single MFC item retrieval by copying
and adapting the respective IPv4 code.

Tested against FRRouting's IPv6 PIM stack.

Signed-off-by: David Lamparter <equinox@diac24.net>
Cc: David Ahern <dsahern@kernel.org>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
---

v3: reorder/remove some redundant bits, fix style.  Thanks Nikolay for
pointing them out.  The "extra" validation loop is still there for the
time being;  happy to drop it if that's the consensus.

v2: changeover to strict netlink attribute parsing.  Doing so actually
exposed a bunch of other issues, first and foremost that rtm_ipv6_policy
does not have RTA_SRC or RTA_DST.  This made reusing that policy rather
pointless so I changed it to use a separate rtm_ipv6_mr_policy.

Thanks again dsahern@ for the feedback on the previous version!

---
 net/ipv6/ip6mr.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 121 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ec6e1509fc7c..9909ff77f5a6 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -95,6 +95,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
 static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
 			      int cmd);
 static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack);
 static int ip6mr_rtm_dumproute(struct sk_buff *skb,
 			       struct netlink_callback *cb);
 static void mroute_clean_tables(struct mr_table *mrt, int flags);
@@ -1390,7 +1392,7 @@ int __init ip6_mr_init(void)
 	}
 #endif
 	err = rtnl_register_module(THIS_MODULE, RTNL_FAMILY_IP6MR, RTM_GETROUTE,
-				   NULL, ip6mr_rtm_dumproute, 0);
+				   ip6mr_rtm_getroute, ip6mr_rtm_dumproute, 0);
 	if (err == 0)
 		return 0;
 
@@ -2510,6 +2512,124 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
 	rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
 }
 
+const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
+	[RTA_SRC]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+	[RTA_DST]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+	[RTA_TABLE]		= { .type = NLA_U32 },
+};
+
+static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
+					const struct nlmsghdr *nlh,
+					struct nlattr **tb,
+					struct netlink_ext_ack *extack)
+{
+	struct rtmsg *rtm;
+	int i, err;
+
+	err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_mr_policy,
+			  extack);
+	if (err)
+		return err;
+
+	rtm = nlmsg_data(nlh);
+	if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
+	    (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
+	    rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
+	    rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
+		NL_SET_ERR_MSG(extack,
+			       "ipv6: Invalid values in header for multicast route get request");
+		return -EINVAL;
+	}
+
+	if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+	    (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+		NL_SET_ERR_MSG(extack, "ipv6: rtm_src_len and rtm_dst_len must be 128 for IPv6");
+		return -EINVAL;
+	}
+
+	/* rtm_ipv6_mr_policy does not list other attributes right now, but
+	 * future changes may reuse rtm_ipv6_mr_policy with adding further
+	 * attrs.  Enforce the subset.
+	 */
+	for (i = 0; i <= RTA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case RTA_SRC:
+		case RTA_DST:
+		case RTA_TABLE:
+			break;
+		default:
+			NL_SET_ERR_MSG_ATTR(extack, tb[i],
+					    "ipv6: Unsupported attribute in multicast route get request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct in6_addr src = {}, grp = {};
+	struct nlattr *tb[RTA_MAX + 1];
+	struct sk_buff *skb = NULL;
+	struct mfc6_cache *cache;
+	struct mr_table *mrt;
+	u32 tableid;
+	int err;
+
+	err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
+	if (err < 0)
+		goto errout;
+
+	if (tb[RTA_SRC])
+		src = nla_get_in6_addr(tb[RTA_SRC]);
+	if (tb[RTA_DST])
+		grp = nla_get_in6_addr(tb[RTA_DST]);
+	tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
+
+	mrt = ip6mr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
+	if (!mrt) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR table does not exist");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	/* entries are added/deleted only under RTNL */
+	rcu_read_lock();
+	cache = ip6mr_cache_find(mrt, &src, &grp);
+	rcu_read_unlock();
+	if (!cache) {
+		NL_SET_ERR_MSG_MOD(extack, "ipv6 MR cache entry not found");
+		err = -ENOENT;
+		goto errout_free;
+	}
+
+	skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
+	if (!skb) {
+		err = -ENOBUFS;
+		goto errout_free;
+	}
+
+	err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
+				nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
+	if (err < 0)
+		goto errout_free;
+
+	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout:
+	return err;
+
+errout_free:
+	kfree_skb(skb);
+	goto errout;
+}
+
 static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nlmsghdr *nlh = cb->nlh;
-- 
2.36.1

Re: [PATCH net-next v3] net: ip6mr: add RTM_GETROUTE netlink op

[Jakub Kicinski]

On Mon,  4 Jul 2022 12:52:23 +0200 David Lamparter wrote:
> +const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
> +	[RTA_SRC]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
> +	[RTA_DST]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
> +	[RTA_TABLE]		= { .type = NLA_U32 },
> +};

net/ipv6/ip6mr.c:2515:25: warning: symbol 'rtm_ipv6_mr_policy' was not declared. Should it be static?

Re: [PATCH net-next v2] net: ip6mr: add RTM_GETROUTE netlink op

[kernel test robot]

Hi David,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/David-Lamparter/net-ip6mr-add-RTM_GETROUTE-netlink-op/20220704-180235
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git d0bf1fe6454e976e39bc1524b9159fa2c0fcf321
config: x86_64-rhel-8.3-kselftests (https://download.01.org/0day-ci/archive/20220705/202207051158.Vo7Qj6VM-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-39-gce1a6720-dirty
        # https://github.com/intel-lab-lkp/linux/commit/ab5f843c60bd5c7ef119d8be390e67f9c43d8d3b
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review David-Lamparter/net-ip6mr-add-RTM_GETROUTE-netlink-op/20220704-180235
        git checkout ab5f843c60bd5c7ef119d8be390e67f9c43d8d3b
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 SHELL=/bin/bash net/ipv6/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)
>> net/ipv6/ip6mr.c:2515:25: sparse: sparse: symbol 'rtm_ipv6_mr_policy' was not declared. Should it be static?
   net/ipv6/ip6mr.c:407:13: sparse: sparse: context imbalance in 'ip6mr_vif_seq_start' - different lock contexts for basic block
   net/ipv6/ip6mr.c: note: in included file (through include/linux/rculist.h, include/linux/pid.h, include/linux/sched.h, ...):
   include/linux/rcupdate.h:726:9: sparse: sparse: context imbalance in 'ip6_mr_forward' - unexpected unlock
   net/ipv6/ip6mr.c: note: in included file (through include/linux/mroute6.h):
   include/linux/mroute_base.h:432:31: sparse: sparse: context imbalance in 'mr_mfc_seq_stop' - unexpected unlock

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH net-next v3] net: ip6mr: add RTM_GETROUTE netlink op

[David Lamparter]

On Mon, Jul 04, 2022 at 07:50:11PM -0700, Jakub Kicinski wrote:
> On Mon,  4 Jul 2022 12:52:23 +0200 David Lamparter wrote:
> > +const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
> > +	[RTA_SRC]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
> > +	[RTA_DST]		= NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
> > +	[RTA_TABLE]		= { .type = NLA_U32 },
> > +};
> 
> net/ipv6/ip6mr.c:2515:25: warning: symbol 'rtm_ipv6_mr_policy' was not declared. Should it be static?

As the great poet of our time, Homer Simpson, would say:  "d'oh"

After thinking about it for a bit more, I agree with Nikolay that the
policy shouldn't be reused, so apart from adding the "static" here I'll
also rename it to clarify it's the RTM_GETROUTE policy.


-equi/David