[PATCH net-next v2 0/6] netconsole: validate a target's IP address configuration

[PATCH net-next v2 0/6] netconsole: validate a target's IP address configuration

[Gustavo Luiz Duarte]

This series adds two validations to the target configuration when the
user tries to enable it: first whether remote_ip was set, and second
whether local_ip and remote_ip address families match. Refuse to enable
the target if any of those validations fail.

These validations are already done for the target passed on the
command-line, so this aligns dynamic targets with the command-line
behavior.

The first two patches replace the per-target 'ipv6' flag with a
per-address 'family' field, which makes it easier to detect these error
conditions. Patches 3 and 4 implement the actual validations.

Patches 5 and 6 are follow-ups from review of v1: move inet_addr from
netpoll.h into netconsole.c, and show an unset address as an empty
string rather than "0.0.0.0".

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
Changes in v2:
- Show empty string in configfs for an unset IP address
- Moved inet_addr definition from netpoll.h to netconsole.c
- Moved address checks out of rtnl_lock()
- Link to v1: https://patch.msgid.link/20260805-netcons_ipv6-v1-0-170a35b92da1@gmail.com

To: Breno Leitao <leitao@debian.org>
To: Andrew Lunn <andrew+netdev@lunn.ch>
To: "David S. Miller" <davem@davemloft.net>
To: Eric Dumazet <edumazet@google.com>
To: Jakub Kicinski <kuba@kernel.org>
To: Paolo Abeni <pabeni@redhat.com>
To: Simon Horman <horms@kernel.org>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

---
Gustavo Luiz Duarte (6):
      netconsole: add an address family to struct inet_addr
      netconsole: use the address family instead of the ipv6 flag
      netconsole: reject enabling a target with no remote IP address
      netconsole: reject a target mixing IPv4 and IPv6 addresses
      netconsole: show empty string for an unset IP address
      netconsole: move struct inet_addr into netconsole.c

 drivers/net/netconsole.c | 132 +++++++++++++++++++++++------------------------
 include/linux/netpoll.h  |   5 --
 2 files changed, 65 insertions(+), 72 deletions(-)
---
base-commit: a23b36233d4103def55dc8cf65698106d0bd1e62
change-id: 20260730-netcons_ipv6-565d55f55729

Best regards,
--  
Gustavo Luiz Duarte <gustavold@gmail.com>

[PATCH net-next v2 1/6] netconsole: add an address family to struct inet_addr

[Gustavo Luiz Duarte]

netconsole_target stores a single 'bool ipv6' to denote the target's
address family. This makes it hard to detect conditions like "no address
set" or ipv4/ipv6 mixup between local_ip and remote_ip.

Add a 'family' field to inet_addr so each address stores its own address
family: AF_UNSPEC while unset, else AF_INET or AF_INET6.

Nothing reads the new field yet. The next patch switches the users over
and removes the bool. No functional change.

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
 drivers/net/netconsole.c | 24 +++++++++++++++---------
 include/linux/netpoll.h  | 10 +++++++---
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 03913302328c..94a662c7369a 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -212,7 +212,7 @@ struct netconsole_target {
 	bool			extended;
 	bool			release;
 	struct netpoll		np;
-	union inet_addr		local_ip, remote_ip;
+	struct inet_addr	local_ip, remote_ip;
 	bool			ipv6;
 	u16			local_port, remote_port;
 	u8			remote_mac[ETH_ALEN];
@@ -415,6 +415,7 @@ static int netcons_take_ipv6(struct netconsole_target *nt,
 				continue;
 			/* Got the IP, let's return */
 			nt->local_ip.in6 = ifp->addr;
+			nt->local_ip.family = AF_INET6;
 			err = 0;
 			break;
 		}
@@ -456,6 +457,7 @@ static int netcons_take_ipv4(struct netconsole_target *nt,
 	}
 
 	nt->local_ip.ip = ifa->ifa_local;
+	nt->local_ip.family = AF_INET;
 	np_info(np, "local IP %pI4\n", &nt->local_ip.ip);
 
 	return 0;
@@ -728,10 +730,10 @@ static void netconsole_print_banner(struct netconsole_target *nt)
 	np_info(np, "remote ethernet address %pM\n", nt->remote_mac);
 }
 
-/* Parse the string and populate the `inet_addr` union. Return 0 if IPv4 is
+/* Parse the string and populate the `inet_addr` struct. Return 0 if IPv4 is
  * populated, 1 if IPv6 is populated, and -1 upon failure.
  */
-static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
+static int netpoll_parse_ip_addr(const char *str, struct inet_addr *addr)
 {
 	const char *end = NULL;
 	int len;
@@ -743,14 +745,18 @@ static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 	if (str[len - 1] == '\n')
 		len -= 1;
 
-	if (in4_pton(str, len, (void *)addr, -1, &end) > 0 &&
-	    (!end || *end == 0 || *end == '\n'))
+	if (in4_pton(str, len, (void *)&addr->ip, -1, &end) > 0 &&
+	    (!end || *end == 0 || *end == '\n')) {
+		addr->family = AF_INET;
 		return 0;
+	}
 
 	if (IS_ENABLED(CONFIG_IPV6) &&
-	    in6_pton(str, len, (void *)addr, -1, &end) > 0 &&
-	    (!end || *end == 0 || *end == '\n'))
+	    in6_pton(str, len, (void *)&addr->in6, -1, &end) > 0 &&
+	    (!end || *end == 0 || *end == '\n')) {
+		addr->family = AF_INET6;
 		return 1;
+	}
 
 	return -1;
 }
@@ -858,7 +864,7 @@ static ssize_t local_ip_show(struct config_item *item, char *buf)
 	if (nt->ipv6)
 		return sysfs_emit(buf, "%pI6c\n", &nt->local_ip.in6);
 	else
-		return sysfs_emit(buf, "%pI4\n", &nt->local_ip);
+		return sysfs_emit(buf, "%pI4\n", &nt->local_ip.ip);
 }
 
 static ssize_t remote_ip_show(struct config_item *item, char *buf)
@@ -868,7 +874,7 @@ static ssize_t remote_ip_show(struct config_item *item, char *buf)
 	if (nt->ipv6)
 		return sysfs_emit(buf, "%pI6c\n", &nt->remote_ip.in6);
 	else
-		return sysfs_emit(buf, "%pI4\n", &nt->remote_ip);
+		return sysfs_emit(buf, "%pI4\n", &nt->remote_ip.ip);
 }
 
 static ssize_t local_mac_show(struct config_item *item, char *buf)
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 1c6b1eec5efd..de97f001a0f9 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -16,9 +16,13 @@
 #include <linux/ip.h>
 #include <linux/udp.h>
 
-union inet_addr {
-	__be32		ip;
-	struct in6_addr	in6;
+struct inet_addr {
+	/* Address family: AF_UNSPEC when unset, else AF_INET or AF_INET6 */
+	u8			family;
+	union {
+		__be32		ip;
+		struct in6_addr	in6;
+	};
 };
 
 struct netpoll {

-- 
2.55.0

[PATCH net-next v2 2/6] netconsole: use the address family instead of the ipv6 flag

[Gustavo Luiz Duarte]

Now that we have the address family in inet_addr, use that and remove
nt->ipv6.

We no longer need netcons_local_ip_unset() to check that all bytes are
zeroes, as that is now denoted by (family == AF_UNSPEC).

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
 drivers/net/netconsole.c | 82 ++++++++++++++----------------------------------
 1 file changed, 23 insertions(+), 59 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 94a662c7369a..070bae7b4fd7 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -181,7 +181,6 @@ enum target_state {
  *		local_mac	(read-only)
  * @local_ip:	Source IP address of the target (read-write).
  * @remote_ip:	Destination IP address of the target (read-write).
- * @ipv6:	Whether the target addresses are IPv6 (read-write).
  * @local_port:	Source UDP port of the target (read-write).
  * @remote_port: Destination UDP port of the target (read-write).
  * @remote_mac:	Destination ethernet address of the target (read-write).
@@ -213,7 +212,6 @@ struct netconsole_target {
 	bool			release;
 	struct netpoll		np;
 	struct inet_addr	local_ip, remote_ip;
-	bool			ipv6;
 	u16			local_port, remote_port;
 	u8			remote_mac[ETH_ALEN];
 	/* protected by target_list_lock; +1 gives scnprintf() room for its
@@ -463,23 +461,6 @@ static int netcons_take_ipv4(struct netconsole_target *nt,
 	return 0;
 }
 
-/*
- * Test whether the caller left nt->local_ip unset, so that
- * netcons_netpoll_setup() should auto-populate it from the egress device.
- *
- * nt->local_ip is a union of __be32 (IPv4) and struct in6_addr (IPv6),
- * so an IPv6 address whose first 4 bytes are zero (e.g. ::1, ::2,
- * IPv4-mapped ::ffff:a.b.c.d) must not be tested via the IPv4 arm —
- * doing so would misclassify a caller-supplied address as unset and
- * silently overwrite it with whatever address the device exposes.
- */
-static bool netcons_local_ip_unset(const struct netconsole_target *nt)
-{
-	if (nt->ipv6)
-		return ipv6_addr_any(&nt->local_ip.in6);
-	return !nt->local_ip.ip;
-}
-
 static int netcons_netpoll_setup(struct netconsole_target *nt)
 {
 	struct net *net = current->nsproxy->net_ns;
@@ -525,16 +506,13 @@ static int netcons_netpoll_setup(struct netconsole_target *nt)
 		rtnl_lock();
 	}
 
-	if (netcons_local_ip_unset(nt)) {
-		if (!nt->ipv6) {
-			err = netcons_take_ipv4(nt, ndev);
-			if (err)
-				goto put;
-		} else {
+	if (nt->local_ip.family == AF_UNSPEC) {
+		if (nt->remote_ip.family == AF_INET6)
 			err = netcons_take_ipv6(nt, ndev);
-			if (err)
-				goto put;
-		}
+		else
+			err = netcons_take_ipv4(nt, ndev);
+		if (err)
+			goto put;
 		ip_overwritten = true;
 	}
 
@@ -716,22 +694,22 @@ static void netconsole_print_banner(struct netconsole_target *nt)
 	struct netpoll *np = &nt->np;
 
 	np_info(np, "local port %d\n", nt->local_port);
-	if (nt->ipv6)
+	if (nt->local_ip.family == AF_INET6)
 		np_info(np, "local IPv6 address %pI6c\n", &nt->local_ip.in6);
 	else
 		np_info(np, "local IPv4 address %pI4\n", &nt->local_ip.ip);
 	np_info(np, "interface name '%s'\n", np->dev_name);
 	np_info(np, "local ethernet address '%pM'\n", np->dev_mac);
 	np_info(np, "remote port %d\n", nt->remote_port);
-	if (nt->ipv6)
+	if (nt->remote_ip.family == AF_INET6)
 		np_info(np, "remote IPv6 address %pI6c\n", &nt->remote_ip.in6);
 	else
 		np_info(np, "remote IPv4 address %pI4\n", &nt->remote_ip.ip);
 	np_info(np, "remote ethernet address %pM\n", nt->remote_mac);
 }
 
-/* Parse the string and populate the `inet_addr` struct. Return 0 if IPv4 is
- * populated, 1 if IPv6 is populated, and -1 upon failure.
+/* Parse the string and populate the `inet_addr` struct. Return 0 on success
+ * and -1 upon failure.
  */
 static int netpoll_parse_ip_addr(const char *str, struct inet_addr *addr)
 {
@@ -755,7 +733,7 @@ static int netpoll_parse_ip_addr(const char *str, struct inet_addr *addr)
 	    in6_pton(str, len, (void *)&addr->in6, -1, &end) > 0 &&
 	    (!end || *end == 0 || *end == '\n')) {
 		addr->family = AF_INET6;
-		return 1;
+		return 0;
 	}
 
 	return -1;
@@ -861,7 +839,7 @@ static ssize_t local_ip_show(struct config_item *item, char *buf)
 {
 	struct netconsole_target *nt = to_target(item);
 
-	if (nt->ipv6)
+	if (nt->local_ip.family == AF_INET6)
 		return sysfs_emit(buf, "%pI6c\n", &nt->local_ip.in6);
 	else
 		return sysfs_emit(buf, "%pI4\n", &nt->local_ip.ip);
@@ -871,7 +849,7 @@ static ssize_t remote_ip_show(struct config_item *item, char *buf)
 {
 	struct netconsole_target *nt = to_target(item);
 
-	if (nt->ipv6)
+	if (nt->remote_ip.family == AF_INET6)
 		return sysfs_emit(buf, "%pI6c\n", &nt->remote_ip.in6);
 	else
 		return sysfs_emit(buf, "%pI4\n", &nt->remote_ip.ip);
@@ -1219,7 +1197,6 @@ static ssize_t local_ip_store(struct config_item *item, const char *buf,
 {
 	struct netconsole_target *nt = to_target(item);
 	ssize_t ret = -EINVAL;
-	int ipv6;
 
 	dynamic_netconsole_mutex_lock();
 	if (nt->state == STATE_ENABLED) {
@@ -1228,10 +1205,8 @@ static ssize_t local_ip_store(struct config_item *item, const char *buf,
 		goto out_unlock;
 	}
 
-	ipv6 = netpoll_parse_ip_addr(buf, &nt->local_ip);
-	if (ipv6 == -1)
+	if (netpoll_parse_ip_addr(buf, &nt->local_ip) < 0)
 		goto out_unlock;
-	nt->ipv6 = !!ipv6;
 
 	ret = count;
 out_unlock:
@@ -1244,7 +1219,6 @@ static ssize_t remote_ip_store(struct config_item *item, const char *buf,
 {
 	struct netconsole_target *nt = to_target(item);
 	ssize_t ret = -EINVAL;
-	int ipv6;
 
 	dynamic_netconsole_mutex_lock();
 	if (nt->state == STATE_ENABLED) {
@@ -1253,10 +1227,8 @@ static ssize_t remote_ip_store(struct config_item *item, const char *buf,
 		goto out_unlock;
 	}
 
-	ipv6 = netpoll_parse_ip_addr(buf, &nt->remote_ip);
-	if (ipv6 == -1)
+	if (netpoll_parse_ip_addr(buf, &nt->remote_ip) < 0)
 		goto out_unlock;
-	nt->ipv6 = !!ipv6;
 
 	ret = count;
 out_unlock:
@@ -2067,7 +2039,7 @@ static void netpoll_udp_checksum(struct netconsole_target *nt,
 
 	/* check needs to be set, since it will be consumed in csum_partial */
 	udph->check = 0;
-	if (nt->ipv6)
+	if (nt->remote_ip.family == AF_INET6)
 		udph->check = csum_ipv6_magic(&nt->local_ip.in6,
 					      &nt->remote_ip.in6,
 					      udp_len, IPPROTO_UDP,
@@ -2108,7 +2080,7 @@ static void push_eth(struct netconsole_target *nt, struct sk_buff *skb)
 	skb_reset_mac_header(skb);
 	ether_addr_copy(eth->h_source, np->dev->dev_addr);
 	ether_addr_copy(eth->h_dest, nt->remote_mac);
-	if (nt->ipv6)
+	if (nt->remote_ip.family == AF_INET6)
 		eth->h_proto = htons(ETH_P_IPV6);
 	else
 		eth->h_proto = htons(ETH_P_IP);
@@ -2177,7 +2149,7 @@ static int netpoll_send_udp(struct netconsole_target *nt, const char *msg,
 		WARN_ON_ONCE(!irqs_disabled());
 
 	udp_len = len + sizeof(struct udphdr);
-	if (nt->ipv6)
+	if (nt->remote_ip.family == AF_INET6)
 		ip_len = udp_len + sizeof(struct ipv6hdr);
 	else
 		ip_len = udp_len + sizeof(struct iphdr);
@@ -2193,7 +2165,7 @@ static int netpoll_send_udp(struct netconsole_target *nt, const char *msg,
 	skb_put(skb, len);
 
 	push_udp(nt, skb, len);
-	if (nt->ipv6)
+	if (nt->remote_ip.family == AF_INET6)
 		push_ipv6(nt, skb, len);
 	else
 		push_ipv4(nt, skb, len);
@@ -2513,10 +2485,8 @@ __releases(&target_list_lock)
 static int netconsole_parser_cmdline(struct netconsole_target *nt, char *opt)
 {
 	struct netpoll *np = &nt->np;
-	bool ipversion_set = false;
 	char *cur = opt;
 	char *delim;
-	int ipv6;
 
 	if (*cur != '@') {
 		delim = strchr(cur, '@');
@@ -2530,16 +2500,12 @@ static int netconsole_parser_cmdline(struct netconsole_target *nt, char *opt)
 	cur++;
 
 	if (*cur != '/') {
-		ipversion_set = true;
 		delim = strchr(cur, '/');
 		if (!delim)
 			goto parse_failed;
 		*delim = 0;
-		ipv6 = netpoll_parse_ip_addr(cur, &nt->local_ip);
-		if (ipv6 < 0)
+		if (netpoll_parse_ip_addr(cur, &nt->local_ip) < 0)
 			goto parse_failed;
-		else
-			nt->ipv6 = (bool)ipv6;
 		cur = delim;
 	}
 	cur++;
@@ -2581,13 +2547,11 @@ static int netconsole_parser_cmdline(struct netconsole_target *nt, char *opt)
 	if (!delim)
 		goto parse_failed;
 	*delim = 0;
-	ipv6 = netpoll_parse_ip_addr(cur, &nt->remote_ip);
-	if (ipv6 < 0)
+	if (netpoll_parse_ip_addr(cur, &nt->remote_ip) < 0)
 		goto parse_failed;
-	else if (ipversion_set && nt->ipv6 != (bool)ipv6)
+	if (nt->local_ip.family != AF_UNSPEC &&
+	    nt->local_ip.family != nt->remote_ip.family)
 		goto parse_failed;
-	else
-		nt->ipv6 = (bool)ipv6;
 	cur = delim + 1;
 
 	if (*cur != 0) {

-- 
2.55.0

[PATCH net-next v2 3/6] netconsole: reject enabling a target with no remote IP address

[Gustavo Luiz Duarte]

The command-line path already requires a remote address, but if a user
creates a dynamic target and enables it without setting a remote
address, we currently try sending netconsole traffic to "0.0.0.0".

Refuse to enable a target if the remote address is unset.

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
 drivers/net/netconsole.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 070bae7b4fd7..7fcdff53b3a4 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -470,6 +470,11 @@ static int netcons_netpoll_setup(struct netconsole_target *nt)
 	bool ip_overwritten = false;
 	int err;
 
+	if (nt->remote_ip.family == AF_UNSPEC) {
+		np_err(np, "remote IP address not configured, aborting\n");
+		return -EDESTADDRREQ;
+	}
+
 	rtnl_lock();
 	if (np->dev_name[0])
 		ndev = __dev_get_by_name(net, np->dev_name);

-- 
2.55.0

[PATCH net-next v2 4/6] netconsole: reject a target mixing IPv4 and IPv6 addresses

[Gustavo Luiz Duarte]

The local_ip and remote_ip configfs attributes are written independently
and nothing stops a user from mixing ipv4 and ipv6. This leads to an
ipv4 address being zero-extended into an ipv6 header or an ipv6 address
being truncated to its first 4 bytes for an ipv4 header.

The command-line parser already refuses such a mismatch. This adds a
similar check when a dynamic target is being enabled.

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
 drivers/net/netconsole.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 7fcdff53b3a4..054c39066043 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -475,6 +475,12 @@ static int netcons_netpoll_setup(struct netconsole_target *nt)
 		return -EDESTADDRREQ;
 	}
 
+	if (nt->local_ip.family != AF_UNSPEC &&
+	    nt->local_ip.family != nt->remote_ip.family) {
+		np_err(np, "local and remote IP address families differ, aborting\n");
+		return -EINVAL;
+	}
+
 	rtnl_lock();
 	if (np->dev_name[0])
 		ndev = __dev_get_by_name(net, np->dev_name);

-- 
2.55.0

[PATCH net-next v2 5/6] netconsole: show empty string for an unset IP address

[Gustavo Luiz Duarte]

An unset address (local_ip/remote_ip), now denoted by AF_UNSPEC,
currently shows "0.0.0.0" in configfs. Print an empty string instead,
which is more clear.

In netconsole_print_banner() we can be even more explicit about it, as
we don't have the risk of userspace trying to parse it.

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
 drivers/net/netconsole.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 054c39066043..0418031b6bc9 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -705,14 +705,18 @@ static void netconsole_print_banner(struct netconsole_target *nt)
 	struct netpoll *np = &nt->np;
 
 	np_info(np, "local port %d\n", nt->local_port);
-	if (nt->local_ip.family == AF_INET6)
+	if (nt->local_ip.family == AF_UNSPEC)
+		np_info(np, "local IP unset\n");
+	else if (nt->local_ip.family == AF_INET6)
 		np_info(np, "local IPv6 address %pI6c\n", &nt->local_ip.in6);
 	else
 		np_info(np, "local IPv4 address %pI4\n", &nt->local_ip.ip);
 	np_info(np, "interface name '%s'\n", np->dev_name);
 	np_info(np, "local ethernet address '%pM'\n", np->dev_mac);
 	np_info(np, "remote port %d\n", nt->remote_port);
-	if (nt->remote_ip.family == AF_INET6)
+	if (nt->remote_ip.family == AF_UNSPEC)
+		np_info(np, "remote IP unset\n");
+	else if (nt->remote_ip.family == AF_INET6)
 		np_info(np, "remote IPv6 address %pI6c\n", &nt->remote_ip.in6);
 	else
 		np_info(np, "remote IPv4 address %pI4\n", &nt->remote_ip.ip);
@@ -850,6 +854,8 @@ static ssize_t local_ip_show(struct config_item *item, char *buf)
 {
 	struct netconsole_target *nt = to_target(item);
 
+	if (nt->local_ip.family == AF_UNSPEC)
+		return sysfs_emit(buf, "\n");
 	if (nt->local_ip.family == AF_INET6)
 		return sysfs_emit(buf, "%pI6c\n", &nt->local_ip.in6);
 	else
@@ -860,6 +866,8 @@ static ssize_t remote_ip_show(struct config_item *item, char *buf)
 {
 	struct netconsole_target *nt = to_target(item);
 
+	if (nt->remote_ip.family == AF_UNSPEC)
+		return sysfs_emit(buf, "\n");
 	if (nt->remote_ip.family == AF_INET6)
 		return sysfs_emit(buf, "%pI6c\n", &nt->remote_ip.in6);
 	else

-- 
2.55.0

[PATCH net-next v2 6/6] netconsole: move struct inet_addr into netconsole.c

[Gustavo Luiz Duarte]

The struct inet_addr lives in netpoll.h, but since commit a1116396476f
("netconsole: move local_ip/remote_ip/ipv6 to netconsole_target") the
only user is netconsole. Move the definition into netconsole.c

Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
Suggested-by: Breno Leitao <leitao@debian.org>
---
 drivers/net/netconsole.c | 9 +++++++++
 include/linux/netpoll.h  | 9 ---------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 0418031b6bc9..810ded6e48f3 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -151,6 +151,15 @@ enum target_state {
 	STATE_DEACTIVATED,
 };
 
+struct inet_addr {
+	/* Address family: AF_UNSPEC when unset, else AF_INET or AF_INET6 */
+	u8			family;
+	union {
+		__be32		ip;
+		struct in6_addr	in6;
+	};
+};
+
 /**
  * struct netconsole_target - Represents a configured netconsole target.
  * @list:	Links this target into the target_list.
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index de97f001a0f9..ec0821a5b02d 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -16,15 +16,6 @@
 #include <linux/ip.h>
 #include <linux/udp.h>
 
-struct inet_addr {
-	/* Address family: AF_UNSPEC when unset, else AF_INET or AF_INET6 */
-	u8			family;
-	union {
-		__be32		ip;
-		struct in6_addr	in6;
-	};
-};
-
 struct netpoll {
 	struct net_device *dev;
 	netdevice_tracker dev_tracker;

-- 
2.55.0

Re: [PATCH net-next v2 1/6] netconsole: add an address family to struct inet_addr

[Breno Leitao]

On Mon, Aug 10, 2026 at 05:47:25PM +0100, Gustavo Luiz Duarte wrote:
> netconsole_target stores a single 'bool ipv6' to denote the target's
> address family. This makes it hard to detect conditions like "no address
> set" or ipv4/ipv6 mixup between local_ip and remote_ip.
> 
> Add a 'family' field to inet_addr so each address stores its own address
> family: AF_UNSPEC while unset, else AF_INET or AF_INET6.
> 
> Nothing reads the new field yet. The next patch switches the users over
> and removes the bool. No functional change.
> 
> Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>

Reviewed-by: Breno Leitao <leitao@debian.org>

Re: [PATCH net-next v2 2/6] netconsole: use the address family instead of the ipv6 flag

[Breno Leitao]

On Mon, Aug 10, 2026 at 05:47:26PM +0100, Gustavo Luiz Duarte wrote:
> Now that we have the address family in inet_addr, use that and remove
> nt->ipv6.
> 
> We no longer need netcons_local_ip_unset() to check that all bytes are
> zeroes, as that is now denoted by (family == AF_UNSPEC).
> 
> Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>

Reviewed-by: Breno Leitao <leitao@debian.org>

> - * Test whether the caller left nt->local_ip unset, so that
> - * netcons_netpoll_setup() should auto-populate it from the egress device.

This will change the behaviour when a user setting an explict 0.0.0.0 IP
would not have auto-populate (which only happens with family ==
AF_UNSPEC).

At the same time, I don't think this is a big deal, but, I think it is
worth getting this documented.

Please add an additional patch that would make it clear that, if the
user passes an IP (even 0.0.0.0, it will be used, and auto-populate is
only used when no IP is passed)

Re: [PATCH net-next v2 3/6] netconsole: reject enabling a target with no remote IP address

[Breno Leitao]

On Mon, Aug 10, 2026 at 05:47:27PM +0100, Gustavo Luiz Duarte wrote:
> The command-line path already requires a remote address, but if a user
> creates a dynamic target and enables it without setting a remote
> address, we currently try sending netconsole traffic to "0.0.0.0".
> 
> Refuse to enable a target if the remote address is unset.
> 
> Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>

Reviewed-by: Breno Leitao <leitao@debian.org>

Re: [PATCH net-next v2 4/6] netconsole: reject a target mixing IPv4 and IPv6 addresses

[Breno Leitao]

On Mon, Aug 10, 2026 at 05:47:28PM +0100, Gustavo Luiz Duarte wrote:
> The local_ip and remote_ip configfs attributes are written independently
> and nothing stops a user from mixing ipv4 and ipv6. This leads to an
> ipv4 address being zero-extended into an ipv6 header or an ipv6 address
> being truncated to its first 4 bytes for an ipv4 header.
> 
> The command-line parser already refuses such a mismatch. This adds a
> similar check when a dynamic target is being enabled.
> 
> Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>

Reviewed-by: Breno Leitao <leitao@debian.org>

Re: [PATCH net-next v2 5/6] netconsole: show empty string for an unset IP address

[Breno Leitao]

On Mon, Aug 10, 2026 at 05:47:29PM +0100, Gustavo Luiz Duarte wrote:
> An unset address (local_ip/remote_ip), now denoted by AF_UNSPEC,
> currently shows "0.0.0.0" in configfs. Print an empty string instead,
> which is more clear.

Ack. Now 0.0.0.0 is different than an empty string (AF_UNSPEC).

> In netconsole_print_banner() we can be even more explicit about it, as
> we don't have the risk of userspace trying to parse it.
> 
> Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>

Reviewed-by: Breno Leitao <leitao@debian.org>

Re: [PATCH net-next v2 6/6] netconsole: move struct inet_addr into netconsole.c

[Breno Leitao]

On Mon, Aug 10, 2026 at 05:47:30PM +0100, Gustavo Luiz Duarte wrote:
> The struct inet_addr lives in netpoll.h, but since commit a1116396476f
> ("netconsole: move local_ip/remote_ip/ipv6 to netconsole_target") the
> only user is netconsole. Move the definition into netconsole.c
> 
> Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
> Suggested-by: Breno Leitao <leitao@debian.org>

Reviewed-by: Breno Leitao <leitao@debian.org>

Thanks for the patch!