[PATCH net 0/2] rtnetlink: add missing attributes in if_nlmsg_size

[PATCH net 0/2] rtnetlink: add missing attributes in if_nlmsg_size

[Sabrina Dubroca]

Once again we have some attributes added by rtnl_fill_ifinfo() that
aren't counted in if_nlmsg_size().

Sabrina Dubroca (2):
  rtnetlink: count IFLA_PARENT_DEV_{NAME,BUS_NAME} in if_nlmsg_size
  rtnetlink: count IFLA_INFO_SLAVE_KIND in if_nlmsg_size

 net/core/rtnetlink.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

-- 
2.51.2

[PATCH net 1/2] rtnetlink: count IFLA_PARENT_DEV_{NAME,BUS_NAME} in if_nlmsg_size

[Sabrina Dubroca]

Commit 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
added those attributes to rtnl_fill_ifinfo, but forgot to extend
if_nlmsg_size.

Fixes: 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
---
 net/core/rtnetlink.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index dad4b1054955..a116362f5f32 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1267,6 +1267,21 @@ static size_t rtnl_dpll_pin_size(const struct net_device *dev)
 	return size;
 }
 
+static size_t rtnl_dev_parent_size(const struct net_device *dev)
+{
+	size_t size = 0;
+
+	/* IFLA_PARENT_DEV_NAME */
+	if (dev->dev.parent)
+		size += strlen(dev_name(dev->dev.parent)) + 1;
+
+	/* IFLA_PARENT_DEV_BUS_NAME */
+	if (dev->dev.parent && dev->dev.parent->bus)
+		size += strlen(dev->dev.parent->bus->name) + 1;
+
+	return size;
+}
+
 static noinline size_t if_nlmsg_size(const struct net_device *dev,
 				     u32 ext_filter_mask)
 {
@@ -1328,6 +1343,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
 	       + nla_total_size(8)  /* IFLA_MAX_PACING_OFFLOAD_HORIZON */
 	       + nla_total_size(2)  /* IFLA_HEADROOM */
 	       + nla_total_size(2)  /* IFLA_TAILROOM */
+	       + rtnl_dev_parent_size(dev)
 	       + 0;
 
 	if (!(ext_filter_mask & RTEXT_FILTER_SKIP_STATS))
-- 
2.51.2

[PATCH net 2/2] rtnetlink: count IFLA_INFO_SLAVE_KIND in if_nlmsg_size

[Sabrina Dubroca]

rtnl_link_get_slave_info_data_size counts IFLA_INFO_SLAVE_DATA, but
rtnl_link_slave_info_fill adds both IFLA_INFO_SLAVE_DATA and
IFLA_INFO_SLAVE_KIND.

Fixes: ba7d49b1f0f8 ("rtnetlink: provide api for getting and setting slave info")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
---
 net/core/rtnetlink.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a116362f5f32..cebc00d02fbb 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -707,11 +707,14 @@ static size_t rtnl_link_get_slave_info_data_size(const struct net_device *dev)
 		goto out;
 
 	ops = master_dev->rtnl_link_ops;
-	if (!ops || !ops->get_slave_size)
+	if (!ops)
+		goto out;
+	size += nla_total_size(strlen(ops->kind) + 1);  /* IFLA_INFO_SLAVE_KIND */
+	if (!ops->get_slave_size)
 		goto out;
 	/* IFLA_INFO_SLAVE_DATA + nested data */
-	size = nla_total_size(sizeof(struct nlattr)) +
-	       ops->get_slave_size(master_dev, dev);
+	size += nla_total_size(sizeof(struct nlattr)) +
+		ops->get_slave_size(master_dev, dev);
 
 out:
 	rcu_read_unlock();
-- 
2.51.2

Re: [PATCH net 2/2] rtnetlink: count IFLA_INFO_SLAVE_KIND in if_nlmsg_size

[Jiri Pirko]

Wed, Mar 18, 2026 at 11:45:53AM +0100, sd@queasysnail.net wrote:
>rtnl_link_get_slave_info_data_size counts IFLA_INFO_SLAVE_DATA, but
>rtnl_link_slave_info_fill adds both IFLA_INFO_SLAVE_DATA and
>IFLA_INFO_SLAVE_KIND.
>
>Fixes: ba7d49b1f0f8 ("rtnetlink: provide api for getting and setting slave info")
>Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>

Reviewed-by: Jiri Pirko <jiri@nvidia.com>

Thanks for the fix!

Re: [PATCH net 1/2] rtnetlink: count IFLA_PARENT_DEV_{NAME,BUS_NAME} in if_nlmsg_size

[Sergey Ryazanov]

On March 18, 2026 12:45:52 PM, Sabrina Dubroca <sd@queasysnail.net> wrote:
>Commit 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
>added those attributes to rtnl_fill_ifinfo, but forgot to extend
>if_nlmsg_size.

Nice catch! Please find an implementation question below.

>Fixes: 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
>Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
>---
> net/core/rtnetlink.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
>diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
>index dad4b1054955..a116362f5f32 100644
>--- a/net/core/rtnetlink.c
>+++ b/net/core/rtnetlink.c
>@@ -1267,6 +1267,21 @@ static size_t rtnl_dpll_pin_size(const struct net_device *dev)
> 	return size;
> }
> 
>+static size_t rtnl_dev_parent_size(const struct net_device *dev)
>+{
>+	size_t size = 0;
>+
>+	/* IFLA_PARENT_DEV_NAME */
>+	if (dev->dev.parent)
>+		size += strlen(dev_name(dev->dev.parent)) + 1;

Shall we use nla_total_size() to account alignment?

>+	/* IFLA_PARENT_DEV_BUS_NAME */
>+	if (dev->dev.parent && dev->dev.parent->bus)
>+		size += strlen(dev->dev.parent->bus->name) + 1;
>+
>+	return size;
>+}
>+
> static noinline size_t if_nlmsg_size(const struct net_device *dev,
> 				     u32 ext_filter_mask)
> {
>@@ -1328,6 +1343,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
> 	       + nla_total_size(8)  /* IFLA_MAX_PACING_OFFLOAD_HORIZON */
> 	       + nla_total_size(2)  /* IFLA_HEADROOM */
> 	       + nla_total_size(2)  /* IFLA_TAILROOM */
>+	       + rtnl_dev_parent_size(dev)
> 	       + 0;
> 
> 	if (!(ext_filter_mask & RTEXT_FILTER_SKIP_STATS))

--
Sergey
Hi Sabrina,

Re: [PATCH net 1/2] rtnetlink: count IFLA_PARENT_DEV_{NAME,BUS_NAME} in if_nlmsg_size

[Sergey Ryazanov]

On March 18, 2026 12:45:52 PM, Sabrina Dubroca <sd@queasysnail.net> wrote:
>Commit 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
>added those attributes to rtnl_fill_ifinfo, but forgot to extend
>if_nlmsg_size.

Nice catch! Please find an implementation question below.

>Fixes: 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
>Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
>---
> net/core/rtnetlink.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
>diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
>index dad4b1054955..a116362f5f32 100644
>--- a/net/core/rtnetlink.c
>+++ b/net/core/rtnetlink.c
>@@ -1267,6 +1267,21 @@ static size_t rtnl_dpll_pin_size(const struct net_device *dev)
> 	return size;
> }
> 
>+static size_t rtnl_dev_parent_size(const struct net_device *dev)
>+{
>+	size_t size = 0;
>+
>+	/* IFLA_PARENT_DEV_NAME */
>+	if (dev->dev.parent)
>+		size += strlen(dev_name(dev->dev.parent)) + 1;

Shall we use nla_total_size() to account alignment?

>+	/* IFLA_PARENT_DEV_BUS_NAME */
>+	if (dev->dev.parent && dev->dev.parent->bus)
>+		size += strlen(dev->dev.parent->bus->name) + 1;
>+
>+	return size;
>+}
>+
> static noinline size_t if_nlmsg_size(const struct net_device *dev,
> 				     u32 ext_filter_mask)
> {
>@@ -1328,6 +1343,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
> 	       + nla_total_size(8)  /* IFLA_MAX_PACING_OFFLOAD_HORIZON */
> 	       + nla_total_size(2)  /* IFLA_HEADROOM */
> 	       + nla_total_size(2)  /* IFLA_TAILROOM */
>+	       + rtnl_dev_parent_size(dev)
> 	       + 0;
> 
> 	if (!(ext_filter_mask & RTEXT_FILTER_SKIP_STATS))

--
Sergey
Hi Sabrina,

Re: [PATCH net 1/2] rtnetlink: count IFLA_PARENT_DEV_{NAME,BUS_NAME} in if_nlmsg_size

[Sabrina Dubroca]

2026-03-19, 08:59:47 +0200, Sergey Ryazanov wrote:
> On March 18, 2026 12:45:52 PM, Sabrina Dubroca <sd@queasysnail.net> wrote:
> >Commit 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
> >added those attributes to rtnl_fill_ifinfo, but forgot to extend
> >if_nlmsg_size.
> 
> Nice catch! Please find an implementation question below.
> 
> >Fixes: 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME")
> >Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
> >---
> > net/core/rtnetlink.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> >
> >diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> >index dad4b1054955..a116362f5f32 100644
> >--- a/net/core/rtnetlink.c
> >+++ b/net/core/rtnetlink.c
> >@@ -1267,6 +1267,21 @@ static size_t rtnl_dpll_pin_size(const struct net_device *dev)
> > 	return size;
> > }
> > 
> >+static size_t rtnl_dev_parent_size(const struct net_device *dev)
> >+{
> >+	size_t size = 0;
> >+
> >+	/* IFLA_PARENT_DEV_NAME */
> >+	if (dev->dev.parent)
> >+		size += strlen(dev_name(dev->dev.parent)) + 1;
> 
> Shall we use nla_total_size() to account alignment?

Oops, thanks for catching my brainfart (it's not alignment but the
attribute header). I'll send a v2 later today.

-- 
Sabrina