[PATCH v3 net-next 1/2] net: centralize net_device min/max MTU checking
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STALE3662d
From: Jarod Wilson <hidden>
Date: 2016-10-08 02:04:59
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Subsystem:
networking drivers, networking [general], the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Revision v3 (3 revisions archived).
Revisions (3)
- v1
- v2 [diff against previous] re-posted go to this post
- v3 current [diff against previous]
While looking into an MTU issue with sfc, I started noticing that almost
every NIC driver with an ndo_change_mtu function implemented almost
exactly the same range checks, and in many cases, that was the only
practical thing their ndo_change_mtu function was doing. Quite a few
drivers have either 68, 64, 60 or 46 as their minimum MTU value checked,
and then various sizes from 1500 to 65535 for their maximum MTU value. We
can remove a whole lot of redundant code here if we simple store min_mtu
and max_mtu in net_device, and check against those in net/core/dev.c's
dev_set_mtu().
In theory, there should be zero functional change with this patch, it just
puts the infrastructure in place. Subsequent patches will attempt to start
using said infrastructure, with theoretically zero change in
functionality.
CC: <redacted>
Signed-off-by: Jarod Wilson <redacted>
---
v3: retain new_mtu < 0 check to prevent integral promotions,
as pointed out by Jakub Sitnicki.
include/linux/netdevice.h | 4 ++++
net/core/dev.c | 13 +++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 136ae6bb..fbdf923 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h@@ -1506,6 +1506,8 @@ enum netdev_priv_flags { * @if_port: Selectable AUI, TP, ... * @dma: DMA channel * @mtu: Interface MTU value + * @min_mtu: Interface Minimum MTU value + * @max_mtu: Interface Maximum MTU value * @type: Interface hardware type * @hard_header_len: Maximum hardware header length. *
@@ -1726,6 +1728,8 @@ struct net_device { unsigned char dma; unsigned int mtu; + unsigned int min_mtu; + unsigned int max_mtu; unsigned short type; unsigned short hard_header_len;
diff --git a/net/core/dev.c b/net/core/dev.c
index f1fe26f..f376639 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -6499,9 +6499,18 @@ int dev_set_mtu(struct net_device *dev, int new_mtu) if (new_mtu == dev->mtu) return 0; - /* MTU must be positive. */ - if (new_mtu < 0) + /* MTU must be positive, and in range */ + if (new_mtu < 0 || new_mtu < dev->min_mtu) { + net_err_ratelimited("%s: Invalid MTU %d requested, hw min %d\n", + dev->name, new_mtu, dev->min_mtu); return -EINVAL; + } + + if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) { + net_err_ratelimited("%s: Invalid MTU %d requested, hw max %d\n", + dev->name, new_mtu, dev->min_mtu); + return -EINVAL; + } if (!netif_device_present(dev)) return -ENODEV;
--
2.10.0