| From 3a23e1c2a34563f6607b56a699ae62ea09811073 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sat, 7 Aug 2021 15:27:03 +0200 |
| Subject: ppp: Fix generating ifname when empty IFLA_IFNAME is specified |
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| |
| From: Pali Rohár <pali@kernel.org> |
| |
| [ Upstream commit 2459dcb96bcba94c08d6861f8a050185ff301672 ] |
| |
| IFLA_IFNAME is nul-term string which means that IFLA_IFNAME buffer can be |
| larger than length of string which contains. |
| |
| Function __rtnl_newlink() generates new own ifname if either IFLA_IFNAME |
| was not specified at all or userspace passed empty nul-term string. |
| |
| It is expected that if userspace does not specify ifname for new ppp netdev |
| then kernel generates one in format "ppp<id>" where id matches to the ppp |
| unit id which can be later obtained by PPPIOCGUNIT ioctl. |
| |
| And it works in this way if IFLA_IFNAME is not specified at all. But it |
| does not work when IFLA_IFNAME is specified with empty string. |
| |
| So fix this logic also for empty IFLA_IFNAME in ppp_nl_newlink() function |
| and correctly generates ifname based on ppp unit identifier if userspace |
| did not provided preferred ifname. |
| |
| Without this patch when IFLA_IFNAME was specified with empty string then |
| kernel created a new ppp interface in format "ppp<id>" but id did not |
| match ppp unit id returned by PPPIOCGUNIT ioctl. In this case id was some |
| number generated by __rtnl_newlink() function. |
| |
| Signed-off-by: Pali Rohár <pali@kernel.org> |
| Fixes: bb8082f69138 ("ppp: build ifname using unit identifier for rtnl based devices") |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/net/ppp/ppp_generic.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c |
| index b9dd47bd597f..7a099c37527f 100644 |
| --- a/drivers/net/ppp/ppp_generic.c |
| +++ b/drivers/net/ppp/ppp_generic.c |
| @@ -1317,7 +1317,7 @@ static int ppp_nl_newlink(struct net *src_net, struct net_device *dev, |
| * the PPP unit identifer as suffix (i.e. ppp<unit_id>). This allows |
| * userspace to infer the device name using to the PPPIOCGUNIT ioctl. |
| */ |
| - if (!tb[IFLA_IFNAME]) |
| + if (!tb[IFLA_IFNAME] || !nla_len(tb[IFLA_IFNAME]) || !*(char *)nla_data(tb[IFLA_IFNAME])) |
| conf.ifname_is_set = false; |
| |
| err = ppp_dev_configure(src_net, dev, &conf); |
| -- |
| 2.30.2 |
| |
