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Date: Thu, 31 Mar 2022 14:35:02 +0200 From: Florent Fourcot <florent.fourcot@...irst.fr> To: netdev@...r.kernel.org Cc: Florent Fourcot <florent.fourcot@...irst.fr>, Brian Baboch <brian.baboch@...irst.fr> Subject: [PATCH net-next] rtnetlink: return ENODEV when ifname does not exist and group is given When the interface does not exist, and a group is given, the given parameters are being set to all interfaces of the given group. The given IFNAME/ALT_IF_NAME are being ignored in that case. That can be dangerous since a typo (or a deleted interface) can produce weird side effects for caller: Case 1: IFLA_IFNAME=valid_interface IFLA_GROUP=1 MTU=1234 Case 1 will update MTU and group of the given interface "valid_interface". Case 2: IFLA_IFNAME=doesnotexist IFLA_GROUP=1 MTU=1234 Case 2 will update MTU of all interfaces in group 1. IFLA_IFNAME is ignored in this case This behaviour is not consistent and dangerous. In order to fix this issue, we now return ENODEV when the given IFNAME does not exist. Signed-off-by: Florent Fourcot <florent.fourcot@...irst.fr> Signed-off-by: Brian Baboch <brian.baboch@...irst.fr> --- net/core/rtnetlink.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 159c9c61e6af..3313419bbcba 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3417,10 +3417,15 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, } if (!(nlh->nlmsg_flags & NLM_F_CREATE)) { - if (ifm->ifi_index == 0 && tb[IFLA_GROUP]) + if (ifm->ifi_index == 0 && tb[IFLA_GROUP]) { + if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME]) { + NL_SET_ERR_MSG(extack, "Cannot find interface with given name"); + return -ENODEV; + } return rtnl_group_changelink(skb, net, nla_get_u32(tb[IFLA_GROUP]), ifm, extack, tb); + } return -ENODEV; } -- 2.30.2
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