5.15-stable review patch. If anyone has any objections, please let me know.
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From: Florent Fourcot florent.fourcot@wifirst.fr
[ Upstream commit ef2a7c9065cea4e3fbc0390e82d05141abbccd7f ]
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@wifirst.fr Signed-off-by: Brian Baboch brian.baboch@wifirst.fr Reviewed-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Stable-dep-of: 30188bd7838c ("rtnetlink: Reject negative ifindexes in RTM_NEWLINK") Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/rtnetlink.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 03dd8dc9e1425..7c1a2fd7d9532 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3294,6 +3294,7 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, struct ifinfomsg *ifm; char ifname[IFNAMSIZ]; struct nlattr **data; + bool link_specified; int err;
#ifdef CONFIG_MODULES @@ -3314,12 +3315,16 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, ifname[0] = '\0';
ifm = nlmsg_data(nlh); - if (ifm->ifi_index > 0) + if (ifm->ifi_index > 0) { + link_specified = true; dev = __dev_get_by_index(net, ifm->ifi_index); - else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME]) + } else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME]) { + link_specified = true; dev = rtnl_dev_get(net, NULL, tb[IFLA_ALT_IFNAME], ifname); - else + } else { + link_specified = false; dev = NULL; + }
master_dev = NULL; m_ops = NULL; @@ -3422,7 +3427,12 @@ 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]) + /* No dev found and NLM_F_CREATE not set. Requested dev does not exist, + * or it's for a group + */ + if (link_specified) + return -ENODEV; + if (tb[IFLA_GROUP]) return rtnl_group_changelink(skb, net, nla_get_u32(tb[IFLA_GROUP]), ifm, extack, tb);