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ethtool: reject unrecognized request flags
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As pointed out by Jakub Kicinski, we ethtool netlink code should respond
with an error if request head has flags set which are not recognized by
kernel, either as a mistake or because it expects functionality introduced
in later kernel versions.

To avoid unnecessary roundtrips, use extack cookie to provide the
information about supported request flags.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Michal Kubecek authored and David S. Miller committed Mar 16, 2020
1 parent f1388ec commit 2363d73
Showing 1 changed file with 12 additions and 4 deletions.
16 changes: 12 additions & 4 deletions net/ethtool/netlink.c
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ int ethnl_parse_header(struct ethnl_req_info *req_info,
struct nlattr *tb[ETHTOOL_A_HEADER_MAX + 1];
const struct nlattr *devname_attr;
struct net_device *dev = NULL;
u32 flags = 0;
int ret;

if (!header) {
Expand All @@ -50,8 +51,17 @@ int ethnl_parse_header(struct ethnl_req_info *req_info,
ethnl_header_policy, extack);
if (ret < 0)
return ret;
devname_attr = tb[ETHTOOL_A_HEADER_DEV_NAME];
if (tb[ETHTOOL_A_HEADER_FLAGS]) {
flags = nla_get_u32(tb[ETHTOOL_A_HEADER_FLAGS]);
if (flags & ~ETHTOOL_FLAG_ALL) {
NL_SET_ERR_MSG_ATTR(extack, tb[ETHTOOL_A_HEADER_FLAGS],
"unrecognized request flags");
nl_set_extack_cookie_u32(extack, ETHTOOL_FLAG_ALL);
return -EOPNOTSUPP;
}
}

devname_attr = tb[ETHTOOL_A_HEADER_DEV_NAME];
if (tb[ETHTOOL_A_HEADER_DEV_INDEX]) {
u32 ifindex = nla_get_u32(tb[ETHTOOL_A_HEADER_DEV_INDEX]);

Expand Down Expand Up @@ -90,9 +100,7 @@ int ethnl_parse_header(struct ethnl_req_info *req_info,
}

req_info->dev = dev;
if (tb[ETHTOOL_A_HEADER_FLAGS])
req_info->flags = nla_get_u32(tb[ETHTOOL_A_HEADER_FLAGS]);

req_info->flags = flags;
return 0;
}

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