From fe2a31d790f81bd14a76de3d3b87f4f1362f60cd Mon Sep 17 00:00:00 2001 From: Michal Kubecek Date: Sun, 15 Mar 2020 18:17:43 +0100 Subject: [PATCH 1/3] netlink: allow extack cookie also for error messages Commit ba0dc5f6e0ba ("netlink: allow sending extended ACK with cookie on success") introduced a cookie which can be sent to userspace as part of extended ack message in the form of NLMSGERR_ATTR_COOKIE attribute. Currently the cookie is ignored if error code is non-zero but there is no technical reason for such limitation and it can be useful to provide machine parseable information as part of an error message. Include NLMSGERR_ATTR_COOKIE whenever the cookie has been set, regardless of error code. Signed-off-by: Michal Kubecek Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 43 ++++++++++++++++------------------------ 1 file changed, 17 insertions(+), 26 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 5313f1cec1706..2f234791b879f 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2392,19 +2392,14 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, if (nlk_has_extack && extack && extack->_msg) tlvlen += nla_total_size(strlen(extack->_msg) + 1); - if (err) { - if (!(nlk->flags & NETLINK_F_CAP_ACK)) - payload += nlmsg_len(nlh); - else - flags |= NLM_F_CAPPED; - if (nlk_has_extack && extack && extack->bad_attr) - tlvlen += nla_total_size(sizeof(u32)); - } else { + if (err && !(nlk->flags & NETLINK_F_CAP_ACK)) + payload += nlmsg_len(nlh); + else flags |= NLM_F_CAPPED; - - if (nlk_has_extack && extack && extack->cookie_len) - tlvlen += nla_total_size(extack->cookie_len); - } + if (err && nlk_has_extack && extack && extack->bad_attr) + tlvlen += nla_total_size(sizeof(u32)); + if (nlk_has_extack && extack && extack->cookie_len) + tlvlen += nla_total_size(extack->cookie_len); if (tlvlen) flags |= NLM_F_ACK_TLVS; @@ -2427,20 +2422,16 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg)); } - if (err) { - if (extack->bad_attr && - !WARN_ON((u8 *)extack->bad_attr < in_skb->data || - (u8 *)extack->bad_attr >= in_skb->data + - in_skb->len)) - WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS, - (u8 *)extack->bad_attr - - (u8 *)nlh)); - } else { - if (extack->cookie_len) - WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE, - extack->cookie_len, - extack->cookie)); - } + if (err && extack->bad_attr && + !WARN_ON((u8 *)extack->bad_attr < in_skb->data || + (u8 *)extack->bad_attr >= in_skb->data + + in_skb->len)) + WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS, + (u8 *)extack->bad_attr - + (u8 *)nlh)); + if (extack->cookie_len) + WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE, + extack->cookie_len, extack->cookie)); } nlmsg_end(skb, rep); From f1388ec4a144f40348321a0915c5535d623e165c Mon Sep 17 00:00:00 2001 From: Michal Kubecek Date: Sun, 15 Mar 2020 18:17:48 +0100 Subject: [PATCH 2/3] netlink: add nl_set_extack_cookie_u32() Similar to existing nl_set_extack_cookie_u64(), add new helper nl_set_extack_cookie_u32() which sets extack cookie to a u32 value. Signed-off-by: Michal Kubecek Signed-off-by: David S. Miller --- include/linux/netlink.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 205fa7b1f07ad..4090524c3462f 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -119,6 +119,15 @@ static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, extack->cookie_len = sizeof(__cookie); } +static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack, + u32 cookie) +{ + u32 __cookie = cookie; + + memcpy(extack->cookie, &__cookie, sizeof(__cookie)); + extack->cookie_len = sizeof(__cookie); +} + void netlink_kernel_release(struct sock *sk); int __netlink_change_ngroups(struct sock *sk, unsigned int groups); int netlink_change_ngroups(struct sock *sk, unsigned int groups); From 2363d73a2f3e92787f336721c40918ba2eb0c74c Mon Sep 17 00:00:00 2001 From: Michal Kubecek Date: Sun, 15 Mar 2020 18:17:53 +0100 Subject: [PATCH 3/3] ethtool: reject unrecognized request flags 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 Signed-off-by: David S. Miller --- net/ethtool/netlink.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c index 180c194fab076..fc9e0b8068898 100644 --- a/net/ethtool/netlink.c +++ b/net/ethtool/netlink.c @@ -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) { @@ -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]); @@ -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; }