From 5ab8c41cef30d8b6160a80b69d2eb39d570491ac Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Fri, 9 Jun 2023 14:53:30 -0700 Subject: [PATCH 1/2] netlink: support extack in dump ->start() Commit 4a19edb60d02 ("netlink: Pass extack to dump handlers") added extack support to netlink dumps. It was focused on rtnl and since rtnl does not use ->start(), ->done() callbacks it ignored those. Genetlink on the other hand uses ->start() extensively, for parsing and input validation. Pass the extact in via struct netlink_dump_control and link it to cb for the time of ->start(). Both struct netlink_dump_control and extack itself live on the stack so we can't keep the same extack for the duration of the dump. This means that the extack visible in ->start() and each ->dump() callbacks will be different. Corner cases like reporting a warning message in DONE across dump calls are still not supported. We could put the extack (for dumps) in the socket struct, but layering makes it slightly awkward (extack pointer is decided before the DO / DUMP split). The genetlink dump error extacks are now surfaced: $ cli.py --spec netlink/specs/ethtool.yaml --dump channels-get lib.ynl.NlError: Netlink error: Invalid argument nl_len = 64 (48) nl_flags = 0x300 nl_type = 2 error: -22 extack: {'msg': 'request header missing'} Previously extack was missing: $ cli.py --spec netlink/specs/ethtool.yaml --dump channels-get lib.ynl.NlError: Netlink error: Invalid argument nl_len = 36 (20) nl_flags = 0x100 nl_type = 2 error: -22 Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- include/linux/netlink.h | 1 + net/netlink/af_netlink.c | 2 ++ net/netlink/genetlink.c | 2 ++ 3 files changed, 5 insertions(+) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 19c0791ed9d56..9eec3f4f5351e 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -311,6 +311,7 @@ struct netlink_dump_control { int (*start)(struct netlink_callback *); int (*dump)(struct sk_buff *skb, struct netlink_callback *); int (*done)(struct netlink_callback *); + struct netlink_ext_ack *extack; void *data; struct module *module; u32 min_dump_alloc; diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 3a1e0fd5bf149..cbd9aa7ee24ae 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2360,7 +2360,9 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, cb->strict_check = !!(nlk2->flags & NETLINK_F_STRICT_CHK); if (control->start) { + cb->extack = control->extack; ret = control->start(cb); + cb->extack = NULL; if (ret) goto error_put; } diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index 04c4036bf4064..a157247a1e452 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -912,6 +912,7 @@ static int genl_family_rcv_msg_dumpit(const struct genl_family *family, .start = genl_start, .dump = genl_lock_dumpit, .done = genl_lock_done, + .extack = extack, }; genl_unlock(); @@ -924,6 +925,7 @@ static int genl_family_rcv_msg_dumpit(const struct genl_family *family, .start = genl_start, .dump = ops->dumpit, .done = genl_parallel_done, + .extack = extack, }; err = __netlink_dump_start(net->genl_sock, skb, nlh, &c); From 500e1340d1d2695de3f15fc0b3781f593a77acc2 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Fri, 9 Jun 2023 14:53:31 -0700 Subject: [PATCH 2/2] net: ethtool: don't require empty header nests Ethtool currently requires a header nest (which is used to carry the common family options) in all requests including dumps. $ cli.py --spec netlink/specs/ethtool.yaml --dump channels-get lib.ynl.NlError: Netlink error: Invalid argument nl_len = 64 (48) nl_flags = 0x300 nl_type = 2 error: -22 extack: {'msg': 'request header missing'} $ cli.py --spec netlink/specs/ethtool.yaml --dump channels-get \ --json '{"header":{}}'; ) [{'combined-count': 1, 'combined-max': 1, 'header': {'dev-index': 2, 'dev-name': 'enp1s0'}}] Requiring the header nest to always be there may seem nice from the consistency perspective, but it's not serving any practical purpose. We shouldn't burden the user like this. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- net/ethtool/netlink.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c index 08120095cc689..5dd5e8222c456 100644 --- a/net/ethtool/netlink.c +++ b/net/ethtool/netlink.c @@ -96,6 +96,8 @@ int ethnl_parse_header_dev_get(struct ethnl_req_info *req_info, int ret; if (!header) { + if (!require_dev) + return 0; NL_SET_ERR_MSG(extack, "request header missing"); return -EINVAL; }