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-rw-r--r--include/linux/netlink.h7
-rw-r--r--include/uapi/linux/netlink.h4
-rw-r--r--net/netlink/af_netlink.c33
3 files changed, 33 insertions, 11 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 60e7137f840d..8d2a8924705c 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -62,15 +62,22 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
}
+/* this can be increased when necessary - don't expose to userland */
+#define NETLINK_MAX_COOKIE_LEN 20
+
/**
* struct netlink_ext_ack - netlink extended ACK report struct
* @_msg: message string to report - don't access directly, use
* %NL_SET_ERR_MSG
* @bad_attr: attribute with error
+ * @cookie: cookie data to return to userspace (for success)
+ * @cookie_len: actual cookie data length
*/
struct netlink_ext_ack {
const char *_msg;
const struct nlattr *bad_attr;
+ u8 cookie[NETLINK_MAX_COOKIE_LEN];
+ u8 cookie_len;
};
/* Always use this macro, this allows later putting the
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index 7df88770e029..f86127a46cfc 100644
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h
@@ -122,6 +122,9 @@ struct nlmsgerr {
* @NLMSGERR_ATTR_MSG: error message string (string)
* @NLMSGERR_ATTR_OFFS: offset of the invalid attribute in the original
* message, counting from the beginning of the header (u32)
+ * @NLMSGERR_ATTR_COOKIE: arbitrary subsystem specific cookie to
+ * be used - in the success case - to identify a created
+ * object or operation or similar (binary)
* @__NLMSGERR_ATTR_MAX: number of attributes
* @NLMSGERR_ATTR_MAX: highest attribute number
*/
@@ -129,6 +132,7 @@ enum nlmsgerr_attrs {
NLMSGERR_ATTR_UNUSED,
NLMSGERR_ATTR_MSG,
NLMSGERR_ATTR_OFFS,
+ NLMSGERR_ATTR_COOKIE,
__NLMSGERR_ATTR_MAX,
NLMSGERR_ATTR_MAX = __NLMSGERR_ATTR_MAX - 1
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index c1564768000e..ee841f00a6ec 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2311,6 +2311,10 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
}
} else {
flags |= NLM_F_CAPPED;
+
+ if (nlk->flags & NETLINK_F_EXT_ACK &&
+ extack && extack->cookie_len)
+ tlvlen += nla_total_size(extack->cookie_len);
}
if (tlvlen)
@@ -2337,17 +2341,24 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
errmsg->error = err;
memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
- if (err && nlk->flags & NETLINK_F_EXT_ACK && extack) {
- if (extack->_msg)
- WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
- extack->_msg));
- 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 -
- in_skb->data));
+ if (nlk->flags & NETLINK_F_EXT_ACK && extack) {
+ if (err) {
+ if (extack->_msg)
+ WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
+ extack->_msg));
+ 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 -
+ in_skb->data));
+ } else {
+ if (extack->cookie_len)
+ WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
+ extack->cookie_len,
+ extack->cookie));
+ }
}
nlmsg_end(skb, rep);