inet_diag: fix reporting cgroup classid and fallback to priority

Field idiag_ext in struct inet_diag_req_v2 used as bitmap of requested extensions has only 8 bits. Thus extensions starting from DCTCPINFO cannot be requested directly. Some of them included into response unconditionally or hook into some of lower 8 bits. Extension INET_DIAG_CLASS_ID has not way to request from the beginning. This patch bundle it with INET_DIAG_TCLASS (ipv6 tos), fixes space reservation, and documents behavior for other extensions. Also this patch adds fallback to reporting socket priority. This filed is more widely used for traffic classification because ipv4 sockets automatically maps TOS to priority and default qdisc pfifo_fast knows about that. But priority could be changed via setsockopt SO_PRIORITY so INET_DIAG_TOS isn't enough for predicting class. Also cgroup2 obsoletes net_cls classid (it always zero), but we cannot reuse this field for reporting cgroup2 id because it is 64-bit (ino+gen). So, after this patch INET_DIAG_CLASS_ID will report socket priority for most common setup when net_cls isn't set and/or cgroup2 in use.

Konstantin Khlebnikov committed 7 years ago

Commit 1ec17db1 parent 4ffcbfa3 files · +21 −6Browse files

Showing the changes to include/uapi/linux (1 of 3 files). Show all

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include/uapi/linux/inet_diag.h+11−5

@@ -137,15 +137,21 @@ enum { · 136 unmodified lines
137	137	INET_DIAG_TCLASS,
138	138	INET_DIAG_SKMEMINFO,
139	139	INET_DIAG_SHUTDOWN,
140		− INET_DIAG_DCTCPINFO,
141		− INET_DIAG_PROTOCOL, /* response attribute only */
	140	+
	141	+ /*
	142	+ * Next extenstions cannot be requested in struct inet_diag_req_v2:
	143	+ * its field idiag_ext has only 8 bits.
	144	+ */
	145	+
	146	+ INET_DIAG_DCTCPINFO, /* request as INET_DIAG_VEGASINFO */
	147	+ INET_DIAG_PROTOCOL, /* response attribute only */
142	148	INET_DIAG_SKV6ONLY,
143	149	INET_DIAG_LOCALS,
144	150	INET_DIAG_PEERS,
145	151	INET_DIAG_PAD,
146		− INET_DIAG_MARK,
147		− INET_DIAG_BBRINFO,
148		− INET_DIAG_CLASS_ID,
	152	+ INET_DIAG_MARK, /* only with CAP_NET_ADMIN */
	153	+ INET_DIAG_BBRINFO, /* request as INET_DIAG_VEGASINFO */
	154	+ INET_DIAG_CLASS_ID, /* request as INET_DIAG_TCLASS */
149	155	INET_DIAG_MD5SIG,
150	156	__INET_DIAG_MAX,
151	157	};