inet_diag: fix reporting cgroup classid and fallback to priority

[ Upstream commit 1ec17dbd90f8b638f41ee650558609c1af63dfa0 ]

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.

Fixes: 0888e372c37f ("net: inet: diag: expose sockets cgroup classid")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
index 817d807e9481d30d7267a44223fbec0f4360692c..f7df51ffd2a49eea33aa3a7d9843d3c145598bcc 100644 (file)
--- a/include/uapi/linux/inet_diag.h
+++ b/include/uapi/linux/inet_diag.h
@@ -135,15 +135,21 @@ enum {
        INET_DIAG_TCLASS,
        INET_DIAG_SKMEMINFO,
        INET_DIAG_SHUTDOWN,
-       INET_DIAG_DCTCPINFO,
-       INET_DIAG_PROTOCOL,  /* response attribute only */
+
+       /*
+        * Next extenstions cannot be requested in struct inet_diag_req_v2:
+        * its field idiag_ext has only 8 bits.
+        */
+
+       INET_DIAG_DCTCPINFO,    /* request as INET_DIAG_VEGASINFO */
+       INET_DIAG_PROTOCOL,     /* response attribute only */
        INET_DIAG_SKV6ONLY,
        INET_DIAG_LOCALS,
        INET_DIAG_PEERS,
        INET_DIAG_PAD,
-       INET_DIAG_MARK,
-       INET_DIAG_BBRINFO,
-       INET_DIAG_CLASS_ID,
+       INET_DIAG_MARK,         /* only with CAP_NET_ADMIN */
+       INET_DIAG_BBRINFO,      /* request as INET_DIAG_VEGASINFO */
+       INET_DIAG_CLASS_ID,     /* request as INET_DIAG_TCLASS */
        INET_DIAG_MD5SIG,
        __INET_DIAG_MAX,
 };

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 857ec3dbb742b32b5593d8cda43f33103ecb3bb4..33edccfebc304b17c48f1c50b45bf5d2540a1c6b 100644 (file)
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -109,6 +109,7 @@ static size_t inet_sk_attr_size(struct sock *sk,
                + nla_total_size(1) /* INET_DIAG_TOS */
                + nla_total_size(1) /* INET_DIAG_TCLASS */
                + nla_total_size(4) /* INET_DIAG_MARK */
+               + nla_total_size(4) /* INET_DIAG_CLASS_ID */
                + nla_total_size(sizeof(struct inet_diag_meminfo))
                + nla_total_size(sizeof(struct inet_diag_msg))
                + nla_total_size(SK_MEMINFO_VARS * sizeof(u32))
@@ -288,12 +289,19 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
                        goto errout;
        }
 
-       if (ext & (1 << (INET_DIAG_CLASS_ID - 1))) {
+       if (ext & (1 << (INET_DIAG_CLASS_ID - 1)) ||
+           ext & (1 << (INET_DIAG_TCLASS - 1))) {
                u32 classid = 0;
 
 #ifdef CONFIG_SOCK_CGROUP_DATA
                classid = sock_cgroup_classid(&sk->sk_cgrp_data);
 #endif
+               /* Fallback to socket priority if class id isn't set.
+                * Classful qdiscs use it as direct reference to class.
+                * For cgroup2 classid is always zero.
+                */
+               if (!classid)
+                       classid = sk->sk_priority;
 
                if (nla_put_u32(skb, INET_DIAG_CLASS_ID, classid))
                        goto errout;

diff --git a/net/sctp/sctp_diag.c b/net/sctp/sctp_diag.c
index a72a7d925d4631e30cfb0743df392ff4cef456ca..75274a60b77ab0f40903ae0ea38c633085b0a336 100644 (file)
--- a/net/sctp/sctp_diag.c
+++ b/net/sctp/sctp_diag.c
@@ -225,6 +225,7 @@ static size_t inet_assoc_attr_size(struct sctp_association *asoc)
                + nla_total_size(1) /* INET_DIAG_TOS */
                + nla_total_size(1) /* INET_DIAG_TCLASS */
                + nla_total_size(4) /* INET_DIAG_MARK */
+               + nla_total_size(4) /* INET_DIAG_CLASS_ID */
                + nla_total_size(addrlen * asoc->peer.transport_count)
                + nla_total_size(addrlen * addrcnt)
                + nla_total_size(sizeof(struct inet_diag_meminfo))