netdev - Re: [PATCHv2 net-next 1/6] sctp: add sctp_info dump api for sctp

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Message-ID: <1460179179.6473.476.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Fri, 08 Apr 2016 22:19:39 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Xin Long <lucien.xin@...il.com>
Cc:	network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
	Vlad Yasevich <vyasevich@...il.com>, daniel@...earbox.net,
	davem@...emloft.net
Subject: Re: [PATCHv2 net-next 1/6] sctp: add sctp_info dump api for
 sctp_diag

On Sat, 2016-04-09 at 12:53 +0800, Xin Long wrote:
> sctp_diag will dump some important details of sctp's assoc or ep, we use
> sctp_info to describe them,  sctp_get_sctp_info to get them, and export
> it to sctp_diag.ko.
> 


> +int sctp_get_sctp_info(struct sock *sk, struct sctp_association *asoc,
> +		       struct sctp_info *info)
> +{
> +	struct sctp_transport *prim;
> +	struct list_head *pos, *temp;
> +	int mask;
> +
> +	memset(info, 0, sizeof(*info));
> +	if (!asoc) {
> +		struct sctp_sock *sp = sctp_sk(sk);
> +
> +		info->sctpi_s_autoclose = sp->autoclose;
> +		info->sctpi_s_adaptation_ind = sp->adaptation_ind;
> +		info->sctpi_s_pd_point = sp->pd_point;
> +		info->sctpi_s_nodelay = sp->nodelay;
> +		info->sctpi_s_disable_fragments = sp->disable_fragments;
> +		info->sctpi_s_v4mapped = sp->v4mapped;
> +		info->sctpi_s_frag_interleave = sp->frag_interleave;
> +
> +		return 0;
> +	}
> +
> +	info->sctpi_tag = asoc->c.my_vtag;
> +	info->sctpi_state = asoc->state;
> +	info->sctpi_rwnd = asoc->a_rwnd;
> +	info->sctpi_unackdata = asoc->unack_data;
> +	info->sctpi_penddata = sctp_tsnmap_pending(&asoc->peer.tsn_map);
> +	info->sctpi_instrms = asoc->c.sinit_max_instreams;
> +	info->sctpi_outstrms = asoc->c.sinit_num_ostreams;
> +	list_for_each_safe(pos, temp, &asoc->base.inqueue.in_chunk_list)
> +		info->sctpi_inqueue++;
> +	list_for_each_safe(pos, temp, &asoc->outqueue.out_chunk_list)
> +		info->sctpi_outqueue++;

Is this safe ?

Do you own the lock on socket or whatever lock protecting this list ?


> +	info->sctpi_overall_error = asoc->overall_error_count;
> +	info->sctpi_max_burst = asoc->max_burst;
> +	info->sctpi_maxseg = asoc->frag_point;
> +	info->sctpi_peer_rwnd = asoc->peer.rwnd;
> +	info->sctpi_peer_tag = asoc->c.peer_vtag;
> +
> +	mask = asoc->peer.ecn_capable << 1;
> +	mask = (mask | asoc->peer.ipv4_address) << 1;
> +	mask = (mask | asoc->peer.ipv6_address) << 1;
> +	mask = (mask | asoc->peer.hostname_address) << 1;
> +	mask = (mask | asoc->peer.asconf_capable) << 1;
> +	mask = (mask | asoc->peer.prsctp_capable) << 1;
> +	mask = (mask | asoc->peer.auth_capable);
> +	info->sctpi_peer_capable = mask;
> +	mask = asoc->peer.sack_needed << 1;
> +	mask = (mask | asoc->peer.sack_generation) << 1;
> +	mask = (mask | asoc->peer.zero_window_announced);
> +	info->sctpi_peer_sack = mask;
> +
> +	info->sctpi_isacks = asoc->stats.isacks;
> +	info->sctpi_osacks = asoc->stats.osacks;
> +	info->sctpi_opackets = asoc->stats.opackets;
> +	info->sctpi_ipackets = asoc->stats.ipackets;
> +	info->sctpi_rtxchunks = asoc->stats.rtxchunks;
> +	info->sctpi_outofseqtsns = asoc->stats.outofseqtsns;
> +	info->sctpi_idupchunks = asoc->stats.idupchunks;
> +	info->sctpi_gapcnt = asoc->stats.gapcnt;
> +	info->sctpi_ouodchunks = asoc->stats.ouodchunks;
> +	info->sctpi_iuodchunks = asoc->stats.iuodchunks;
> +	info->sctpi_oodchunks = asoc->stats.oodchunks;
> +	info->sctpi_iodchunks = asoc->stats.iodchunks;
> +	info->sctpi_octrlchunks = asoc->stats.octrlchunks;
> +	info->sctpi_ictrlchunks = asoc->stats.ictrlchunks;
> +
> +	prim = asoc->peer.primary_path;
> +	memcpy(&info->sctpi_p_address, &prim->ipaddr,
> +	       sizeof(struct sockaddr_storage));
> +	info->sctpi_p_state = prim->state;
> +	info->sctpi_p_cwnd = prim->cwnd;
> +	info->sctpi_p_srtt = prim->srtt;
> +	info->sctpi_p_rto = jiffies_to_msecs(prim->rto);
> +	info->sctpi_p_hbinterval = prim->hbinterval;
> +	info->sctpi_p_pathmaxrxt = prim->pathmaxrxt;
> +	info->sctpi_p_sackdelay = jiffies_to_msecs(prim->sackdelay);
> +	info->sctpi_p_ssthresh = prim->ssthresh;
> +	info->sctpi_p_partial_bytes_acked = prim->partial_bytes_acked;
> +	info->sctpi_p_flight_size = prim->flight_size;
> +	info->sctpi_p_error = prim->error_count;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(sctp_get_sctp_info);

info is not guaranteed to be aligned on 8 bytes.

You need to use put_unaligned()

Check commit ff5d749772018 ("tcp: beware of alignments in
tcp_get_info()") for details.