Subject: Re: [RFC PATCH 2/5] sctp: Add ip option support

From: Richard Haines <[email-masked]>
Date: Wed, 01 Nov 2017 21:29:13 +0000

On Tue, 2017-10-31 at 15:06 -0200, Marcelo Ricardo Leitner wrote:
> Hello,
> 
> On Tue, Oct 17, 2017 at 02:58:06PM +0100, Richard Haines wrote:
> > Add ip option support to allow LSM security modules to utilise
> > CIPSO/IPv4
> > and CALIPSO/IPv6 services.
> > 
> > Signed-off-by: Richard Haines <[email-masked]>
> > ---
> >  include/net/sctp/structs.h |  2 ++
> >  net/sctp/chunk.c           |  7 ++++---
> >  net/sctp/ipv6.c            | 37 ++++++++++++++++++++++++++++++--
> > -----
> >  net/sctp/output.c          |  3 ++-
> >  net/sctp/protocol.c        | 36
> > ++++++++++++++++++++++++++++++++++++
> >  net/sctp/socket.c          |  5 ++++-
> >  6 files changed, 78 insertions(+), 12 deletions(-)
> > 
> > diff --git a/include/net/sctp/structs.h
> > b/include/net/sctp/structs.h
> > index 5ab29af..7767577 100644
> > --- a/include/net/sctp/structs.h
> > +++ b/include/net/sctp/structs.h
> > @@ -461,6 +461,7 @@ struct sctp_af {
> >  	void		(*ecn_capable)(struct sock *sk);
> >  	__u16		net_header_len;
> >  	int		sockaddr_len;
> > +	int		(*ip_options_len)(struct sock *sk);
> >  	sa_family_t	sa_family;
> >  	struct list_head list;
> >  };
> > @@ -485,6 +486,7 @@ struct sctp_pf {
> >  	int (*addr_to_user)(struct sctp_sock *sk, union sctp_addr
> > *addr);
> >  	void (*to_sk_saddr)(union sctp_addr *, struct sock *sk);
> >  	void (*to_sk_daddr)(union sctp_addr *, struct sock *sk);
> > +	void (*copy_ip_options)(struct sock *sk, struct sock
> > *newsk);
> >  	struct sctp_af *af;
> >  };
> >  
> > diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
> > index 1323d41..e49e240 100644
> > --- a/net/sctp/chunk.c
> > +++ b/net/sctp/chunk.c
> > @@ -153,7 +153,6 @@ static void sctp_datamsg_assign(struct
> > sctp_datamsg *msg, struct sctp_chunk *chu
> >  	chunk->msg = msg;
> >  }
> >  
> > -
> >  /* A data chunk can have a maximum payload of (2^16 - 20).  Break
> >   * down any such message into smaller chunks.  Opportunistically,
> > fragment
> >   * the chunks down to the current MTU constraints.  We may get
> > refragmented
> > @@ -190,7 +189,10 @@ struct sctp_datamsg
> > *sctp_datamsg_from_user(struct sctp_association *asoc,
> >  	 */
> >  	max_data = asoc->pathmtu -
> >  		   sctp_sk(asoc->base.sk)->pf->af->net_header_len
> > -
> 
>                                         ^^^^^^^^
> > -		   sizeof(struct sctphdr) - sizeof(struct
> > sctp_data_chunk);
> > +		   sizeof(struct sctphdr) - sizeof(struct
> > sctp_data_chunk) -
> > +		   sctp_sk(asoc->base.sk)->pf->af->
> 
>                                         ^^^^^^^^
> > +		   ip_options_len(asoc->base.sk);
> 
> Please add a var for sctp_sk(asoc->base.sk)->pf->af. That should also
> help to not break the dereferencing into multiple lines.
DONE
> 
> > +
> >  	max_data = SCTP_TRUNC4(max_data);
> >  
> >  	/* If the the peer requested that we authenticate DATA
> > chunks
> > @@ -210,7 +212,6 @@ struct sctp_datamsg
> > *sctp_datamsg_from_user(struct sctp_association *asoc,
> >  
> >  	/* Set first_len and then account for possible bundles on
> > first frag */
> >  	first_len = max_data;
> > -
> >  	/* Check to see if we have a pending SACK and try to let
> > it be bundled
> >  	 * with this message.  Do this if we don't have any data
> > queued already.
> >  	 * To check that, look at out_qlen and retransmit list.
> > diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> > index a4b6ffb..49c9011 100644
> > --- a/net/sctp/ipv6.c
> > +++ b/net/sctp/ipv6.c
> > @@ -423,6 +423,33 @@ static void sctp_v6_copy_addrlist(struct
> > list_head *addrlist,
> >  	rcu_read_unlock();
> >  }
> >  
> > +/* Copy over any ip options */
> > +static void sctp_v6_copy_ip_options(struct sock *sk, struct sock
> > *newsk)
> > +{
> > +	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
> > +	struct ipv6_txoptions *opt;
> > +
> > +	newnp = inet6_sk(newsk);
> > +
> > +	rcu_read_lock();
> > +	opt = rcu_dereference(np->opt);
> > +	if (opt)
> > +		opt = ipv6_dup_options(newsk, opt);
> > +	RCU_INIT_POINTER(newnp->opt, opt);
> > +	rcu_read_unlock();
> > +}
> > +
> > +/* Account for the IP options */
> > +static int sctp_v6_ip_options_len(struct sock *sk)
> > +{
> > +	struct ipv6_pinfo *inet6 = inet6_sk(sk);
> > +
> > +	if (inet6->opt)
> > +		return inet6->opt->opt_flen + inet6->opt-
> > >opt_nflen;
> 
> Seems we need RCU protection here.
> And please add a var for inet6->opt.
I've changed and tested the following:

/* Account for the IP options */
static int sctp_v6_ip_options_len(struct sock *sk)
{
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct ipv6_txoptions *opt;
	int len = 0;

	rcu_read_lock();
	opt = rcu_dereference(np->opt);
	if (opt)
		len = opt->opt_flen + opt->opt_nflen;

	rcu_read_unlock();
	return len;
}
> 
> > +	else
> > +		return 0;
> > +}
> > +
> >  /* Initialize a sockaddr_storage from in incoming skb. */
> >  static void sctp_v6_from_skb(union sctp_addr *addr, struct sk_buff
> > *skb,
> >  			     int is_saddr)
> > @@ -662,7 +689,6 @@ static struct sock
> > *sctp_v6_create_accept_sk(struct sock *sk,
> >  	struct sock *newsk;
> >  	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
> >  	struct sctp6_sock *newsctp6sk;
> > -	struct ipv6_txoptions *opt;
> >  
> >  	newsk = sk_alloc(sock_net(sk), PF_INET6, GFP_KERNEL, sk-
> > >sk_prot, kern);
> >  	if (!newsk)
> > @@ -685,12 +711,7 @@ static struct sock
> > *sctp_v6_create_accept_sk(struct sock *sk,
> >  	newnp->ipv6_ac_list = NULL;
> >  	newnp->ipv6_fl_list = NULL;
> >  
> > -	rcu_read_lock();
> > -	opt = rcu_dereference(np->opt);
> > -	if (opt)
> > -		opt = ipv6_dup_options(newsk, opt);
> > -	RCU_INIT_POINTER(newnp->opt, opt);
> > -	rcu_read_unlock();
> > +	sctp_v6_copy_ip_options(sk, newsk);
> >  
> >  	/* Initialize sk's sport, dport, rcv_saddr and daddr for
> > getsockname()
> >  	 * and getpeername().
> > @@ -1033,6 +1054,7 @@ static struct sctp_af sctp_af_inet6 = {
> >  	.ecn_capable	   = sctp_v6_ecn_capable,
> >  	.net_header_len	   = sizeof(struct ipv6hdr),
> >  	.sockaddr_len	   = sizeof(struct sockaddr_in6),
> > +	.ip_options_len	   = sctp_v6_ip_options_len,
> >  #ifdef CONFIG_COMPAT
> >  	.compat_setsockopt = compat_ipv6_setsockopt,
> >  	.compat_getsockopt = compat_ipv6_getsockopt,
> > @@ -1051,6 +1073,7 @@ static struct sctp_pf sctp_pf_inet6 = {
> >  	.addr_to_user  = sctp_v6_addr_to_user,
> >  	.to_sk_saddr   = sctp_v6_to_sk_saddr,
> >  	.to_sk_daddr   = sctp_v6_to_sk_daddr,
> > +	.copy_ip_options = sctp_v6_copy_ip_options,
> >  	.af            = &sctp_af_inet6,
> >  };
> >  
> > diff --git a/net/sctp/output.c b/net/sctp/output.c
> > index 9d85049..85bcd5b 100644
> > --- a/net/sctp/output.c
> > +++ b/net/sctp/output.c
> > @@ -151,7 +151,8 @@ void sctp_packet_init(struct sctp_packet
> > *packet,
> >  	INIT_LIST_HEAD(&packet->chunk_list);
> >  	if (asoc) {
> >  		struct sctp_sock *sp = sctp_sk(asoc->base.sk);
> > -		overhead = sp->pf->af->net_header_len;
> > +		overhead = sp->pf->af->net_header_len +
> > +			   sp->pf->af->ip_options_len(asoc-
> > >base.sk);
> 
> Here you may also add a var for sp->pf->af.
DONE
> 
> >  	} else {
> >  		overhead = sizeof(struct ipv6hdr);
> >  	}
> > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> > index 989a900..a9e54ac 100644
> > --- a/net/sctp/protocol.c
> > +++ b/net/sctp/protocol.c
> > @@ -237,6 +237,38 @@ int sctp_copy_local_addr_list(struct net *net,
> > struct sctp_bind_addr *bp,
> >  	return error;
> >  }
> >  
> > +/* Copy over any ip options */
> > +static void sctp_v4_copy_ip_options(struct sock *sk, struct sock
> > *newsk)
> > +{
> > +	struct inet_sock *newinet, *inet = inet_sk(sk);
> > +	struct ip_options_rcu *inet_opt, *newopt = NULL;
> > +
> > +	newinet = inet_sk(newsk);
> > +
> > +	rcu_read_lock();
> > +	inet_opt = rcu_dereference(inet->inet_opt);
> > +	if (inet_opt) {
> > +		newopt = sock_kmalloc(newsk, sizeof(*inet_opt) +
> > +				      inet_opt->opt.optlen,
> > GFP_ATOMIC);
> > +		if (newopt)
> > +			memcpy(newopt, inet_opt, sizeof(*inet_opt)
> > +
> > +			       inet_opt->opt.optlen);
> > +	}
> > +	RCU_INIT_POINTER(newinet->inet_opt, newopt);
> > +	rcu_read_unlock();
> > +}
> > +
> > +/* Account for the IP options */
> > +static int sctp_v4_ip_options_len(struct sock *sk)
> > +{
> > +	struct inet_sock *inet = inet_sk(sk);
> > +
> > +	if (inet->inet_opt)
> > +		return inet->inet_opt->opt.optlen;
> > +	else
> > +		return 0;
> > +}
> > +
> >  /* Initialize a sctp_addr from in incoming skb.  */
> >  static void sctp_v4_from_skb(union sctp_addr *addr, struct sk_buff
> > *skb,
> >  			     int is_saddr)
> > @@ -590,6 +622,8 @@ static struct sock
> > *sctp_v4_create_accept_sk(struct sock *sk,
> >  	sctp_copy_sock(newsk, sk, asoc);
> >  	sock_reset_flag(newsk, SOCK_ZAPPED);
> >  
> > +	sctp_v4_copy_ip_options(sk, newsk);
> > +
> >  	newinet = inet_sk(newsk);
> >  
> >  	newinet->inet_daddr = asoc-
> > >peer.primary_addr.v4.sin_addr.s_addr;
> > @@ -1008,6 +1042,7 @@ static struct sctp_pf sctp_pf_inet = {
> >  	.addr_to_user  = sctp_v4_addr_to_user,
> >  	.to_sk_saddr   = sctp_v4_to_sk_saddr,
> >  	.to_sk_daddr   = sctp_v4_to_sk_daddr,
> > +	.copy_ip_options = sctp_v4_copy_ip_options,
> >  	.af            = &sctp_af_inet
> >  };
> >  
> > @@ -1092,6 +1127,7 @@ static struct sctp_af sctp_af_inet = {
> >  	.ecn_capable	   = sctp_v4_ecn_capable,
> >  	.net_header_len	   = sizeof(struct iphdr),
> >  	.sockaddr_len	   = sizeof(struct sockaddr_in),
> > +	.ip_options_len	   = sctp_v4_ip_options_len,
> >  #ifdef CONFIG_COMPAT
> >  	.compat_setsockopt = compat_ip_setsockopt,
> >  	.compat_getsockopt = compat_ip_getsockopt,
> > diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> > index 8d76086..70355a0 100644
> > --- a/net/sctp/socket.c
> > +++ b/net/sctp/socket.c
> > @@ -3124,6 +3124,7 @@ static int sctp_setsockopt_maxseg(struct sock
> > *sk, char __user *optval, unsigned
> >  	if (asoc) {
> >  		if (val == 0) {
> >  			val = asoc->pathmtu;
> > +			val -= sp->pf->af->ip_options_len(asoc-
> > >base.sk);
> >  			val -= sp->pf->af->net_header_len;
> 
> Also here. May even be inside the if() block.
DONE
> 
> Thanks
> 
> >  			val -= sizeof(struct sctphdr) +
> >  					sizeof(struct
> > sctp_data_chunk);
> > @@ -4917,9 +4918,11 @@ int sctp_do_peeloff(struct sock *sk,
> > sctp_assoc_t id, struct socket **sockp)
> >  	sctp_copy_sock(sock->sk, sk, asoc);
> >  
> >  	/* Make peeled-off sockets more like 1-1 accepted sockets.
> > -	 * Set the daddr and initialize id to something more
> > random
> > +	 * Set the daddr and initialize id to something more
> > random and also
> > +	 * copy over any ip options.
> >  	 */
> >  	sp->pf->to_sk_daddr(&asoc->peer.primary_addr, sk);
> > +	sp->pf->copy_ip_options(sk, sock->sk);
> >  
> >  	/* Populate the fields of the newsk from the oldsk and
> > migrate the
> >  	 * asoc to the newsk.
> > -- 
> > 2.13.6
> > 
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> > 
> 
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