Subject: Re: [devel-ipsec] [PATCH ipsec-next v1 6/8] iptfs: xfrm: Add mode_cbs module functionality

From: Christian Hopps <[email-masked]>
Date: Fri, 08 Mar 2024 17:21:20 -0500

Antony Antony <[email-masked]> writes:

> Hi Chris,
>
> I was testing this version.
> And I ran into issues when migrating states. IP-TFS values are set to 0.
> I noticed 2-3 issues both in this patch and 8/8
>
> On Mon, Feb 19, 2024 at 03:57:33AM -0500, Christian Hopps via Devel wrote:
>> From: Christian Hopps <[email-masked]>
>>
>> Add a set of callbacks xfrm_mode_cbs to xfrm_state. These callbacks
>> enable the addition of new xfrm modes, such as IP-TFS to be defined
>> in modules.
>>
>> Signed-off-by: Christian Hopps <[email-masked]>
>> ---
>>  include/net/xfrm.h     | 38 ++++++++++++++++++++++++++++++++++
>>  net/xfrm/xfrm_device.c |  3 ++-
>>  net/xfrm/xfrm_input.c  | 14 +++++++++++--
>>  net/xfrm/xfrm_output.c |  2 ++
>>  net/xfrm/xfrm_policy.c | 18 +++++++++-------
>>  net/xfrm/xfrm_state.c  | 47 ++++++++++++++++++++++++++++++++++++++++++
>>  net/xfrm/xfrm_user.c   | 10 +++++++++
>>  7 files changed, 122 insertions(+), 10 deletions(-)
>>
>> diff --git a/include/net/xfrm.h b/include/net/xfrm.h
>> index 1d107241b901..f1d5e99f0a47 100644
>> --- a/include/net/xfrm.h
>> +++ b/include/net/xfrm.h
>> @@ -204,6 +204,7 @@ struct xfrm_state {
>>  		u16		family;
>>  		xfrm_address_t	saddr;
>>  		int		header_len;
>> +		int		enc_hdr_len;
>>  		int		trailer_len;
>>  		u32		extra_flags;
>>  		struct xfrm_mark	smark;
>> @@ -289,6 +290,9 @@ struct xfrm_state {
>>  	/* Private data of this transformer, format is opaque,
>>  	 * interpreted by xfrm_type methods. */
>>  	void			*data;
>> +
>> +	const struct xfrm_mode_cbs	*mode_cbs;
>> +	void				*mode_data;
>>  };
>>
>>  static inline struct net *xs_net(struct xfrm_state *x)
>> @@ -441,6 +445,40 @@ struct xfrm_type_offload {
>>  int xfrm_register_type_offload(const struct xfrm_type_offload *type, unsigned short family);
>>  void xfrm_unregister_type_offload(const struct xfrm_type_offload *type, unsigned short family);
>>
>> +struct xfrm_mode_cbs {
>> +	struct module	*owner;
>> +	/* Add/delete state in the new xfrm_state in `x`. */
>> +	int	(*create_state)(struct xfrm_state *x);
>> +	void	(*delete_state)(struct xfrm_state *x);
>> +
>> +	/* Called while handling the user netlink options. */
>> +	int	(*user_init)(struct net *net, struct xfrm_state *x,
>> +			     struct nlattr **attrs,
>> +			     struct netlink_ext_ack *extack);
>> +	int	(*copy_to_user)(struct xfrm_state *x, struct sk_buff *skb);
>> +	int     (*clone)(struct xfrm_state *x, struct xfrm_state *orig);
>> +
>> +	u32	(*get_inner_mtu)(struct xfrm_state *x, int outer_mtu);
>> +
>> +	/* Called to handle received xfrm (egress) packets. */
>> +	int	(*input)(struct xfrm_state *x, struct sk_buff *skb);
>> +
>> +	/* Placed in dst_output of the dst when an xfrm_state is bound. */
>> +	int	(*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
>> +
>> +	/**
>> +	 * Prepare the skb for output for the given mode. Returns:
>> +	 *    Error value, if 0 then skb values should be as follows:
>> +	 *    transport_header should point at ESP header
>> +	 *    network_header should point at Outer IP header
>> +	 *    mac_header should point at protocol/nexthdr of the outer IP
>> +	 */
>> +	int	(*prepare_output)(struct xfrm_state *x, struct sk_buff *skb);
>> +};
>> +
>> +int xfrm_register_mode_cbs(u8 mode, const struct xfrm_mode_cbs *mode_cbs);
>> +void xfrm_unregister_mode_cbs(u8 mode);
>> +
>>  static inline int xfrm_af2proto(unsigned int family)
>>  {
>>  	switch(family) {
>> diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
>> index 3784534c9185..8b848540ea47 100644
>> --- a/net/xfrm/xfrm_device.c
>> +++ b/net/xfrm/xfrm_device.c
>> @@ -42,7 +42,8 @@ static void __xfrm_mode_tunnel_prep(struct xfrm_state *x, struct sk_buff *skb,
>>  		skb->transport_header = skb->network_header + hsize;
>>
>>  	skb_reset_mac_len(skb);
>> -	pskb_pull(skb, skb->mac_len + x->props.header_len);
>> +	pskb_pull(skb,
>> +		  skb->mac_len + x->props.header_len - x->props.enc_hdr_len);
>>  }
>>
>>  static void __xfrm_mode_beet_prep(struct xfrm_state *x, struct sk_buff *skb,
>> diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
>> index bd4ce21d76d7..824f7b7f90e0 100644
>> --- a/net/xfrm/xfrm_input.c
>> +++ b/net/xfrm/xfrm_input.c
>> @@ -437,6 +437,9 @@ static int xfrm_inner_mode_input(struct xfrm_state *x,
>>  		WARN_ON_ONCE(1);
>>  		break;
>>  	default:
>> +		if (x->mode_cbs && x->mode_cbs->input)
>> +			return x->mode_cbs->input(x, skb);
>> +
>>  		WARN_ON_ONCE(1);
>>  		break;
>>  	}
>> @@ -479,6 +482,10 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
>>
>>  		family = x->props.family;
>>
>> +		/* An encap_type of -3 indicates reconstructed inner packet */
>> +		if (encap_type == -3)
>> +			goto resume_decapped;
>> +
>>  		/* An encap_type of -1 indicates async resumption. */
>>  		if (encap_type == -1) {
>>  			async = 1;
>> @@ -660,11 +667,14 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
>>
>>  		XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
>>
>> -		if (xfrm_inner_mode_input(x, skb)) {
>> +		err = xfrm_inner_mode_input(x, skb);
>> +		if (err == -EINPROGRESS)
>> +			return 0;
>> +		else if (err) {
>>  			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMODEERROR);
>>  			goto drop;
>>  		}
>> -
>> +resume_decapped:
>>  		if (x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL) {
>>  			decaps = 1;
>>  			break;
>> diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
>> index 662c83beb345..8f98e42d4252 100644
>> --- a/net/xfrm/xfrm_output.c
>> +++ b/net/xfrm/xfrm_output.c
>> @@ -472,6 +472,8 @@ static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
>>  		WARN_ON_ONCE(1);
>>  		break;
>>  	default:
>> +		if (x->mode_cbs && x->mode_cbs->prepare_output)
>> +			return x->mode_cbs->prepare_output(x, skb);
>>  		WARN_ON_ONCE(1);
>>  		break;
>>  	}
>> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
>> index 53b7ce4a4db0..f3cd8483d427 100644
>> --- a/net/xfrm/xfrm_policy.c
>> +++ b/net/xfrm/xfrm_policy.c
>> @@ -2713,13 +2713,17 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
>>
>>  		dst1->input = dst_discard;
>>
>> -		rcu_read_lock();
>> -		afinfo = xfrm_state_afinfo_get_rcu(inner_mode->family);
>> -		if (likely(afinfo))
>> -			dst1->output = afinfo->output;
>> -		else
>> -			dst1->output = dst_discard_out;
>> -		rcu_read_unlock();
>> +		if (xfrm[i]->mode_cbs && xfrm[i]->mode_cbs->output) {
>> +			dst1->output = xfrm[i]->mode_cbs->output;
>> +		} else {
>> +			rcu_read_lock();
>> +			afinfo = xfrm_state_afinfo_get_rcu(inner_mode->family);
>> +			if (likely(afinfo))
>> +				dst1->output = afinfo->output;
>> +			else
>> +				dst1->output = dst_discard_out;
>> +			rcu_read_unlock();
>> +		}
>>
>>  		xdst_prev = xdst;
>>
>> diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
>> index bda5327bf34d..2b58e35bea63 100644
>> --- a/net/xfrm/xfrm_state.c
>> +++ b/net/xfrm/xfrm_state.c
>> @@ -513,6 +513,36 @@ static const struct xfrm_mode *xfrm_get_mode(unsigned int encap, int family)
>>  	return NULL;
>>  }
>>
>> +static struct xfrm_mode_cbs xfrm_mode_cbs_map[XFRM_MODE_MAX];
>> +
>> +int xfrm_register_mode_cbs(u8 mode, const struct xfrm_mode_cbs *mode_cbs)
>> +{
>> +	if (mode >= XFRM_MODE_MAX)
>> +		return -EINVAL;
>> +
>> +	xfrm_mode_cbs_map[mode] = *mode_cbs;
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(xfrm_register_mode_cbs);
>> +
>> +void xfrm_unregister_mode_cbs(u8 mode)
>> +{
>> +	if (mode >= XFRM_MODE_MAX)
>> +		return;
>> +
>> +	memset(&xfrm_mode_cbs_map[mode], 0, sizeof(xfrm_mode_cbs_map[mode]));
>> +}
>> +EXPORT_SYMBOL(xfrm_unregister_mode_cbs);
>> +
>> +static const struct xfrm_mode_cbs *xfrm_get_mode_cbs(u8 mode)
>> +{
>> +	if (mode >= XFRM_MODE_MAX)
>> +		return NULL;
>> +	if (mode == XFRM_MODE_IPTFS && !xfrm_mode_cbs_map[mode].create_state)
>> +		request_module("xfrm-iptfs");
>> +	return &xfrm_mode_cbs_map[mode];
>> +}
>> +
>>  void xfrm_state_free(struct xfrm_state *x)
>>  {
>>  	kmem_cache_free(xfrm_state_cache, x);
>> @@ -521,6 +551,8 @@ EXPORT_SYMBOL(xfrm_state_free);
>>
>>  static void ___xfrm_state_destroy(struct xfrm_state *x)
>>  {
>> +	if (x->mode_cbs && x->mode_cbs->delete_state)
>> +		x->mode_cbs->delete_state(x);
>>  	hrtimer_cancel(&x->mtimer);
>>  	del_timer_sync(&x->rtimer);
>>  	kfree(x->aead);
>> @@ -678,6 +710,7 @@ struct xfrm_state *xfrm_state_alloc(struct net *net)
>>  		x->replay_maxage = 0;
>>  		x->replay_maxdiff = 0;
>>  		spin_lock_init(&x->lock);
>> +		x->mode_data = NULL;
>>  	}
>>  	return x;
>>  }
>> @@ -1745,6 +1778,11 @@ static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
>>  	x->new_mapping = 0;
>>  	x->new_mapping_sport = 0;
>>
>> +	if (x->mode_cbs && x->mode_cbs->clone) {
>
> I notice x->mode_cbs,  it should check old state?
>
> + if (orig->mode_cbs && orig->mode_cbs->clone) {

Actually we need:

+	x->mode_cbs = orig->mode_cbs;
	if (x->mode_cbs && x->mode_cbs->clone) {

>> +		if (!x->mode_cbs->clone(x, orig))
>
> iptfs_clone()  return 0 on success. So
> "!". x->mode_cbs->clone -> iptfs_clone()
> also use orig?
> +		if (orig->mode_cbs->clone(x, orig))

Thanks for catching these!
Chris.