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mptcp: move option parsing into mptcp_incoming_options()
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The mptcp_options_received structure carries several per
packet flags (mp_capable, mp_join, etc.). Such fields must
be cleared on each packet, even on dropped ones or packet
not carrying any MPTCP options, but the current mptcp
code clears them only on TCP option reset.

On several races/corner cases we end-up with stray bits in
incoming options, leading to WARN_ON splats. e.g.:

[  171.164906] Bad mapping: ssn=32714 map_seq=1 map_data_len=32713
[  171.165006] WARNING: CPU: 1 PID: 5026 at net/mptcp/subflow.c:533 warn_bad_map (linux-mptcp/net/mptcp/subflow.c:533 linux-mptcp/net/mptcp/subflow.c:531)
[  171.167632] Modules linked in: ip6_vti ip_vti ip_gre ipip sit tunnel4 ip_tunnel geneve ip6_udp_tunnel udp_tunnel macsec macvtap tap ipvlan macvlan 8021q garp mrp xfrm_interface veth netdevsim nlmon dummy team bonding vcan bridge stp llc ip6_gre gre ip6_tunnel tunnel6 tun binfmt_misc intel_rapl_msr intel_rapl_common rfkill kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel joydev virtio_balloon pcspkr i2c_piix4 sunrpc ip_tables xfs libcrc32c crc32c_intel serio_raw virtio_console ata_generic virtio_blk virtio_net net_failover failover ata_piix libata
[  171.199464] CPU: 1 PID: 5026 Comm: repro Not tainted 5.7.0-rc1.mptcp_f227fdf5d388+ linux-sunxi#95
[  171.200886] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
[  171.202546] RIP: 0010:warn_bad_map (linux-mptcp/net/mptcp/subflow.c:533 linux-mptcp/net/mptcp/subflow.c:531)
[  171.206537] Code: c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 1d 8b 55 3c 44 89 e6 48 c7 c7 20 51 13 95 e8 37 8b 22 fe <0f> 0b 48 83 c4 08 5b 5d 41 5c c3 89 4c 24 04 e8 db d6 94 fe 8b 4c
[  171.220473] RSP: 0018:ffffc90000150560 EFLAGS: 00010282
[  171.221639] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  171.223108] RDX: 0000000000000000 RSI: 0000000000000008 RDI: fffff5200002a09e
[  171.224388] RBP: ffff8880aa6e3c00 R08: 0000000000000001 R09: fffffbfff2ec9955
[  171.225706] R10: ffffffff9764caa7 R11: fffffbfff2ec9954 R12: 0000000000007fca
[  171.227211] R13: ffff8881066f4a7f R14: ffff8880aa6e3c00 R15: 0000000000000020
[  171.228460] FS:  00007f8623719740(0000) GS:ffff88810be00000(0000) knlGS:0000000000000000
[  171.230065] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  171.231303] CR2: 00007ffdab190a50 CR3: 00000001038ea006 CR4: 0000000000160ee0
[  171.232586] Call Trace:
[  171.233109]  <IRQ>
[  171.233531] get_mapping_status (linux-mptcp/net/mptcp/subflow.c:691)
[  171.234371] mptcp_subflow_data_available (linux-mptcp/net/mptcp/subflow.c:736 linux-mptcp/net/mptcp/subflow.c:832)
[  171.238181] subflow_state_change (linux-mptcp/net/mptcp/subflow.c:1085 (discriminator 1))
[  171.239066] tcp_fin (linux-mptcp/net/ipv4/tcp_input.c:4217)
[  171.240123] tcp_data_queue (linux-mptcp/./include/linux/compiler.h:199 linux-mptcp/net/ipv4/tcp_input.c:4822)
[  171.245083] tcp_rcv_established (linux-mptcp/./include/linux/skbuff.h:1785 linux-mptcp/./include/net/tcp.h:1774 linux-mptcp/./include/net/tcp.h:1847 linux-mptcp/net/ipv4/tcp_input.c:5238 linux-mptcp/net/ipv4/tcp_input.c:5730)
[  171.254089] tcp_v4_rcv (linux-mptcp/./include/linux/spinlock.h:393 linux-mptcp/net/ipv4/tcp_ipv4.c:2009)
[  171.258969] ip_protocol_deliver_rcu (linux-mptcp/net/ipv4/ip_input.c:204 (discriminator 1))
[  171.260214] ip_local_deliver_finish (linux-mptcp/./include/linux/rcupdate.h:651 linux-mptcp/net/ipv4/ip_input.c:232)
[  171.261389] ip_local_deliver (linux-mptcp/./include/linux/netfilter.h:307 linux-mptcp/./include/linux/netfilter.h:301 linux-mptcp/net/ipv4/ip_input.c:252)
[  171.265884] ip_rcv (linux-mptcp/./include/linux/netfilter.h:307 linux-mptcp/./include/linux/netfilter.h:301 linux-mptcp/net/ipv4/ip_input.c:539)
[  171.273666] process_backlog (linux-mptcp/./include/linux/rcupdate.h:651 linux-mptcp/net/core/dev.c:6135)
[  171.275328] net_rx_action (linux-mptcp/net/core/dev.c:6572 linux-mptcp/net/core/dev.c:6640)
[  171.280472] __do_softirq (linux-mptcp/./arch/x86/include/asm/jump_label.h:25 linux-mptcp/./include/linux/jump_label.h:200 linux-mptcp/./include/trace/events/irq.h:142 linux-mptcp/kernel/softirq.c:293)
[  171.281379] do_softirq_own_stack (linux-mptcp/arch/x86/entry/entry_64.S:1083)
[  171.282358]  </IRQ>

We could address the issue clearing explicitly the relevant fields
in several places - tcp_parse_option, tcp_fast_parse_options,
possibly others.

Instead we move the MPTCP option parsing into the already existing
mptcp ingress hook, so that we need to clear the fields in a single
place.

This allows us dropping an MPTCP hook from the TCP code and
removing the quite large mptcp_options_received from the tcp_sock
struct. On the flip side, the MPTCP sockets will traverse the
option space twice (in tcp_parse_option() and in
mptcp_incoming_options(). That looks acceptable: we already
do that for syn and 3rd ack packets, plain TCP socket will
benefit from it, and even MPTCP sockets will experience better
code locality, reducing the jumps between TCP and MPTCP code.

v1 -> v2:
 - rebased on current '-net' tree

Fixes: 648ef4b ("mptcp: Implement MPTCP receive path")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@davem330
Paolo Abeni authored and davem330 committed Apr 30, 2020
1 parent 263e120 commit cfde141
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Showing 7 changed files with 115 additions and 122 deletions.
51 changes: 0 additions & 51 deletions include/linux/tcp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -78,47 +78,6 @@ struct tcp_sack_block {
#define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
#define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/

#if IS_ENABLED(CONFIG_MPTCP)
struct mptcp_options_received {
u64 sndr_key;
u64 rcvr_key;
u64 data_ack;
u64 data_seq;
u32 subflow_seq;
u16 data_len;
u16 mp_capable : 1,
mp_join : 1,
dss : 1,
add_addr : 1,
rm_addr : 1,
family : 4,
echo : 1,
backup : 1;
u32 token;
u32 nonce;
u64 thmac;
u8 hmac[20];
u8 join_id;
u8 use_map:1,
dsn64:1,
data_fin:1,
use_ack:1,
ack64:1,
mpc_map:1,
__unused:2;
u8 addr_id;
u8 rm_id;
union {
struct in_addr addr;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
struct in6_addr addr6;
#endif
};
u64 ahmac;
u16 port;
};
#endif

struct tcp_options_received {
/* PAWS/RTTM data */
int ts_recent_stamp;/* Time we stored ts_recent (for aging) */
Expand All @@ -136,9 +95,6 @@ struct tcp_options_received {
u8 num_sacks; /* Number of SACK blocks */
u16 user_mss; /* mss requested by user in ioctl */
u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
#if IS_ENABLED(CONFIG_MPTCP)
struct mptcp_options_received mptcp;
#endif
};

static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
Expand All @@ -148,13 +104,6 @@ static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
#if IS_ENABLED(CONFIG_SMC)
rx_opt->smc_ok = 0;
#endif
#if IS_ENABLED(CONFIG_MPTCP)
rx_opt->mptcp.mp_capable = 0;
rx_opt->mptcp.mp_join = 0;
rx_opt->mptcp.add_addr = 0;
rx_opt->mptcp.rm_addr = 0;
rx_opt->mptcp.dss = 0;
#endif
}

/* This is the max number of SACKS that we'll generate and process. It's safe
Expand Down
2 changes: 0 additions & 2 deletions include/net/mptcp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,8 +68,6 @@ static inline bool rsk_is_mptcp(const struct request_sock *req)
return tcp_rsk(req)->is_mptcp;
}

void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
int opsize, struct tcp_options_received *opt_rx);
bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
unsigned int *size, struct mptcp_out_options *opts);
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
Expand Down
4 changes: 0 additions & 4 deletions net/ipv4/tcp_input.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3926,10 +3926,6 @@ void tcp_parse_options(const struct net *net,
*/
break;
#endif
case TCPOPT_MPTCP:
mptcp_parse_option(skb, ptr, opsize, opt_rx);
break;

case TCPOPT_FASTOPEN:
tcp_parse_fastopen_option(
opsize - TCPOLEN_FASTOPEN_BASE,
Expand Down
66 changes: 37 additions & 29 deletions net/mptcp/options.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,10 +16,10 @@ static bool mptcp_cap_flag_sha256(u8 flags)
return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
}

void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
int opsize, struct tcp_options_received *opt_rx)
static void mptcp_parse_option(const struct sk_buff *skb,
const unsigned char *ptr, int opsize,
struct mptcp_options_received *mp_opt)
{
struct mptcp_options_received *mp_opt = &opt_rx->mptcp;
u8 subtype = *ptr >> 4;
int expected_opsize;
u8 version;
Expand Down Expand Up @@ -283,12 +283,20 @@ void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
}

void mptcp_get_options(const struct sk_buff *skb,
struct tcp_options_received *opt_rx)
struct mptcp_options_received *mp_opt)
{
const unsigned char *ptr;
const struct tcphdr *th = tcp_hdr(skb);
int length = (th->doff * 4) - sizeof(struct tcphdr);
const unsigned char *ptr;
int length;

/* initialize option status */
mp_opt->mp_capable = 0;
mp_opt->mp_join = 0;
mp_opt->add_addr = 0;
mp_opt->rm_addr = 0;
mp_opt->dss = 0;

length = (th->doff * 4) - sizeof(struct tcphdr);
ptr = (const unsigned char *)(th + 1);

while (length > 0) {
Expand All @@ -308,7 +316,7 @@ void mptcp_get_options(const struct sk_buff *skb,
if (opsize > length)
return; /* don't parse partial options */
if (opcode == TCPOPT_MPTCP)
mptcp_parse_option(skb, ptr, opsize, opt_rx);
mptcp_parse_option(skb, ptr, opsize, mp_opt);
ptr += opsize - 2;
length -= opsize;
}
Expand Down Expand Up @@ -797,50 +805,50 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
struct mptcp_options_received *mp_opt;
struct mptcp_options_received mp_opt;
struct mptcp_ext *mpext;

mp_opt = &opt_rx->mptcp;
if (!check_fully_established(msk, sk, subflow, skb, mp_opt))
mptcp_get_options(skb, &mp_opt);
if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
return;

if (mp_opt->add_addr && add_addr_hmac_valid(msk, mp_opt)) {
if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
struct mptcp_addr_info addr;

addr.port = htons(mp_opt->port);
addr.id = mp_opt->addr_id;
if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
addr.port = htons(mp_opt.port);
addr.id = mp_opt.addr_id;
if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
addr.family = AF_INET;
addr.addr = mp_opt->addr;
addr.addr = mp_opt.addr;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (mp_opt->family == MPTCP_ADDR_IPVERSION_6) {
else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
addr.family = AF_INET6;
addr.addr6 = mp_opt->addr6;
addr.addr6 = mp_opt.addr6;
}
#endif
if (!mp_opt->echo)
if (!mp_opt.echo)
mptcp_pm_add_addr_received(msk, &addr);
mp_opt->add_addr = 0;
mp_opt.add_addr = 0;
}

if (!mp_opt->dss)
if (!mp_opt.dss)
return;

/* we can't wait for recvmsg() to update the ack_seq, otherwise
* monodirectional flows will stuck
*/
if (mp_opt->use_ack)
update_una(msk, mp_opt);
if (mp_opt.use_ack)
update_una(msk, &mp_opt);

mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
if (!mpext)
return;

memset(mpext, 0, sizeof(*mpext));

if (mp_opt->use_map) {
if (mp_opt->mpc_map) {
if (mp_opt.use_map) {
if (mp_opt.mpc_map) {
/* this is an MP_CAPABLE carrying MPTCP data
* we know this map the first chunk of data
*/
Expand All @@ -851,12 +859,12 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
mpext->dsn64 = 1;
mpext->mpc_map = 1;
} else {
mpext->data_seq = mp_opt->data_seq;
mpext->subflow_seq = mp_opt->subflow_seq;
mpext->dsn64 = mp_opt->dsn64;
mpext->data_fin = mp_opt->data_fin;
mpext->data_seq = mp_opt.data_seq;
mpext->subflow_seq = mp_opt.subflow_seq;
mpext->dsn64 = mp_opt.dsn64;
mpext->data_fin = mp_opt.data_fin;
}
mpext->data_len = mp_opt->data_len;
mpext->data_len = mp_opt.data_len;
mpext->use_map = 1;
}
}
Expand Down
6 changes: 3 additions & 3 deletions net/mptcp/protocol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1334,7 +1334,7 @@ static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
#endif

struct sock *mptcp_sk_clone(const struct sock *sk,
const struct tcp_options_received *opt_rx,
const struct mptcp_options_received *mp_opt,
struct request_sock *req)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
Expand Down Expand Up @@ -1373,9 +1373,9 @@ struct sock *mptcp_sk_clone(const struct sock *sk,

msk->write_seq = subflow_req->idsn + 1;
atomic64_set(&msk->snd_una, msk->write_seq);
if (opt_rx->mptcp.mp_capable) {
if (mp_opt->mp_capable) {
msk->can_ack = true;
msk->remote_key = opt_rx->mptcp.sndr_key;
msk->remote_key = mp_opt->sndr_key;
mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);
ack_seq++;
msk->ack_seq = ack_seq;
Expand Down
43 changes: 41 additions & 2 deletions net/mptcp/protocol.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,45 @@
#define MPTCP_WORK_RTX 2
#define MPTCP_WORK_EOF 3

struct mptcp_options_received {
u64 sndr_key;
u64 rcvr_key;
u64 data_ack;
u64 data_seq;
u32 subflow_seq;
u16 data_len;
u16 mp_capable : 1,
mp_join : 1,
dss : 1,
add_addr : 1,
rm_addr : 1,
family : 4,
echo : 1,
backup : 1;
u32 token;
u32 nonce;
u64 thmac;
u8 hmac[20];
u8 join_id;
u8 use_map:1,
dsn64:1,
data_fin:1,
use_ack:1,
ack64:1,
mpc_map:1,
__unused:2;
u8 addr_id;
u8 rm_id;
union {
struct in_addr addr;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
struct in6_addr addr6;
#endif
};
u64 ahmac;
u16 port;
};

static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
{
return htonl((TCPOPT_MPTCP << 24) | (len << 16) | (subopt << 12) |
Expand Down Expand Up @@ -331,10 +370,10 @@ int mptcp_proto_v6_init(void);
#endif

struct sock *mptcp_sk_clone(const struct sock *sk,
const struct tcp_options_received *opt_rx,
const struct mptcp_options_received *mp_opt,
struct request_sock *req);
void mptcp_get_options(const struct sk_buff *skb,
struct tcp_options_received *opt_rx);
struct mptcp_options_received *mp_opt);

void mptcp_finish_connect(struct sock *sk);
void mptcp_data_ready(struct sock *sk, struct sock *ssk);
Expand Down
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