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mptcp: fix data races on local_id

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commit a7cfe77663 upstream.

The local address id is accessed lockless by the NL PM, add
all the required ONCE annotation. There is a caveat: the local
id can be initialized late in the subflow life-cycle, and its
validity is controlled by the local_id_valid flag.

Remove such flag and encode the validity in the local_id field
itself with negative value before initialization. That allows
accessing the field consistently with a single read operation.

Fixes: 0ee4261a36 ("mptcp: implement mptcp_pm_remove_subflow")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paolo Abeni 2024-02-15 19:25:31 +01:00 committed by Greg Kroah-Hartman
parent e074c8297e
commit ba2cf92250
5 changed files with 22 additions and 12 deletions
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2
net/mptcp/diag.c
View file

@ -65,7 +65,7 @@ static int subflow_get_info(struct sock *sk, struct sk_buff *skb)
sf->map_data_len) ||
nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_FLAGS, flags) ||
nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_REM, sf->remote_id) ||
nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_LOC, sf->local_id)) {
nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_LOC, subflow_get_local_id(sf))) {
err = -EMSGSIZE;
goto nla_failure;
}

6
net/mptcp/pm_netlink.c
View file

@ -800,7 +800,7 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
mptcp_for_each_subflow_safe(msk, subflow, tmp) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
int how = RCV_SHUTDOWN | SEND_SHUTDOWN;
u8 id = subflow->local_id;
u8 id = subflow_get_local_id(subflow);
if (rm_type == MPTCP_MIB_RMADDR && subflow->remote_id != rm_id)
continue;
@ -809,7 +809,7 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
pr_debug(" -> %s rm_list_ids[%d]=%u local_id=%u remote_id=%u mpc_id=%u",
rm_type == MPTCP_MIB_RMADDR ? "address" : "subflow",
i, rm_id, subflow->local_id, subflow->remote_id,
i, rm_id, id, subflow->remote_id,
msk->mpc_endpoint_id);
spin_unlock_bh(&msk->pm.lock);
mptcp_subflow_shutdown(sk, ssk, how);
@ -2005,7 +2005,7 @@ static int mptcp_event_add_subflow(struct sk_buff *skb, const struct sock *ssk)
if (WARN_ON_ONCE(!sf))
return -EINVAL;
if (nla_put_u8(skb, MPTCP_ATTR_LOC_ID, sf->local_id))
if (nla_put_u8(skb, MPTCP_ATTR_LOC_ID, subflow_get_local_id(sf)))
return -EMSGSIZE;
if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, sf->remote_id))

2
net/mptcp/protocol.c
View file

@ -99,7 +99,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk)
subflow->subflow_id = msk->subflow_id++;
/* This is the first subflow, always with id 0 */
subflow->local_id_valid = 1;
WRITE_ONCE(subflow->local_id, 0);
mptcp_sock_graft(msk->first, sk->sk_socket);
iput(SOCK_INODE(ssock));

15
net/mptcp/protocol.h
View file

@ -493,10 +493,9 @@ struct mptcp_subflow_context {
remote_key_valid : 1, /* received the peer key from */
disposable : 1, /* ctx can be free at ulp release time */
stale : 1, /* unable to snd/rcv data, do not use for xmit */
local_id_valid : 1, /* local_id is correctly initialized */
valid_csum_seen : 1, /* at least one csum validated */
is_mptfo : 1, /* subflow is doing TFO */
__unused : 9;
__unused : 10;
enum mptcp_data_avail data_avail;
bool scheduled;
u32 remote_nonce;
@ -507,7 +506,7 @@ struct mptcp_subflow_context {
u8 hmac[MPTCPOPT_HMAC_LEN]; /* MPJ subflow only */
u64 iasn; /* initial ack sequence number, MPC subflows only */
};
u8 local_id;
s16 local_id; /* if negative not initialized yet */
u8 remote_id;
u8 reset_seen:1;
u8 reset_transient:1;
@ -558,6 +557,7 @@ mptcp_subflow_ctx_reset(struct mptcp_subflow_context *subflow)
{
memset(&subflow->reset, 0, sizeof(subflow->reset));
subflow->request_mptcp = 1;
WRITE_ONCE(subflow->local_id, -1);
}
static inline u64
@ -1008,6 +1008,15 @@ int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc);
int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc);
static inline u8 subflow_get_local_id(const struct mptcp_subflow_context *subflow)
{
int local_id = READ_ONCE(subflow->local_id);
if (local_id < 0)
return 0;
return local_id;
}
void __init mptcp_pm_nl_init(void);
void mptcp_pm_nl_work(struct mptcp_sock *msk);
void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk,

9
net/mptcp/subflow.c
View file

@ -577,8 +577,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
{
subflow->local_id = local_id;
subflow->local_id_valid = 1;
WARN_ON_ONCE(local_id < 0 || local_id > 255);
WRITE_ONCE(subflow->local_id, local_id);
}
static int subflow_chk_local_id(struct sock *sk)
@ -587,7 +587,7 @@ static int subflow_chk_local_id(struct sock *sk)
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
int err;
if (likely(subflow->local_id_valid))
if (likely(subflow->local_id >= 0))
return 0;
err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
@ -1723,6 +1723,7 @@ static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
pr_debug("subflow=%p", ctx);
ctx->tcp_sock = sk;
WRITE_ONCE(ctx->local_id, -1);
return ctx;
}
@ -1958,7 +1959,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
new_ctx->idsn = subflow_req->idsn;
/* this is the first subflow, id is always 0 */
new_ctx->local_id_valid = 1;
subflow_set_local_id(new_ctx, 0);
} else if (subflow_req->mp_join) {
new_ctx->ssn_offset = subflow_req->ssn_offset;
new_ctx->mp_join = 1;