[PATCH 5.14 096/172] mptcp: dont return sockets in foreign netns

Greg Kroah-Hartman
2021-10-04T13:38:10Z

From: Florian Westphal <fw@strlen.de>

[ Upstream commit ea1300b9df7c8e8b65695a08b8f6aaf4b25fec9c ]

mptcp_token_get_sock() may return a mptcp socket that is in
a different net namespace than the socket that received the token value.

The mptcp syncookie code path had an explicit check for this,
this moves the test into mptcp_token_get_sock() function.

Eventually token.c should be converted to pernet storage, but
such change is not suitable for net tree.

Fixes: 2c5ebd001d4f0 ("mptcp: refactor token container")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mptcp/mptcp_diag.c | 2 +-
net/mptcp/protocol.h | 2 +-
net/mptcp/subflow.c | 2 +-
net/mptcp/syncookies.c | 13 +------------
net/mptcp/token.c | 11 ++++++++---
net/mptcp/token_test.c | 14 ++++++++------
6 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/net/mptcp/mptcp_diag.c b/net/mptcp/mptcp_diag.c
index f48eb6315bbb..292374fb0779 100644
--- a/net/mptcp/mptcp_diag.c
+++ b/net/mptcp/mptcp_diag.c
@@ -36,7 +36,7 @@ static int mptcp_diag_dump_one(struct netlink_callback *cb,
struct sock *sk;

net = sock_net(in_skb->sk);
- msk = mptcp_token_get_sock(req->id.idiag_cookie[0]);
+ msk = mptcp_token_get_sock(net, req->id.idiag_cookie[0]);
if (!msk)
goto out_nosk;

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 6ac564d584c1..c8a49e92e66f 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -680,7 +680,7 @@ int mptcp_token_new_connect(struct sock *sk);
void mptcp_token_accept(struct mptcp_subflow_request_sock *r,
struct mptcp_sock *msk);
bool mptcp_token_exists(u32 token);
-struct mptcp_sock *mptcp_token_get_sock(u32 token);
+struct mptcp_sock *mptcp_token_get_sock(struct net *net, u32 token);
struct mptcp_sock *mptcp_token_iter_next(const struct net *net, long *s_slot,
long *s_num);
void mptcp_token_destroy(struct mptcp_sock *msk);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 966f777d35ce..1f3039b829a7 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -86,7 +86,7 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
struct mptcp_sock *msk;
int local_id;

- msk = mptcp_token_get_sock(subflow_req->token);
+ msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
if (!msk) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
return NULL;
diff --git a/net/mptcp/syncookies.c b/net/mptcp/syncookies.c
index 37127781aee9..7f22526346a7 100644
--- a/net/mptcp/syncookies.c
+++ b/net/mptcp/syncookies.c
@@ -108,18 +108,12 @@ bool mptcp_token_join_cookie_init_state(struct mptcp_subflow_request_sock *subfl

e->valid = 0;

- msk = mptcp_token_get_sock(e->token);
+ msk = mptcp_token_get_sock(net, e->token);
if (!msk) {
spin_unlock_bh(&join_entry_locks[i]);
return false;
}

- /* If this fails, the token got re-used in the mean time by another
- * mptcp socket in a different netns, i.e. entry is outdated.
- */
- if (!net_eq(sock_net((struct sock *)msk), net))
- goto err_put;
-
subflow_req->remote_nonce = e->remote_nonce;
subflow_req->local_nonce = e->local_nonce;
subflow_req->backup = e->backup;
@@ -128,11 +122,6 @@ bool mptcp_token_join_cookie_init_state(struct mptcp_subflow_request_sock *subfl
subflow_req->msk = msk;
spin_unlock_bh(&join_entry_locks[i]);
return true;
-
-err_put:
- spin_unlock_bh(&join_entry_locks[i]);
- sock_put((struct sock *)msk);
- return false;
}

void __init mptcp_join_cookie_init(void)
diff --git a/net/mptcp/token.c b/net/mptcp/token.c
index a98e554b034f..e581b341c5be 100644
--- a/net/mptcp/token.c
+++ b/net/mptcp/token.c
@@ -231,6 +231,7 @@ bool mptcp_token_exists(u32 token)

/**
* mptcp_token_get_sock - retrieve mptcp connection sock using its token
+ * @net: restrict to this namespace
* @token: token of the mptcp connection to retrieve
*
* This function returns the mptcp connection structure with the given token.
@@ -238,7 +239,7 @@ bool mptcp_token_exists(u32 token)
*
* returns NULL if no connection with the given token value exists.
*/
-struct mptcp_sock *mptcp_token_get_sock(u32 token)
+struct mptcp_sock *mptcp_token_get_sock(struct net *net, u32 token)
{
struct hlist_nulls_node *pos;
struct token_bucket *bucket;
@@ -251,11 +252,15 @@ struct mptcp_sock *mptcp_token_get_sock(u32 token)
again:
sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
msk = mptcp_sk(sk);
- if (READ_ONCE(msk->token) != token)
+ if (READ_ONCE(msk->token) != token ||
+ !net_eq(sock_net(sk), net))
continue;
+
if (!refcount_inc_not_zero(&sk->sk_refcnt))
goto not_found;
- if (READ_ONCE(msk->token) != token) {
+
+ if (READ_ONCE(msk->token) != token ||
+ !net_eq(sock_net(sk), net)) {
sock_put(sk);
goto again;
}
diff --git a/net/mptcp/token_test.c b/net/mptcp/token_test.c
index e1bd6f0a0676..5d984bec1cd8 100644
--- a/net/mptcp/token_test.c
+++ b/net/mptcp/token_test.c
@@ -11,6 +11,7 @@ static struct mptcp_subflow_request_sock *build_req_sock(struct kunit *test)
GFP_USER);
KUNIT_EXPECT_NOT_ERR_OR_NULL(test, req);
mptcp_token_init_request((struct request_sock *)req);
+ sock_net_set((struct sock *)req, &init_net);
return req;
}

@@ -22,7 +23,7 @@ static void mptcp_token_test_req_basic(struct kunit *test)
KUNIT_ASSERT_EQ(test, 0,
mptcp_token_new_request((struct request_sock *)req));
KUNIT_EXPECT_NE(test, 0, (int)req->token);
- KUNIT_EXPECT_PTR_EQ(test, null_msk, mptcp_token_get_sock(req->token));
+ KUNIT_EXPECT_PTR_EQ(test, null_msk, mptcp_token_get_sock(&init_net, req->token));

/* cleanup */
mptcp_token_destroy_request((struct request_sock *)req);
@@ -55,6 +56,7 @@ static struct mptcp_sock *build_msk(struct kunit *test)
msk = kunit_kzalloc(test, sizeof(struct mptcp_sock), GFP_USER);
KUNIT_EXPECT_NOT_ERR_OR_NULL(test, msk);
refcount_set(&((struct sock *)msk)->sk_refcnt, 1);
+ sock_net_set((struct sock *)msk, &init_net);
return msk;
}

@@ -74,11 +76,11 @@ static void mptcp_token_test_msk_basic(struct kunit *test)
mptcp_token_new_connect((struct sock *)icsk));
KUNIT_EXPECT_NE(test, 0, (int)ctx->token);
KUNIT_EXPECT_EQ(test, ctx->token, msk->token);
- KUNIT_EXPECT_PTR_EQ(test, msk, mptcp_token_get_sock(ctx->token));
+ KUNIT_EXPECT_PTR_EQ(test, msk, mptcp_token_get_sock(&init_net, ctx->token));
KUNIT_EXPECT_EQ(test, 2, (int)refcount_read(&sk->sk_refcnt));

mptcp_token_destroy(msk);
- KUNIT_EXPECT_PTR_EQ(test, null_msk, mptcp_token_get_sock(ctx->token));
+ KUNIT_EXPECT_PTR_EQ(test, null_msk, mptcp_token_get_sock(&init_net, ctx->token));
}

static void mptcp_token_test_accept(struct kunit *test)
@@ -90,11 +92,11 @@ static void mptcp_token_test_accept(struct kunit *test)
mptcp_token_new_request((struct request_sock *)req));
msk->token = req->token;
mptcp_token_accept(req, msk);
- KUNIT_EXPECT_PTR_EQ(test, msk, mptcp_token_get_sock(msk->token));
+ KUNIT_EXPECT_PTR_EQ(test, msk, mptcp_token_get_sock(&init_net, msk->token));

/* this is now a no-op */
mptcp_token_destroy_request((struct request_sock *)req);
- KUNIT_EXPECT_PTR_EQ(test, msk, mptcp_token_get_sock(msk->token));
+ KUNIT_EXPECT_PTR_EQ(test, msk, mptcp_token_get_sock(&init_net, msk->token));

/* cleanup */
mptcp_token_destroy(msk);
@@ -116,7 +118,7 @@ static void mptcp_token_test_destroyed(struct kunit *test)

/* simulate race on removal */
refcount_set(&sk->sk_refcnt, 0);
- KUNIT_EXPECT_PTR_EQ(test, null_msk, mptcp_token_get_sock(msk->token));
+ KUNIT_EXPECT_PTR_EQ(test, null_msk, mptcp_token_get_sock(&init_net, msk->token));

/* cleanup */
mptcp_token_destroy(msk);
--
2.33.0