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From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
Date: Thu, 06 Mar 2025 12:29:28 +0100
Subject: [PATCH net-next 2/2] tcp: ulp: diag: more info without
CAP_NET_ADMIN
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To: mptcp@lists.linux.dev, Eric Dumazet <edumazet@google.com>,
Neal Cardwell <ncardwell@google.com>, Kuniyuki Iwashima <kuniyu@amazon.com>,
"David S. Miller" <davem@davemloft.net>, David Ahern <dsahern@kernel.org>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>, Mat Martineau <martineau@kernel.org>,
Geliang Tang <geliang@kernel.org>, Boris Pismenny <borisp@nvidia.com>,
John Fastabend <john.fastabend@gmail.com>
Cc: Davide Caratti <dcaratti@redhat.com>, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
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When introduced in commit 61723b393292 ("tcp: ulp: add functions to dump
ulp-specific information"), the whole ULP diag info has been exported
only if the requester had CAP_NET_ADMIN.
It looks like not everything is sensitive, and some info can be exported
to all users in order to ease the debugging from the userspace side
without requiring additional capabilities. Each layer should then decide
what can be exposed to everybody. The 'net_admin' boolean is then passed
to the different layers.
On kTLS side, it looks like there is nothing sensitive there: version,
cipher type, tx/rx user config type, plus some flags. So, only some
metadata about the configuration, no cryptographic info like keys, etc.
Then, everything can be exported to all users.
On MPTCP side, that's different. The MPTCP-related sequence numbers per
subflow should certainly not be exposed to everybody. For example, the
DSS mapping and ssn_offset would give all users on the system access to
narrow ranges of values for the subflow TCP sequence numbers and
MPTCP-level DSNs, and then ease packet injection. The TCP diag interface
doesn't expose the TCP sequence numbers for TCP sockets, so best to do
the same here. The rest -- token, IDs, flags -- can be exported to
everybody.
Acked-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
include/net/tcp.h | 4 ++--
net/ipv4/tcp_diag.c | 8 ++++----
net/mptcp/diag.c | 42 ++++++++++++++++++++++++++----------------
net/tls/tls_main.c | 4 ++--
4 files changed, 34 insertions(+), 24 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index a9bc959fb102fc6697b4a664b3773b47b3309f13..7207c52b1fc9ce3cd9cf2a85803=
10d0e629f82d6 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2598,8 +2598,8 @@ struct tcp_ulp_ops {
/* cleanup ulp */
void (*release)(struct sock *sk);
/* diagnostic */
- int (*get_info)(struct sock *sk, struct sk_buff *skb);
- size_t (*get_info_size)(const struct sock *sk);
+ int (*get_info)(struct sock *sk, struct sk_buff *skb, bool net_admin);
+ size_t (*get_info_size)(const struct sock *sk, bool net_admin);
/* clone ulp */
void (*clone)(const struct request_sock *req, struct sock *newsk,
const gfp_t priority);
diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index d8bba37dbffd8c6cc7fab2328a88b6ce6ea3e9f4..45e174b8cd22173b6b8eeffe71d=
f334c45498b15 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -96,8 +96,8 @@ static int tcp_diag_put_ulp(struct sk_buff *skb, struct s=
ock *sk,
if (err)
goto nla_failure;
=20
- if (net_admin && ulp_ops->get_info)
- err =3D ulp_ops->get_info(sk, skb);
+ if (ulp_ops->get_info)
+ err =3D ulp_ops->get_info(sk, skb, net_admin);
if (err)
goto nla_failure;
=20
@@ -170,8 +170,8 @@ static size_t tcp_diag_get_aux_size(struct sock *sk, bo=
ol net_admin)
if (ulp_ops) {
size +=3D nla_total_size(0) +
nla_total_size(TCP_ULP_NAME_MAX);
- if (net_admin && ulp_ops->get_info_size)
- size +=3D ulp_ops->get_info_size(sk);
+ if (ulp_ops->get_info_size)
+ size +=3D ulp_ops->get_info_size(sk, net_admin);
}
}
return size;
diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c
index 02205f7994d752cc505991efdf7aa0bbbfd830db..70cf9ebce8338bde3b0bb10fc86=
20905b15f5190 100644
--- a/net/mptcp/diag.c
+++ b/net/mptcp/diag.c
@@ -12,7 +12,7 @@
#include <net/netlink.h>
#include "protocol.h"
=20
-static int subflow_get_info(struct sock *sk, struct sk_buff *skb)
+static int subflow_get_info(struct sock *sk, struct sk_buff *skb, bool net=
_admin)
{
struct mptcp_subflow_context *sf;
struct nlattr *start;
@@ -56,15 +56,6 @@ static int subflow_get_info(struct sock *sk, struct sk_b=
uff *skb)
=20
if (nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_TOKEN_REM, sf->remote_token) ||
nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_TOKEN_LOC, sf->token) ||
- nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
- sf->rel_write_seq) ||
- nla_put_u64_64bit(skb, MPTCP_SUBFLOW_ATTR_MAP_SEQ, sf->map_seq,
- MPTCP_SUBFLOW_ATTR_PAD) ||
- nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
- sf->map_subflow_seq) ||
- nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_SSN_OFFSET, sf->ssn_offset) ||
- nla_put_u16(skb, MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
- 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, subflow_get_local_id(sf)))=
{
@@ -72,6 +63,21 @@ static int subflow_get_info(struct sock *sk, struct sk_b=
uff *skb)
goto nla_failure;
}
=20
+ /* Only export seq related counters to user with CAP_NET_ADMIN */
+ if (net_admin &&
+ (nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
+ sf->rel_write_seq) ||
+ nla_put_u64_64bit(skb, MPTCP_SUBFLOW_ATTR_MAP_SEQ, sf->map_seq,
+ MPTCP_SUBFLOW_ATTR_PAD) ||
+ nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
+ sf->map_subflow_seq) ||
+ nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_SSN_OFFSET, sf->ssn_offset) ||
+ nla_put_u16(skb, MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
+ sf->map_data_len))) {
+ err =3D -EMSGSIZE;
+ goto nla_failure;
+ }
+
rcu_read_unlock();
unlock_sock_fast(sk, slow);
nla_nest_end(skb, start);
@@ -84,22 +90,26 @@ static int subflow_get_info(struct sock *sk, struct sk_=
buff *skb)
return err;
}
=20
-static size_t subflow_get_info_size(const struct sock *sk)
+static size_t subflow_get_info_size(const struct sock *sk, bool net_admin)
{
size_t size =3D 0;
=20
size +=3D nla_total_size(0) + /* INET_ULP_INFO_MPTCP */
nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_TOKEN_REM */
nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_TOKEN_LOC */
- nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ */
- nla_total_size_64bit(8) + /* MPTCP_SUBFLOW_ATTR_MAP_SEQ */
- nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_MAP_SFSEQ */
- nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_SSN_OFFSET */
- nla_total_size(2) + /* MPTCP_SUBFLOW_ATTR_MAP_DATALEN */
nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_FLAGS */
nla_total_size(1) + /* MPTCP_SUBFLOW_ATTR_ID_REM */
nla_total_size(1) + /* MPTCP_SUBFLOW_ATTR_ID_LOC */
0;
+
+ if (net_admin)
+ size +=3D nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ */
+ nla_total_size_64bit(8) + /* MPTCP_SUBFLOW_ATTR_MAP_SEQ */
+ nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_MAP_SFSEQ */
+ nla_total_size(4) + /* MPTCP_SUBFLOW_ATTR_SSN_OFFSET */
+ nla_total_size(2) + /* MPTCP_SUBFLOW_ATTR_MAP_DATALEN */
+ 0;
+
return size;
}
=20
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 99ca4465f70216c5a44e4ca7477df0e93df6b76d..cb86b0bf9a53e1ff060d8e69edd=
bd6acfbee5194 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -1057,7 +1057,7 @@ static u16 tls_user_config(struct tls_context *ctx, b=
ool tx)
return 0;
}
=20
-static int tls_get_info(struct sock *sk, struct sk_buff *skb)
+static int tls_get_info(struct sock *sk, struct sk_buff *skb, bool net_adm=
in)
{
u16 version, cipher_type;
struct tls_context *ctx;
@@ -1115,7 +1115,7 @@ static int tls_get_info(struct sock *sk, struct sk_bu=
ff *skb)
return err;
}
=20
-static size_t tls_get_info_size(const struct sock *sk)
+static size_t tls_get_info_size(const struct sock *sk, bool net_admin)
{
size_t size =3D 0;
=20
--=20
2.47.1