From: Mat Martineau <martineau@kernel.org>
To: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
Cc: mptcp@lists.linux.dev, Davide Caratti <dcaratti@redhat.com>
Subject: Re: [PATCH mptcp-next v2 2/2] tcp: ulp: diag: more info without CAP_NET_ADMIN
Date: Wed, 5 Mar 2025 13:31:07 -0800 (PST) [thread overview]
Message-ID: <e1663bf9-76f1-1660-1ce1-43d4af629473@kernel.org> (raw)
In-Reply-To: <20250305-mptcp-tcp-ulp-diag-cap-v2-2-d53fd80748eb@kernel.org>
On Wed, 5 Mar 2025, Matthieu Baerts (NGI0) wrote:
> 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, only some
> metadata about the configuration, no cryptographic information. 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.
>
> 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(-)
Matthieu -
This patch also LGTM:
Acked-by: Mat Martineau <martineau@kernel.org>
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index a9bc959fb102fc6697b4a664b3773b47b3309f13..7207c52b1fc9ce3cd9cf2a8580310d0e629f82d6 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..45e174b8cd22173b6b8eeffe71df334c45498b15 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 sock *sk,
> if (err)
> goto nla_failure;
>
> - if (net_admin && ulp_ops->get_info)
> - err = ulp_ops->get_info(sk, skb);
> + if (ulp_ops->get_info)
> + err = ulp_ops->get_info(sk, skb, net_admin);
> if (err)
> goto nla_failure;
>
> @@ -170,8 +170,8 @@ static size_t tcp_diag_get_aux_size(struct sock *sk, bool net_admin)
> if (ulp_ops) {
> size += nla_total_size(0) +
> nla_total_size(TCP_ULP_NAME_MAX);
> - if (net_admin && ulp_ops->get_info_size)
> - size += ulp_ops->get_info_size(sk);
> + if (ulp_ops->get_info_size)
> + size += ulp_ops->get_info_size(sk, net_admin);
> }
> }
> return size;
> diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c
> index 02205f7994d752cc505991efdf7aa0bbbfd830db..70cf9ebce8338bde3b0bb10fc8620905b15f5190 100644
> --- a/net/mptcp/diag.c
> +++ b/net/mptcp/diag.c
> @@ -12,7 +12,7 @@
> #include <net/netlink.h>
> #include "protocol.h"
>
> -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_buff *skb)
>
> 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_buff *skb)
> goto nla_failure;
> }
>
> + /* 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 = -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;
> }
>
> -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 = 0;
>
> size += 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 += 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;
> }
>
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index 99ca4465f70216c5a44e4ca7477df0e93df6b76d..cb86b0bf9a53e1ff060d8e69eddbd6acfbee5194 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, bool tx)
> return 0;
> }
>
> -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_admin)
> {
> u16 version, cipher_type;
> struct tls_context *ctx;
> @@ -1115,7 +1115,7 @@ static int tls_get_info(struct sock *sk, struct sk_buff *skb)
> return err;
> }
>
> -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 = 0;
>
>
> --
> 2.47.1
>
>
next prev parent reply other threads:[~2025-03-05 21:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-05 18:34 [PATCH mptcp-next v2 0/2] tcp: ulp: diag: remove net admin restriction Matthieu Baerts (NGI0)
2025-03-05 18:34 ` [PATCH mptcp-next v2 1/2] tcp: ulp: diag: always print the name if any Matthieu Baerts (NGI0)
2025-03-05 21:29 ` Mat Martineau
2025-03-05 18:34 ` [PATCH mptcp-next v2 2/2] tcp: ulp: diag: more info without CAP_NET_ADMIN Matthieu Baerts (NGI0)
2025-03-05 21:31 ` Mat Martineau [this message]
2025-03-05 19:45 ` [PATCH mptcp-next v2 0/2] tcp: ulp: diag: remove net admin restriction MPTCP CI
2025-03-06 8:41 ` Matthieu Baerts
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