diff mbox series

[net-next,2/2] tcp: ulp: diag: more info without CAP_NET_ADMIN

Message ID 20250306-net-next-tcp-ulp-diag-net-admin-v1-2-06afdd860fc9@kernel.org (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series tcp: ulp: diag: expose more to non net admin users | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 7 this patch: 7
netdev/build_tools success Errors and warnings before: 26 (+0) this patch: 26 (+0)
netdev/cc_maintainers success CCed 14 of 14 maintainers
netdev/build_clang success Errors and warnings before: 10 this patch: 10
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 911 this patch: 911
netdev/checkpatch warning WARNING: line length of 81 exceeds 80 columns WARNING: line length of 82 exceeds 80 columns WARNING: line length of 83 exceeds 80 columns WARNING: line length of 84 exceeds 80 columns WARNING: line length of 85 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 1 this patch: 1
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-03-06--15-00 (tests: 893)

Commit Message

Matthieu Baerts (NGI0) March 6, 2025, 11:29 a.m. UTC
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 mbox series

Patch

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;