From 6b22d433aa13f68e3cd9534ca9a5f4277bfa01c2 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Mon, 25 May 2026 12:51:17 -0400 Subject: [PATCH] net/handshake: Pass negative errno through handshake_complete() handshake_complete() declares status as unsigned int and tls_handshake_done() negates that value (-status) before handing it to the TLS consumer. Consumers match on negative errno constants -- xs_tls_handshake_done() has switch (status) { case 0: case -EACCES: case -ETIMEDOUT: lower_transport->xprt_err = status; break; default: lower_transport->xprt_err = -EACCES; } so the API as designed expects callers to pass positive errno values that the tlshd shim then negates. Three internal callers in handshake_nl_accept_doit(), the net-exit drain, and a kunit test follow kernel convention and pass negative errnos -- -EIO, -ETIMEDOUT, -ETIMEDOUT. The implicit conversion to unsigned int turns -ETIMEDOUT into 0xFFFFFF92; the subsequent -status in tls_handshake_done() wraps back to 110, the consumer's switch falls through, and the xprt reports -EACCES on what should be -ETIMEDOUT or -EIO. Fix the API rather than the call sites. The natural kernel convention is negative errno in, negative errno out. Change handshake_complete() and hp_done to take int status, drop the negation in tls_handshake_done(), and negate once in handshake_nl_done_doit() where status arrives from the wire as an unsigned netlink attribute. The three internal callers were already correct under that convention and need no change. At the same wire boundary, declare MAX_ERRNO as the netlink policy upper bound for HANDSHAKE_A_DONE_STATUS. Attribute validation rejects out-of-range values before handshake_nl_done_doit() runs, and negating a bounded u32 there stays within int range -- closing the UBSAN-visible signed- integer overflow that an unconstrained u32 would invoke. Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests") Signed-off-by: Chuck Lever Reviewed-by: Hannes Reinecke Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-3-66c616906ead@oracle.com Signed-off-by: Paolo Abeni --- Documentation/netlink/specs/handshake.yaml | 8 ++++++++ net/handshake/genl.c | 3 ++- net/handshake/genl.h | 1 + net/handshake/handshake-test.c | 2 +- net/handshake/handshake.h | 4 ++-- net/handshake/netlink.c | 2 +- net/handshake/request.c | 2 +- net/handshake/tlshd.c | 4 ++-- 8 files changed, 18 insertions(+), 8 deletions(-) diff --git a/Documentation/netlink/specs/handshake.yaml b/Documentation/netlink/specs/handshake.yaml index 95c3fade7a8d..1024297b3851 100644 --- a/Documentation/netlink/specs/handshake.yaml +++ b/Documentation/netlink/specs/handshake.yaml @@ -12,6 +12,12 @@ protocol: genetlink doc: Netlink protocol to request a transport layer security handshake. definitions: + - + type: const + name: max-errno + value: 4095 + header: linux/err.h + scope: kernel - type: enum name: handler-class @@ -80,6 +86,8 @@ attribute-sets: - name: status type: u32 + checks: + max: max-errno - name: sockfd type: s32 diff --git a/net/handshake/genl.c b/net/handshake/genl.c index 870612609491..4b20cd9cdd0e 100644 --- a/net/handshake/genl.c +++ b/net/handshake/genl.c @@ -10,6 +10,7 @@ #include "genl.h" #include +#include /* HANDSHAKE_CMD_ACCEPT - do */ static const struct nla_policy handshake_accept_nl_policy[HANDSHAKE_A_ACCEPT_HANDLER_CLASS + 1] = { @@ -18,7 +19,7 @@ static const struct nla_policy handshake_accept_nl_policy[HANDSHAKE_A_ACCEPT_HAN /* HANDSHAKE_CMD_DONE - do */ static const struct nla_policy handshake_done_nl_policy[HANDSHAKE_A_DONE_REMOTE_AUTH + 1] = { - [HANDSHAKE_A_DONE_STATUS] = { .type = NLA_U32, }, + [HANDSHAKE_A_DONE_STATUS] = NLA_POLICY_MAX(NLA_U32, MAX_ERRNO), [HANDSHAKE_A_DONE_SOCKFD] = { .type = NLA_S32, }, [HANDSHAKE_A_DONE_REMOTE_AUTH] = { .type = NLA_U32, }, }; diff --git a/net/handshake/genl.h b/net/handshake/genl.h index 8d3e18672daf..46b65f131669 100644 --- a/net/handshake/genl.h +++ b/net/handshake/genl.h @@ -11,6 +11,7 @@ #include #include +#include int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info); int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info); diff --git a/net/handshake/handshake-test.c b/net/handshake/handshake-test.c index 55442b2f518a..df3948e807a0 100644 --- a/net/handshake/handshake-test.c +++ b/net/handshake/handshake-test.c @@ -25,7 +25,7 @@ static int test_accept_func(struct handshake_req *req, struct genl_info *info, return 0; } -static void test_done_func(struct handshake_req *req, unsigned int status, +static void test_done_func(struct handshake_req *req, int status, struct genl_info *info) { } diff --git a/net/handshake/handshake.h b/net/handshake/handshake.h index a48163765a7a..2289b0e274f4 100644 --- a/net/handshake/handshake.h +++ b/net/handshake/handshake.h @@ -57,7 +57,7 @@ struct handshake_proto { int (*hp_accept)(struct handshake_req *req, struct genl_info *info, int fd); void (*hp_done)(struct handshake_req *req, - unsigned int status, + int status, struct genl_info *info); void (*hp_destroy)(struct handshake_req *req); }; @@ -86,7 +86,7 @@ struct handshake_req *handshake_req_hash_lookup(struct sock *sk); struct handshake_req *handshake_req_next(struct handshake_net *hn, int class); int handshake_req_submit(struct socket *sock, struct handshake_req *req, gfp_t flags); -void handshake_complete(struct handshake_req *req, unsigned int status, +void handshake_complete(struct handshake_req *req, int status, struct genl_info *info); bool handshake_req_cancel(struct sock *sk); diff --git a/net/handshake/netlink.c b/net/handshake/netlink.c index 97114ec8027a..039344979de9 100644 --- a/net/handshake/netlink.c +++ b/net/handshake/netlink.c @@ -160,7 +160,7 @@ int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info) status = -EIO; if (info->attrs[HANDSHAKE_A_DONE_STATUS]) - status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]); + status = -(int)nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]); handshake_complete(req, status, info); sockfd_put(sock); diff --git a/net/handshake/request.c b/net/handshake/request.c index 5d4a17f902d2..97f9f8239949 100644 --- a/net/handshake/request.c +++ b/net/handshake/request.c @@ -284,7 +284,7 @@ out_err: } EXPORT_SYMBOL(handshake_req_submit); -void handshake_complete(struct handshake_req *req, unsigned int status, +void handshake_complete(struct handshake_req *req, int status, struct genl_info *info) { struct sock *sk = req->hr_sk; diff --git a/net/handshake/tlshd.c b/net/handshake/tlshd.c index af294c6cc717..7567150c2a4f 100644 --- a/net/handshake/tlshd.c +++ b/net/handshake/tlshd.c @@ -93,7 +93,7 @@ static void tls_handshake_remote_peerids(struct tls_handshake_req *treq, * */ static void tls_handshake_done(struct handshake_req *req, - unsigned int status, struct genl_info *info) + int status, struct genl_info *info) { struct tls_handshake_req *treq = handshake_req_private(req); @@ -104,7 +104,7 @@ static void tls_handshake_done(struct handshake_req *req, if (!status) set_bit(HANDSHAKE_F_REQ_SESSION, &req->hr_flags); - treq->th_consumer_done(treq->th_consumer_data, -status, + treq->th_consumer_done(treq->th_consumer_data, status, treq->th_peerid[0]); }