From patchwork Wed Jan 27 19:31:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Fomichev X-Patchwork-Id: 372186 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A11F8C433E0 for ; Wed, 27 Jan 2021 19:36:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5733664DA0 for ; Wed, 27 Jan 2021 19:36:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344547AbhA0TgB (ORCPT ); Wed, 27 Jan 2021 14:36:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344429AbhA0Tci (ORCPT ); Wed, 27 Jan 2021 14:32:38 -0500 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15312C06178C for ; Wed, 27 Jan 2021 11:31:43 -0800 (PST) Received: by mail-qk1-x749.google.com with SMTP id 70so2370303qkh.4 for ; Wed, 27 Jan 2021 11:31:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:to:cc; bh=VugVEvcIN6GWwOZoLHWpHgZhzGZiUAHGgt3jprdhH8I=; b=J56nZ9GpRrhi9XoH7l6X2IryRO71Du6g1cUVvrIQe4pHKrqnmGfboZ9pzvOuuzjdKS /fg4umtyzEhL/2PEE4s4OWHh97W9nuF1PxOoD48ca4CnIInSC9QnZCw823jrmW6ZJmQ6 Lw1jp4ntwdKPYqdWIz6TEQW8poptejxuLqR20FE6wD15aXpQj6QYpkdzMCvrq3FAdF8g hWOyXaPFiOZlmEh2zTGDtilDmJ2nI+r2yk1KBbdz0GCNXlYUTOcbkNWSCdjb1R3jYhRN QZ+FHIVzrGGS3J1G2lwGTpD85dpkhpnxb04UK4ts7EKbD10VN/9wUhMbay5lurZvLWws zDYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :to:cc; bh=VugVEvcIN6GWwOZoLHWpHgZhzGZiUAHGgt3jprdhH8I=; b=J71t0ERO/Zmj8U+vIbtHohoC+U3obP0XkGyOXH/QbV2IGdw65KrbqOCPbiHX/MtOLh USDObX99fGFN1jZGIhRniHg0zMkNF6OJdIe3AFiQnfrqvJHPfFY7UQDiYX0BvO7z9SWN CczuJ/jiFCyZt7XOSFVyqI68QRCxZSZxl+O6yxdbpO/v4Yrb0aNIEnErCetwqY6HAyq4 glYbPTK7D2H4W2sXOi/EN2Nx1q2iI9Si98FeSF7zl8Ci9qneD+tMdxy4nns9QSsa9RtO PZUiKK6qmUvxIonubnycxVRmL6w03wEzTaG4IEHS5NrZPtHTS/08xM/VQOCDZCTHwtfk wiNQ== X-Gm-Message-State: AOAM532muOBO0chT/hdX/4eFCsOsxyKBEXFcYsJVNx3Qu5TxPkzTGUYi yI564EdUM56LdtS+X0S+jj3oT7Tnrps0LSSmhuW1yEcxo3po9yf7reDP6B1UJ8d5vgro5i5dl+v yYudyyyv2iDwjN0DzJP+I/d3EAPSJo9J12ZftwB6wSw50dry7M+KJBg== X-Google-Smtp-Source: ABdhPJzTD96PodYejKjrph4Hw00a+Dxhx3dYUWwoA7b3ifEdxZ4tiQTMrykjbkxF3O/RRu0nG3MvCOo= Sender: "sdf via sendgmr" X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:1:7220:84ff:fe09:7732]) (user=sdf job=sendgmr) by 2002:ad4:4349:: with SMTP id q9mr12066842qvs.23.1611775902018; Wed, 27 Jan 2021 11:31:42 -0800 (PST) Date: Wed, 27 Jan 2021 11:31:39 -0800 Message-Id: <20210127193140.3170382-1-sdf@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.30.0.280.ga3ce27912f-goog Subject: [PATCH bpf-next v5 1/2] bpf: allow rewriting to ports under ip_unprivileged_port_start From: Stanislav Fomichev To: netdev@vger.kernel.org, bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, Stanislav Fomichev , Andrey Ignatov , Martin KaFai Lau Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org At the moment, BPF_CGROUP_INET{4,6}_BIND hooks can rewrite user_port to the privileged ones (< ip_unprivileged_port_start), but it will be rejected later on in the __inet_bind or __inet6_bind. Let's add another return value to indicate that CAP_NET_BIND_SERVICE check should be ignored. Use the same idea as we currently use in cgroup/egress where bit #1 indicates CN. Instead, for cgroup/bind{4,6}, bit #1 indicates that CAP_NET_BIND_SERVICE should be bypassed. v5: - rename flags to be less confusing (Andrey Ignatov) - rework BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY to work on flags and accept BPF_RET_SET_CN (no behavioral changes) v4: - Add missing IPv6 support (Martin KaFai Lau) v3: - Update description (Martin KaFai Lau) - Fix capability restore in selftest (Martin KaFai Lau) v2: - Switch to explicit return code (Martin KaFai Lau) Acked-by: Andrey Ignatov Reviewed-by: Martin KaFai Lau Signed-off-by: Stanislav Fomichev --- include/linux/bpf-cgroup.h | 38 ++++++++++++++++++++-------- include/linux/bpf.h | 52 ++++++++++++++++++++++++-------------- include/net/inet_common.h | 2 ++ kernel/bpf/cgroup.c | 8 ++++-- kernel/bpf/verifier.c | 3 +++ net/ipv4/af_inet.c | 9 ++++--- net/ipv6/af_inet6.c | 9 ++++--- 7 files changed, 84 insertions(+), 37 deletions(-) diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index 0748fd87969e..c42e02b4d84b 100644 --- a/include/linux/bpf-cgroup.h +++ b/include/linux/bpf-cgroup.h @@ -125,7 +125,8 @@ int __cgroup_bpf_run_filter_sk(struct sock *sk, int __cgroup_bpf_run_filter_sock_addr(struct sock *sk, struct sockaddr *uaddr, enum bpf_attach_type type, - void *t_ctx); + void *t_ctx, + u32 *flags); int __cgroup_bpf_run_filter_sock_ops(struct sock *sk, struct bpf_sock_ops_kern *sock_ops, @@ -231,30 +232,48 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key, #define BPF_CGROUP_RUN_SA_PROG(sk, uaddr, type) \ ({ \ + u32 __unused_flags; \ int __ret = 0; \ if (cgroup_bpf_enabled(type)) \ __ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \ - NULL); \ + NULL, \ + &__unused_flags); \ __ret; \ }) #define BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, type, t_ctx) \ ({ \ + u32 __unused_flags; \ int __ret = 0; \ if (cgroup_bpf_enabled(type)) { \ lock_sock(sk); \ __ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \ - t_ctx); \ + t_ctx, \ + &__unused_flags); \ release_sock(sk); \ } \ __ret; \ }) -#define BPF_CGROUP_RUN_PROG_INET4_BIND_LOCK(sk, uaddr) \ - BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET4_BIND, NULL) - -#define BPF_CGROUP_RUN_PROG_INET6_BIND_LOCK(sk, uaddr) \ - BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET6_BIND, NULL) +/* BPF_CGROUP_INET4_BIND and BPF_CGROUP_INET6_BIND can return extra flags + * via upper bits of return code. The only flag that is supported + * (at bit position 0) is to indicate CAP_NET_BIND_SERVICE capability check + * should be bypassed (BPF_RET_BIND_NO_CAP_NET_BIND_SERVICE). + */ +#define BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr, type, bind_flags) \ +({ \ + u32 __flags = 0; \ + int __ret = 0; \ + if (cgroup_bpf_enabled(type)) { \ + lock_sock(sk); \ + __ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \ + NULL, &__flags); \ + release_sock(sk); \ + if (__flags & BPF_RET_BIND_NO_CAP_NET_BIND_SERVICE) \ + *bind_flags |= BIND_NO_CAP_NET_BIND_SERVICE; \ + } \ + __ret; \ +}) #define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) \ ((cgroup_bpf_enabled(BPF_CGROUP_INET4_CONNECT) || \ @@ -453,8 +472,7 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map, #define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; }) #define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) ({ 0; }) #define BPF_CGROUP_RUN_PROG_INET_SOCK_RELEASE(sk) ({ 0; }) -#define BPF_CGROUP_RUN_PROG_INET4_BIND_LOCK(sk, uaddr) ({ 0; }) -#define BPF_CGROUP_RUN_PROG_INET6_BIND_LOCK(sk, uaddr) ({ 0; }) +#define BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr, type, flags) ({ 0; }) #define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk) ({ 0; }) #define BPF_CGROUP_RUN_PROG_INET6_POST_BIND(sk) ({ 0; }) #define BPF_CGROUP_RUN_PROG_INET4_CONNECT(sk, uaddr) ({ 0; }) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1aac2af12fed..321966fc35db 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1073,6 +1073,34 @@ int bpf_prog_array_copy(struct bpf_prog_array *old_array, struct bpf_prog *include_prog, struct bpf_prog_array **new_array); +/* BPF program asks to bypass CAP_NET_BIND_SERVICE in bind. */ +#define BPF_RET_BIND_NO_CAP_NET_BIND_SERVICE (1 << 0) +/* BPF program asks to set CN on the packet. */ +#define BPF_RET_SET_CN (1 << 0) + +#define BPF_PROG_RUN_ARRAY_FLAGS(array, ctx, func, ret_flags) \ + ({ \ + struct bpf_prog_array_item *_item; \ + struct bpf_prog *_prog; \ + struct bpf_prog_array *_array; \ + u32 _ret = 1; \ + u32 func_ret; \ + migrate_disable(); \ + rcu_read_lock(); \ + _array = rcu_dereference(array); \ + _item = &_array->items[0]; \ + while ((_prog = READ_ONCE(_item->prog))) { \ + bpf_cgroup_storage_set(_item->cgroup_storage); \ + func_ret = func(_prog, ctx); \ + _ret &= (func_ret & 1); \ + *(ret_flags) |= (func_ret >> 1); \ + _item++; \ + } \ + rcu_read_unlock(); \ + migrate_enable(); \ + _ret; \ + }) + #define __BPF_PROG_RUN_ARRAY(array, ctx, func, check_non_null) \ ({ \ struct bpf_prog_array_item *_item; \ @@ -1120,25 +1148,11 @@ _out: \ */ #define BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY(array, ctx, func) \ ({ \ - struct bpf_prog_array_item *_item; \ - struct bpf_prog *_prog; \ - struct bpf_prog_array *_array; \ - u32 ret; \ - u32 _ret = 1; \ - u32 _cn = 0; \ - migrate_disable(); \ - rcu_read_lock(); \ - _array = rcu_dereference(array); \ - _item = &_array->items[0]; \ - while ((_prog = READ_ONCE(_item->prog))) { \ - bpf_cgroup_storage_set(_item->cgroup_storage); \ - ret = func(_prog, ctx); \ - _ret &= (ret & 1); \ - _cn |= (ret & 2); \ - _item++; \ - } \ - rcu_read_unlock(); \ - migrate_enable(); \ + u32 _flags = 0; \ + bool _cn; \ + u32 _ret; \ + _ret = BPF_PROG_RUN_ARRAY_FLAGS(array, ctx, func, &_flags); \ + _cn = _flags & BPF_RET_SET_CN; \ if (_ret) \ _ret = (_cn ? NET_XMIT_CN : NET_XMIT_SUCCESS); \ else \ diff --git a/include/net/inet_common.h b/include/net/inet_common.h index cb2818862919..cad2a611efde 100644 --- a/include/net/inet_common.h +++ b/include/net/inet_common.h @@ -41,6 +41,8 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len); #define BIND_WITH_LOCK (1 << 1) /* Called from BPF program. */ #define BIND_FROM_BPF (1 << 2) +/* Skip CAP_NET_BIND_SERVICE check. */ +#define BIND_NO_CAP_NET_BIND_SERVICE (1 << 3) int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, u32 flags); int inet_getname(struct socket *sock, struct sockaddr *uaddr, diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index da649f20d6b2..cdf3c7e611d9 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -1055,6 +1055,8 @@ EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk); * @uaddr: sockaddr struct provided by user * @type: The type of program to be exectuted * @t_ctx: Pointer to attach type specific context + * @flags: Pointer to u32 which contains higher bits of BPF program + * return value (OR'ed together). * * socket is expected to be of type INET or INET6. * @@ -1064,7 +1066,8 @@ EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk); int __cgroup_bpf_run_filter_sock_addr(struct sock *sk, struct sockaddr *uaddr, enum bpf_attach_type type, - void *t_ctx) + void *t_ctx, + u32 *flags) { struct bpf_sock_addr_kern ctx = { .sk = sk, @@ -1087,7 +1090,8 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk, } cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data); - ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN); + ret = BPF_PROG_RUN_ARRAY_FLAGS(cgrp->bpf.effective[type], &ctx, + BPF_PROG_RUN, flags); return ret == 1 ? 0 : -EPERM; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d0eae51b31e4..972fc38eb62d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7986,6 +7986,9 @@ static int check_return_code(struct bpf_verifier_env *env) env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME || env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME) range = tnum_range(1, 1); + if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND || + env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND) + range = tnum_range(0, 3); break; case BPF_PROG_TYPE_CGROUP_SKB: if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) { diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 6ba2930ff49b..aaa94bea19c3 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -438,6 +438,7 @@ EXPORT_SYMBOL(inet_release); int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) { struct sock *sk = sock->sk; + u32 flags = BIND_WITH_LOCK; int err; /* If the socket has its own bind function then use it. (RAW) */ @@ -450,11 +451,12 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) /* BPF prog is run before any checks are done so that if the prog * changes context in a wrong way it will be caught. */ - err = BPF_CGROUP_RUN_PROG_INET4_BIND_LOCK(sk, uaddr); + err = BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr, + BPF_CGROUP_INET4_BIND, &flags); if (err) return err; - return __inet_bind(sk, uaddr, addr_len, BIND_WITH_LOCK); + return __inet_bind(sk, uaddr, addr_len, flags); } EXPORT_SYMBOL(inet_bind); @@ -499,7 +501,8 @@ int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, snum = ntohs(addr->sin_port); err = -EACCES; - if (snum && inet_port_requires_bind_service(net, snum) && + if (!(flags & BIND_NO_CAP_NET_BIND_SERVICE) && + snum && inet_port_requires_bind_service(net, snum) && !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) goto out; diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index b9c654836b72..f091fe9b4da5 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -295,7 +295,8 @@ static int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, return -EINVAL; snum = ntohs(addr->sin6_port); - if (snum && inet_port_requires_bind_service(net, snum) && + if (!(flags & BIND_NO_CAP_NET_BIND_SERVICE) && + snum && inet_port_requires_bind_service(net, snum) && !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) return -EACCES; @@ -439,6 +440,7 @@ static int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) { struct sock *sk = sock->sk; + u32 flags = BIND_WITH_LOCK; int err = 0; /* If the socket has its own bind function then use it. */ @@ -451,11 +453,12 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) /* BPF prog is run before any checks are done so that if the prog * changes context in a wrong way it will be caught. */ - err = BPF_CGROUP_RUN_PROG_INET6_BIND_LOCK(sk, uaddr); + err = BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr, + BPF_CGROUP_INET6_BIND, &flags); if (err) return err; - return __inet6_bind(sk, uaddr, addr_len, BIND_WITH_LOCK); + return __inet6_bind(sk, uaddr, addr_len, flags); } EXPORT_SYMBOL(inet6_bind);