From patchwork Thu Jan 21 01:22:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Fomichev X-Patchwork-Id: 368529 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=-26.3 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, 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 2348BC433E9 for ; Thu, 21 Jan 2021 01:49:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD8842388B for ; Thu, 21 Jan 2021 01:49:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392602AbhAUBqy (ORCPT ); Wed, 20 Jan 2021 20:46:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390181AbhAUBXY (ORCPT ); Wed, 20 Jan 2021 20:23:24 -0500 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BEC2C061757 for ; Wed, 20 Jan 2021 17:22:44 -0800 (PST) Received: by mail-qv1-xf49.google.com with SMTP id j24so320921qvg.8 for ; Wed, 20 Jan 2021 17:22:44 -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=cqqLarYZEILZJj5WEn8kYVS4VFpMhoB239WWzcW299Q=; b=nLI58/Qwvh75XxEdy2ctCbqmULCF0tsfBi+0O+1mGvjo1j/SDARcNaPVPxpzZuK3Gz 92kdetH6J67aly/O4pTCuOnDe21eanq5erDNjKdTPYmaUv2Po5oiyJHgosSr82wdkglh H8HEExyx4Mb+FQe6qRGrGgynTTob8tP4MWRXTCNCguf4m8eq8UisbcjKk2TFmamSXu8G BGYdJ+S2/aM2OCSjbMxobnU3gsgAGhS1R5dx4CM0zFEije5V/oCfIcXfAhkP85nX74Rq Y+C1ly7lEvb5G7eS3YGBT8lFeHCgJG3r7g10senUFx3iLYv+76JTTutOSIyUdVlrmCg9 pLZw== 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=cqqLarYZEILZJj5WEn8kYVS4VFpMhoB239WWzcW299Q=; b=pOCoFx2O3bA7JAqKveSlYlHmlnV3O27UbKv1tErUfH4FiNz9rgMs4XZ799xSYaDBHs GH6oLT8cX4Odn3kwd3c/sWjWCoUzX1LfC6tSyvW0iwnExBBKLJEWancZnfOL5scI9goI SgOGK36kceZ6ZTioonnz8ltZsGjW0PZKm0NnHvEkowlK+vtj9HsurKFQurZJtY7bexVM LarVyi9fje3RafQfUKTYpzjobEwpgfFhE4/ObBhvD/8/M/2jfINvVvBiLp9NmHd6PFxP 9pl8rUzUl2E+s2fBfhbuosjCnEfxhR4KFZT61GOlW8emxzzXsqjnpbHJJLEjhxrjbdX3 nTmw== X-Gm-Message-State: AOAM532JWBcqyQY576XNgHg1WD6v21JjewlVWYNi7d6Uu09pjiR8Xy/d 5iEchJjdyraBgZ+4rygnHy7HjTGAF0k+G/GoEFe+KMM6mgTxWtLyvoMT15B0/XkkLSxnRxzsny/ Vy1kSICYTSK6cWsUj56KZfANxc5CNN/Is0DitkabIhqn8GOUBKppkXw== X-Google-Smtp-Source: ABdhPJyPr6rGlt/2CYc5rsFFFODJXgui0NWlO0arQSRt4b+KtaYag7WIjtuubNLlim4J1SZGfSgAlEI= 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:a05:6214:321:: with SMTP id j1mr12646475qvu.32.1611192163405; Wed, 20 Jan 2021 17:22:43 -0800 (PST) Date: Wed, 20 Jan 2021 17:22:40 -0800 Message-Id: <20210121012241.2109147-1-sdf@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.30.0.284.gd98b1dd5eaa7-goog Subject: [PATCH bpf-next 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 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 export 'port_changed' event from the BPF program and bypass ip_unprivileged_port_start range check when we've seen that the program explicitly overrode the port. This is accomplished by generating instructions to set ctx->port_changed along with updating ctx->user_port. Signed-off-by: Stanislav Fomichev --- include/linux/bpf-cgroup.h | 30 ++++++++++++++++++++---------- include/linux/filter.h | 1 + include/net/inet_common.h | 3 +++ kernel/bpf/cgroup.c | 8 +++++++- net/core/filter.c | 13 +++++++++++++ net/ipv4/af_inet.c | 9 ++++++--- net/ipv6/af_inet6.c | 6 ++++-- 7 files changed, 54 insertions(+), 16 deletions(-) diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index 0748fd87969e..874ed865bea1 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, + bool *port_changed); int __cgroup_bpf_run_filter_sock_ops(struct sock *sk, struct bpf_sock_ops_kern *sock_ops, @@ -234,7 +235,7 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key, int __ret = 0; \ if (cgroup_bpf_enabled(type)) \ __ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \ - NULL); \ + NULL, NULL); \ __ret; \ }) @@ -244,17 +245,27 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key, if (cgroup_bpf_enabled(type)) { \ lock_sock(sk); \ __ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \ - t_ctx); \ + t_ctx, NULL); \ 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) +#define BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr, type, flags) \ +({ \ + bool port_changed = false; \ + int __ret = 0; \ + if (cgroup_bpf_enabled(type)) { \ + lock_sock(sk); \ + __ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \ + NULL, \ + &port_changed); \ + release_sock(sk); \ + if (port_changed) \ + *flags |= BIND_NO_CAP_NET_BIND_SERVICE; \ + } \ + __ret; \ +}) #define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) \ ((cgroup_bpf_enabled(BPF_CGROUP_INET4_CONNECT) || \ @@ -453,8 +464,7 @@ 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/filter.h b/include/linux/filter.h index 5b3137d7b690..9bee8c057dd2 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1258,6 +1258,7 @@ struct bpf_sock_addr_kern { */ u64 tmp_reg; void *t_ctx; /* Attach type specific context. */ + u32 port_changed; }; struct bpf_sock_ops_kern { diff --git a/include/net/inet_common.h b/include/net/inet_common.h index cb2818862919..9ba935c15869 100644 --- a/include/net/inet_common.h +++ b/include/net/inet_common.h @@ -41,6 +41,9 @@ 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..f5d6205f1717 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 + * @port_changed: Pointer to bool which will be set to 'true' when BPF + * program updates user_port * * 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, + bool *port_changed) { struct bpf_sock_addr_kern ctx = { .sk = sk, @@ -1089,6 +1092,9 @@ 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); + if (port_changed) + *port_changed = ctx.port_changed; + return ret == 1 ? 0 : -EPERM; } EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr); diff --git a/net/core/filter.c b/net/core/filter.c index 9ab94e90d660..b3dd02eb9551 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9028,6 +9028,19 @@ static u32 sock_addr_convert_ctx_access(enum bpf_access_type type, offsetof(struct sockaddr_in6, sin6_port)); BUILD_BUG_ON(sizeof_field(struct sockaddr_in, sin_port) != sizeof_field(struct sockaddr_in6, sin6_port)); + + /* Set bpf_sock_addr_kern->port_changed=1 whenever + * the port is updated from the BPF program. + */ + if (type == BPF_WRITE) { + *insn++ = BPF_ST_MEM(BPF_FIELD_SIZEOF(struct bpf_sock_addr_kern, + port_changed), + si->dst_reg, + offsetof(struct bpf_sock_addr_kern, + port_changed), + 1); + } + /* Account for sin6_port being smaller than user_port. */ port_size = min(port_size, BPF_LDST_BYTES(si)); SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD_SIZE_OFF( 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..3e523c4f5226 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -439,6 +439,7 @@ 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 +452,12 @@ 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);