From patchwork Tue Sep 22 18:38:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Patchwork-Id: 1369157 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=EcWyhwKb; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4Bwqnz2PxFz9sTH for ; Wed, 23 Sep 2020 04:38:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726682AbgIVSiq (ORCPT ); Tue, 22 Sep 2020 14:38:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39361 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgIVSip (ORCPT ); Tue, 22 Sep 2020 14:38:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600799922; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GWYrHvmr3XeRYW2UYJjZ/yBJV2z+Wc7zdFuDzopftII=; b=EcWyhwKbV8ciCOC/bJa11x8XOqVLLeKFxCJpI55qmYyTa00MJ3VY/zr2Z3nRDPJgwS5RJN dZObq/kYWciaDJQnqqOMfrWDy2tgaHQmhmSxaBcq5w9CGDJ+IFD4R+CfhXr6yUN8cew4Jc tEnOd16ynSFXrw/tfPy3m3siUBpwf8w= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-541-iVlqRWFqM6WopV2tUA5V2Q-1; Tue, 22 Sep 2020 14:38:40 -0400 X-MC-Unique: iVlqRWFqM6WopV2tUA5V2Q-1 Received: by mail-wr1-f69.google.com with SMTP id i10so7761451wrq.5 for ; Tue, 22 Sep 2020 11:38:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=GWYrHvmr3XeRYW2UYJjZ/yBJV2z+Wc7zdFuDzopftII=; b=WleUcZG50n5ZKVW+5+S8TmTqNTrqa9NKbw/fHPo/aHB7gSQFFbFob7QzFuRHATMbwA amQQ6hWxWmVfC9T8tjZI9f2LKGdFP8G6EHOUxGS8O3y2ZORyLtjmzflnxynPGwResxDk p5GQT4aI4U4tRvoQd5LkwLh4flSPNtV4pfsx96l5+70M0BdvOuBAyEBL3BQOMyXSPYiw xhjSoo9AVP08Ih8PXspsTroel3+M1V1T8f6zw7e/xxGTgP92DO8fkmvgzWb7nA+hV24D Q75h1mSqDtF5WuHi2jSrs9b+tC1kJiMZWRBrYpKKJnB8eudYD50KIYT1Dzn14QC52a2K U97g== X-Gm-Message-State: AOAM532Vm8FXWuB0lvXMm85mKzd1Jx1vvAKmDr12ApaPT5Z25bn9YJOm fflSDZvymqPnG9BhwZSNigILsLQib/dVRv8A94Kd1msI8HJ0aE3JACf4WUtjrlf26otuN7caFMn rWgsN7vcHkDR8wzMi X-Received: by 2002:a5d:60d0:: with SMTP id x16mr6796768wrt.196.1600799919563; Tue, 22 Sep 2020 11:38:39 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzeWZ6Sj3fbsf9LqhMPCgjTJpuu7g5cVQ+dj2fUpqVXe5U6UUSwy1smveV2/cdkV3kSlrWBDA== X-Received: by 2002:a5d:60d0:: with SMTP id x16mr6796744wrt.196.1600799919283; Tue, 22 Sep 2020 11:38:39 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id w14sm27943281wrk.95.2020.09.22.11.38.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Sep 2020 11:38:38 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 14D2F183A94; Tue, 22 Sep 2020 20:38:37 +0200 (CEST) Subject: [PATCH bpf-next v8 03/11] bpf: verifier: refactor check_attach_btf_id() From: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Alexei Starovoitov Cc: Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , Jiri Olsa , Eelco Chaudron , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org Date: Tue, 22 Sep 2020 20:38:37 +0200 Message-ID: <160079991702.8301.18141427563623823055.stgit@toke.dk> In-Reply-To: <160079991372.8301.10648588027560707258.stgit@toke.dk> References: <160079991372.8301.10648588027560707258.stgit@toke.dk> User-Agent: StGit/0.23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Toke Høiland-Jørgensen The check_attach_btf_id() function really does three things: 1. It performs a bunch of checks on the program to ensure that the attachment is valid. 2. It stores a bunch of state about the attachment being requested in the verifier environment and struct bpf_prog objects. 3. It allocates a trampoline for the attachment. This patch splits out (1.) and (3.) into separate functions in preparation for reusing them when the actual attachment is happening (in the raw_tracepoint_open syscall operation), which will allow tracing programs to have multiple (compatible) attachments. This also fixes a bug where a bunch of checks were skipped if a trampoline already existed for the tracing target. Fixes: 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN") Fixes: 1e6c62a88215 ("bpf: Introduce sleepable BPF programs") Acked-by: Andrii Nakryiko Signed-off-by: Toke Høiland-Jørgensen --- include/linux/bpf.h | 7 + include/linux/bpf_verifier.h | 9 ++ kernel/bpf/trampoline.c | 20 ++++ kernel/bpf/verifier.c | 200 ++++++++++++++++++++++++------------------ 4 files changed, 150 insertions(+), 86 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1f9e7c22cc7e..a1760fd87815 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -621,6 +621,8 @@ static __always_inline unsigned int bpf_dispatcher_nop_func( struct bpf_trampoline *bpf_trampoline_lookup(u64 key); int bpf_trampoline_link_prog(struct bpf_prog *prog); int bpf_trampoline_unlink_prog(struct bpf_prog *prog); +struct bpf_trampoline *bpf_trampoline_get(u64 key, void *addr, + struct btf_func_model *fmodel); void bpf_trampoline_put(struct bpf_trampoline *tr); #define BPF_DISPATCHER_INIT(_name) { \ .mutex = __MUTEX_INITIALIZER(_name.mutex), \ @@ -677,6 +679,11 @@ static inline int bpf_trampoline_unlink_prog(struct bpf_prog *prog) { return -ENOTSUPP; } +static inline struct bpf_trampoline *bpf_trampoline_get(u64 key, void *addr, + struct btf_func_model *fmodel) +{ + return ERR_PTR(-EOPNOTSUPP); +} static inline void bpf_trampoline_put(struct bpf_trampoline *tr) {} #define DEFINE_BPF_DISPATCHER(name) #define DECLARE_BPF_DISPATCHER(name) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 7bc9276c4ef4..4fe718a5b4cd 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -450,4 +450,13 @@ bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); int check_ctx_reg(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno); +int bpf_check_attach_target(struct bpf_verifier_log *log, + const struct bpf_prog *prog, + const struct bpf_prog *tgt_prog, + u32 btf_id, + struct btf_func_model *fmodel, + long *tgt_addr, + const char **tgt_name, + const struct btf_type **tgt_type); + #endif /* _LINUX_BPF_VERIFIER_H */ diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 7dd523a7e32d..e86d32f7f7dc 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -336,6 +336,26 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog) return err; } +struct bpf_trampoline *bpf_trampoline_get(u64 key, void *addr, + struct btf_func_model *fmodel) +{ + struct bpf_trampoline *tr; + + tr = bpf_trampoline_lookup(key); + if (!tr) + return NULL; + + mutex_lock(&tr->mutex); + if (tr->func.addr) + goto out; + + memcpy(&tr->func.model, fmodel, sizeof(*fmodel)); + tr->func.addr = addr; +out: + mutex_unlock(&tr->mutex); + return tr; +} + void bpf_trampoline_put(struct bpf_trampoline *tr) { if (!tr) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 81e1bdc492f8..ad244a606d7a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11174,11 +11174,11 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } #define SECURITY_PREFIX "security_" -static int check_attach_modify_return(struct bpf_prog *prog, unsigned long addr) +static int check_attach_modify_return(const struct bpf_prog *prog, unsigned long addr, + const char *func_name) { if (within_error_injection_list(addr) || - !strncmp(SECURITY_PREFIX, prog->aux->attach_func_name, - sizeof(SECURITY_PREFIX) - 1)) + !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1)) return 0; return -EINVAL; @@ -11215,43 +11215,29 @@ static int check_non_sleepable_error_inject(u32 btf_id) return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id); } -static int check_attach_btf_id(struct bpf_verifier_env *env) +int bpf_check_attach_target(struct bpf_verifier_log *log, + const struct bpf_prog *prog, + const struct bpf_prog *tgt_prog, + u32 btf_id, + struct btf_func_model *fmodel, + long *tgt_addr, + const char **tgt_name, + const struct btf_type **tgt_type) { - struct bpf_prog *prog = env->prog; bool prog_extension = prog->type == BPF_PROG_TYPE_EXT; - struct bpf_prog *tgt_prog = prog->aux->linked_prog; - struct bpf_verifier_log *log = &env->log; - u32 btf_id = prog->aux->attach_btf_id; const char prefix[] = "btf_trace_"; - struct btf_func_model fmodel; int ret = 0, subprog = -1, i; - struct bpf_trampoline *tr; const struct btf_type *t; bool conservative = true; const char *tname; struct btf *btf; - long addr; - u64 key; - - if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING && - prog->type != BPF_PROG_TYPE_LSM) { - verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n"); - return -EINVAL; - } - - if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) - return check_struct_ops_btf_id(env); - - if (prog->type != BPF_PROG_TYPE_TRACING && - prog->type != BPF_PROG_TYPE_LSM && - !prog_extension) - return 0; + long addr = 0; if (!btf_id) { bpf_log(log, "Tracing programs must provide btf_id\n"); return -EINVAL; } - btf = bpf_prog_get_target_btf(prog); + btf = tgt_prog ? tgt_prog->aux->btf : btf_vmlinux; if (!btf) { bpf_log(log, "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n"); @@ -11291,8 +11277,6 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) "Extension programs should be JITed\n"); return -EINVAL; } - env->ops = bpf_verifier_ops[tgt_prog->type]; - prog->expected_attach_type = tgt_prog->expected_attach_type; } if (!tgt_prog->jited) { bpf_log(log, "Can attach to only JITed progs\n"); @@ -11328,13 +11312,11 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) bpf_log(log, "Cannot extend fentry/fexit\n"); return -EINVAL; } - key = ((u64)aux->id) << 32 | btf_id; } else { if (prog_extension) { bpf_log(log, "Cannot replace kernel functions\n"); return -EINVAL; } - key = btf_id; } switch (prog->expected_attach_type) { @@ -11364,13 +11346,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) /* should never happen in valid vmlinux build */ return -EINVAL; - /* remember two read only pointers that are valid for - * the life time of the kernel - */ - prog->aux->attach_func_name = tname; - prog->aux->attach_func_proto = t; - prog->aux->attach_btf_trace = true; - return 0; + break; case BPF_TRACE_ITER: if (!btf_type_is_func(t)) { bpf_log(log, "attach_btf_id %u is not a function\n", @@ -11380,12 +11356,10 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) return -EINVAL; - prog->aux->attach_func_name = tname; - prog->aux->attach_func_proto = t; - if (!bpf_iter_prog_supported(prog)) - return -EINVAL; - ret = btf_distill_func_proto(log, btf, t, tname, &fmodel); - return ret; + ret = btf_distill_func_proto(log, btf, t, tname, fmodel); + if (ret) + return ret; + break; default: if (!prog_extension) return -EINVAL; @@ -11394,13 +11368,6 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) case BPF_LSM_MAC: case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: - prog->aux->attach_func_name = tname; - if (prog->type == BPF_PROG_TYPE_LSM) { - ret = bpf_lsm_verify_prog(log, prog); - if (ret < 0) - return ret; - } - if (!btf_type_is_func(t)) { bpf_log(log, "attach_btf_id %u is not a function\n", btf_id); @@ -11412,24 +11379,14 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) return -EINVAL; - tr = bpf_trampoline_lookup(key); - if (!tr) - return -ENOMEM; - /* t is either vmlinux type or another program's type */ - prog->aux->attach_func_proto = t; - mutex_lock(&tr->mutex); - if (tr->func.addr) { - prog->aux->trampoline = tr; - goto out; - } - if (tgt_prog && conservative) { - prog->aux->attach_func_proto = NULL; + + if (tgt_prog && conservative) t = NULL; - } - ret = btf_distill_func_proto(log, btf, t, - tname, &tr->func.model); + + ret = btf_distill_func_proto(log, btf, t, tname, fmodel); if (ret < 0) - goto out; + return ret; + if (tgt_prog) { if (subprog == 0) addr = (long) tgt_prog->bpf_func; @@ -11441,8 +11398,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) bpf_log(log, "The address of function %s cannot be found\n", tname); - ret = -ENOENT; - goto out; + return -ENOENT; } } @@ -11467,30 +11423,102 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) default: break; } - if (ret) - bpf_log(log, "%s is not sleepable\n", - prog->aux->attach_func_name); + if (ret) { + bpf_log(log, "%s is not sleepable\n", tname); + return ret; + } } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) { if (tgt_prog) { bpf_log(log, "can't modify return codes of BPF programs\n"); - ret = -EINVAL; - goto out; + return -EINVAL; + } + ret = check_attach_modify_return(prog, addr, tname); + if (ret) { + bpf_log(log, "%s() is not modifiable\n", tname); + return ret; } - ret = check_attach_modify_return(prog, addr); - if (ret) - bpf_log(log, "%s() is not modifiable\n", - prog->aux->attach_func_name); } - if (ret) - goto out; - tr->func.addr = (void *)addr; - prog->aux->trampoline = tr; -out: - mutex_unlock(&tr->mutex); - if (ret) - bpf_trampoline_put(tr); + + break; + } + *tgt_addr = addr; + if (tgt_name) + *tgt_name = tname; + if (tgt_type) + *tgt_type = t; + return 0; +} + +static int check_attach_btf_id(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + struct bpf_prog *tgt_prog = prog->aux->linked_prog; + u32 btf_id = prog->aux->attach_btf_id; + struct btf_func_model fmodel; + struct bpf_trampoline *tr; + const struct btf_type *t; + const char *tname; + long addr; + int ret; + u64 key; + + if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM) { + verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n"); + return -EINVAL; + } + + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) + return check_struct_ops_btf_id(env); + + if (prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM && + prog->type != BPF_PROG_TYPE_EXT) + return 0; + + ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, + &fmodel, &addr, &tname, &t); + if (ret) return ret; + + if (tgt_prog) { + if (prog->type == BPF_PROG_TYPE_EXT) { + env->ops = bpf_verifier_ops[tgt_prog->type]; + prog->expected_attach_type = + tgt_prog->expected_attach_type; + } + key = ((u64)tgt_prog->aux->id) << 32 | btf_id; + } else { + key = btf_id; } + + /* remember two read only pointers that are valid for + * the life time of the kernel + */ + prog->aux->attach_func_proto = t; + prog->aux->attach_func_name = tname; + + if (prog->expected_attach_type == BPF_TRACE_RAW_TP) { + prog->aux->attach_btf_trace = true; + return 0; + } else if (prog->expected_attach_type == BPF_TRACE_ITER) { + if (!bpf_iter_prog_supported(prog)) + return -EINVAL; + return 0; + } + + if (prog->type == BPF_PROG_TYPE_LSM) { + ret = bpf_lsm_verify_prog(&env->log, prog); + if (ret < 0) + return ret; + } + + tr = bpf_trampoline_get(key, (void *)addr, &fmodel); + if (!tr) + return -ENOMEM; + + prog->aux->trampoline = tr; + return 0; } int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,