From patchwork Wed Sep 9 18:24:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Fomichev X-Patchwork-Id: 1360917 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.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=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20161025 header.b=afXZik5c; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4Bmr5q3B8Nz9sTM for ; Thu, 10 Sep 2020 04:24:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728611AbgIISY1 (ORCPT ); Wed, 9 Sep 2020 14:24:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727005AbgIISYP (ORCPT ); Wed, 9 Sep 2020 14:24:15 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1414C061755 for ; Wed, 9 Sep 2020 11:24:14 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id x10so3039010ybj.19 for ; Wed, 09 Sep 2020 11:24:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=Kp0FBrpofhNJI+kmmwHfi2Nq63x0XIfSCSb00FSkJPA=; b=afXZik5cfyiAAg4USSINaxi07eTcXvUFDvmzMlaDDJ69cxoQ8TqAy8YUwqmzPn5Zrc MvInKeEjqhq7jyCwSZO9Dw7xolMNyyZTyZ3abQn0/InrVHnEiUAUgP7fDMlvCCu7EWsb O0L0jdU4aZyxJlWV0x808jRMdGYpTdOLk7j1fQF8KQ4O+gdVfn9KpUOOH2HQFKIe/nZ+ D2nruda2SA8Vd3tNw4+6S/OZCHZmTSutViGTiO3uRn13XeB6RlR7bjH4Y79FL33CoLDA 5i6xQx5R/95i4uKxajUD57/M/pd1Qu6/oANb6K8uvXnXYeGH4UQXedigrbEctBSWXeV8 o3Zg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=Kp0FBrpofhNJI+kmmwHfi2Nq63x0XIfSCSb00FSkJPA=; b=SSv0zYyxE0QB62yP9HIUD9Asa7oQx4HU5XTPLeSYnjFmkFkSTGB0wV1aNe3jh8ooPD 7w3/eLTWOzm1SkQfMSRYbfGq+Dqtt6uyVoQpM4isvwM7ciAgm+bnK1XdMdT+PHUIajJX PhYc+rqabfXwAGXIydXq74jTZehu64lmFAb2HlQgJtGfCJ+93VAB6QoWskLtBPFxQOwx +dlq6Vg8VRLcYx2DNrJiU6nPR3+QDPE0urn5+LdoAZmgelgzjttZfLnUbzBG0Q74gRSL j+NwrcmzUK/e/I3S6gEEAuD4iedkGZynDLZmLEHX4KbYpZ6AZ2kdrd9n63NlHEgEkRSn NurQ== X-Gm-Message-State: AOAM531xcsqAngKPjK9HCmLviQLPN0MMyrC/cT1z1YdGlyC9RFxxcrKw da/qPjfr5sgT9/uHUBmO9H2CLRo= X-Google-Smtp-Source: ABdhPJzdQl/DtmvRdisK6Z1bgExtHgErmst9kwdRUu1Taswo9nYt99YEmvxDUscE5M+j96/rOv1cMh0= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:1:7220:84ff:fe09:7732]) (user=sdf job=sendgmr) by 2002:a25:d348:: with SMTP id e69mr7964941ybf.273.1599675853854; Wed, 09 Sep 2020 11:24:13 -0700 (PDT) Date: Wed, 9 Sep 2020 11:24:04 -0700 In-Reply-To: <20200909182406.3147878-1-sdf@google.com> Message-Id: <20200909182406.3147878-4-sdf@google.com> Mime-Version: 1.0 References: <20200909182406.3147878-1-sdf@google.com> X-Mailer: git-send-email 2.28.0.526.ge36021eeef-goog Subject: [PATCH bpf-next v4 3/5] libbpf: Add BPF_PROG_BIND_MAP syscall and use it on .metadata section From: Stanislav Fomichev To: netdev@vger.kernel.org, bpf@vger.kernel.org Cc: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net, YiFei Zhu , YiFei Zhu , Stanislav Fomichev Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: YiFei Zhu The patch adds a simple wrapper bpf_prog_bind_map around the syscall. When the libbpf tries to load a program, it will probe the kernel for the support of this syscall and unconditionally bind .rodata section to the program. Cc: YiFei Zhu Signed-off-by: YiFei Zhu Signed-off-by: Stanislav Fomichev --- tools/lib/bpf/bpf.c | 13 ++++++ tools/lib/bpf/bpf.h | 8 ++++ tools/lib/bpf/libbpf.c | 94 ++++++++++++++++++++++++++++++++-------- tools/lib/bpf/libbpf.map | 1 + 4 files changed, 98 insertions(+), 18 deletions(-) diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 82b983ff6569..5f6c5676cc45 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -872,3 +872,16 @@ int bpf_enable_stats(enum bpf_stats_type type) return sys_bpf(BPF_ENABLE_STATS, &attr, sizeof(attr)); } + +int bpf_prog_bind_map(int prog_fd, int map_fd, + const struct bpf_prog_bind_opts *opts) +{ + union bpf_attr attr; + + memset(&attr, 0, sizeof(attr)); + attr.prog_bind_map.prog_fd = prog_fd; + attr.prog_bind_map.map_fd = map_fd; + attr.prog_bind_map.flags = OPTS_GET(opts, flags, 0); + + return sys_bpf(BPF_PROG_BIND_MAP, &attr, sizeof(attr)); +} diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index 015d13f25fcc..8c1ac4b42f90 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -243,6 +243,14 @@ LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf, enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */ LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type); +struct bpf_prog_bind_opts { + size_t sz; /* size of this struct for forward/backward compatibility */ + __u32 flags; +}; +#define bpf_prog_bind_opts__last_field flags + +LIBBPF_API int bpf_prog_bind_map(int prog_fd, int map_fd, + const struct bpf_prog_bind_opts *opts); #ifdef __cplusplus } /* extern "C" */ #endif diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 550950eb1860..f500ae7e9126 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -174,6 +174,8 @@ enum kern_feature_id { FEAT_EXP_ATTACH_TYPE, /* bpf_probe_read_{kernel,user}[_str] helpers */ FEAT_PROBE_READ_KERN, + /* BPF_PROG_BIND_MAP is supported */ + FEAT_PROG_BIND_MAP, __FEAT_CNT, }; @@ -409,6 +411,7 @@ struct bpf_object { struct extern_desc *externs; int nr_extern; int kconfig_map_idx; + int rodata_map_idx; bool loaded; bool has_subcalls; @@ -1070,6 +1073,7 @@ static struct bpf_object *bpf_object__new(const char *path, obj->efile.bss_shndx = -1; obj->efile.st_ops_shndx = -1; obj->kconfig_map_idx = -1; + obj->rodata_map_idx = -1; obj->kern_version = get_kernel_version(); obj->loaded = false; @@ -1428,6 +1432,8 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) obj->efile.rodata->d_size); if (err) return err; + + obj->rodata_map_idx = obj->nr_maps - 1; } if (obj->efile.bss_shndx >= 0) { err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS, @@ -3729,18 +3735,13 @@ static int probe_kern_prog_name(void) return probe_fd(ret); } -static int probe_kern_global_data(void) +static void probe_create_global_data(int *prog, int *map, + struct bpf_insn *insns, size_t insns_cnt) { struct bpf_load_program_attr prg_attr; struct bpf_create_map_attr map_attr; char *cp, errmsg[STRERR_BUFSIZE]; - struct bpf_insn insns[] = { - BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16), - BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42), - BPF_MOV64_IMM(BPF_REG_0, 0), - BPF_EXIT_INSN(), - }; - int ret, map; + int err; memset(&map_attr, 0, sizeof(map_attr)); map_attr.map_type = BPF_MAP_TYPE_ARRAY; @@ -3748,26 +3749,40 @@ static int probe_kern_global_data(void) map_attr.value_size = 32; map_attr.max_entries = 1; - map = bpf_create_map_xattr(&map_attr); - if (map < 0) { - ret = -errno; - cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); + *map = bpf_create_map_xattr(&map_attr); + if (*map < 0) { + err = errno; + cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", - __func__, cp, -ret); - return ret; + __func__, cp, -err); + return; } - insns[0].imm = map; + insns[0].imm = *map; memset(&prg_attr, 0, sizeof(prg_attr)); prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; prg_attr.insns = insns; - prg_attr.insns_cnt = ARRAY_SIZE(insns); + prg_attr.insns_cnt = insns_cnt; prg_attr.license = "GPL"; - ret = bpf_load_program_xattr(&prg_attr, NULL, 0); + *prog = bpf_load_program_xattr(&prg_attr, NULL, 0); +} + +static int probe_kern_global_data(void) +{ + struct bpf_insn insns[] = { + BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16), + BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int prog = -1, map = -1; + + probe_create_global_data(&prog, &map, insns, ARRAY_SIZE(insns)); + close(map); - return probe_fd(ret); + return probe_fd(prog); } static int probe_kern_btf(void) @@ -3894,6 +3909,32 @@ static int probe_kern_probe_read_kernel(void) return probe_fd(bpf_load_program_xattr(&attr, NULL, 0)); } +static int probe_prog_bind_map(void) +{ + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int prog = -1, map = -1, ret = 0; + + if (!kernel_supports(FEAT_GLOBAL_DATA)) + return 0; + + probe_create_global_data(&prog, &map, insns, ARRAY_SIZE(insns)); + + if (map >= 0 && prog < 0) { + close(map); + return 0; + } + + if (!bpf_prog_bind_map(prog, map, NULL)) + ret = 1; + + close(map); + close(prog); + return ret; +} + enum kern_feature_result { FEAT_UNKNOWN = 0, FEAT_SUPPORTED = 1, @@ -3934,6 +3975,9 @@ static struct kern_feature_desc { }, [FEAT_PROBE_READ_KERN] = { "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel, + }, + [FEAT_PROG_BIND_MAP] = { + "BPF_PROG_BIND_MAP support", probe_prog_bind_map, } }; @@ -6468,6 +6512,20 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, if (ret >= 0) { if (log_buf && load_attr.log_level) pr_debug("verifier log:\n%s", log_buf); + + if (prog->obj->rodata_map_idx >= 0 && + kernel_supports(FEAT_PROG_BIND_MAP)) { + struct bpf_map *rodata_map = + &prog->obj->maps[prog->obj->rodata_map_idx]; + + if (bpf_prog_bind_map(ret, bpf_map__fd(rodata_map), NULL)) { + cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + pr_warn("prog '%s': failed to bind .rodata map: %s\n", + prog->name, cp); + /* Don't fail hard if can't bind rodata. */ + } + } + *pfd = ret; ret = 0; goto out; diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 92ceb48a5ca2..0b7830f4ff8b 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -308,4 +308,5 @@ LIBBPF_0.2.0 { perf_buffer__epoll_fd; perf_buffer__consume_buffer; xsk_socket__create_shared; + bpf_prog_bind_map; } LIBBPF_0.1.0;