From mboxrd@z Thu Jan 1 00:00:00 1970 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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 3F5E0ECE596 for ; Mon, 7 Oct 2019 16:14:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E66F620659 for ; Mon, 7 Oct 2019 16:14:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=fomichev-me.20150623.gappssmtp.com header.i=@fomichev-me.20150623.gappssmtp.com header.b="KRcsAxbx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728786AbfJGQOk (ORCPT ); Mon, 7 Oct 2019 12:14:40 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:45498 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728552AbfJGQOk (ORCPT ); Mon, 7 Oct 2019 12:14:40 -0400 Received: by mail-pf1-f196.google.com with SMTP id y72so8924713pfb.12 for ; Mon, 07 Oct 2019 09:14:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fomichev-me.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=lhkQIICT57llAxJWjSnnycoopGn+onBA90k6Esl/Rro=; b=KRcsAxbx1gYJ42q1JsLHEpc5xrdNZptMMnOd0GkSxr39yEN0k/jFbCbpCIpXvEUfC4 pjRzooTWgnM0A6PgI1zQd48EEUUiPiSb9r/JFps25hG+XWpIV68OZK/in2EcEz6Oto1D P9UR6+3qh4oMn4SI+EP309cx/VGc9xFBzsu33rztpmbCqA9+I+oNaZIQfHfLF+0mw1TT x0g5V6ysIxigXSylfw8HQ0fsuClEgdsxIkoynKekvUs2jxAU8+YOPwn08PAjQD/c9mKH tMkQAVvJIFYJK+D0pWtfvfs4s10sfgSrjAg+inTNUbMZZYLCCZ1CbTq3HEeaJKvTYIIL HLJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=lhkQIICT57llAxJWjSnnycoopGn+onBA90k6Esl/Rro=; b=O8wlK03NFidrF2hqPFjWjppUi/hhcJC/Adzo5ziMXNBUIC32aFoD6JRnAgREtcisrO BQR6pkizDkeZ0KT5BgIZviq5tQ8yKGOQeIdPgZ3eWMWUWdEvoHZ+LSRoa/kqt9jdet+Y LgG6HSagPJ5fQr/6gCh9FFkFwRieBOlLvJIv+M7oU8K+lCRAT79PlRkDw5RTkHqr/Kf5 rpQDKPc/feoTScokD2dKHgMVV8iNsmN6mQKYRfgVCkdWvYplfslpYncdaVpFrfYHI1nW KtRpvR4+1kHYKim0zex2iYWrK3TxZOb+L4WEtgutA/GMFezkFkMcpX4PS0zePIRNwUcd e8ew== X-Gm-Message-State: APjAAAUA3daLeCoo4VAj7GPpRMHXuXISofaEDYq02QEzqdb8HLjXX2SS o8y/EzhjunUdsOcFOIxp32DPhg== X-Google-Smtp-Source: APXvYqxyR4IxTbg0rbgEwFk0BZv670ApnbRMlWsmbCFd0fwwIVGbU5cZ6MY6Rc933NPHvZUNaC6SAw== X-Received: by 2002:a17:90a:21a9:: with SMTP id q38mr66757pjc.23.1570464878972; Mon, 07 Oct 2019 09:14:38 -0700 (PDT) Received: from localhost ([2601:646:8f00:18d9:d0fa:7a4b:764f:de48]) by smtp.gmail.com with ESMTPSA id bx18sm9676pjb.26.2019.10.07.09.14.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Oct 2019 09:14:38 -0700 (PDT) Date: Mon, 7 Oct 2019 09:14:37 -0700 From: Stanislav Fomichev To: Andrii Nakryiko Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, ast@fb.com, daniel@iogearbox.net, andrii.nakryiko@gmail.com, kernel-team@fb.com Subject: Re: [PATCH v3 bpf-next 1/4] libbpf: stop enforcing kern_version, populate it for users Message-ID: <20191007161437.GB2096@mini-arch> References: <20191004224037.1625049-1-andriin@fb.com> <20191004224037.1625049-2-andriin@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191004224037.1625049-2-andriin@fb.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/04, Andrii Nakryiko wrote: > Kernel version enforcement for kprobes/kretprobes was removed from > 5.0 kernel in 6c4fc209fcf9 ("bpf: remove useless version check for prog load"). > Since then, BPF programs were specifying SEC("version") just to please > libbpf. We should stop enforcing this in libbpf, if even kernel doesn't > care. Furthermore, libbpf now will pre-populate current kernel version > of the host system, in case we are still running on old kernel. [..] > This patch also removes __bpf_object__open_xattr from libbpf.h, as > nothing in libbpf is relying on having it in that header. That function > was never exported as LIBBPF_API and even name suggests its internal > version. So this should be safe to remove, as it doesn't break ABI. This gives me the following (I don't know why bpftool was allowed to link against non-LIBBPF_API exposed function): + make -s -j72 -C tools/bpf/bpftool prog.c: In function ‘load_with_options’: prog.c:1227:8: warning: implicit declaration of function ‘__bpf_object__open_xattr’; did you mean ‘bpf_object__open_xattr’? [-Wimplicit-function-declaration] obj = __bpf_object__open_xattr(&open_attr, bpf_flags); ^~~~~~~~~~~~~~~~~~~~~~~~ bpf_object__open_xattr prog.c:1227:8: warning: nested extern declaration of ‘__bpf_object__open_xattr’ [-Wnested-externs] prog.c:1227:6: warning: assignment to ‘struct bpf_object *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion] obj = __bpf_object__open_xattr(&open_attr, bpf_flags); ^ Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' differs from latest version at 'include/uapi/linux/if_link.h' /usr/bin/ld: prog.o: in function `load_with_options': prog.c:(.text+0x49b): undefined reference to `__bpf_object__open_xattr' collect2: error: ld returned 1 exit statu > Signed-off-by: Andrii Nakryiko > --- > tools/lib/bpf/libbpf.c | 100 ++++-------------- > tools/lib/bpf/libbpf.h | 2 - > .../selftests/bpf/progs/test_attach_probe.c | 1 - > .../bpf/progs/test_get_stack_rawtp.c | 1 - > .../selftests/bpf/progs/test_perf_buffer.c | 1 - > .../selftests/bpf/progs/test_stacktrace_map.c | 1 - > 6 files changed, 23 insertions(+), 83 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index e0276520171b..024334b29b54 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -33,6 +33,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -255,7 +256,7 @@ struct bpf_object { > */ > struct { > int fd; > - void *obj_buf; > + const void *obj_buf; > size_t obj_buf_sz; > Elf *elf; > GElf_Ehdr ehdr; > @@ -491,8 +492,19 @@ bpf_object__init_prog_names(struct bpf_object *obj) > return 0; > } > > +static __u32 get_kernel_version(void) > +{ > + __u32 major, minor, patch; > + struct utsname info; > + > + uname(&info); > + if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3) > + return 0; > + return KERNEL_VERSION(major, minor, patch); > +} > + > static struct bpf_object *bpf_object__new(const char *path, > - void *obj_buf, > + const void *obj_buf, > size_t obj_buf_sz) > { > struct bpf_object *obj; > @@ -526,6 +538,7 @@ static struct bpf_object *bpf_object__new(const char *path, > obj->efile.rodata_shndx = -1; > obj->efile.bss_shndx = -1; > > + obj->kern_version = get_kernel_version(); > obj->loaded = false; > > INIT_LIST_HEAD(&obj->list); > @@ -569,7 +582,7 @@ static int bpf_object__elf_init(struct bpf_object *obj) > * obj_buf should have been validated by > * bpf_object__open_buffer(). > */ > - obj->efile.elf = elf_memory(obj->efile.obj_buf, > + obj->efile.elf = elf_memory((char *)obj->efile.obj_buf, > obj->efile.obj_buf_sz); > } else { > obj->efile.fd = open(obj->path, O_RDONLY); > @@ -636,21 +649,6 @@ bpf_object__init_license(struct bpf_object *obj, void *data, size_t size) > return 0; > } > > -static int > -bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size) > -{ > - __u32 kver; > - > - if (size != sizeof(kver)) { > - pr_warning("invalid kver section in %s\n", obj->path); > - return -LIBBPF_ERRNO__FORMAT; > - } > - memcpy(&kver, data, sizeof(kver)); > - obj->kern_version = kver; > - pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version); > - return 0; > -} > - > static int compare_bpf_map(const void *_a, const void *_b) > { > const struct bpf_map *a = _a; > @@ -1568,11 +1566,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > if (err) > return err; > } else if (strcmp(name, "version") == 0) { > - err = bpf_object__init_kversion(obj, > - data->d_buf, > - data->d_size); > - if (err) > - return err; > + /* skip, we don't need it anymore */ > } else if (strcmp(name, "maps") == 0) { > obj->efile.maps_shndx = idx; > } else if (strcmp(name, MAPS_ELF_SEC) == 0) { > @@ -3551,54 +3545,9 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level) > return 0; > } > > -static bool bpf_prog_type__needs_kver(enum bpf_prog_type type) > -{ > - switch (type) { > - case BPF_PROG_TYPE_SOCKET_FILTER: > - case BPF_PROG_TYPE_SCHED_CLS: > - case BPF_PROG_TYPE_SCHED_ACT: > - case BPF_PROG_TYPE_XDP: > - case BPF_PROG_TYPE_CGROUP_SKB: > - case BPF_PROG_TYPE_CGROUP_SOCK: > - case BPF_PROG_TYPE_LWT_IN: > - case BPF_PROG_TYPE_LWT_OUT: > - case BPF_PROG_TYPE_LWT_XMIT: > - case BPF_PROG_TYPE_LWT_SEG6LOCAL: > - case BPF_PROG_TYPE_SOCK_OPS: > - case BPF_PROG_TYPE_SK_SKB: > - case BPF_PROG_TYPE_CGROUP_DEVICE: > - case BPF_PROG_TYPE_SK_MSG: > - case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: > - case BPF_PROG_TYPE_LIRC_MODE2: > - case BPF_PROG_TYPE_SK_REUSEPORT: > - case BPF_PROG_TYPE_FLOW_DISSECTOR: > - case BPF_PROG_TYPE_UNSPEC: > - case BPF_PROG_TYPE_TRACEPOINT: > - case BPF_PROG_TYPE_RAW_TRACEPOINT: > - case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: > - case BPF_PROG_TYPE_PERF_EVENT: > - case BPF_PROG_TYPE_CGROUP_SYSCTL: > - case BPF_PROG_TYPE_CGROUP_SOCKOPT: > - return false; > - case BPF_PROG_TYPE_KPROBE: > - default: > - return true; > - } > -} > - > -static int bpf_object__validate(struct bpf_object *obj, bool needs_kver) > -{ > - if (needs_kver && obj->kern_version == 0) { > - pr_warning("%s doesn't provide kernel version\n", > - obj->path); > - return -LIBBPF_ERRNO__KVERSION; > - } > - return 0; > -} > - > static struct bpf_object * > -__bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz, > - bool needs_kver, int flags) > +__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, > + int flags) > { > struct bpf_object *obj; > int err; > @@ -3617,7 +3566,6 @@ __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz, > CHECK_ERR(bpf_object__probe_caps(obj), err, out); > CHECK_ERR(bpf_object__elf_collect(obj, flags), err, out); > CHECK_ERR(bpf_object__collect_reloc(obj), err, out); > - CHECK_ERR(bpf_object__validate(obj, needs_kver), err, out); > > bpf_object__elf_finish(obj); > return obj; > @@ -3626,8 +3574,8 @@ __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz, > return ERR_PTR(err); > } > > -struct bpf_object *__bpf_object__open_xattr(struct bpf_object_open_attr *attr, > - int flags) > +static struct bpf_object * > +__bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags) > { > /* param validation */ > if (!attr->file) > @@ -3635,9 +3583,7 @@ struct bpf_object *__bpf_object__open_xattr(struct bpf_object_open_attr *attr, > > pr_debug("loading %s\n", attr->file); > > - return __bpf_object__open(attr->file, NULL, 0, > - bpf_prog_type__needs_kver(attr->prog_type), > - flags); > + return __bpf_object__open(attr->file, NULL, 0, flags); > } > > struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr) > @@ -3673,7 +3619,7 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf, > } > pr_debug("loading object '%s' from buffer\n", name); > > - return __bpf_object__open(name, obj_buf, obj_buf_sz, true, true); > + return __bpf_object__open(name, obj_buf, obj_buf_sz, true); > } > > int bpf_object__unload(struct bpf_object *obj) > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index e8f70977d137..2905dffd70b2 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -70,8 +70,6 @@ struct bpf_object_open_attr { > LIBBPF_API struct bpf_object *bpf_object__open(const char *path); > LIBBPF_API struct bpf_object * > bpf_object__open_xattr(struct bpf_object_open_attr *attr); > -struct bpf_object *__bpf_object__open_xattr(struct bpf_object_open_attr *attr, > - int flags); > LIBBPF_API struct bpf_object *bpf_object__open_buffer(void *obj_buf, > size_t obj_buf_sz, > const char *name); > diff --git a/tools/testing/selftests/bpf/progs/test_attach_probe.c b/tools/testing/selftests/bpf/progs/test_attach_probe.c > index 63a8dfef893b..534621e38906 100644 > --- a/tools/testing/selftests/bpf/progs/test_attach_probe.c > +++ b/tools/testing/selftests/bpf/progs/test_attach_probe.c > @@ -49,4 +49,3 @@ int handle_uprobe_return(struct pt_regs *ctx) > } > > char _license[] SEC("license") = "GPL"; > -__u32 _version SEC("version") = 1; > diff --git a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c > index f8ffa3f3d44b..736b6955bba7 100644 > --- a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c > +++ b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c > @@ -100,4 +100,3 @@ int bpf_prog1(void *ctx) > } > > char _license[] SEC("license") = "GPL"; > -__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */ > diff --git a/tools/testing/selftests/bpf/progs/test_perf_buffer.c b/tools/testing/selftests/bpf/progs/test_perf_buffer.c > index 876c27deb65a..07c09ca5546a 100644 > --- a/tools/testing/selftests/bpf/progs/test_perf_buffer.c > +++ b/tools/testing/selftests/bpf/progs/test_perf_buffer.c > @@ -22,4 +22,3 @@ int handle_sys_nanosleep_entry(struct pt_regs *ctx) > } > > char _license[] SEC("license") = "GPL"; > -__u32 _version SEC("version") = 1; > diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > index fa0be3e10a10..3b7e1dca8829 100644 > --- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > +++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c > @@ -74,4 +74,3 @@ int oncpu(struct sched_switch_args *ctx) > } > > char _license[] SEC("license") = "GPL"; > -__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */ > -- > 2.17.1 >