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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3EC1C4332F for ; Thu, 28 Oct 2021 18:10:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9BEED60F0F for ; Thu, 28 Oct 2021 18:10:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230467AbhJ1SNC (ORCPT ); Thu, 28 Oct 2021 14:13:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230258AbhJ1SNB (ORCPT ); Thu, 28 Oct 2021 14:13:01 -0400 Received: from mail-yb1-xb2a.google.com (mail-yb1-xb2a.google.com [IPv6:2607:f8b0:4864:20::b2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A761C061570; Thu, 28 Oct 2021 11:10:34 -0700 (PDT) Received: by mail-yb1-xb2a.google.com with SMTP id y3so6397973ybf.2; Thu, 28 Oct 2021 11:10:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PibadPtFXRDa44ZUmOQfsMNDa2MEM73QABZ8NV45MJ8=; b=m2ICJo9qn/Rdn8KjUKxWxzAGQjl54SJUcsmKj+h5j1053QPETpn03RaDqzAyLI2V/Q tRt471H+AlSQEOXO8TcszLQcPvxsJk6p6/UbF+vF2oEiJFMUdruLU//D0A8pNrxS/OPI /4xgOf0lGRfBjDz4s3LcvpI8yQbgm3bXzTXvO2tXMqyxaI6rPWjB2OYEDO1GhUjiFYLu YWWCabsBoSs33FdoVYpN6KoHnDtK2wwt3OmFylCr+QOIA9l/bzn3w+XTgWZ0UFJlvvt0 FnDxv292gOfblQAPm3SwBCiIBxlrQGyyTn41L93haC02uH9VdG6gMzdsh1zIMe0eqQNG dbnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PibadPtFXRDa44ZUmOQfsMNDa2MEM73QABZ8NV45MJ8=; b=tKpfZwiR5k+4nR9X3NQYrd9roxROm5rMQNI4UvezSmU4Aiv3zQQzd1ilpgY746vAko P91ZKyR6O9RtXR3FCjebmwOkP2LfKI0KyKqXLxWufdOFBJd+JfP8MiZAxWjUQx7+1qDs 0Yz6kwoSonrd/NJWEg48HIlBadmKwBtorFTj6jhe2KW33qiHpDP7Fq2YaNhuFgKCZXly 7fuKkFtqO39Wx7dMWxmiqpgZegArsDNfXGru1SukCwwwbekI/y4OuojPb2EKCLLHsLHq WqibzbB/g1uTEkoJRgvLHcJuw7agEfFXsHyf1ssFP+FuWKqCYXaEPk3f0dJ6qTKqu6zk QJGw== X-Gm-Message-State: AOAM533twUOYRBKejO4KgNWRQPil9OyJuFzWOQCGPJ1QCsujPtgL8Dyo jjs8toEvLvb4b2kejNZ3JkUUaJ+nRF38l4dRU4s= X-Google-Smtp-Source: ABdhPJyrTl/NA+L1Emy0kUxtKXajMu0rlKAmOnm3h+cqY7G0a3QMAR9iv3/So9DBaeK3FLnqgRx6rTG2kd79dOJhiAs= X-Received: by 2002:a25:afcd:: with SMTP id d13mr6805131ybj.504.1635444633394; Thu, 28 Oct 2021 11:10:33 -0700 (PDT) MIME-Version: 1.0 References: <20211028063501.2239335-1-memxor@gmail.com> <20211028063501.2239335-2-memxor@gmail.com> In-Reply-To: <20211028063501.2239335-2-memxor@gmail.com> From: Andrii Nakryiko Date: Thu, 28 Oct 2021 11:10:22 -0700 Message-ID: Subject: Re: [PATCH bpf-next v5 1/8] bpf: Add bpf_kallsyms_lookup_name helper To: Kumar Kartikeya Dwivedi Cc: bpf , Song Liu , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Yonghong Song , Jesper Dangaard Brouer , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , Networking Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Oct 27, 2021 at 11:35 PM Kumar Kartikeya Dwivedi wrote: > > This helper allows us to get the address of a kernel symbol from inside > a BPF_PROG_TYPE_SYSCALL prog (used by gen_loader), so that we can > relocate typeless ksym vars. > > Acked-by: Song Liu > Signed-off-by: Kumar Kartikeya Dwivedi > --- > include/linux/bpf.h | 1 + > include/uapi/linux/bpf.h | 16 ++++++++++++++++ > kernel/bpf/syscall.c | 27 +++++++++++++++++++++++++++ > tools/include/uapi/linux/bpf.h | 16 ++++++++++++++++ > 4 files changed, 60 insertions(+) > [...] > +BPF_CALL_4(bpf_kallsyms_lookup_name, const char *, name, int, name_sz, int, flags, u64 *, res) > +{ > + if (flags) > + return -EINVAL; > + > + if (name_sz <= 1 || name[name_sz - 1]) > + return -EINVAL; > + > + if (!bpf_dump_raw_ok(current_cred())) > + return -EPERM; > + > + *res = kallsyms_lookup_name(name); > + return *res ? 0 : -ENOENT; > +} > + > +const struct bpf_func_proto bpf_kallsyms_lookup_name_proto = { > + .func = bpf_kallsyms_lookup_name, > + .gpl_only = false, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_PTR_TO_MEM, > + .arg2_type = ARG_CONST_SIZE, can you make it ARG_CONST_SIZE_OR_ZERO? Not because zero makes sense, but because it removes the need to prove to the verifier that the size (which you can get at runtime) is > 0. Just less unnecessary fussing with preventing Clang optimizations. > + .arg3_type = ARG_ANYTHING, > + .arg4_type = ARG_PTR_TO_LONG, > +}; > + [...]