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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no 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 8F975C3F2C6 for ; Tue, 3 Mar 2020 14:10:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 664FC20848 for ; Tue, 3 Mar 2020 14:10:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="laBzjI5h" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729560AbgCCOKD (ORCPT ); Tue, 3 Mar 2020 09:10:03 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:35815 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728533AbgCCOKC (ORCPT ); Tue, 3 Mar 2020 09:10:02 -0500 Received: by mail-wr1-f67.google.com with SMTP id r7so4541842wro.2 for ; Tue, 03 Mar 2020 06:10:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=JL2Fpw/lCnaQ/XUN6zAHALWLaBMkxZHS+mEJ+EF0ZVY=; b=laBzjI5h6krI1uPEgUkHv/ZKSQ+Z8ids/RVkJijNF9hmmkdASTBoYnB/7xl7Hgb1Mg BubzGGprkGLSjK6uC17l7JKFmAuNKQAe7mebom121Rb1ZX7t8afUG1d1oG5ksP4iW46a WR8Rvo74RTKxnPZPwBPH3sMykyYqZfLGRC0mc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=JL2Fpw/lCnaQ/XUN6zAHALWLaBMkxZHS+mEJ+EF0ZVY=; b=RWFUkVLdxo65JgdJbVbaY21iGmNe7B3uuz/81FzSwxVefq/mYANFRlBh6gXvDDy1Cb Ig8zN6SsY6XYVwrDER8RDjzvtHgXezfFABbmC8J/QQoDVDN6zuV1+liNCxG/3K6ZudXu Y/fkfJerCckJVSfW82LOvUeD2E3rfwjV5Y1xDIWSGHH+nNNtUFv2425G/XuL+w/QrHNF BnOGoPEIhQ48DXqTUbrjZwHbqYhpl8mCIG8P5pS33lluU+cRkD+WJAVUHSjQaYvT5A0S nCMnfGhu7D3UDQ0vlOddk0dglHociE/U+oj2daYqChD/DkFLpT+4kX/hGgWlgryfgmsS Oa2g== X-Gm-Message-State: ANhLgQ1Pn8ZSCxnHyT9Xe1Zliyl8BbbhfJ6oE0Bt5kWJqKeGKQbwyBBH ZY9Nc5MbsS9FXIp+jXumAfbxtdf6lj4= X-Google-Smtp-Source: ADFU+vuL6Zt9apvq5/5BIeAmC8CeHZPk64Alb7HZEf7e0A/TFMw48bXS8bAGo5m+C3cCwKs6DCLf0Q== X-Received: by 2002:a05:6000:10c8:: with SMTP id b8mr5438416wrx.287.1583244600891; Tue, 03 Mar 2020 06:10:00 -0800 (PST) Received: from kpsingh-kernel.localdomain ([2a00:79e1:abc:308:2811:c80d:9375:bf8a]) by smtp.gmail.com with ESMTPSA id h20sm11746823wrc.47.2020.03.03.06.10.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Mar 2020 06:10:00 -0800 (PST) From: KP Singh To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Paul Turner , Florent Revest , Brendan Jackman Subject: [PATCH bpf-next 0/7] Introduce BPF_MODIFY_RET tracing progs. Date: Tue, 3 Mar 2020 15:09:43 +0100 Message-Id: <20200303140950.6355-1-kpsingh@chromium.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: KP Singh This was brought up in the KRSI v4 discussion and found to be useful both for security and tracing programs. https://lore.kernel.org/bpf/20200225193108.GB22391@chromium.org/ The modify_return programs are allowed for security hooks (with an extra CAP_MAC_ADMIN check) and functions whitelisted for error injection (ALLOW_ERROR_INJECTION). The "security_" check is expected to be cleaned up with the KRSI patch series. Here is an example of how a fmod_ret program behaves: int func_to_be_attached(int a, int b) { <--- do_fentry do_fmod_ret: if (ret != 0) goto do_fexit; original_function: } <--- do_fexit ALLOW_ERROR_INJECTION(func_to_be_attached, ERRNO) The fmod_ret program attached to this function can be defined as: SEC("fmod_ret/func_to_be_attached") BPF_PROG(func_name, int a, int b, int ret) { // This will skip the original function logic. return -1; } KP Singh (7): bpf: Refactor trampoline update code bpf: JIT helpers for fmod_ret progs bpf: Introduce BPF_MODIFY_RETURN bpf: Attachment verification for BPF_MODIFY_RETURN tools/libbpf: Add support for BPF_MODIFY_RETURN bpf: Add test ops for BPF_PROG_TYPE_TRACING bpf: Add selftests for BPF_MODIFY_RETURN arch/x86/net/bpf_jit_comp.c | 261 +++++++++++++----- include/linux/bpf.h | 24 +- include/uapi/linux/bpf.h | 1 + kernel/bpf/bpf_struct_ops.c | 13 +- kernel/bpf/btf.c | 27 +- kernel/bpf/syscall.c | 1 + kernel/bpf/trampoline.c | 66 +++-- kernel/bpf/verifier.c | 32 +++ kernel/trace/bpf_trace.c | 1 + net/bpf/test_run.c | 57 +++- tools/include/uapi/linux/bpf.h | 1 + tools/lib/bpf/libbpf.c | 4 + .../selftests/bpf/prog_tests/fentry_fexit.c | 12 +- .../selftests/bpf/prog_tests/fentry_test.c | 14 +- .../selftests/bpf/prog_tests/fexit_test.c | 69 ++--- .../selftests/bpf/prog_tests/modify_return.c | 65 +++++ .../selftests/bpf/progs/modify_return.c | 49 ++++ 17 files changed, 509 insertions(+), 188 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/modify_return.c create mode 100644 tools/testing/selftests/bpf/progs/modify_return.c -- 2.20.1