From patchwork Wed Nov 27 14:09:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marco Elver X-Patchwork-Id: 13887085 Received: from mail-ed1-f74.google.com (mail-ed1-f74.google.com [209.85.208.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7CAC61E51D for ; Wed, 27 Nov 2024 14:10:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732716614; cv=none; b=tmlueDhg5oV7yz45tLGZP90OEtbrrWzx+9AUIheQgT6EY/GSAJd3JaoWOFhuBtB/85L57y4wQGBMhJTNsCOt4Y/byJy7nfQDZHtfndt0zX/bm/Md/vpgWqKS76gyzEpC9PA+DzeFocREtSY44m3cyUvzPKZZ8ekRHl118QgZaA0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732716614; c=relaxed/simple; bh=kFR9PUIfM5ND9o1WW+w41Hok+j3QIJY6jvBaATu8WzY=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=rI8UdlFeECxH6dwzKPV9ZkBIpFWaLl7pu9M0WeaVxWyNLsSsZtaFfa7FVrLxbU+ieBh+wGbIGZb8d1W8Q5flfjuwGxClz7A4m7bgcd0nE47jSjFG7/NT/akQ3qxe86RQh5v43WUh2WQYWj6DlBCRPG0PajDVivdhrR+TQBp3gs8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--elver.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=obfBiBlc; arc=none smtp.client-ip=209.85.208.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--elver.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="obfBiBlc" Received: by mail-ed1-f74.google.com with SMTP id 4fb4d7f45d1cf-5cfd15ff42cso907455a12.1 for ; Wed, 27 Nov 2024 06:10:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1732716611; x=1733321411; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=3jMhxXVf1QUdWvEy2vp558o5guO3soGdUIj9ntlxOTI=; b=obfBiBlcaPrODzdJqxRzRNZUGivowy1jFQM/HquQr9ROS98NN9ZAnEbizq7HuVnaiO iklIk726bsWEzv/DSKHN9gylbPz/saWcEkFPRy+J/YGGw7Nmq15QBMamYSFJLbL/ucUM +n5RBwwzLJcJdhKIk30BC8Ul7HanQQcnNpEuTPp0mEXoAE53LAJWfwbaOQWHQTTSP2SR HXTrgAMOvA68Lxxs4TWFV6UK3grUhwY9eEWrV5yl/UvYIS9hILIWT61s+zSKqfcDG3sl vTMHIvhATQdGtcMSngR+0RXj9VjpzeY2f0yu5dVd9NHr92437SP7lt1QwXyJg2iv8SqF T8PA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732716611; x=1733321411; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=3jMhxXVf1QUdWvEy2vp558o5guO3soGdUIj9ntlxOTI=; b=YzkwmucwNueM/SWdgRDj8j9kL6gDvtzNd5Pp4Nzi/M+6TMD5y503LgxDbrTgDEAcKd dynAT8ArN/65EnlvJxkXxunlGMYlI4p4Q2lUutfp6AGoKd77wmeClWTf9pRTxz+KC34v TPosL/gmNAK2bs8FURCjsmakZvS9kvz0PLKDeT91fXPh+Hw3crQAB64i7/rHQnd+I3x5 fKI/NuRSyqEE8MKL0dDuWID40GCM5hevQnZRRZlUS4wyReOPiwfZmQ1creX2HXuJihOH pmt43NTuOrDbVZwYyjK0RUN0GcnMTS6rsm0DaYRvJxzTDhDg0hbzGTxaoQXK5HM5sSXY 66GA== X-Forwarded-Encrypted: i=1; AJvYcCUQPFGsweNAar14kLC9iwtzR1XwwFqBkqzO0MzrSM5qeP502IqzEK2N5HRDXHK47Ea2xJ7uK3s1uqips5MPrQkEVXg=@vger.kernel.org X-Gm-Message-State: AOJu0Yx7CTJT6JweMjc1pazp/zhImufkUOgFzwp1n5Hv2PbmT4ItuEzx 6sVbvATJ7pd1eNImQl5rQlChSypnphY5ekzYasi/NCE7mHrMrVUc+rQnEpyrs/OtS2f3R/Eejw= = X-Google-Smtp-Source: AGHT+IFwlhr766qLc1hn4ldFnhIVaefGNadp5e+TUp8EreJ0cfnmr57nrisQx2lW5b/EFk+oKdUqLhIavA== X-Received: from edb5.prod.google.com ([2002:a05:6402:2385:b0:5cf:e3b0:4e89]) (user=elver job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:5309:b0:5d0:ada:e44b with SMTP id 4fb4d7f45d1cf-5d080c6dcc1mr3352422a12.16.1732716611041; Wed, 27 Nov 2024 06:10:11 -0800 (PST) Date: Wed, 27 Nov 2024 15:09:35 +0100 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241127140958.1828012-1-elver@google.com> Subject: [PATCH bpf-next v3 1/2] bpf: Remove bpf_probe_write_user() warning message From: Marco Elver To: elver@google.com, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Nikola Grcevski , bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org The warning message for bpf_probe_write_user() was introduced in 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers"), with the following in the commit message: Given this feature is meant for experiments, and it has a risk of crashing the system, and running programs, we print a warning on when a proglet that attempts to use this helper is installed, along with the pid and process name. After 8 years since 96ae52279594, bpf_probe_write_user() has found successful applications beyond experiments [1, 2], with no other good alternatives. Despite its intended purpose for "experiments", that doesn't stop Hyrum's law, and there are likely many more users depending on this helper: "[..] it does not matter what you promise [..] all observable behaviors of your system will be depended on by somebody." The ominous "helper that may corrupt user memory!" has offered no real benefit, and has been found to lead to confusion where the system administrator is loading programs with valid use cases. As such, remove the warning message. Link: https://lore.kernel.org/lkml/20240404190146.1898103-1-elver@google.com/ [1] Link: https://lore.kernel.org/r/lkml/CAAn3qOUMD81-vxLLfep0H6rRd74ho2VaekdL4HjKq+Y1t9KdXQ@mail.gmail.com/ [2] Link: https://lore.kernel.org/all/CAEf4Bzb4D_=zuJrg3PawMOW3KqF8JvJm9SwF81_XHR2+u5hkUg@mail.gmail.com/ Signed-off-by: Marco Elver Acked-by: Jiri Olsa --- v3: * Collect Ack from Jiri. v2: * Just delete the message entirely (suggested by Andrii Nakryiko) --- kernel/trace/bpf_trace.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 630b763e5240..0ab56af2e298 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -362,9 +362,6 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void) if (!capable(CAP_SYS_ADMIN)) return NULL; - pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!", - current->comm, task_pid_nr(current)); - return &bpf_probe_write_user_proto; }