From patchwork Tue Feb 6 22:04:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 13547827 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pf1-f182.google.com (mail-pf1-f182.google.com [209.85.210.182]) (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 1BE8E1BDED for ; Tue, 6 Feb 2024 22:05:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707257123; cv=none; b=t9uTi68vdqlm3sc6Al3DetB1IZH14kj70US8U61oL30Zlmap6QVDlnBtvXryFrMTH8hROJgxNAxWOtiLF8hK+H3nlm8lmC5iX3ZM1MrcyNSqZ+4bsB73vVzDcIE2hHXEOEikHUeFPTwUNDl0TDK3TkB+R6vPDfF3Syk8SXX0je8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707257123; c=relaxed/simple; bh=eueHQE607LnJ9GtCHljb8AaXRLkGlzLEzibT//2GRiY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=bOgqKOqAq9be1w/ni0lPl+5DLctw4HGx9EHaLzghM1cnq6ruKO5kFyoF/bV0X052Nszb2z5cbYmsxpq0Sd1hWKpNdXfOsrdZ6uTWgawA1n5ozG2s9RSEN9kYVO+RzO6qyC3lPebEJH5zecnmIv5kjkk/8Vd28cGePv6fKKY7Jvw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=cAYU5QCR; arc=none smtp.client-ip=209.85.210.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cAYU5QCR" Received: by mail-pf1-f182.google.com with SMTP id d2e1a72fcca58-6e02597a0afso12137b3a.1 for ; Tue, 06 Feb 2024 14:05:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1707257121; x=1707861921; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=waJIZfpNliIHPa/9880riUne4F1M98q2cd6wla9GZjk=; b=cAYU5QCR847DECzpKXaWauFdML4N3o8+vpgtWRMWYKi+LIZaRCj4dZzq4YgGzxe0hi qO122rK5pmuktZ0XEwabECQ+K4GRArocMzp9QA6eNEDu6cfznqpyk7NpiKJprs8Naj46 LCtWXpkrLZRKckl/3vRI62M+Xvy5llP0YNjK8kqGbiiqPmbA2esAMei/q+mhdwylYGcg xlfm64D1Ip+2qtkOENZRSHk4wL8nROXDyVj83cHwvQCJM5UW1ZsElpamZTGSmfnol43V zwoEfUV+TunxCgw46GHV2duuqC83wfnNkx2ofRaEKGVMenP8TyjcScD4UEh0bmUn8GXK wCUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707257121; x=1707861921; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=waJIZfpNliIHPa/9880riUne4F1M98q2cd6wla9GZjk=; b=DPwtsRwkVddHhxmdFXvULYpw+JiJjRmHBaGhpt5zequrgKu+Srdu49ls7sx+RCHbR8 XAZMp0MkImrmUSnYzL5UpX1vu3YVGwQH4NTuzluYXVkq90UsN/qArPejLQETBQ/hak0f JBJofJbMWkJbFbBoSHyHv6mRZAbq8iir82+L0Gbfs8dABTg86mJQGaryqnjOF9rKX7CM XIH5ve4QYAVk+g6Va48sjbfFQVq1XFcmwThOJ1Bmto1rT/AjkDQLxIVGROJ6HRB5YDWh KSRec7Ed3XRywJdLazCM6H300E7ZO/QERlCwORc63+sYnQdniDIPQ1qw0ZCq7ZkFfcRm l7eA== X-Gm-Message-State: AOJu0Yyra3MhBnL7JZeXSFyP8/Vhr1OxQXKxoIELc7zYKeB/31w3KFb8 ERMYAxePRDreKB4TARecD0aA2ZvYLlwcWQT/nULzpUMvlFoJmDghlA8vvsqK X-Google-Smtp-Source: AGHT+IGEm41W1mIMfg18EMXRi5EZlNoYfBurQNFDegQZNFeL2j9w6VizaJwjHHTqyxrGN0HSh8f/bg== X-Received: by 2002:a05:6a20:8154:b0:19e:a23f:fa73 with SMTP id u20-20020a056a20815400b0019ea23ffa73mr606797pza.5.1707257121125; Tue, 06 Feb 2024 14:05:21 -0800 (PST) X-Forwarded-Encrypted: i=0; AJvYcCXxN8orindXUKGG1h/zyY3mQyICEUtCIntzBop61kdfolwDs7jXajQYTwYORXc3hFm7NsG4OasP13LHB6c852skW89A5Q3SEJ9IeXDoIlf8HFxDkSEQwtp0/hR6/4zyqyoEUUOyZl7qxTHsrtAYLfY96aJG11wKBcbQfUK+jAghxuHvzl5GfAONh4LbS5QeBT2B9USv2mg4iHKbjiyPWsCkS1ydEmzx+CC1iJngFwB5VSmgSP3SEUQKbB3N9kyl4hqzgAWt3xXJbEfM3pfWaP0AZ0sXpYwjQtuN Received: from localhost.localdomain ([2620:10d:c090:400::4:27bf]) by smtp.gmail.com with ESMTPSA id x17-20020a056a00271100b006e0542f9689sm2474751pfv.103.2024.02.06.14.05.19 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 06 Feb 2024 14:05:20 -0800 (PST) From: Alexei Starovoitov To: bpf@vger.kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, memxor@gmail.com, eddyz87@gmail.com, tj@kernel.org, brho@google.com, hannes@cmpxchg.org, linux-mm@kvack.org, kernel-team@fb.com Subject: [PATCH bpf-next 09/16] bpf: Recognize btf_decl_tag("arg:arena") as PTR_TO_ARENA. Date: Tue, 6 Feb 2024 14:04:34 -0800 Message-Id: <20240206220441.38311-10-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) In-Reply-To: <20240206220441.38311-1-alexei.starovoitov@gmail.com> References: <20240206220441.38311-1-alexei.starovoitov@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov In global bpf functions recognize btf_decl_tag("arg:arena") as PTR_TO_ARENA. Note, when the verifier sees: __weak void foo(struct bar *p) it recognizes 'p' as PTR_TO_MEM and 'struct bar' has to be a struct with scalars. Hence the only way to use arena pointers in global functions is to tag them with "arg:arena". Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 + kernel/bpf/btf.c | 19 +++++++++++++++---- kernel/bpf/verifier.c | 15 +++++++++++++++ 3 files changed, 31 insertions(+), 4 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 82f7727e434a..401c0031090d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -715,6 +715,7 @@ enum bpf_arg_type { * on eBPF program stack */ ARG_PTR_TO_MEM, /* pointer to valid memory (stack, packet, map value) */ + ARG_PTR_TO_ARENA, ARG_CONST_SIZE, /* number of bytes accessed from memory */ ARG_CONST_SIZE_OR_ZERO, /* number of bytes accessed from memory or 0 */ diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index f7725cb6e564..6d2effb65943 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7053,10 +7053,11 @@ static int btf_get_ptr_to_btf_id(struct bpf_verifier_log *log, int arg_idx, } enum btf_arg_tag { - ARG_TAG_CTX = 0x1, - ARG_TAG_NONNULL = 0x2, - ARG_TAG_TRUSTED = 0x4, - ARG_TAG_NULLABLE = 0x8, + ARG_TAG_CTX = BIT_ULL(0), + ARG_TAG_NONNULL = BIT_ULL(1), + ARG_TAG_TRUSTED = BIT_ULL(2), + ARG_TAG_NULLABLE = BIT_ULL(3), + ARG_TAG_ARENA = BIT_ULL(4), }; /* Process BTF of a function to produce high-level expectation of function @@ -7168,6 +7169,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) tags |= ARG_TAG_NONNULL; } else if (strcmp(tag, "nullable") == 0) { tags |= ARG_TAG_NULLABLE; + } else if (strcmp(tag, "arena") == 0) { + tags |= ARG_TAG_ARENA; } else { bpf_log(log, "arg#%d has unsupported set of tags\n", i); return -EOPNOTSUPP; @@ -7222,6 +7225,14 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) sub->args[i].btf_id = kern_type_id; continue; } + if (tags & ARG_TAG_ARENA) { + if (tags & ~ARG_TAG_ARENA) { + bpf_log(log, "arg#%d arena cannot be combined with any other tags\n", i); + return -EINVAL; + } + sub->args[i].arg_type = ARG_PTR_TO_ARENA; + continue; + } if (is_global) { /* generic user data pointer */ u32 mem_size; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6bd5a0f30f72..07b8eec2f006 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9348,6 +9348,18 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, bpf_log(log, "arg#%d is expected to be non-NULL\n", i); return -EINVAL; } + } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) { + /* + * Can pass any value and the kernel won't crash, but + * only PTR_TO_ARENA or SCALAR make sense. Everything + * else is a bug in the bpf program. Point it out to + * the user at the verification time instead of + * run-time debug nightmare. + */ + if (reg->type != PTR_TO_ARENA && reg->type != SCALAR_VALUE) { + bpf_log(log, "R%d is not a pointer to arena or scalar.\n", regno); + return -EINVAL; + } } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) { ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0); if (ret) @@ -20321,6 +20333,9 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) reg->btf = bpf_get_btf_vmlinux(); /* can't fail at this point */ reg->btf_id = arg->btf_id; reg->id = ++env->id_gen; + } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) { + /* caller can pass either PTR_TO_ARENA or SCALAR */ + mark_reg_unknown(env, regs, i); } else { WARN_ONCE(1, "BUG: unhandled arg#%d type %d\n", i - BPF_REG_1, arg->arg_type);