From patchwork Fri Jan 12 15:20:10 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Sun X-Patchwork-Id: 13518573 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-wm1-f41.google.com (mail-wm1-f41.google.com [209.85.128.41]) (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 8B23A6DD1D; Fri, 12 Jan 2024 15:20:34 +0000 (UTC) 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="WpIAopN0" Received: by mail-wm1-f41.google.com with SMTP id 5b1f17b1804b1-40e69b314e0so696495e9.1; Fri, 12 Jan 2024 07:20:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1705072832; x=1705677632; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=Uoyz0fX05VFZUA0YqL9VDmTIjZubn+1o1Tubn/qOGIQ=; b=WpIAopN0Hb9CXQDrliZnqkD+jzNE8pBnM8lIMH5kkMt5PgP5gFQkMpQ91rajY3mO+Q unVQ6ZHjmwETUTltJ2T2KfAkvvD/1L1TXDNlKAUC8kImIYRqRq2xoWB7a/pMTGRq6vhT 4VIz9FnhkgeFSG0+Pm/g9OWMUrlJoq5ZmRA7U2Odtble+D6x915C40q0H7HXpFgxJaII HON5yGYhzvSomcjHpMtaMyvjX2vAAfItwo7VcZw/kaT57C7I9WU+TMJpBfoclZfgqibu yH0SZmvS7knHy9bQN98ndMxGTeQnWH6otfT2DTmhhriB4s5pVbP5Ujmo6WEcxBozsLP/ sewQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705072832; x=1705677632; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Uoyz0fX05VFZUA0YqL9VDmTIjZubn+1o1Tubn/qOGIQ=; b=m3/NVusqORLqnIq/Lwwj+GjwXDZNuyj+3RcoO/dXxIn7RUUHvIFORoxcSpLN75nPPu FYM8r9QtWHtKWUN3LSZtsAcaHPIobiMXueyX7P6n6dPAYRUnNsBA6hhBNq5ODGYmUrMT hhHCguzXYigbZBCdK1L8cjgqeo7wDvgf3IRCOcrSZVSq1E6ETu9UZ1crAR2NerFXb6T0 qVxZAf/2BiDJwQKROYejnbVqQpjZAhtIKkw+pA8ZegFUT0MTmw085uUfznyvqqnAcrkQ FMePiWXPAHrzzgdmDgfolXA2i98pXHoPR83DToHD1LLdY2ueQq4PI4+FK5c6zZoIxwhK pXgw== X-Gm-Message-State: AOJu0Yw+f2va5eMw+kPUq9Lo3bcWygTzqhszOru9R/bORPZaomngC9LX C5JKINdFB7LpJt13+IFijxj3vIKkkw== X-Google-Smtp-Source: AGHT+IHHZeFyMpKhH/9NZUPYGoPS59noDveXdZGapwC4YE9+IpLbuXeeZXS1ZGK3B7Qz/X6uuuEBfw== X-Received: by 2002:a05:600c:3381:b0:40e:427d:4b02 with SMTP id o1-20020a05600c338100b0040e427d4b02mr960326wmp.67.1705072832187; Fri, 12 Jan 2024 07:20:32 -0800 (PST) Received: from staff-net-cx-3510.intern.ethz.ch (2001-67c-10ec-5784-8000--16b.net6.ethz.ch. [2001:67c:10ec:5784:8000::16b]) by smtp.gmail.com with ESMTPSA id o23-20020a05600c511700b0040e4c1b0c14sm10157728wms.34.2024.01.12.07.20.31 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 12 Jan 2024 07:20:31 -0800 (PST) From: Hao Sun To: bpf@vger.kernel.org Cc: willemb@google.com, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, linux-kernel@vger.kernel.org, Hao Sun Subject: [PATCH v3 1/2] bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS Date: Fri, 12 Jan 2024 16:20:10 +0100 Message-ID: <20240112152011.6264-1-sunhao.th@gmail.com> X-Mailer: git-send-email 2.43.0 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 For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off for validation. However, variable offset ptr alu is not prohibited for this ptr kind. So the variable offset is not checked. The following prog is accepted: func#0 @0 0: R1=ctx() R10=fp0 0: (bf) r6 = r1 ; R1=ctx() R6_w=ctx() 1: (79) r7 = *(u64 *)(r6 +144) ; R6_w=ctx() R7_w=flow_keys() 2: (b7) r8 = 1024 ; R8_w=1024 3: (37) r8 /= 1 ; R8_w=scalar() 4: (57) r8 &= 1024 ; R8_w=scalar(smin=smin32=0, smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400)) 5: (0f) r7 += r8 mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1 mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024 mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1 mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024 6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off =(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024, var_off=(0x0; 0x400)) 6: (79) r0 = *(u64 *)(r7 +0) ; R0_w=scalar() 7: (95) exit This prog loads flow_keys to r7, and adds the variable offset r8 to r7, and finally causes out-of-bounds access: BUG: unable to handle page fault for address: ffffc90014c80038 ... Call Trace: bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline] __bpf_prog_run include/linux/filter.h:651 [inline] bpf_prog_run include/linux/filter.h:658 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline] bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991 bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359 bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline] __sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475 __do_sys_bpf kernel/bpf/syscall.c:5561 [inline] __se_sys_bpf kernel/bpf/syscall.c:5559 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Fix this by rejecting ptr alu with variable offset on flow_keys. Applying the patch makes the program rejected with "R7 pointer arithmetic on flow_keys prohibited" Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Signed-off-by: Hao Sun Acked-by: Yonghong Song --- kernel/bpf/verifier.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index adbf330d364b..65f598694d55 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12826,6 +12826,10 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, } switch (base_type(ptr_reg->type)) { + case PTR_TO_FLOW_KEYS: + if (known) + break; + fallthrough; case CONST_PTR_TO_MAP: /* smin_val represents the known value */ if (known && smin_val == 0 && opcode == BPF_ADD) From patchwork Fri Jan 12 15:20:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Sun X-Patchwork-Id: 13518574 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-wm1-f46.google.com (mail-wm1-f46.google.com [209.85.128.46]) (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 163436DD1D; Fri, 12 Jan 2024 15:20:40 +0000 (UTC) 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="GRWvsh33" Received: by mail-wm1-f46.google.com with SMTP id 5b1f17b1804b1-40e60e135a7so15708465e9.0; Fri, 12 Jan 2024 07:20:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1705072839; x=1705677639; 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=8I1BW+/RBUVVGnyZE279+XSC+1yYL53hkEdjOLq0rlQ=; b=GRWvsh33wZpIViaLre+J5Q0UD0h+Dkag3Ufb2dDXi7TP7tswSqLbOKAbtEeVJEGzbA jEzacjDMqGg3sLODNX3nNfFHM/CCBzbF3mkHyTbytiF5uVaFVcO86kbhjUDOIW/rkB6s A56XdwCpi31kOy3GeTDShkcxhUYjFyXvjfdmNvlZtj9Gs63jDf7Jj9mI5x3TZ2OiL+D2 Ma1Wp1Qv+wZAszoC/YR3y/irIuwC0nY8AOn9WbLeIRoVut8MnPfW3o4Y3Fx63RBRZVE3 2LdInY0rZ0ubjR4jkWd78FTepAqe7lRvMAsd2p32q+qjBOt88TxMVPHrxS65tUc+1O39 0jig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705072839; x=1705677639; 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=8I1BW+/RBUVVGnyZE279+XSC+1yYL53hkEdjOLq0rlQ=; b=sp1g9WMYXQFaFBIg/0KIFc/R4NkH8XIhgW1xqPSNTa8EMQSoR0NoHdQchhaYZM2NN5 Excp3mmB2Elkpyc1/vOQzemByLDKZWx3ksnyOc46ZN8Lu2hxP9a/9k0tuF0C1ZSglSt7 WFJHu9xQQbcmBRXdh0LsfU4PjuUD5ErXEAE41B1GFj53x+AhJR/4KweBOfFjeeLfBUma unE3VOZP8GEysV7QFY5PxAgqcqkKdBzHZ2VqxzzorBHU5pUCOigYsu5ykZWM/Zr23B70 JizuU7akSLtQM9hWFK812LBpcH9/iYbsz41i1idw2poN4uVysD24+B0xymEw6c9povY7 KGDg== X-Gm-Message-State: AOJu0Ywh3y3FmvLpAH6SfCKURuOqMpl9P83nZ1g7BZIrTS/FSEikWLUA ab46XwqA16Qq/vFLE5tvhgTtviPV1A== X-Google-Smtp-Source: AGHT+IGr1zqDhYRqrWFI1pYAikt11L8Pkdr9lZRxEgtaDUa0B4kuqiHhVpOn9gjSgTl5fGNkGB37DA== X-Received: by 2002:a05:600c:45cb:b0:40e:6455:7105 with SMTP id s11-20020a05600c45cb00b0040e64557105mr804945wmo.20.1705072838504; Fri, 12 Jan 2024 07:20:38 -0800 (PST) Received: from staff-net-cx-3510.intern.ethz.ch (2001-67c-10ec-5784-8000--16b.net6.ethz.ch. [2001:67c:10ec:5784:8000::16b]) by smtp.gmail.com with ESMTPSA id o23-20020a05600c511700b0040e4c1b0c14sm10157728wms.34.2024.01.12.07.20.37 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 12 Jan 2024 07:20:38 -0800 (PST) From: Hao Sun To: bpf@vger.kernel.org Cc: willemb@google.com, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, linux-kernel@vger.kernel.org, Hao Sun Subject: [PATCH v3 2/2] selftests/bpf: Add tests for alu on PTR_TO_FLOW_KEYS Date: Fri, 12 Jan 2024 16:20:11 +0100 Message-ID: <20240112152011.6264-2-sunhao.th@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240112152011.6264-1-sunhao.th@gmail.com> References: <20240112152011.6264-1-sunhao.th@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 Add two cases for PTR_TO_FLOW_KEYS alu. One for rejecting alu with variable offset, another for fixed offset. Signed-off-by: Hao Sun --- .../bpf/progs/verifier_value_illegal_alu.c | 36 +++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c b/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c index 71814a753216..3bcccb4cbc85 100644 --- a/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c +++ b/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c @@ -146,4 +146,40 @@ l0_%=: exit; \ : __clobber_all); } +SEC("flow_dissector") +__description("flow_keys illegal alu op with variable offset") +__failure __msg("R7 pointer arithmetic on flow_keys prohibited") +__naked void flow_keys_illegal_variable_offset_alu(void) +{ + asm volatile(" \ + r6 = r1; \ + r7 = *(u64*)(r6 + %[flow_keys_off]); \ + r8 = 8; \ + r8 /= 1; \ + r8 &= 8; \ + r7 += r8; \ + r0 = *(u64*)(r7 + 0); \ + exit; \ +" : + : __imm_const(flow_keys_off, offsetof(struct __sk_buff, flow_keys)) + : __clobber_all); +} + +SEC("flow_dissector") +__description("flow_keys valid alu op with fixed offset") +__success +__naked void flow_keys_legal_fixed_offset_alu(void) +{ + asm volatile(" \ + r6 = r1; \ + r7 = *(u64*)(r6 + %[flow_keys_off]); \ + r8 = 8; \ + r7 += r8; \ + r0 = *(u64*)(r7 + 0); \ + exit; \ +" : + : __imm_const(flow_keys_off, offsetof(struct __sk_buff, flow_keys)) + : __clobber_all); +} + char _license[] SEC("license") = "GPL";