From patchwork Tue Mar 23 20:28:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 1457465 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4F4jcz6Z3Xz9sWF; Wed, 24 Mar 2021 07:28:50 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1lOndu-0006l3-BF; Tue, 23 Mar 2021 20:28:46 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lOnds-0006kS-RM for kernel-team@lists.ubuntu.com; Tue, 23 Mar 2021 20:28:44 +0000 Received: from 1.general.cascardo.us.vpn ([10.172.70.58] helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lOnds-0003eU-3t for kernel-team@lists.ubuntu.com; Tue, 23 Mar 2021 20:28:44 +0000 From: Thadeu Lima de Souza Cascardo To: kernel-team@lists.ubuntu.com Subject: [SRU Focal/Groovy 1/3] bpf: Simplify alu_limit masking for pointer arithmetic Date: Tue, 23 Mar 2021 17:28:24 -0300 Message-Id: <20210323202826.159294-2-cascardo@canonical.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210323202826.159294-1-cascardo@canonical.com> References: <20210323202826.159294-1-cascardo@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Piotr Krysiuk BugLink: https://bugs.launchpad.net/bugs/1920995 Instead of having the mov32 with aux->alu_limit - 1 immediate, move this operation to retrieve_ptr_limit() instead to simplify the logic and to allow for subsequent sanity boundary checks inside retrieve_ptr_limit(). This avoids in future that at the time of the verifier masking rewrite we'd run into an underflow which would not sign extend due to the nature of mov32 instruction. Signed-off-by: Piotr Krysiuk Co-developed-by: Daniel Borkmann Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov (cherry picked from commit b5871dca250cd391885218b99cc015aca1a51aea net.git) Signed-off-by: Thadeu Lima de Souza Cascardo --- kernel/bpf/verifier.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 99b1ae0f7f24..aaec49eb4f87 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4923,16 +4923,16 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, */ off = ptr_reg->off + ptr_reg->var_off.value; if (mask_to_left) - *ptr_limit = MAX_BPF_STACK + off + 1; + *ptr_limit = MAX_BPF_STACK + off; else - *ptr_limit = -off; + *ptr_limit = -off - 1; return 0; case PTR_TO_MAP_VALUE: if (mask_to_left) { - *ptr_limit = ptr_reg->umax_value + ptr_reg->off + 1; + *ptr_limit = ptr_reg->umax_value + ptr_reg->off; } else { off = ptr_reg->smin_value + ptr_reg->off; - *ptr_limit = ptr_reg->map_ptr->value_size - off; + *ptr_limit = ptr_reg->map_ptr->value_size - off - 1; } return 0; default: @@ -10147,7 +10147,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) off_reg = issrc ? insn->src_reg : insn->dst_reg; if (isneg) *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); - *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit - 1); + *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg); *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg); *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0); From patchwork Tue Mar 23 20:28:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 1457467 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4F4jcz6c4Zz9sWK; Wed, 24 Mar 2021 07:28:51 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1lOndw-0006me-KB; Tue, 23 Mar 2021 20:28:48 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lOndv-0006lU-0H for kernel-team@lists.ubuntu.com; Tue, 23 Mar 2021 20:28:47 +0000 Received: from 1.general.cascardo.us.vpn ([10.172.70.58] helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lOndu-0003eU-8I for kernel-team@lists.ubuntu.com; Tue, 23 Mar 2021 20:28:46 +0000 From: Thadeu Lima de Souza Cascardo To: kernel-team@lists.ubuntu.com Subject: [SRU Focal/Groovy 2/3] bpf: Add sanity check for upper ptr_limit Date: Tue, 23 Mar 2021 17:28:25 -0300 Message-Id: <20210323202826.159294-3-cascardo@canonical.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210323202826.159294-1-cascardo@canonical.com> References: <20210323202826.159294-1-cascardo@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Piotr Krysiuk BugLink: https://bugs.launchpad.net/bugs/1920995 Given we know the max possible value of ptr_limit at the time of retrieving the latter, add basic assertions, so that the verifier can bail out if anything looks odd and reject the program. Nothing triggered this so far, but it also does not hurt to have these. Signed-off-by: Piotr Krysiuk Co-developed-by: Daniel Borkmann Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov (cherry picked from commit 1b1597e64e1a610c7a96710fc4717158e98a08b3 net.git) Signed-off-by: Thadeu Lima de Souza Cascardo --- kernel/bpf/verifier.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index aaec49eb4f87..9d413f7dffac 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4914,10 +4914,14 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, { bool mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg); - u32 off; + u32 off, max; switch (ptr_reg->type) { case PTR_TO_STACK: + /* Offset 0 is out-of-bounds, but acceptable start for the + * left direction, see BPF_REG_FP. + */ + max = MAX_BPF_STACK + mask_to_left; /* Indirect variable offset stack access is prohibited in * unprivileged mode so it's not handled here. */ @@ -4926,15 +4930,16 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, *ptr_limit = MAX_BPF_STACK + off; else *ptr_limit = -off - 1; - return 0; + return *ptr_limit >= max ? -ERANGE : 0; case PTR_TO_MAP_VALUE: + max = ptr_reg->map_ptr->value_size; if (mask_to_left) { *ptr_limit = ptr_reg->umax_value + ptr_reg->off; } else { off = ptr_reg->smin_value + ptr_reg->off; *ptr_limit = ptr_reg->map_ptr->value_size - off - 1; } - return 0; + return *ptr_limit >= max ? -ERANGE : 0; default: return -EINVAL; } From patchwork Tue Mar 23 20:28:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 1457468 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4F4jd40t7Mz9sTD; Wed, 24 Mar 2021 07:28:56 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1lOne0-0006pR-A1; Tue, 23 Mar 2021 20:28:52 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lOndw-0006mf-Os for kernel-team@lists.ubuntu.com; Tue, 23 Mar 2021 20:28:48 +0000 Received: from 1.general.cascardo.us.vpn ([10.172.70.58] helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lOndw-0003eU-1G for kernel-team@lists.ubuntu.com; Tue, 23 Mar 2021 20:28:48 +0000 From: Thadeu Lima de Souza Cascardo To: kernel-team@lists.ubuntu.com Subject: [SRU Focal/Groovy 3/3] bpf, selftests: Fix up some test_verifier cases for unprivileged Date: Tue, 23 Mar 2021 17:28:26 -0300 Message-Id: <20210323202826.159294-4-cascardo@canonical.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210323202826.159294-1-cascardo@canonical.com> References: <20210323202826.159294-1-cascardo@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Piotr Krysiuk BugLink: https://bugs.launchpad.net/bugs/1920995 Fix up test_verifier error messages for the case where the original error message changed, or for the case where pointer alu errors differ between privileged and unprivileged tests. Also, add alternative tests for keeping coverage of the original verifier rejection error message (fp alu), and newly reject map_ptr += rX where rX == 0 given we now forbid alu on these types for unprivileged. All test_verifier cases pass after the change. The test case fixups were kept separate to ease backporting of core changes. Signed-off-by: Piotr Krysiuk Co-developed-by: Daniel Borkmann Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov (backported from commit 0a13e3537ea67452d549a6a80da3776d6b7dedb3 net.git) [cascardo: dropped map_ptr.c change as it is not present] Signed-off-by: Thadeu Lima de Souza Cascardo --- .../selftests/bpf/verifier/bounds_deduction.c | 27 +++++++++++++------ tools/testing/selftests/bpf/verifier/unpriv.c | 15 ++++++++++- .../selftests/bpf/verifier/value_ptr_arith.c | 23 +++++++++++++++- 3 files changed, 55 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/bpf/verifier/bounds_deduction.c b/tools/testing/selftests/bpf/verifier/bounds_deduction.c index 1fd07a4f27ac..c162498a64fc 100644 --- a/tools/testing/selftests/bpf/verifier/bounds_deduction.c +++ b/tools/testing/selftests/bpf/verifier/bounds_deduction.c @@ -6,8 +6,9 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", .errstr = "R0 tried to subtract pointer from scalar", + .result = REJECT, }, { "check deducing bounds from const, 2", @@ -20,6 +21,8 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_1, BPF_REG_0), BPF_EXIT_INSN(), }, + .errstr_unpriv = "R1 tried to sub from different maps, paths, or prohibited types", + .result_unpriv = REJECT, .result = ACCEPT, .retval = 1, }, @@ -31,8 +34,9 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", .errstr = "R0 tried to subtract pointer from scalar", + .result = REJECT, }, { "check deducing bounds from const, 4", @@ -45,6 +49,8 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_1, BPF_REG_0), BPF_EXIT_INSN(), }, + .errstr_unpriv = "R1 tried to sub from different maps, paths, or prohibited types", + .result_unpriv = REJECT, .result = ACCEPT, }, { @@ -55,8 +61,9 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", .errstr = "R0 tried to subtract pointer from scalar", + .result = REJECT, }, { "check deducing bounds from const, 6", @@ -67,8 +74,9 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", .errstr = "R0 tried to subtract pointer from scalar", + .result = REJECT, }, { "check deducing bounds from const, 7", @@ -80,8 +88,9 @@ offsetof(struct __sk_buff, mark)), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R1 tried to sub from different maps, paths, or prohibited types", .errstr = "dereference of modified ctx ptr", + .result = REJECT, .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, }, { @@ -94,8 +103,9 @@ offsetof(struct __sk_buff, mark)), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R1 tried to add from different maps, paths, or prohibited types", .errstr = "dereference of modified ctx ptr", + .result = REJECT, .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, }, { @@ -106,8 +116,9 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .result = REJECT, + .errstr_unpriv = "R0 tried to sub from different maps, paths, or prohibited types", .errstr = "R0 tried to subtract pointer from scalar", + .result = REJECT, }, { "check deducing bounds from const, 10", @@ -119,6 +130,6 @@ BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), BPF_EXIT_INSN(), }, - .result = REJECT, .errstr = "math between ctx pointer and register with unbounded min value is not allowed", + .result = REJECT, }, diff --git a/tools/testing/selftests/bpf/verifier/unpriv.c b/tools/testing/selftests/bpf/verifier/unpriv.c index 91bb77c24a2e..0d621c841db1 100644 --- a/tools/testing/selftests/bpf/verifier/unpriv.c +++ b/tools/testing/selftests/bpf/verifier/unpriv.c @@ -495,7 +495,7 @@ .result = ACCEPT, }, { - "unpriv: adding of fp", + "unpriv: adding of fp, reg", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_MOV64_IMM(BPF_REG_1, 0), @@ -503,6 +503,19 @@ BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, -8), BPF_EXIT_INSN(), }, + .errstr_unpriv = "R1 tried to add from different maps, paths, or prohibited types", + .result_unpriv = REJECT, + .result = ACCEPT, +}, +{ + "unpriv: adding of fp, imm", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 0), + BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, -8), + BPF_EXIT_INSN(), + }, .errstr_unpriv = "R1 stack pointer arithmetic goes out of range", .result_unpriv = REJECT, .result = ACCEPT, diff --git a/tools/testing/selftests/bpf/verifier/value_ptr_arith.c b/tools/testing/selftests/bpf/verifier/value_ptr_arith.c index 97ee658e1242..30aac1e5c9b5 100644 --- a/tools/testing/selftests/bpf/verifier/value_ptr_arith.c +++ b/tools/testing/selftests/bpf/verifier/value_ptr_arith.c @@ -169,7 +169,7 @@ .fixup_map_array_48b = { 1 }, .result = ACCEPT, .result_unpriv = REJECT, - .errstr_unpriv = "R2 tried to add from different maps or paths", + .errstr_unpriv = "R2 tried to add from different maps, paths, or prohibited types", .retval = 0, }, { @@ -516,6 +516,27 @@ .result = ACCEPT, .retval = 0xabcdef12, }, +{ + "map access: value_ptr += N, value_ptr -= N known scalar", + .insns = { + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6), + BPF_MOV32_IMM(BPF_REG_1, 0x12345678), + BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 2), + BPF_MOV64_IMM(BPF_REG_1, 2), + BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1), + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map_array_48b = { 3 }, + .result = ACCEPT, + .retval = 0x12345678, +}, { "map access: unknown scalar += value_ptr, 1", .insns = {