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([38.34.87.7]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2038557f093sm7233445ad.63.2024.08.22.01.01.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 01:01:40 -0700 (PDT) From: Eduard Zingerman To: bpf@vger.kernel.org, ast@kernel.org Cc: andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, kernel-team@fb.com, yonghong.song@linux.dev, cnitlrt@gmail.com, Eduard Zingerman Subject: [PATCH bpf-next v3 1/2] bpf: correctly handle malformed BPF_CORE_TYPE_ID_LOCAL relos Date: Thu, 22 Aug 2024 01:01:23 -0700 Message-ID: <20240822080124.2995724-2-eddyz87@gmail.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240822080124.2995724-1-eddyz87@gmail.com> References: <20240822080124.2995724-1-eddyz87@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 In case of malformed relocation record of kind BPF_CORE_TYPE_ID_LOCAL referencing a non-existing BTF type, function bpf_core_calc_relo_insn would cause a null pointer deference. Fix this by adding a proper check upper in call stack, as malformed relocation records could be passed from user space. Simplest reproducer is a program: r0 = 0 exit With a single relocation record: .insn_off = 0, /* patch first instruction */ .type_id = 100500, /* this type id does not exist */ .access_str_off = 6, /* offset of string "0" */ .kind = BPF_CORE_TYPE_ID_LOCAL, See the link for original reproducer or next commit for a test case. Fixes: 74753e1462e7 ("libbpf: Replace btf__type_by_id() with btf_type_by_id().") Reported-by: Liu RuiTong Closes: https://lore.kernel.org/bpf/CAK55_s6do7C+DVwbwY_7nKfUz0YLDoiA1v6X3Y9+p0sWzipFSA@mail.gmail.com/ Acked-by: Andrii Nakryiko Signed-off-by: Eduard Zingerman --- kernel/bpf/btf.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index c9338fb397fc..5de424d3a795 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -8910,6 +8910,7 @@ int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo, struct bpf_core_cand_list cands = {}; struct bpf_core_relo_res targ_res; struct bpf_core_spec *specs; + const struct btf_type *type; int err; /* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5" @@ -8919,6 +8920,13 @@ int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo, if (!specs) return -ENOMEM; + type = btf_type_by_id(ctx->btf, relo->type_id); + if (!type) { + bpf_log(ctx->log, "relo #%u: bad type id %u\n", + relo_idx, relo->type_id); + return -EINVAL; + } + if (need_cands) { struct bpf_cand_cache *cc; int i; From patchwork Thu Aug 22 08:01:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eduard Zingerman X-Patchwork-Id: 13772909 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) (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 B79E719470 for ; Thu, 22 Aug 2024 08:01:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724313704; cv=none; b=UqpoyIouW/fk9Q+jpgCDhwaHv6U24g+9ukILWPmPbZHSLkMXDQmRkUcvD0BZa4KxJ8/GLQJNHG9wg8BhlUmFm+FTA538U5omsK3auGUR2SmD9eFkLzwHXXGM9yHWLoxCsMftED7riIRsz7QQ2J0a79NkjzPGXtiG3K2hMp/r4Hg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724313704; c=relaxed/simple; bh=E8jMbnpSVSd1Wnd75l0McI+0bHNQFt7AMri7u1mGlCs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=i5r/t2xIouskBWNloBwQNhcpl3B5Sd0TioXJbO21yP4mTwZzUhevMxzjMn0Qd8DuROoZQuoVnonObWXVtVK4Ao8hTmn6WtS0QWSrbFuzCUllqdwGe+qsvrgIKyRloBFqGA4apMpxfbquk40FCpSuqqm/QzOAjIhc93cuTGu+W+Q= 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=MY9vFaiR; arc=none smtp.client-ip=209.85.214.171 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="MY9vFaiR" Received: by mail-pl1-f171.google.com with SMTP id d9443c01a7336-201fbd0d7c2so5027125ad.0 for ; Thu, 22 Aug 2024 01:01:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1724313702; x=1724918502; 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=y6vbz8n7f2I/mpXBTtUbKY1l3jcFD8guj2CHH6VYKj4=; b=MY9vFaiRnppc8t1/n2482eIpkXOkp9rUNjgLDlk4nR7zhPlqvGxplnGXqLx+RVFvQx XPJaQhoK2FjBdjVeXls/5oo/yDcbv5NG5xPB4rrh8pu3/xJKK5+lGT3UoHE/ZH9+PhS9 5kj6RqCIlGFJ6jebbL+ZakK6EVSJgsr50kZ5JcO8b7lfxto5ca9KYyeZGK8RA1ML0PL6 /bEFlRmT+6fujHhui6kBEAzlmmF+koXw/yrbK1oNzE/p4otiyvLjeaWFrwnzsyuqd489 R5eYssJLz7LKZ/xirXZUTHv1qI+L+AQMbmF1/QSuqMmJontGp5T/xvXQVYx6h9cE1Ygg jNlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724313702; x=1724918502; 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=y6vbz8n7f2I/mpXBTtUbKY1l3jcFD8guj2CHH6VYKj4=; b=wZl+IIUTYdwvkIJWYtlS8Gqymrfqqz16aGXBwEZJ8/fbQ6jLtdx4DhS3dJryOO9fq4 0RMgABpWRX8oU9mMIOREekLgrevhKc8zAMlHZLHQr+GnRL7GjEbTrt8EJpxWF6i63UY8 FpnNIg7RyWZiRIO7S4bFrqiiHkK+BTXDjPZQY8OEosap62WZE4hDet5Naj84vd4ggSBs xE0POWM7e6LY5d4vUiVkAkYHRw5Y/5xcFkqgbkvo8wMpyJvFFKDx9em1T2K84zsKnpkT CMk8QGn0td343JVugk5RgodP4RXhTJ9K0cqFACTL9XeCkLjZ4OKSMZbwQ95qUm7geMjP Li9Q== X-Gm-Message-State: AOJu0YzonYywMtVx3b9GzD5TVHFoZy/WUTuHNi6upj2xkYdbSyCLzm5W 7vBwLwCHUrILQWy00AlCFpAb/PU0gp7J3gn+c+jtEkWUiaIMOlPQ+TcAIGhH X-Google-Smtp-Source: AGHT+IF7mVzllIoqP1IqUcDM5GUBRNwNqKe7Io+8sMKnzVIYiEEVnN/W1zOMHWbEtZIInm1tuRrVSQ== X-Received: by 2002:a17:903:228a:b0:1ff:5135:130f with SMTP id d9443c01a7336-203681b16fcmr55475145ad.53.1724313701588; Thu, 22 Aug 2024 01:01:41 -0700 (PDT) Received: from honey-badger.. ([38.34.87.7]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2038557f093sm7233445ad.63.2024.08.22.01.01.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 01:01:41 -0700 (PDT) From: Eduard Zingerman To: bpf@vger.kernel.org, ast@kernel.org Cc: andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, kernel-team@fb.com, yonghong.song@linux.dev, cnitlrt@gmail.com, Eduard Zingerman Subject: [PATCH bpf-next v3 2/2] selftests/bpf: test for malformed BPF_CORE_TYPE_ID_LOCAL relocation Date: Thu, 22 Aug 2024 01:01:24 -0700 Message-ID: <20240822080124.2995724-3-eddyz87@gmail.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240822080124.2995724-1-eddyz87@gmail.com> References: <20240822080124.2995724-1-eddyz87@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 Check that verifier rejects BPF program containing relocation pointing to non-existent BTF type. To force relocation resolution on kernel side test case uses bpf_attr->core_relos field. This field is not exposed by libbpf, so directly do BPF system call in the test. Signed-off-by: Eduard Zingerman --- .../selftests/bpf/prog_tests/core_reloc_raw.c | 125 ++++++++++++++++++ 1 file changed, 125 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c b/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c new file mode 100644 index 000000000000..a18d3680fb16 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c @@ -0,0 +1,125 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* Test cases that can't load programs using libbpf and need direct + * BPF syscall access + */ + +#include +#include +#include + +#include "test_progs.h" +#include "test_btf.h" +#include "bpf/libbpf_internal.h" + +static char log[16 * 1024]; + +/* Check that verifier rejects BPF program containing relocation + * pointing to non-existent BTF type. + */ +static void test_bad_local_id(void) +{ + struct test_btf { + struct btf_header hdr; + __u32 types[15]; + char strings[128]; + } raw_btf = { + .hdr = { + .magic = BTF_MAGIC, + .version = BTF_VERSION, + .hdr_len = sizeof(struct btf_header), + .type_off = 0, + .type_len = sizeof(raw_btf.types), + .str_off = offsetof(struct test_btf, strings) - + offsetof(struct test_btf, types), + .str_len = sizeof(raw_btf.strings), + }, + .types = { + BTF_PTR_ENC(0), /* [1] void* */ + BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [2] int */ + BTF_FUNC_PROTO_ENC(2, 1), /* [3] int (*)(void*) */ + BTF_FUNC_PROTO_ARG_ENC(8, 1), + BTF_FUNC_ENC(8, 3) /* [4] FUNC 'foo' type_id=2 */ + }, + .strings = "\0int\0 0\0foo\0" + }; + __u32 log_level = 1 | 2 | 4; + LIBBPF_OPTS(bpf_btf_load_opts, opts, + .log_buf = log, + .log_size = sizeof(log), + .log_level = log_level, + ); + struct bpf_insn insns[] = { + BPF_ALU64_IMM(BPF_MOV, BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + struct bpf_func_info funcs[] = { + { + .insn_off = 0, + .type_id = 4, + } + }; + struct bpf_core_relo relos[] = { + { + .insn_off = 0, /* patch first instruction (r0 = 0) */ + .type_id = 100500, /* !!! this type id does not exist */ + .access_str_off = 6, /* offset of "0" */ + .kind = BPF_CORE_TYPE_ID_LOCAL, + } + }; + union bpf_attr attr; + int saved_errno; + int prog_fd = -1; + int btf_fd = -1; + + btf_fd = bpf_btf_load(&raw_btf, sizeof(raw_btf), &opts); + saved_errno = errno; + if (btf_fd < 0 || env.verbosity > VERBOSE_NORMAL) { + printf("-------- BTF load log start --------\n"); + printf("%s", log); + printf("-------- BTF load log end ----------\n"); + } + if (btf_fd < 0) { + PRINT_FAIL("bpf_btf_load() failed, errno=%d\n", saved_errno); + return; + } + + log[0] = 0; + memset(&attr, 0, sizeof(attr)); + attr.prog_btf_fd = btf_fd; + attr.prog_type = BPF_TRACE_RAW_TP; + attr.license = (__u64)"GPL"; + attr.insns = (__u64)&insns; + attr.insn_cnt = sizeof(insns) / sizeof(*insns); + attr.log_buf = (__u64)log; + attr.log_size = sizeof(log); + attr.log_level = log_level; + attr.func_info = (__u64)funcs; + attr.func_info_cnt = sizeof(funcs) / sizeof(*funcs); + attr.func_info_rec_size = sizeof(*funcs); + attr.core_relos = (__u64)relos; + attr.core_relo_cnt = sizeof(relos) / sizeof(*relos); + attr.core_relo_rec_size = sizeof(*relos); + prog_fd = sys_bpf_prog_load(&attr, sizeof(attr), 1); + saved_errno = errno; + if (prog_fd < 0 || env.verbosity > VERBOSE_NORMAL) { + printf("-------- program load log start --------\n"); + printf("%s", log); + printf("-------- program load log end ----------\n"); + } + if (prog_fd >= 0) { + PRINT_FAIL("sys_bpf_prog_load() expected to fail\n"); + goto out; + } + ASSERT_HAS_SUBSTR(log, "relo #0: bad type id 100500", "program load log"); + +out: + close(prog_fd); + close(btf_fd); +} + +void test_core_reloc_raw(void) +{ + if (test__start_subtest("bad_local_id")) + test_bad_local_id(); +}