From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 101131A4ACC for ; Wed, 25 Sep 2024 23:39:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727307568; cv=none; b=QLcvcqSA2ASZQvlGHw9ktxFAp/R3YK0VfMBvZs5mxda2NMHByp81xq/fggIhMna2Ziw4gXHIFJ9ExvutyzMnTfdvKG+GUH9xMafM4EkdvS5r32CqcDI42wVOqwu/ej0JAFENigaKpwtPxaEI8yGyufMotAEbNdeuoIvU86lDdUk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727307568; c=relaxed/simple; bh=Mm95RZ0gEd/5ILA/sw+Yul4T3HW7v3bJsG9qmFVzqME=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=N8t2wZ5PHBqWB8OgdqtOAULSFc46R5YvOLA4GAA2g3Tja+DbptFewp4arzowMxpGiJG4N6+t1GAMYtHUfT48oIVJmTUoPqZJlON4wkw8OsE2QA5JdqQ/fJZZe3sGFYTKGpHfnFMQqWGthnE7DW4E5itfqggwy89Q4BWzUuYb25g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--mmaurer.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=BFy+CH7Y; arc=none smtp.client-ip=209.85.219.201 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--mmaurer.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="BFy+CH7Y" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-e02b5792baaso693611276.2 for ; Wed, 25 Sep 2024 16:39:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1727307566; x=1727912366; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=+9YZzoCvxvyDdM8B+em9dMKSDuRRuGPZhSev+lAnN9E=; b=BFy+CH7YZLkNTZyJYgs9vhCDHiUzzmhn08xxehQkEY3dEnXzT2riYd/aBv7IL+w+UG yMGGo6eEjGaR39LdTZZE7UHNIpx8GVXKxx5No31DMg1QVUFW4I9kXM39Bt+/6Qoh3XvO u8QM5meJzA8oElAdwsxhn9TwROCWgbSKEPj3IZwJ6yjAQFOTze31AHfDVxpxuopGw1hQ 6y+tiMrWd8kAkKPK0xTYZWPUKKOkvRKJnBSptnexPlrmR0mXIhzb6H8aLku4MpTsZ4s0 84eDXpXY0YNUF1HhezB/Ta7qKj3TH7S+NLWDCWTVp+MYU0fYEjjMln2vfNV+IDSSagbu o9Rw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727307566; x=1727912366; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+9YZzoCvxvyDdM8B+em9dMKSDuRRuGPZhSev+lAnN9E=; b=El5Aoh+QEQRyeasoZXmsrt1b1f0mWZYfDvJFqLLWU57Do2gN8pTO/DYKgnucrneMga hNPLfMh/RdCeQIyss1cpLdxtHj7kefthyKcNhAvRLvqqc/AVC3A6lSXfZCQkyWTt7A+z sSvyJXYPIwZ0Z3HEpvF7wuzMcHvyQ1XlnfEdc9FQdOANJRiCFzsulwsitrhTK2dgw9cG 6lkF/F1J4RK6+/chQ55oTHBhADamZw3tPlyBWWSrQ/vyShQOmGjTLG/GPCaCfaX8/GIn Cm1zB5h2C26JbEV+QNuZG9i4MWOGeXLHAUnQnky4Zy8e2he4m1Wy4IgJtN6tPyzPCHVL f5yw== X-Forwarded-Encrypted: i=1; AJvYcCUetfDcTW2AIiPonTKsFLbHyqHfsIyLdJR//kzcObBd2EFV3OCrSfxp70+0QkJwpGMP+0zI/g==@lists.linux.dev X-Gm-Message-State: AOJu0Ywt1C4QLSa5/UQvkRv7Q7kgPLLkW/PqMtff5WSOajy0CQphK+rK /cmgNHAzYHm5HtRvn8hM6XkJ5yVhFMtxIICJfGqBsCgm1FnoPQAuw1xb4JRDY0r+wIXaoKI6HBo dU1VSbQ== X-Google-Smtp-Source: AGHT+IGHHE+4KWf9auYKryB2lu9/fM/qXObyfiN1uXRNz038JkA/1/xLeMhKPiONI2CFf2+1SxQefRfFrD41 X-Received: from anyblade.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1791]) (user=mmaurer job=sendgmr) by 2002:a25:7801:0:b0:e0e:89e6:aad4 with SMTP id 3f1490d57ef6-e24d44ca00dmr51018276.0.1727307565822; Wed, 25 Sep 2024 16:39:25 -0700 (PDT) Date: Wed, 25 Sep 2024 23:38:17 +0000 In-Reply-To: <20240925233854.90072-1-mmaurer@google.com> Precedence: bulk X-Mailing-List: asahi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240925233854.90072-1-mmaurer@google.com> X-Mailer: git-send-email 2.46.1.824.gd892dcdcdd-goog Message-ID: <20240925233854.90072-3-mmaurer@google.com> Subject: [PATCH v5 02/16] module: Factor out elf_validity_ehdr From: Matthew Maurer To: masahiroy@kernel.org, ndesaulniers@google.com, ojeda@kernel.org, gary@garyguo.net, mcgrof@kernel.org, Alex Gaynor Cc: rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, neal@gompa.dev, marcan@marcan.st, j@jannau.net, asahi@lists.linux.dev, linux-modules@vger.kernel.org, Matthew Maurer , Petr Pavlu , Sami Tolvanen , Daniel Gomez , Boqun Feng , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross Content-Type: text/plain; charset="UTF-8" Factor out verification of the ELF header and document what is checked. Signed-off-by: Matthew Maurer --- kernel/module/main.c | 70 +++++++++++++++++++++++++++++--------------- 1 file changed, 47 insertions(+), 23 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 1a2dd52147ba..59c977acfb44 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1664,6 +1664,50 @@ static int validate_section_offset(const struct load_info *info, Elf_Shdr *shdr) return 0; } +/** + * elf_validity_ehdr() - Checks an ELF header for module validity + * @info: Load info containing the ELF header to check + * + * Checks whether an ELF header could belong to a valid module. Checks: + * + * * ELF header is within the data the user provided + * * ELF magic is present + * * It is relocatable (not final linked, not core file, etc.) + * * The header's machine type matches what the architecture expects. + * * Optional arch-specific hook for other properties + * - module_elf_check_arch() is currently only used by PPC to check + * ELF ABI version, but may be used by others in the future. + * + * Return: %0 if valid, %-ENOEXEC on failure. + */ +static int elf_validity_ehdr(const struct load_info *info) +{ + if (info->len < sizeof(*(info->hdr))) { + pr_err("Invalid ELF header len %lu\n", info->len); + return -ENOEXEC; + } + if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) { + pr_err("Invalid ELF header magic: != %s\n", ELFMAG); + return -ENOEXEC; + } + if (info->hdr->e_type != ET_REL) { + pr_err("Invalid ELF header type: %u != %u\n", + info->hdr->e_type, ET_REL); + return -ENOEXEC; + } + if (!elf_check_arch(info->hdr)) { + pr_err("Invalid architecture in ELF header: %u\n", + info->hdr->e_machine); + return -ENOEXEC; + } + if (!module_elf_check_arch(info->hdr)) { + pr_err("Invalid module architecture in ELF header: %u\n", + info->hdr->e_machine); + return -ENOEXEC; + } + return 0; +} + /* * Check userspace passed ELF module against our expectations, and cache * useful variables for further processing as we go. @@ -1693,30 +1737,10 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) unsigned int num_info_secs = 0, info_idx; unsigned int num_sym_secs = 0, sym_idx; - if (info->len < sizeof(*(info->hdr))) { - pr_err("Invalid ELF header len %lu\n", info->len); - goto no_exec; - } + err = elf_validity_ehdr(info); + if (err < 0) + return err; - if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) { - pr_err("Invalid ELF header magic: != %s\n", ELFMAG); - goto no_exec; - } - if (info->hdr->e_type != ET_REL) { - pr_err("Invalid ELF header type: %u != %u\n", - info->hdr->e_type, ET_REL); - goto no_exec; - } - if (!elf_check_arch(info->hdr)) { - pr_err("Invalid architecture in ELF header: %u\n", - info->hdr->e_machine); - goto no_exec; - } - if (!module_elf_check_arch(info->hdr)) { - pr_err("Invalid module architecture in ELF header: %u\n", - info->hdr->e_machine); - goto no_exec; - } if (info->hdr->e_shentsize != sizeof(Elf_Shdr)) { pr_err("Invalid ELF section header size\n"); goto no_exec; -- 2.46.1.824.gd892dcdcdd-goog