From patchwork Wed Sep 25 23:38:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Maurer X-Patchwork-Id: 13812573 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (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 F36121A4AB4 for ; Wed, 25 Sep 2024 23:39:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727307569; cv=none; b=cZng674AwS7vBL8twS0JSfxDFmvKsoN0Ry3eHBHGxXzPBV/0aDonLZMyG0H5uKgJ/j/YzhSoAOzuSh8UQ1IIahuWU4Wy32Nwn5x1wd6z+K8pz+WZXmQBqVwZdA+8rDb1LIbzJFyJOfkf+5U3KGaogLR9lhbv8Iw7OxDWVYYGQB4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727307569; 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=dyvqbcSpHfLfzKItYiLyTw0wTztkwiAJXm+Gg5rfruYg0vadx8jeX3vF8kLGcNcFpxofM2X7EZl5cE+5GGw05QFV4dLThX1b90folZN2E1mQx76mJ6fLUe2bTk6EbMPfbWxmg2VDagQ0O35bYTIr1IYkIVkyteafRkm6ioLG1i8= 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=tXfD7CXj; arc=none smtp.client-ip=209.85.128.201 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="tXfD7CXj" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-6e1fbe2a6b1so8836457b3.2 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=vger.kernel.org; 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=tXfD7CXjz4wZB2/ddpedVBun7FwWYkTwT5jkNs4IJgfnwfXiy4LSVv4RX+OAYrv035 2TQoSEG8TmcTr8s9ZfHyXmLleupcr1QzoBnaf2A01lnHXRIRqv13B9fKWD+ikeogU+Yd 32b68d+IYGSxvqZWpCqR5I7z1urq5x1rRfok5oqB7EW+uWRgzNSIAHLCU+kC08OWluoQ VbdgHFtNj2Bx9fJ+0ji+bXWgXIjfnNT6cCrLP1QrpntizC1VuVjlla95u74qLIm3bqk4 lami4hLe5geRmL2CyPcg+1jcas+bA5m66ScVkkqaORCr69Akq0YPJlo30uy5SniGYJ3R BxLA== 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=uCkCEL4bjTgVfYPNAlqFn41UNadDQpB4b4URjJNLqHq8ZxiWN52mYGLpvXSV/K8S3W qV2LuUxZS3sMB1wdSrxqGME2wCb4szYBlhI5RnVYn1phBBos36B2fj+zsAx0avEgK+cF Pbd6Jrd2TVI1x0WbhskybvCLjmMx/ODhhMo/6Tf+rO9EEFtX0oopSJq8erb5ITg/2j27 +Q7+Dtz/TGmRz0C+Pu6XIa+/swXO2NLrz7DUXxW6BNPL8HEJEkVQc8y//xomlIQwcmjr pCsJUEL1UjNAVkV1POzwRtSFmtAhMrs2sCrCFiWOxazH+EGdDarwlc5xn/vJLZQ6dBmq RVBg== X-Forwarded-Encrypted: i=1; AJvYcCUPylrbqEcpKKpkWuzd0nwbaGz+hEAxrGkZhWwCFg0PiOVlMBupDPD3/zKTNgKSZd5lNehhiCMYi+FoM61g@vger.kernel.org X-Gm-Message-State: AOJu0YwHmgC97OLP8kjv8/qWCqT9yf3JpOT50R28VbjqsUsKGu95Sdh1 w7HkccvVb/ORBzF1gWpv5eB5T5Soi5DyCK31GJ33OSP4AuLvqnIlBrWYRKeJlr7Fz6wa2XS2+Fo 674fqNg== 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: linux-modules@vger.kernel.org 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_Roy_Baron?= " , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross 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;