From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (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 D880416C6AB for ; Tue, 6 Aug 2024 21:21:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722979277; cv=none; b=au5iLOAh4QtyaicjNKUyZ22u1fDwkFc1Ukqhhd1Fip4gO2mggdu1/uepq9IkJq+/YPb186F4U4obRm7z4atN6OtYkRmCCcjf+i6CO8T6jjF6xYWqHbSj0cMLQK9RnAYlm92mvKXqXHgPrFW57YoeverAbHiGn3QeBsqh5ZlOcaU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722979277; c=relaxed/simple; bh=7o/q0V/8nz20ZimeKJ7F4Niz14kg6QxkIphDjXT52fk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=WBK0quFkOl83vp/+RKIYYKH0rNnDpYD/UcCZPtxa8a68MVlMu8mIi51elfwn+2zbPvoRPjOacYhhSPoHVxiKshq9j8Y0apy9QNjhjupiZy/Ip1t5nDWroMTqqJzY9bb1+7r/0cBRrbC34R+KcTteFGKDq/7vR48Tio8Wy/7BvyA= 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=TW8UvhEF; arc=none smtp.client-ip=209.85.219.202 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="TW8UvhEF" Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-e0872023b7dso2010645276.2 for ; Tue, 06 Aug 2024 14:21:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722979275; x=1723584075; 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=Fo9KIzckPaWjR62wzQWzW1E6r1YIZ+FzcJKNKEd2cbc=; b=TW8UvhEFanBz/L5eFqduNki+vNg7J2V83gwlkCWQ+nifpngnACK+sR2vOtJRypSrVu mWUsrDum3Yoq3hYylqhyJrfd/GyIvExJQzJ2OMlZXJm2lgpM9tRvu+zPoUXPyFA8FVAc zBhCpNrwcrtLmeeBECjLdixzoi8ed63V7QJ0RkcPyg01Dgj9NiMDhNjtv41xBNDsdQtF C/XwSASQWaPlJbwW/NYj0aDsrfY+/cWpccEh2CQIQgtEPjk5NgMabxTo38jLGfKygs4v GaBylz9z7vsjN145P32hBow8Th/T2CbsYsIcEQ9m29gKDTYxjvbPzOMH+boAHhq3QI5S ydTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722979275; x=1723584075; 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=Fo9KIzckPaWjR62wzQWzW1E6r1YIZ+FzcJKNKEd2cbc=; b=bNfRVOsn3Rj10S9GHcOljcRhU2QHHfr8Nl0ESF88oLSFoEhu9m8QBUJOGeZLM2xv4W j0wSmqd154SRU97wyB9JrwYIPwSQPxaw/2k6ILRH6bVWk0c/nHHs3aQqtZrKJ30G3kg7 qVZTqJ3k+6f2JKXbtXKaYP9t0idOrSqbOwC2TisMnkQBLd5H1T2R0iSJcrEeF7pse8Xh Yx81Vz77DKVQcGWFUx9P0V+GpyKzNfAPmqdUcdWSH3BxWaXDTYIHVwTgEu4H7yPJ0Hsm 1seGalnkrWXmqt8H9G6boqTeNerR35+tb7mLtCSfs5L9quSvc3ZQ3ODAfuyITBX8QUNr VK+A== X-Forwarded-Encrypted: i=1; AJvYcCUW8D5YB2Og5qKdC0mrHv3AZYWPqT/QF7bnCtp39EeLUMc4SFSodGckCBR6sm28q0yfnof0ACOcqqsCL4ohWcI8t7tEl6U= X-Gm-Message-State: AOJu0YxT74ykQ/W+ujFwDIWHwtOiUe11AjLrpycTwi16jAeuXrWgjgFJ 6ofuntFsS4OQbZhfpotL9eomBsUD3jpJBuiawR+zsGIPRmVno5aUJKM4gbBzgQCCo6e/q7l/Sz8 R7OYt7A== X-Google-Smtp-Source: AGHT+IH7JJ+cAD9RGztSP5vgRVCBQElvxeH9dvZHKNMgEx11Gqo+XyM2E9Dbljxi3vzskmoey/eoE16MBt22 X-Received: from anyblade.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1791]) (user=mmaurer job=sendgmr) by 2002:a05:6902:100c:b0:e0b:4dd5:3995 with SMTP id 3f1490d57ef6-e0bde4abb59mr28777276.7.1722979274758; Tue, 06 Aug 2024 14:21:14 -0700 (PDT) Date: Tue, 6 Aug 2024 21:20:28 +0000 In-Reply-To: <20240806212106.617164-1-mmaurer@google.com> Precedence: bulk X-Mailing-List: asahi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240806212106.617164-1-mmaurer@google.com> X-Mailer: git-send-email 2.46.0.rc2.264.g509ed76dc8-goog Message-ID: <20240806212106.617164-3-mmaurer@google.com> Subject: [PATCH v3 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 , Wedson Almeida Filho Cc: Matthew Maurer , 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, Boqun Feng , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , linux-modules@vger.kernel.org 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 141a964b6b13..1218cc7e1196 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; -- 2.46.0.rc2.264.g509ed76dc8-goog