From nobody Mon Nov 25 04:54:44 2024 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (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 E615F1DFE1D for ; Wed, 30 Oct 2024 23:05:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730329511; cv=none; b=IVgT67DX6MiAdCMvEX6/uPN+Zspks+2FKNZovEgJsOkThHFHVGo2ocXt9sdlBMczg0ZsRVr6GDmlYqxY1dL08K4F+MqyAi/xTCqQ0Jpx3g43XqUFbd6G0PcIUhmislAuXNEuabPHLhHTYnYMiI9Q+X0e3ykjTHvFGzGN3OTmxjg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730329511; c=relaxed/simple; bh=Q6PChDL+oyVIftKwE+bBAXZjV7BwBjURcBa1udfZz4U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hrV7ihYTtosAeDPYZwqFpQgb5S4FluAeS8OQLgLgxAmVZfvYeRKi8JICu94kvBpCs9Wj+H05QFxGUKqHa2JeXCRFJVPbFfcrGqdLdhSMuwd4grK8BWlI1AMkQaqMKmRjclpWI5PzQzQpMPQeSGSl5FDfLr5+c7gd4Bjm4INSvkM= 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=0jF8bFwX; arc=none smtp.client-ip=209.85.128.202 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="0jF8bFwX" Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-6e32b43e053so5068097b3.1 for ; Wed, 30 Oct 2024 16:05:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730329508; x=1730934308; 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=M9nQk6Vo8fRWDZnjgBzQeNQ0t1uhkA+WPna5Ivbnx+E=; b=0jF8bFwXYLiS2HJwZbzFaNEs1QJ9spGh3Cmn5jTsRDKSVf07GTmf3wQlaXNlMyMI2K dkBKkiDFQJxadbKWk+zv8I4q7N1kAgJLWxb92SYki35tcVXmqIzG4fsvJwvFNGaVq1N9 uzqlDXwr/GEvhu4xOYZutrZkOOyKLisCCsKQNVxayvV0TxdwAvTANR8UDI6Z/iue2I3k U1dxz0SqVSM0nr2iXg9WVmMRA+2wCCOhDzQb4U7cYoiUJXzLUqNjDhD09/XxvE7hjNz4 s5U4AzPlAUMCM4XBlWS1pH7bO+jhdZuJhpf/opKZqk33ZJbpLoDHR1aW3ZQ9nRR7ClSw rC1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730329508; x=1730934308; 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=M9nQk6Vo8fRWDZnjgBzQeNQ0t1uhkA+WPna5Ivbnx+E=; b=VOV2Wk/JzVk9NB52pO17XlH+gAOTiR3AdCnkXMNEG00d2B9VwPzrl0K4sKGZ4Md/mP tlzDHBPXIm4nYl66nJSsMgg0FRt1+1+KxDGL7/Uar7g7p34dwF10c6fODPdmZdfZQTTe t2T2JFfe2RanI3J1RZulPgKvhMCoocteVBqi8X5nc2x+mFKBhH73LXQ59k4RQlvHgX6N NBJ00RzecQIbBJQoeloS5TBkMskhj8UDaE9APB9sSZ673Mvg9rCjv9szAiMSvEm07hoQ 9a7/9ZYxQA+gEIWgOMCiJo7dieSOMaRPc9Xuouz+TOb20JrwqqBk2Tkt9HGu2nhgeB51 vsKA== X-Forwarded-Encrypted: i=1; AJvYcCUvJINEYnXui+JgM3pEGmfZO1tOkWxg3YcXVwOWFPyJQQoX0PYBQzmEaby8EaPh40/SlrwqscBiTsFG01k=@vger.kernel.org X-Gm-Message-State: AOJu0YxDL+yX0k3KYMb7nt8Ot+haCf4Zv+MPT+rMUBke8TWzscYzh9MY px3SzMS9QsW/KRZsBxiEjRbJChZ4cX8DvIrnVHH/JnkhMRDeU4pW4XyRj0hNV1D1UHPS39+gG9v F5dsb7w== X-Google-Smtp-Source: AGHT+IFvZLz7CVdvhJjJoh+yqpQ35aVD3PCtqu26YbxX8dAJAbgIAzOeOK4f9sJtySMAH38zABThUZljaU2M X-Received: from anyblade.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1791]) (user=mmaurer job=sendgmr) by 2002:a25:838d:0:b0:e27:3e6a:345 with SMTP id 3f1490d57ef6-e3087c22e77mr11084276.10.1730329507922; Wed, 30 Oct 2024 16:05:07 -0700 (PDT) Date: Wed, 30 Oct 2024 23:05:02 +0000 In-Reply-To: <20241030-extended-modversions-v8-0-93acdef62ce8@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241030-extended-modversions-v8-0-93acdef62ce8@google.com> X-Mailer: b4 0.15-dev Message-ID: <20241030-extended-modversions-v8-1-93acdef62ce8@google.com> Subject: [PATCH v8 1/3] modules: Support extended MODVERSIONS info From: Matthew Maurer To: Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Madhavan Srinivasan , Luis Chamberlain , Petr Pavlu , Sami Tolvanen , Daniel Gomez , Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, linux-kbuild@vger.kernel.org, rust-for-linux@vger.kernel.org, Matthew Maurer Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Adds a new format for MODVERSIONS which stores each field in a separate ELF section. This initially adds support for variable length names, but could later be used to add additional fields to MODVERSIONS in a backwards compatible way if needed. Any new fields will be ignored by old user tooling, unlike the current format where user tooling cannot tolerate adjustments to the format (for example making the name field longer). Since PPC munges its version records to strip leading dots, we reproduce the munging for the new format. Other architectures do not appear to have architecture-specific usage of this information. Reviewed-by: Sami Tolvanen Signed-off-by: Matthew Maurer Acked-by: Michael Ellerman (powerpc) --- arch/powerpc/kernel/module_64.c | 24 ++++++++++- kernel/module/internal.h | 11 +++++ kernel/module/main.c | 92 +++++++++++++++++++++++++++++++++++++= ---- kernel/module/version.c | 45 ++++++++++++++++++++ 4 files changed, 162 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_6= 4.c index e9bab599d0c2745e4d2b5cae04f2c56395c24654..02ada0b057cef6b2f29fa7519a5= d52acac740ee5 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -355,6 +355,24 @@ static void dedotify_versions(struct modversion_info *= vers, } } =20 +/* Same as normal versions, remove a leading dot if present. */ +static void dedotify_ext_version_names(char *str_seq, unsigned long size) +{ + unsigned long out =3D 0; + unsigned long in; + char last =3D '\0'; + + for (in =3D 0; in < size; in++) { + /* Skip one leading dot */ + if (last =3D=3D '\0' && str_seq[in] =3D=3D '.') + in++; + last =3D str_seq[in]; + str_seq[out++] =3D last; + } + /* Zero the trailing portion of the names table for robustness */ + memset(&str_seq[out], 0, size - out); +} + /* * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC. * seem to be defined (value set later). @@ -424,10 +442,12 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr, me->arch.toc_section =3D i; if (sechdrs[i].sh_addralign < 8) sechdrs[i].sh_addralign =3D 8; - } - else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")=3D=3D0) + } else if (strcmp(secstrings + sechdrs[i].sh_name, "__versions") =3D=3D = 0) dedotify_versions((void *)hdr + sechdrs[i].sh_offset, sechdrs[i].sh_size); + else if (strcmp(secstrings + sechdrs[i].sh_name, "__version_ext_names") = =3D=3D 0) + dedotify_ext_version_names((void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size); =20 if (sechdrs[i].sh_type =3D=3D SHT_SYMTAB) dedotify((void *)hdr + sechdrs[i].sh_offset, diff --git a/kernel/module/internal.h b/kernel/module/internal.h index daef2be8390222c22220e2f168baa8d35ad531b9..59959c21b205bf91c0073260885= 743098c4022cf 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -86,6 +86,8 @@ struct load_info { unsigned int vers; unsigned int info; unsigned int pcpu; + unsigned int vers_ext_crc; + unsigned int vers_ext_name; } index; }; =20 @@ -389,6 +391,15 @@ void module_layout(struct module *mod, struct modversi= on_info *ver, struct kerne struct kernel_symbol *ks, struct tracepoint * const *tp); int check_modstruct_version(const struct load_info *info, struct module *m= od); int same_magic(const char *amagic, const char *bmagic, bool has_crcs); +struct modversion_info_ext { + size_t remaining; + const s32 *crc; + const char *name; +}; +void modversion_ext_start(const struct load_info *info, struct modversion_= info_ext *ver); +void modversion_ext_advance(struct modversion_info_ext *ver); +#define for_each_modversion_info_ext(ver, info) \ + for (modversion_ext_start(info, &ver); ver.remaining > 0; modversion_ext_= advance(&ver)) #else /* !CONFIG_MODVERSIONS */ static inline int check_version(const struct load_info *info, const char *symname, diff --git a/kernel/module/main.c b/kernel/module/main.c index b40b632f00a65e66ed73c4b386ef1f323a5b790c..9a9feca344f8bb06408d350e13f= 759bb909962cd 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2039,6 +2039,82 @@ static int elf_validity_cache_index_str(struct load_= info *info) return 0; } =20 +/** + * elf_validity_cache_index_versions() - Validate and cache version indices + * @info: Load info to cache version indices in. + * Must have &load_info->sechdrs and &load_info->secstrings popula= ted. + * @flags: Load flags, relevant to suppress version loading, see + * uapi/linux/module.h + * + * If we're ignoring modversions based on @flags, zero all version indices + * and return validity. Othewrise check: + * + * * If "__version_ext_crcs" is present, "__version_ext_names" is present + * * There is a name present for every crc + * + * Then populate: + * + * * &load_info->index.vers + * * &load_info->index.vers_ext_crc + * * &load_info->index.vers_ext_names + * + * if present. + * + * Return: %0 if valid, %-ENOEXEC on failure. + */ +static int elf_validity_cache_index_versions(struct load_info *info, int f= lags) +{ + unsigned int vers_ext_crc; + unsigned int vers_ext_name; + size_t crc_count; + size_t remaining_len; + size_t name_size; + char *name; + + /* If modversions were suppressed, pretend we didn't find any */ + if (flags & MODULE_INIT_IGNORE_MODVERSIONS) { + info->index.vers =3D 0; + info->index.vers_ext_crc =3D 0; + info->index.vers_ext_name =3D 0; + return 0; + } + + vers_ext_crc =3D find_sec(info, "__version_ext_crcs"); + vers_ext_name =3D find_sec(info, "__version_ext_names"); + + /* If we have one field, we must have the other */ + if (!!vers_ext_crc !=3D !!vers_ext_name) { + pr_err("extended version crc+name presence does not match"); + return -ENOEXEC; + } + + /* + * If we have extended version information, we should have the same + * number of entries in every section. + */ + if (vers_ext_crc) { + crc_count =3D info->sechdrs[vers_ext_crc].sh_size / sizeof(s32); + name =3D (void *)info->hdr + + info->sechdrs[vers_ext_name].sh_offset; + remaining_len =3D info->sechdrs[vers_ext_name].sh_size; + + while (crc_count--) { + name_size =3D strnlen(name, remaining_len) + 1; + if (name_size > remaining_len) { + pr_err("more extended version crcs than names"); + return -ENOEXEC; + } + remaining_len -=3D name_size; + name +=3D name_size; + } + } + + info->index.vers =3D find_sec(info, "__versions"); + info->index.vers_ext_crc =3D vers_ext_crc; + info->index.vers_ext_name =3D vers_ext_name; + return 0; +} + /** * elf_validity_cache_index() - Resolve, validate, cache section indices * @info: Load info to read from and update. @@ -2053,9 +2129,7 @@ static int elf_validity_cache_index_str(struct load_i= nfo *info) * * elf_validity_cache_index_mod() * * elf_validity_cache_index_sym() * * elf_validity_cache_index_str() - * - * If versioning is not suppressed via flags, load the version index from - * a section called "__versions" with no validation. + * * elf_validity_cache_index_versions() * * If CONFIG_SMP is enabled, load the percpu section by name with no * validation. @@ -2078,11 +2152,9 @@ static int elf_validity_cache_index(struct load_info= *info, int flags) err =3D elf_validity_cache_index_str(info); if (err < 0) return err; - - if (flags & MODULE_INIT_IGNORE_MODVERSIONS) - info->index.vers =3D 0; /* Pretend no __versions section! */ - else - info->index.vers =3D find_sec(info, "__versions"); + err =3D elf_validity_cache_index_versions(info, flags); + if (err < 0) + return err; =20 info->index.pcpu =3D find_pcpusec(info); =20 @@ -2293,6 +2365,10 @@ static int rewrite_section_headers(struct load_info = *info, int flags) =20 /* Track but don't keep modinfo and version sections. */ info->sechdrs[info->index.vers].sh_flags &=3D ~(unsigned long)SHF_ALLOC; + info->sechdrs[info->index.vers_ext_crc].sh_flags &=3D + ~(unsigned long)SHF_ALLOC; + info->sechdrs[info->index.vers_ext_name].sh_flags &=3D + ~(unsigned long)SHF_ALLOC; info->sechdrs[info->index.info].sh_flags &=3D ~(unsigned long)SHF_ALLOC; =20 return 0; diff --git a/kernel/module/version.c b/kernel/module/version.c index 53f43ac5a73e9d537a9e95ff97728a51fad0e797..c246d40879706d4f413fa7ea9bb= e2264ea1b2aa8 100644 --- a/kernel/module/version.c +++ b/kernel/module/version.c @@ -19,11 +19,28 @@ int check_version(const struct load_info *info, unsigned int versindex =3D info->index.vers; unsigned int i, num_versions; struct modversion_info *versions; + struct modversion_info_ext version_ext; =20 /* Exporting module didn't supply crcs? OK, we're already tainted. */ if (!crc) return 1; =20 + /* If we have extended version info, rely on it */ + if (info->index.vers_ext_crc) { + for_each_modversion_info_ext(version_ext, info) { + if (strcmp(version_ext.name, symname) !=3D 0) + continue; + if (*version_ext.crc =3D=3D *crc) + return 1; + pr_debug("Found checksum %X vs module %X\n", + *crc, *version_ext.crc); + goto bad_version; + } + pr_warn_once("%s: no extended symbol version for %s\n", + info->name, symname); + return 1; + } + /* No versions at all? modprobe --force does this. */ if (versindex =3D=3D 0) return try_to_force_load(mod, symname) =3D=3D 0; @@ -87,6 +104,34 @@ int same_magic(const char *amagic, const char *bmagic, return strcmp(amagic, bmagic) =3D=3D 0; } =20 +void modversion_ext_start(const struct load_info *info, + struct modversion_info_ext *start) +{ + unsigned int crc_idx =3D info->index.vers_ext_crc; + unsigned int name_idx =3D info->index.vers_ext_name; + Elf_Shdr *sechdrs =3D info->sechdrs; + + /* + * Both of these fields are needed for this to be useful + * Any future fields should be initialized to NULL if absent. + */ + if (crc_idx =3D=3D 0 || name_idx =3D=3D 0) { + start->remaining =3D 0; + return; + } + + start->crc =3D (const s32 *)sechdrs[crc_idx].sh_addr; + start->name =3D (const char *)sechdrs[name_idx].sh_addr; + start->remaining =3D sechdrs[crc_idx].sh_size / sizeof(*start->crc); +} + +void modversion_ext_advance(struct modversion_info_ext *vers) +{ + vers->remaining--; + vers->crc++; + vers->name +=3D strlen(vers->name) + 1; +} + /* * Generate the signature for all relevant module structures here. * If these change, we don't want to try to parse the module. --=20 2.47.0.163.g1226f6d8fa-goog