| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20211207171112.03850036@rhtmp>
Date: Tue, 7 Dec 2021 17:11:12 +0100
From: Philipp Rudo <prudo@...hat.com>
To: Michal Suchanek <msuchanek@...e.de>
Cc: keyrings@...r.kernel.org, kexec@...ts.infradead.org,
Mimi Zohar <zohar@...ux.ibm.com>,
Nayna <nayna@...ux.vnet.ibm.com>, Rob Herring <robh@...nel.org>,
linux-s390@...r.kernel.org, Vasily Gorbik <gor@...ux.ibm.com>,
Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Jessica Yu <jeyu@...nel.org>, linux-kernel@...r.kernel.org,
David Howells <dhowells@...hat.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Paul Mackerras <paulus@...ba.org>,
Hari Bathini <hbathini@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
linuxppc-dev@...ts.ozlabs.org,
Frank van der Linden <fllinden@...zon.com>,
Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
Daniel Axtens <dja@...ens.net>, buendgen@...ibm.com,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Baoquan He <bhe@...hat.com>, linux-crypto@...r.kernel.org,
linux-integrity@...r.kernel.org,
linux-security-module@...r.kernel.org
Subject: Re: [PATCH v2 4/6] module: strip the signature marker in the
verification function.
Hi Michal,
On Thu, 25 Nov 2021 19:02:42 +0100
Michal Suchanek <msuchanek@...e.de> wrote:
> It is stripped by each caller separately.
>
> Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> ---
> arch/powerpc/kexec/elf_64.c | 9 ---------
> arch/s390/kernel/machine_kexec_file.c | 9 ---------
> kernel/module.c | 7 +------
> kernel/module_signing.c | 12 ++++++++++--
kernel/module_signing.c is only compiled with MODULE_SIG enabled but
KEXEC_SIG only selects MODULE_SIG_FORMAT. In the unlikely case that
KEXEC_SIG is enabled but MODULE_SIG isn't this causes a build breakage.
So you need to update KEXEC_SIG to select MODULE_SIG instead of
MODULE_SIG_FORMAT for s390 and ppc.
Thanks
Philipp
> 4 files changed, 11 insertions(+), 26 deletions(-)
>
> diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
> index 266cb26d3ca0..63634c95265d 100644
> --- a/arch/powerpc/kexec/elf_64.c
> +++ b/arch/powerpc/kexec/elf_64.c
> @@ -156,15 +156,6 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
> int elf64_verify_sig(const char *kernel, unsigned long length)
> {
> size_t kernel_len = length;
> - const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1;
> -
> - if (marker_len > kernel_len)
> - return -EKEYREJECTED;
> -
> - if (memcmp(kernel + kernel_len - marker_len, MODULE_SIG_STRING,
> - marker_len))
> - return -EKEYREJECTED;
> - kernel_len -= marker_len;
>
> return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING,
> "kexec_file");
> diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
> index 432797249db3..c4632c1a1b59 100644
> --- a/arch/s390/kernel/machine_kexec_file.c
> +++ b/arch/s390/kernel/machine_kexec_file.c
> @@ -27,20 +27,11 @@ const struct kexec_file_ops * const kexec_file_loaders[] = {
> int s390_verify_sig(const char *kernel, unsigned long length)
> {
> size_t kernel_len = length;
> - const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1;
>
> /* Skip signature verification when not secure IPLed. */
> if (!ipl_secure_flag)
> return 0;
>
> - if (marker_len > kernel_len)
> - return -EKEYREJECTED;
> -
> - if (memcmp(kernel + kernel_len - marker_len, MODULE_SIG_STRING,
> - marker_len))
> - return -EKEYREJECTED;
> - kernel_len -= marker_len;
> -
> return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING,
> "kexec_file");
> }
> diff --git a/kernel/module.c b/kernel/module.c
> index 8481933dfa92..d91ca0f93a40 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -2882,7 +2882,6 @@ static inline void kmemleak_load_module(const struct module *mod,
> static int module_sig_check(struct load_info *info, int flags)
> {
> int err = -ENODATA;
> - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
> const char *reason;
> const void *mod = info->hdr;
>
> @@ -2890,11 +2889,7 @@ static int module_sig_check(struct load_info *info, int flags)
> * Require flags == 0, as a module with version information
> * removed is no longer the module that was signed
> */
> - if (flags == 0 &&
> - info->len > markerlen &&
> - memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
> - /* We truncate the module to discard the signature */
> - info->len -= markerlen;
> + if (flags == 0) {
> err = verify_appended_signature(mod, &info->len,
> VERIFY_USE_SECONDARY_KEYRING, "module");
> if (!err) {
> diff --git a/kernel/module_signing.c b/kernel/module_signing.c
> index f492e410564d..4c28cb55275f 100644
> --- a/kernel/module_signing.c
> +++ b/kernel/module_signing.c
> @@ -15,8 +15,7 @@
> #include "module-internal.h"
>
> /**
> - * verify_appended_signature - Verify the signature on a module with the
> - * signature marker stripped.
> + * verify_appended_signature - Verify the signature on a module
> * @data: The data to be verified
> * @len: Size of @data.
> * @trusted_keys: Keyring to use for verification
> @@ -25,12 +24,21 @@
> int verify_appended_signature(const void *data, size_t *len,
> struct key *trusted_keys, const char *what)
> {
> + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
> struct module_signature ms;
> size_t sig_len, modlen = *len;
> int ret;
>
> pr_devel("==>%s(,%zu)\n", __func__, modlen);
>
> + if (markerlen > modlen)
> + return -ENODATA;
> +
> + if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING,
> + markerlen))
> + return -ENODATA;
> + modlen -= markerlen;
> +
> if (modlen <= sizeof(ms))
> return -EBADMSG;
>
Powered by blists - more mailing lists