Re: [PATCH v4 1/6] s390/kexec_file: Don't opencode appended signature check.
From: Luis Chamberlain <mcgrof@kernel.org>
Date: 2022-01-25 19:50:56
Also in:
kexec, keyrings, linux-crypto, linux-integrity, linux-s390, linux-security-module, lkml
On Mon, Jan 10, 2022 at 02:49:53PM +0100, Michal Suchanek wrote:
quoted hunk ↗ jump to hunk
Module verification already implements appeded signature check. Reuse it for kexec_file. The kexec_file implementation uses EKEYREJECTED error in some cases when there is no key and the common implementation uses ENOPKG or EBADMSG instead. Signed-off-by: Michal Suchanek <redacted> Acked-by: Heiko Carstens <hca@linux.ibm.com> --- v3: Philipp Rudo [off-list ref]: Update the commit with note about change of return value --- arch/s390/kernel/machine_kexec_file.c | 22 +++++----------------- 1 file changed, 5 insertions(+), 17 deletions(-)diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c index 8f43575a4dd3..c944d71316c7 100644 --- a/arch/s390/kernel/machine_kexec_file.c +++ b/arch/s390/kernel/machine_kexec_file.c@@ -31,6 +31,7 @@ int s390_verify_sig(const char *kernel, unsigned long kernel_len) const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1; struct module_signature *ms; unsigned long sig_len; + int ret; /* Skip signature verification when not secure IPLed. */ if (!ipl_secure_flag)@@ -45,25 +46,12 @@ int s390_verify_sig(const char *kernel, unsigned long kernel_len) kernel_len -= marker_len; ms = (void *)kernel + kernel_len - sizeof(*ms); - kernel_len -= sizeof(*ms); + ret = mod_check_sig(ms, kernel_len, "kexec"); + if (ret) + return ret; sig_len = be32_to_cpu(ms->sig_len); - if (sig_len >= kernel_len) - return -EKEYREJECTED;
There is a small minor fix here, where by using mod_check_sig() now decreased the kernel_len by the sizeof(*ms). It is minor though.
- kernel_len -= sig_len; - - if (ms->id_type != PKEY_ID_PKCS7) - return -EKEYREJECTED;
More importantly is the return value used here changes but given the Ack by Heiko I suspect this if fine and does not break old userspace, the only change here is the possible error value returned by the kexec_file_load() system call. Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Luis