[PATCH v5 1/6] s390/kexec_file: Don't opencode appended signature check.

Michal Suchanek
2022-01-11T11:38:03Z

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 <msuchanek@suse.de>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
---
v3: Philipp Rudo <prudo@redhat.com>: 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;
- kernel_len -= sig_len;
-
- if (ms->id_type != PKEY_ID_PKCS7)
- return -EKEYREJECTED;
-
- if (ms->algo != 0 ||
- ms->hash != 0 ||
- ms->signer_len != 0 ||
- ms->key_id_len != 0 ||
- ms->__pad[0] != 0 ||
- ms->__pad[1] != 0 ||
- ms->__pad[2] != 0) {
- return -EBADMSG;
- }
+ kernel_len -= sizeof(*ms) + sig_len;

return verify_pkcs7_signature(kernel, kernel_len,
kernel + kernel_len, sig_len,
--
2.31.1