On 9/17/25 19:21, Zhuoying Cai wrote: Just some nits below based on how far along this patch has come.
> From: Collin Walling <[email protected]> > > DIAG 508 subcode 1 performs signature-verification on signed components. > A signed component may be a Linux kernel image, or any other signed > binary. **Verification of initrd is not supported.** The initrd case should be included in the document as well for subcode 1. > > The instruction call expects two item-pairs: an address of a device > component, an address of the analogous signature file (in PKCS#7 DER format), > and their respective lengths. All of this data should be encapsulated > within a Diag508SigVerifBlock. > > The DIAG handler will read from the provided addresses > to retrieve the necessary data, parse the signature file, then > perform the signature-verification. Because there is no way to > correlate a specific certificate to a component, each certificate > in the store is tried until either verification succeeds, or all > certs have been exhausted. > > The subcode value is denoted by setting the second-to-left-most bit of > a 2-byte field. > Remove the sentence above. As for the info below, it should also be included in the document under subcode 1. > A return code of 1 indicates success, and the index and length of the > corresponding certificate will be set in the Diag508SigVerifBlock. > The following values indicate failure: > > 0x0102: certificate not available Change to: no certificates are available in the store > 0x0202: component data is invalid > 0x0302: signature is not in PKCS#7 format > 0x0402: signature-verification failed > 0x0502: length of Diag508SigVerifBlock is invalid > > Signed-off-by: Collin Walling <[email protected]> > Signed-off-by: Zhuoying Cai <[email protected]> > --- > docs/specs/s390x-secure-ipl.rst | 5 ++ > include/hw/s390x/ipl/diag508.h | 23 +++++++ > target/s390x/diag.c | 115 +++++++++++++++++++++++++++++++- > 3 files changed, 142 insertions(+), 1 deletion(-) > > diff --git a/docs/specs/s390x-secure-ipl.rst b/docs/specs/s390x-secure-ipl.rst > index 0919425e9a..eec368d17b 100644 > --- a/docs/specs/s390x-secure-ipl.rst > +++ b/docs/specs/s390x-secure-ipl.rst > @@ -66,3 +66,8 @@ that requires assistance from QEMU. > > Subcode 0 - query installed subcodes > Returns a 64-bit mask indicating which subcodes are supported. > + > +Subcode 1 - perform signature verification > + Perform signature-verification on a signed component, using certificates > + from the certificate store and leveraging qcrypto libraries to perform > + this operation. > diff --git a/include/hw/s390x/ipl/diag508.h b/include/hw/s390x/ipl/diag508.h > index 6281ad8299..ad401cc867 100644 > --- a/include/hw/s390x/ipl/diag508.h > +++ b/include/hw/s390x/ipl/diag508.h > @@ -11,5 +11,28 @@ > #define S390X_DIAG508_H > > #define DIAG_508_SUBC_QUERY_SUBC 0x0000 > +#define DIAG_508_SUBC_SIG_VERIF 0x8000 > + > +#define DIAG_508_RC_OK 0x0001 > +#define DIAG_508_RC_NO_CERTS 0x0102 > +#define DIAG_508_RC_INVAL_COMP_DATA 0x0202 > +#define DIAG_508_RC_INVAL_PKCS7_SIG 0x0302 > +#define DIAG_508_RC_FAIL_VERIF 0x0402 > +#define DIAG_508_RC_INVAL_LEN 0x0502 > + > +struct Diag508SigVerifBlock { > + uint32_t length; > + uint8_t reserved0[3]; > + uint8_t version; > + uint32_t reserved[2]; > + uint8_t cert_store_index; > + uint8_t reserved1[7]; > + uint64_t cert_len; > + uint64_t comp_len; > + uint64_t comp_addr; > + uint64_t sig_len; > + uint64_t sig_addr; > +}; > +typedef struct Diag508SigVerifBlock Diag508SigVerifBlock; > > #endif > diff --git a/target/s390x/diag.c b/target/s390x/diag.c > index ee64257dbc..379fb8f2b4 100644 > --- a/target/s390x/diag.c > +++ b/target/s390x/diag.c > @@ -602,9 +602,112 @@ void handle_diag_320(CPUS390XState *env, uint64_t r1, > uint64_t r3, uintptr_t ra) > } > } > > +static int diag_508_verify_sig(uint8_t *cert, size_t cert_size, > + uint8_t *comp, size_t comp_size, > + uint8_t *sig, size_t sig_size) > +{ > + g_autofree uint8_t *sig_pem = NULL; > + size_t sig_size_pem; > + int rc; > + > + /* > + * PKCS#7 signature with DER format > + * Convert to PEM format for signature verification > + */ > + rc = qcrypto_pkcs7_convert_sig_pem(sig, sig_size, &sig_pem, > &sig_size_pem, NULL); > + if (rc < 0) { > + return -1; > + } > + > + rc = qcrypto_x509_verify_sig(cert, cert_size, > + comp, comp_size, > + sig_pem, sig_size_pem, NULL); > + if (rc < 0) { > + return -1; > + } > + > + return 0; > +} > + > +static int handle_diag508_sig_verif(uint64_t addr, size_t svb_size, > + S390IPLCertificateStore *qcs) > +{ > + int rc; > + int verified; > + uint32_t svb_len; > + uint64_t comp_len, comp_addr; > + uint64_t sig_len, sig_addr; > + g_autofree uint8_t *svb_comp = NULL; > + g_autofree uint8_t *svb_sig = NULL; nit: maybe just call these comp and sig? > + g_autofree Diag508SigVerifBlock *svb = NULL; > + > + if (!qcs || !qcs->count) { > + return DIAG_508_RC_NO_CERTS; > + } > + > + svb = g_new0(Diag508SigVerifBlock, 1); > + cpu_physical_memory_read(addr, svb, svb_size); > + > + svb_len = be32_to_cpu(svb->length); > + if (svb_len != svb_size) { > + return DIAG_508_RC_INVAL_LEN; > + } > + > + comp_len = be64_to_cpu(svb->comp_len); > + comp_addr = be64_to_cpu(svb->comp_addr); > + sig_len = be64_to_cpu(svb->sig_len); > + sig_addr = be64_to_cpu(svb->sig_addr); > + > + if (!comp_len || !comp_addr) { > + return DIAG_508_RC_INVAL_COMP_DATA; > + } > + > + if (!sig_len || !sig_addr) { > + return DIAG_508_RC_INVAL_PKCS7_SIG; > + } > + > + svb_comp = g_malloc0(comp_len); > + cpu_physical_memory_read(comp_addr, svb_comp, comp_len); > + > + svb_sig = g_malloc0(sig_len); > + cpu_physical_memory_read(sig_addr, svb_sig, sig_len); > + > + rc = DIAG_508_RC_FAIL_VERIF; > + /* > + * It is uncertain which certificate contains > + * the analogous key to verify the signed data > + * > + * Ignore errors from signature format convertion and verification, > + * because currently in the certificate lookup process. > + * > + * Any error is treated as a verification failure, > + * and the final result (verified or not) will be reported later. > + */ I think these comments may now be rendered redundant, now with the for-loop significantly simplified since it was originally put in place. You can remove them. As for mentioning how errors are handled, you could put that comment in diag_508_verify_sig since that's where the errors are being ignored. > + for (int i = 0; i < qcs->count; i++) { > + verified = diag_508_verify_sig(qcs->certs[i].raw, > + qcs->certs[i].size, > + svb_comp, comp_len, > + svb_sig, sig_len); > + if (verified == 0) { > + svb->cert_store_index = i; > + svb->cert_len = cpu_to_be64(qcs->certs[i].der_size); > + cpu_physical_memory_write(addr, svb, be32_to_cpu(svb_size)); > + rc = DIAG_508_RC_OK; Could just return DIAG_508_RC_OK... > + break; > + } > + } > + > + return rc; ...and here return DIAG_508_RC_FAIL_VERIF Then get rid of rc. > +} > + > +QEMU_BUILD_BUG_MSG(sizeof(Diag508SigVerifBlock) != 64, > + "size of Diag508SigVerifBlock is wrong"); > + > void handle_diag_508(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t > ra) > { > + S390IPLCertificateStore *qcs = s390_ipl_get_certificate_store(); Move this line into handle_diag508_sig_verif() and remove the qcs param from the function. > uint64_t subcode = env->regs[r3]; > + uint64_t addr = env->regs[r1]; > int rc; > > if (env->psw.mask & PSW_MASK_PSTATE) { > @@ -619,7 +722,17 @@ void handle_diag_508(CPUS390XState *env, uint64_t r1, > uint64_t r3, uintptr_t ra) > > switch (subcode) { > case DIAG_508_SUBC_QUERY_SUBC: > - rc = 0; > + rc = DIAG_508_SUBC_SIG_VERIF; > + break; > + case DIAG_508_SUBC_SIG_VERIF: > + size_t svb_size = sizeof(Diag508SigVerifBlock); Since svb_size is only passed to the functions below, maybe just use sizeof inline and then you can remove another param from handle_diag508_sig_verif()? It should fit nicely now that the struct is less verbose. > + > + if (!diag_parm_addr_valid(addr, sizeof(Diag508SigVerifBlock), true)) > { > + s390_program_interrupt(env, PGM_ADDRESSING, ra); > + return; > + } > + > + rc = handle_diag508_sig_verif(addr, svb_size, qcs); > break; > default: > s390_program_interrupt(env, PGM_SPECIFICATION, ra); -- Regards, Collin
