On Sun, 2024-06-30 at 21:38 +0200, Lukas Wunner wrote: > The upcoming in-kernel SPDM library (Security Protocol and Data > Model, > https://www.dmtf.org/dsp/DSP0274) needs to retrieve the length from > ASN.1 DER-encoded X.509 certificates. > > Such code already exists in x509_load_certificate_list(), so move it > into a new helper for reuse by SPDM. > > Export the helper so that SPDM can be tristate. (Some upcoming users > of > the SPDM libray may be modular, such as SCSI and ATA.) > > No functional change intended. > > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> > Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Reviewed-by: Alistair Francis <alistair.francis@xxxxxxx> Alistair > --- > crypto/asymmetric_keys/x509_loader.c | 38 +++++++++++++++++++------- > -- > include/keys/asymmetric-type.h | 2 ++ > 2 files changed, 28 insertions(+), 12 deletions(-) > > diff --git a/crypto/asymmetric_keys/x509_loader.c > b/crypto/asymmetric_keys/x509_loader.c > index a41741326998..25ff027fad1d 100644 > --- a/crypto/asymmetric_keys/x509_loader.c > +++ b/crypto/asymmetric_keys/x509_loader.c > @@ -4,28 +4,42 @@ > #include <linux/key.h> > #include <keys/asymmetric-type.h> > > +ssize_t x509_get_certificate_length(const u8 *p, unsigned long > buflen) > +{ > + ssize_t plen; > + > + /* Each cert begins with an ASN.1 SEQUENCE tag and must be > more > + * than 256 bytes in size. > + */ > + if (buflen < 4) > + return -EINVAL; > + > + if (p[0] != 0x30 && > + p[1] != 0x82) > + return -EINVAL; > + > + plen = (p[2] << 8) | p[3]; > + plen += 4; > + if (plen > buflen) > + return -EINVAL; > + > + return plen; > +} > +EXPORT_SYMBOL_GPL(x509_get_certificate_length); > + > int x509_load_certificate_list(const u8 cert_list[], > const unsigned long list_size, > const struct key *keyring) > { > key_ref_t key; > const u8 *p, *end; > - size_t plen; > + ssize_t plen; > > p = cert_list; > end = p + list_size; > while (p < end) { > - /* Each cert begins with an ASN.1 SEQUENCE tag and > must be more > - * than 256 bytes in size. > - */ > - if (end - p < 4) > - goto dodgy_cert; > - if (p[0] != 0x30 && > - p[1] != 0x82) > - goto dodgy_cert; > - plen = (p[2] << 8) | p[3]; > - plen += 4; > - if (plen > end - p) > + plen = x509_get_certificate_length(p, end - p); > + if (plen < 0) > goto dodgy_cert; > > key = key_create_or_update(make_key_ref(keyring, 1), > diff --git a/include/keys/asymmetric-type.h > b/include/keys/asymmetric-type.h > index 69a13e1e5b2e..e2af07fec3c6 100644 > --- a/include/keys/asymmetric-type.h > +++ b/include/keys/asymmetric-type.h > @@ -84,6 +84,8 @@ extern struct key *find_asymmetric_key(struct key > *keyring, > const struct > asymmetric_key_id *id_2, > bool partial); > > +ssize_t x509_get_certificate_length(const u8 *p, unsigned long > buflen); > + > int x509_load_certificate_list(const u8 cert_list[], const unsigned > long list_size, > const struct key *keyring); >
