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s390/pkey: Add sysfs attributes to emit secure key blobs

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Add binary read-only sysfs attributes for the pkey module
that can be used to read random ccadata secure keys from.
Keys are read from these attributes using a cat-like interface.

A typical use case for those keys is to encrypt a swap device
using the paes cipher. During processing of /etc/crypttab, the
random random ccadata secure key to encrypt the swap device is
read from one of the attributes.

The following attributes are added:
  ccadata/aes_128
  ccadata/aes_192
  ccadata/aes_256
  ccadata/aes_128_xts
  ccadata/aes_256_xts
Each attribute emits a secure key blob for the corresponding
key size and cipher mode.

Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Ingo Franzki 2018-08-24 10:29:43 +02:00 committed by Martin Schwidefsky
parent d632c0478d
commit af504452d1
1 changed files with 104 additions and 0 deletions
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104
drivers/s390/crypto/pkey_api.c
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@ -1375,8 +1375,112 @@ static struct attribute_group protkey_attr_group = {
.bin_attrs = protkey_attrs,
};
/*
* Sysfs attribute read function for all secure key ccadata binary attributes.
* The implementation can not deal with partial reads, because a new random
* protected key blob is generated with each read. In case of partial reads
* (i.e. off != 0 or count < key blob size) -EINVAL is returned.
*/
static ssize_t pkey_ccadata_aes_attr_read(u32 keytype, bool is_xts, char *buf,
loff_t off, size_t count)
{
int rc;
if (off != 0 || count < sizeof(struct secaeskeytoken))
return -EINVAL;
if (is_xts)
if (count < 2 * sizeof(struct secaeskeytoken))
return -EINVAL;
rc = pkey_genseckey(-1, -1, keytype, (struct pkey_seckey *)buf);
if (rc)
return rc;
if (is_xts) {
buf += sizeof(struct pkey_seckey);
rc = pkey_genseckey(-1, -1, keytype, (struct pkey_seckey *)buf);
if (rc)
return rc;
return 2 * sizeof(struct secaeskeytoken);
}
return sizeof(struct secaeskeytoken);
}
static ssize_t ccadata_aes_128_read(struct file *filp,
struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off,
size_t count)
{
return pkey_ccadata_aes_attr_read(PKEY_KEYTYPE_AES_128, false, buf,
off, count);
}
static ssize_t ccadata_aes_192_read(struct file *filp,
struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off,
size_t count)
{
return pkey_ccadata_aes_attr_read(PKEY_KEYTYPE_AES_192, false, buf,
off, count);
}
static ssize_t ccadata_aes_256_read(struct file *filp,
struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off,
size_t count)
{
return pkey_ccadata_aes_attr_read(PKEY_KEYTYPE_AES_256, false, buf,
off, count);
}
static ssize_t ccadata_aes_128_xts_read(struct file *filp,
struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off,
size_t count)
{
return pkey_ccadata_aes_attr_read(PKEY_KEYTYPE_AES_128, true, buf,
off, count);
}
static ssize_t ccadata_aes_256_xts_read(struct file *filp,
struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off,
size_t count)
{
return pkey_ccadata_aes_attr_read(PKEY_KEYTYPE_AES_256, true, buf,
off, count);
}
static BIN_ATTR_RO(ccadata_aes_128, sizeof(struct secaeskeytoken));
static BIN_ATTR_RO(ccadata_aes_192, sizeof(struct secaeskeytoken));
static BIN_ATTR_RO(ccadata_aes_256, sizeof(struct secaeskeytoken));
static BIN_ATTR_RO(ccadata_aes_128_xts, 2 * sizeof(struct secaeskeytoken));
static BIN_ATTR_RO(ccadata_aes_256_xts, 2 * sizeof(struct secaeskeytoken));
static struct bin_attribute *ccadata_attrs[] = {
&bin_attr_ccadata_aes_128,
&bin_attr_ccadata_aes_192,
&bin_attr_ccadata_aes_256,
&bin_attr_ccadata_aes_128_xts,
&bin_attr_ccadata_aes_256_xts,
NULL
};
static struct attribute_group ccadata_attr_group = {
.name = "ccadata",
.bin_attrs = ccadata_attrs,
};
static const struct attribute_group *pkey_attr_groups[] = {
&protkey_attr_group,
&ccadata_attr_group,
NULL,
};