s390/pkey: Add sysfs attributes to emit protected key blobs
Add binary read-only sysfs attributes for the pkey module
that can be used to read random protected 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 protected key to encrypt the swap device is read from
one of the attributes.
The following attributes are added:
protkey/aes_128
protkey/aes_192
protkey/aes_256
protkey/aes_128_xts
protkey/aes_256_xts
Each attribute emits a protected 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>
diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index fa1044f..b4d8841 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -1254,6 +1254,132 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
/*
* Sysfs and file io operations
*/
+
+/*
+ * Sysfs attribute read function for all protected key 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_protkey_aes_attr_read(u32 keytype, bool is_xts, char *buf,
+ loff_t off, size_t count)
+{
+ struct protaeskeytoken protkeytoken;
+ struct pkey_protkey protkey;
+ int rc;
+
+ if (off != 0 || count < sizeof(protkeytoken))
+ return -EINVAL;
+ if (is_xts)
+ if (count < 2 * sizeof(protkeytoken))
+ return -EINVAL;
+
+ memset(&protkeytoken, 0, sizeof(protkeytoken));
+ protkeytoken.type = TOKTYPE_NON_CCA;
+ protkeytoken.version = TOKVER_PROTECTED_KEY;
+ protkeytoken.keytype = keytype;
+
+ rc = pkey_genprotkey(protkeytoken.keytype, &protkey);
+ if (rc)
+ return rc;
+
+ protkeytoken.len = protkey.len;
+ memcpy(&protkeytoken.protkey, &protkey.protkey, protkey.len);
+
+ memcpy(buf, &protkeytoken, sizeof(protkeytoken));
+
+ if (is_xts) {
+ rc = pkey_genprotkey(protkeytoken.keytype, &protkey);
+ if (rc)
+ return rc;
+
+ protkeytoken.len = protkey.len;
+ memcpy(&protkeytoken.protkey, &protkey.protkey, protkey.len);
+
+ memcpy(buf + sizeof(protkeytoken), &protkeytoken,
+ sizeof(protkeytoken));
+
+ return 2 * sizeof(protkeytoken);
+ }
+
+ return sizeof(protkeytoken);
+}
+
+static ssize_t protkey_aes_128_read(struct file *filp,
+ struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t off,
+ size_t count)
+{
+ return pkey_protkey_aes_attr_read(PKEY_KEYTYPE_AES_128, false, buf,
+ off, count);
+}
+
+static ssize_t protkey_aes_192_read(struct file *filp,
+ struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t off,
+ size_t count)
+{
+ return pkey_protkey_aes_attr_read(PKEY_KEYTYPE_AES_192, false, buf,
+ off, count);
+}
+
+static ssize_t protkey_aes_256_read(struct file *filp,
+ struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t off,
+ size_t count)
+{
+ return pkey_protkey_aes_attr_read(PKEY_KEYTYPE_AES_256, false, buf,
+ off, count);
+}
+
+static ssize_t protkey_aes_128_xts_read(struct file *filp,
+ struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t off,
+ size_t count)
+{
+ return pkey_protkey_aes_attr_read(PKEY_KEYTYPE_AES_128, true, buf,
+ off, count);
+}
+
+static ssize_t protkey_aes_256_xts_read(struct file *filp,
+ struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t off,
+ size_t count)
+{
+ return pkey_protkey_aes_attr_read(PKEY_KEYTYPE_AES_256, true, buf,
+ off, count);
+}
+
+static BIN_ATTR_RO(protkey_aes_128, sizeof(struct protaeskeytoken));
+static BIN_ATTR_RO(protkey_aes_192, sizeof(struct protaeskeytoken));
+static BIN_ATTR_RO(protkey_aes_256, sizeof(struct protaeskeytoken));
+static BIN_ATTR_RO(protkey_aes_128_xts, 2 * sizeof(struct protaeskeytoken));
+static BIN_ATTR_RO(protkey_aes_256_xts, 2 * sizeof(struct protaeskeytoken));
+
+static struct bin_attribute *protkey_attrs[] = {
+ &bin_attr_protkey_aes_128,
+ &bin_attr_protkey_aes_192,
+ &bin_attr_protkey_aes_256,
+ &bin_attr_protkey_aes_128_xts,
+ &bin_attr_protkey_aes_256_xts,
+ NULL
+};
+
+static struct attribute_group protkey_attr_group = {
+ .name = "protkey",
+ .bin_attrs = protkey_attrs,
+};
+
+static const struct attribute_group *pkey_attr_groups[] = {
+ &protkey_attr_group,
+ NULL,
+};
+
static const struct file_operations pkey_fops = {
.owner = THIS_MODULE,
.open = nonseekable_open,
@@ -1266,6 +1392,7 @@ static struct miscdevice pkey_dev = {
.minor = MISC_DYNAMIC_MINOR,
.mode = 0666,
.fops = &pkey_fops,
+ .groups = pkey_attr_groups,
};
/*