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-rw-r--r--drivers/md/dm-verity-verify-sig.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/md/dm-verity-verify-sig.c b/drivers/md/dm-verity-verify-sig.c
new file mode 100644
index 0000000000..4836508ea5
--- /dev/null
+++ b/drivers/md/dm-verity-verify-sig.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 Microsoft Corporation.
+ *
+ * Author: Jaskaran Singh Khurana <jaskarankhurana@linux.microsoft.com>
+ *
+ */
+#include <linux/device-mapper.h>
+#include <linux/verification.h>
+#include <keys/user-type.h>
+#include <linux/module.h>
+#include "dm-verity.h"
+#include "dm-verity-verify-sig.h"
+
+#define DM_VERITY_VERIFY_ERR(s) DM_VERITY_ROOT_HASH_VERIFICATION " " s
+
+static bool require_signatures;
+module_param(require_signatures, bool, 0444);
+MODULE_PARM_DESC(require_signatures,
+ "Verify the roothash of dm-verity hash tree");
+
+#define DM_VERITY_IS_SIG_FORCE_ENABLED() \
+ (require_signatures != false)
+
+bool verity_verify_is_sig_opt_arg(const char *arg_name)
+{
+ return (!strcasecmp(arg_name,
+ DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY));
+}
+
+static int verity_verify_get_sig_from_key(const char *key_desc,
+ struct dm_verity_sig_opts *sig_opts)
+{
+ struct key *key;
+ const struct user_key_payload *ukp;
+ int ret = 0;
+
+ key = request_key(&key_type_user,
+ key_desc, NULL);
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+
+ down_read(&key->sem);
+
+ ukp = user_key_payload_locked(key);
+ if (!ukp) {
+ ret = -EKEYREVOKED;
+ goto end;
+ }
+
+ sig_opts->sig = kmalloc(ukp->datalen, GFP_KERNEL);
+ if (!sig_opts->sig) {
+ ret = -ENOMEM;
+ goto end;
+ }
+ sig_opts->sig_size = ukp->datalen;
+
+ memcpy(sig_opts->sig, ukp->data, sig_opts->sig_size);
+
+end:
+ up_read(&key->sem);
+ key_put(key);
+
+ return ret;
+}
+
+int verity_verify_sig_parse_opt_args(struct dm_arg_set *as,
+ struct dm_verity *v,
+ struct dm_verity_sig_opts *sig_opts,
+ unsigned int *argc,
+ const char *arg_name)
+{
+ struct dm_target *ti = v->ti;
+ int ret = 0;
+ const char *sig_key = NULL;
+
+ if (!*argc) {
+ ti->error = DM_VERITY_VERIFY_ERR("Signature key not specified");
+ return -EINVAL;
+ }
+
+ sig_key = dm_shift_arg(as);
+ (*argc)--;
+
+ ret = verity_verify_get_sig_from_key(sig_key, sig_opts);
+ if (ret < 0)
+ ti->error = DM_VERITY_VERIFY_ERR("Invalid key specified");
+
+ v->signature_key_desc = kstrdup(sig_key, GFP_KERNEL);
+ if (!v->signature_key_desc)
+ return -ENOMEM;
+
+ return ret;
+}
+
+/*
+ * verify_verify_roothash - Verify the root hash of the verity hash device
+ * using builtin trusted keys.
+ *
+ * @root_hash: For verity, the roothash/data to be verified.
+ * @root_hash_len: Size of the roothash/data to be verified.
+ * @sig_data: The trusted signature that verifies the roothash/data.
+ * @sig_len: Size of the signature.
+ *
+ */
+int verity_verify_root_hash(const void *root_hash, size_t root_hash_len,
+ const void *sig_data, size_t sig_len)
+{
+ int ret;
+
+ if (!root_hash || root_hash_len == 0)
+ return -EINVAL;
+
+ if (!sig_data || sig_len == 0) {
+ if (DM_VERITY_IS_SIG_FORCE_ENABLED())
+ return -ENOKEY;
+ else
+ return 0;
+ }
+
+ ret = verify_pkcs7_signature(root_hash, root_hash_len, sig_data,
+ sig_len,
+#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING
+ VERIFY_USE_SECONDARY_KEYRING,
+#else
+ NULL,
+#endif
+ VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL);
+
+ return ret;
+}
+
+void verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts *sig_opts)
+{
+ kfree(sig_opts->sig);
+ sig_opts->sig = NULL;
+ sig_opts->sig_size = 0;
+}