Calculate the digest of the signature, according to the RFC4880 section
5.2.4, get the last suitable signature with type 0x13 (Positive
certification of a User ID and Public Key packet), and store it in the
asym_auth field of the key payload, so that it is available for validating
a restriction on a keyring.
The rationale of taking the last signature is that, if there are multiple
signatures, that would be of a different issuer (not a self-signature),
that likely has more chances to be useful for the restriction verification.
If there is one (the self-signature), that will be used.
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
crypto/asymmetric_keys/pgp_public_key.c | 81 +++++++++++++++++++++++++
1 file changed, 81 insertions(+)
diff --git a/crypto/asymmetric_keys/pgp_public_key.c b/crypto/asymmetric_keys/pgp_public_key.c
index 378ed5ff0a3a..cecd67bab4e6 100644
--- a/crypto/asymmetric_keys/pgp_public_key.c
+++ b/crypto/asymmetric_keys/pgp_public_key.c
@@ -14,6 +14,7 @@
#include <keys/asymmetric-parser.h>
#include <crypto/hash.h>
#include <crypto/public_key.h>
+#include <crypto/pgp.h>
#include "pgp_parser.h"
@@ -61,6 +62,8 @@ struct pgp_key_data_parse_context {
size_t raw_fingerprint_len;
const char *user_id;
size_t user_id_len;
+ const char *key_pkt;
+ size_t key_pkt_len;
};
/*
@@ -226,6 +229,12 @@ static int pgp_process_public_key(struct pgp_parse_context *context,
return -EBADMSG;
}
+ /* Pointer refers to data being processed. */
+ if (type == PGP_PKT_PUBLIC_KEY) {
+ ctx->key_pkt = data;
+ ctx->key_pkt_len = datalen;
+ }
+
pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
if (!pub)
return -ENOMEM;
@@ -314,6 +323,77 @@ static struct asymmetric_key_ids *pgp_key_generate_id(
return NULL;
}
+/*
+ * Calculate the digest of the signature according to the RFC4880, section
+ * 5.2.4 (packet type 0x13).
+ */
+static int pgp_key_add_sig_data(struct pgp_key_data_parse_context *ctx,
+ struct pgp_sig_verify *sig_ctx)
+{
+ loff_t offset = 0;
+ u8 *data;
+
+ if (!ctx->key_pkt_len || !ctx->user_id_len)
+ return 0;
+
+ /* 0x99 + key pkt len + key pkt + 0xb4 + user ID len + user ID */
+ data = kmalloc(1 + sizeof(u16) + ctx->key_pkt_len +
+ 1 + sizeof(u32) + ctx->user_id_len, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data[offset++] = 0x99;
+ data[offset++] = ctx->key_pkt_len >> 8;
+ data[offset++] = ctx->key_pkt_len;
+
+ memcpy(data + offset, ctx->key_pkt, ctx->key_pkt_len);
+ offset += ctx->key_pkt_len;
+
+ if (pgp_sig_get_version(sig_ctx) == PGP_SIG_VERSION_4) {
+ data[offset++] = 0xb4;
+ data[offset++] = ctx->user_id_len >> 24;
+ data[offset++] = ctx->user_id_len >> 16;
+ data[offset++] = ctx->user_id_len >> 8;
+ data[offset++] = ctx->user_id_len;
+ }
+
+ memcpy(data + offset, ctx->user_id, ctx->user_id_len);
+ offset += ctx->user_id_len;
+
+ pgp_sig_add_data(sig_ctx, data, offset);
+ kfree(data);
+ return 0;
+}
+
+static struct public_key_signature *pgp_key_get_sig(
+ struct key_preparsed_payload *prep,
+ struct pgp_key_data_parse_context *ctx)
+{
+ struct public_key_signature *sig = NULL;
+ struct pgp_sig_verify *sig_ctx;
+ bool keep_sig = false;
+ int ret;
+
+ sig_ctx = pgp_sig_parse(prep->data, prep->datalen);
+ if (IS_ERR(sig_ctx))
+ return NULL;
+
+ ret = pgp_key_add_sig_data(ctx, sig_ctx);
+ if (ret < 0)
+ goto out;
+
+ sig = pgp_sig_get_sig(sig_ctx);
+ if (IS_ERR(sig)) {
+ sig = NULL;
+ goto out;
+ }
+
+ keep_sig = true;
+out:
+ pgp_sig_verify_cancel(sig_ctx, keep_sig);
+ return sig;
+}
+
/*
* Attempt to parse the instantiation data blob for a key as a PGP packet
* message holding a key.
@@ -372,6 +452,7 @@ static int pgp_key_parse(struct key_preparsed_payload *prep)
prep->payload.data[asym_subtype] = &public_key_subtype;
prep->payload.data[asym_key_ids] = pgp_key_generate_id(&ctx);
prep->payload.data[asym_crypto] = ctx.pub;
+ prep->payload.data[asym_auth] = pgp_key_get_sig(prep, &ctx);
prep->quotalen = 100;
return 0;
--
2.32.0
