linux-kernel - [PATCH v2 07/14] KEYS: Provide PGP key description autogeneration

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Message-Id: <20240818165756.629203-8-roberto.sassu@huaweicloud.com>
Date: Sun, 18 Aug 2024 18:57:49 +0200
From: Roberto Sassu <roberto.sassu@...weicloud.com>
To: dhowells@...hat.com,
	dwmw2@...radead.org,
	herbert@...dor.apana.org.au,
	davem@...emloft.net
Cc: linux-kernel@...r.kernel.org,
	keyrings@...r.kernel.org,
	linux-crypto@...r.kernel.org,
	zohar@...ux.ibm.com,
	linux-integrity@...r.kernel.org,
	Roberto Sassu <roberto.sassu@...wei.com>
Subject: [PATCH v2 07/14] KEYS: Provide PGP key description autogeneration

From: David Howells <dhowells@...hat.com>

Provide a facility to autogenerate the name of PGP keys from the contents
of the payload.  If add_key() is given a blank description, a description
is constructed from the last user ID packet in the payload data plus the
last 8 hex digits of the key ID.  For instance:

	keyctl padd asymmetric "" @s </tmp/key.pub

might create a key with a constructed description that can be seen in
/proc/keys:

2f674b96 I--Q---     1 perm 39390000     0     0 crypto    \
			Sample kernel key 31f0ae93: PGP.RSA 31f0ae93 []

Signed-off-by: David Howells <dhowells@...hat.com>
Co-developed-by: Roberto Sassu <roberto.sassu@...wei.com>
Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
---
 crypto/asymmetric_keys/pgp_public_key.c | 47 ++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/pgp_public_key.c b/crypto/asymmetric_keys/pgp_public_key.c
index cb399f5cdd3e..e7f74d513a9e 100644
--- a/crypto/asymmetric_keys/pgp_public_key.c
+++ b/crypto/asymmetric_keys/pgp_public_key.c
@@ -59,6 +59,8 @@ struct pgp_key_data_parse_context {
 	struct public_key *pub;
 	u8 raw_fingerprint[HASH_MAX_DIGESTSIZE];
 	size_t raw_fingerprint_len;
+	const char *user_id;
+	size_t user_id_len;
 };
 
 /*
@@ -210,6 +212,15 @@ static int pgp_process_public_key(struct pgp_parse_context *context,
 
 	kenter(",%u,%u,,%zu", type, headerlen, datalen);
 
+	if (type == PGP_PKT_USER_ID) {
+		if (!ctx->user_id_len) {
+			ctx->user_id = data;
+			ctx->user_id_len = datalen;
+		}
+		kleave(" = 0 [user ID]");
+		return 0;
+	}
+
 	if (ctx->raw_fingerprint_len) {
 		kleave(" = -ENOKEY [already]");
 		return -EBADMSG;
@@ -317,7 +328,8 @@ static int pgp_key_parse(struct key_preparsed_payload *prep)
 	kenter("");
 
 	memset(&ctx, 0, sizeof(ctx));
-	ctx.pgp.types_of_interest = (1 << PGP_PKT_PUBLIC_KEY);
+	ctx.pgp.types_of_interest = (1 << PGP_PKT_PUBLIC_KEY) |
+				    (1 << PGP_PKT_USER_ID);
 	ctx.pgp.process_packet = pgp_process_public_key;
 
 	ret = pgp_parse_packets(prep->data, prep->datalen, &ctx.pgp);
@@ -330,6 +342,39 @@ static int pgp_key_parse(struct key_preparsed_payload *prep)
 		goto error;
 	}
 
+	if (ctx.user_id && ctx.user_id_len > 0) {
+		/*
+		 * Propose a description for the key (user ID without the
+		 * comment).
+		 */
+		size_t ulen = ctx.user_id_len;
+		const char *p;
+
+		p = memchr(ctx.user_id, '(', ulen);
+		if (p) {
+			/* Remove the comment */
+			do {
+				p--;
+			} while (*p == ' ' && p > ctx.user_id);
+			if (*p != ' ')
+				p++;
+			ulen = p - ctx.user_id;
+		}
+
+		if (ulen > 255 - 9)
+			ulen = 255 - 9;
+		prep->description = kmalloc(ulen + 1 + 8 + 1, GFP_KERNEL);
+		ret = -ENOMEM;
+		if (!prep->description)
+			goto error;
+		memcpy(prep->description, ctx.user_id, ulen);
+		prep->description[ulen] = ' ';
+		bin2hex(prep->description + ulen + 1,
+			ctx.raw_fingerprint + ctx.raw_fingerprint_len - 4, 4);
+		prep->description[ulen + 9] = 0;
+		pr_debug("desc '%s'\n", prep->description);
+	}
+
 	/* We're pinning the module by being linked against it */
 	__module_get(public_key_subtype.owner);
 	prep->payload.data[asym_subtype] = &public_key_subtype;
-- 
2.34.1