[PATCH v3 07/14] KEYS: Provide PGP key description autogeneration

Roberto Sassu
2024-09-11T12:30:23Z

From: David Howells <dhowells@redhat.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@redhat.com>
Co-developed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.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 94284a78bf9b..22f4a40c7eb7 100644
--- a/crypto/asymmetric_keys/pgp_public_key.c
+++ b/crypto/asymmetric_keys/pgp_public_key.c
@@ -54,6 +54,8 @@ 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;
};

/*
@@ -200,6 +202,15 @@ 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;
@@ -307,7 +318,8 @@ 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);
@@ -320,6 +332,39 @@ 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