diff mbox series

[v4,6/8] lib: rsa: add documentation to padding_pss_verify to document limitations

Message ID 20200522141332.3523031-6-heiko@sntech.de
State Superseded
Delegated to: Tom Rini
Headers show
Series [v4,1/8] lib: rsa: distinguish between tpl and spl for CONFIG_RSA_VERIFY | expand

Commit Message

Heiko Stuebner May 22, 2020, 2:13 p.m. UTC 
From: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>

padding_pss_verify only works with the default pss salt setting of -2
(length to be automatically determined based on the PSS block structure)
not -1 (salt length set to the maximum permissible value), which makes
verifications of signatures with that saltlen fail.

Until this gets implemented at least document this behaviour.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
---
change in v4:
- new patch

 lib/rsa/rsa-verify.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Comments

Philipp Tomsich May 22, 2020, 2:25 p.m. UTC | #1 
> On 22.05.2020, at 16:13, Heiko Stuebner <heiko@sntech.de> wrote:
> 
> From: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
> 
> padding_pss_verify only works with the default pss salt setting of -2
> (length to be automatically determined based on the PSS block structure)
> not -1 (salt length set to the maximum permissible value), which makes
> verifications of signatures with that saltlen fail.
> 
> Until this gets implemented at least document this behaviour.
> 
> Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>

Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff mbox series

Patch

diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
index 048f1ab789..61d98e6e2d 100644
--- a/lib/rsa/rsa-verify.c
+++ b/lib/rsa/rsa-verify.c
@@ -194,6 +194,19 @@  out:
 	return ret;
 }
 
+/*
+ * padding_pss_verify() - verify the pss padding of a signature
+ *
+ * Only works with a rsa_pss_saltlen:-2 (default value) right now
+ * saltlen:-1 "set the salt length to the digest length" is currently
+ * not supported.
+ *
+ * @info:	Specifies key and FIT information
+ * @msg:	byte array of message, len equal to msg_len
+ * @msg_len:	Message length
+ * @hash:	Pointer to the expected hash
+ * @hash_len:	Length of the hash
+ */
 int padding_pss_verify(struct image_sign_info *info,
 		       uint8_t *msg, int msg_len,
 		       const uint8_t *hash, int hash_len)