Merge patch series "rsa: fix dependency, rename and relocate RSASSA PSS symbols"

Quentin Schulz <[email protected]> says:

While historically signature verification is mostly done for FIT such
FIT_SIGNATURE dependency for signature algorithm makes sense, it isn't
the only kind of file we can verify signatures of. It can also be done
manually with rsa_verify_hash() with an embedded public key.

Considering the impacted code is guarded by RSA_VERIFY, let's make the
symbol depend on that otherwise selecting it without RSA_VERIFY won't do
anything. The FIT_SIGNATURE dependency wasn't also enough before as it
only implied RSA_VERIFY.

Then, simply relocate the RSA SSA PSS padding with the other RSA symbols
in lib/rsa instead of in boot/ and rename it to remove the mention to
FIT.

Finally, add the PSS padding wherever PKCS1.5 padding is specified as
one or the other can be used.

Link: https://lore.kernel.org/r/[email protected]

3 files changed, 19 insertions, 5 deletions

diff --git a/lib/rsa/Kconfig b/lib/rsa/Kconfig
index 3eda4bc61b9..1a763149c05 100644
--- a/lib/rsa/Kconfig
+++ b/lib/rsa/Kconfig
@@ -67,6 +67,20 @@ config SPL_RSA_VERIFY_WITH_PKEY
 	  key properties will be calculated on the fly in verification code
 	  in the SPL.
 
+config RSASSA_PSS
+	bool "Support rsassa-pss signature scheme"
+	depends on RSA_VERIFY
+	help
+	  Enable this to support the pss padding algorithm as described
+	  in the rfc8017 (https://tools.ietf.org/html/rfc8017).
+
+config SPL_RSASSA_PSS
+	bool "Support rsassa-pss signature scheme within SPL"
+	depends on SPL_RSA_VERIFY
+	help
+	  Enable this to support the pss padding algorithm as described
+	  in the rfc8017 (https://tools.ietf.org/html/rfc8017) within SPL.
+
 config RSA_SOFTWARE_EXP
 	bool "Enable driver for RSA Modular Exponentiation in software"
 	depends on DM
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index 92b9d7876e5..0e38c9e802f 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -421,7 +421,7 @@ static int rsa_sign_with_key(EVP_PKEY *pkey, struct padding_algo *padding_algo,
 		goto err_sign;
 	}
 
-	if (CONFIG_IS_ENABLED(FIT_RSASSA_PSS) && padding_algo &&
+	if (CONFIG_IS_ENABLED(RSASSA_PSS) && padding_algo &&
 	    !strcmp(padding_algo->name, "pss")) {
 		if (EVP_PKEY_CTX_set_rsa_padding(ckey,
 						 RSA_PKCS1_PSS_PADDING) <= 0) {
diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
index b65fbe44007..e7e612a4688 100644
--- a/lib/rsa/rsa-verify.c
+++ b/lib/rsa/rsa-verify.c
@@ -89,7 +89,7 @@ U_BOOT_PADDING_ALGO(pkcs_15) = {
 };
 #endif
 
-#if CONFIG_IS_ENABLED(FIT_RSASSA_PSS)
+#if CONFIG_IS_ENABLED(RSASSA_PSS)
 static void u32_i2osp(uint32_t val, uint8_t *buf)
 {
 	buf[0] = (uint8_t)((val >> 24) & 0xff);
@@ -310,7 +310,7 @@ U_BOOT_PADDING_ALGO(pss) = {
 /**
  * rsa_verify_key() - Verify a signature against some data using RSA Key
  *
- * Verify a RSA PKCS1.5 signature against an expected hash using
+ * Verify a RSA PKCS1.5/PSS signature against an expected hash using
  * the RSA Key properties in prop structure.
  *
  * @info:	Specifies key and FIT information
@@ -388,7 +388,7 @@ static int rsa_verify_key(struct image_sign_info *info,
  * @sig_len:	Number of bytes in signature
  *
  * Parse a RSA public key blob in DER format pointed to in @info and fill
- * a key_prop structure with properties of the key. Then verify a RSA PKCS1.5
+ * a key_prop structure with properties of the key. Then verify a RSA PKCS1.5/PSS
  * signature against an expected hash using the calculated properties.
  *
  * Return	0 if verified, -ve on error
@@ -423,7 +423,7 @@ int rsa_verify_with_pkey(struct image_sign_info *info,
  * information in node with prperties of RSA Key like modulus, exponent etc.
  *
  * Parse sign-node and fill a key_prop structure with properties of the
- * key.  Verify a RSA PKCS1.5 signature against an expected hash using
+ * key.  Verify a RSA PKCS1.5/PSS signature against an expected hash using
  * the properties parsed
  *
  * @info:	Specifies key and FIT information