From:   Eric Biggers <ebiggers@kernel.org>
To:     keyrings@vger.kernel.org, David Howells <dhowells@redhat.com>,
        Jarkko Sakkinen <jarkko@kernel.org>
Cc:     linux-crypto@vger.kernel.org,
        Marcel Holtmann <marcel@holtmann.org>,
        Denis Kenzior <denkenz@gmail.com>, stable@vger.kernel.org
Subject: [PATCH] KEYS: fix length validation in keyctl_pkey_params_get_2()
Date:   Thu, 13 Jan 2022 12:04:54 -0800
Message-Id: <20220113200454.72609-1-ebiggers@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Eric Biggers <ebiggers@google.com>

In many cases, keyctl_pkey_params_get_2() is validating the user buffer
lengths against the wrong algorithm properties.  Fix it to check against
the correct properties.

Probably this wasn't noticed before because for all asymmetric keys of
the "public_key" subtype, max_data_size == max_sig_size == max_enc_size
== max_dec_size.  However, this isn't necessarily true for the
"asym_tpm" subtype (it should be, but it's not strictly validated).  Of
course, future key types could have different values as well.

Fixes: 00d60fd3b932 ("KEYS: Provide keyctls to drive the new key type ops for asymmetric keys [ver #2]")
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 security/keys/keyctl_pkey.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c
index 5de0d599a274..97bc27bbf079 100644
--- a/security/keys/keyctl_pkey.c
+++ b/security/keys/keyctl_pkey.c
@@ -135,15 +135,23 @@ static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_par
 
 	switch (op) {
 	case KEYCTL_PKEY_ENCRYPT:
+		if (uparams.in_len  > info.max_dec_size ||
+		    uparams.out_len > info.max_enc_size)
+			return -EINVAL;
+		break;
 	case KEYCTL_PKEY_DECRYPT:
 		if (uparams.in_len  > info.max_enc_size ||
 		    uparams.out_len > info.max_dec_size)
 			return -EINVAL;
 		break;
 	case KEYCTL_PKEY_SIGN:
+		if (uparams.in_len  > info.max_data_size ||
+		    uparams.out_len > info.max_sig_size)
+			return -EINVAL;
+		break;
 	case KEYCTL_PKEY_VERIFY:
-		if (uparams.in_len  > info.max_sig_size ||
-		    uparams.out_len > info.max_data_size)
+		if (uparams.in_len  > info.max_data_size ||
+		    uparams.in2_len > info.max_sig_size)
 			return -EINVAL;
 		break;
 	default:
@@ -151,7 +159,7 @@ static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_par
 	}
 
 	params->in_len  = uparams.in_len;
-	params->out_len = uparams.out_len;
+	params->out_len = uparams.out_len; /* Note: same as in2_len */
 	return 0;
 }
 

base-commit: feb7a43de5ef625ad74097d8fd3481d5dbc06a59
-- 
2.34.1