KEYS: fix length validation in keyctl_pkey_params_get_2()

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>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c
index 5de0d599a2748f50f3f4b144b8440f08bc57581b..97bc27bbf079779f193d006ec89e4e2aad881fd1 100644 (file)
--- 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;
 }