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Date:      Fri, 9 May 2025 00:34:08 GMT
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org
Subject:   git: 04421fda140b - main - krb5: Fix handling of transient crypto request failures
Message-ID:  <202505090034.5490Y8OH029883@gitrepo.freebsd.org>
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The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=04421fda140b92eb0d22bc4c0f81b6de05f21225

commit 04421fda140b92eb0d22bc4c0f81b6de05f21225
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2025-05-09 00:16:53 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2025-05-09 00:29:15 +0000

    krb5: Fix handling of transient crypto request failures
    
    - Instead of using CRYPTO_F_DONE to decide whether a request has
      completed, use a custom protocol of setting crp_opaque = NULL in the
      callback and checking that instead.  CRYPTO_F_DONE is set independent
      of whether an error occurred, but for transient errors signaled by
      EAGAIN, we want to simply retry the request.
    - Clear CRYPTO_F_DONE before retrying the request.
    - Panic if the request truly failed, as we currently have no way to
      pass hard errors back up.
    
    Reviewed by:    jhb
    MFC after:      2 weeks
    Differential Revision:  https://reviews.freebsd.org/D50238
---
 sys/kgssapi/krb5/kcrypto_aes.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/sys/kgssapi/krb5/kcrypto_aes.c b/sys/kgssapi/krb5/kcrypto_aes.c
index ddaf1cec5b45..6761b7c815ad 100644
--- a/sys/kgssapi/krb5/kcrypto_aes.c
+++ b/sys/kgssapi/krb5/kcrypto_aes.c
@@ -116,19 +116,24 @@ aes_random_to_key(struct krb5_key_state *ks, const void *in)
 static int
 aes_crypto_cb(struct cryptop *crp)
 {
-	int error;
 	struct aes_state *as = (struct aes_state *) crp->crp_opaque;
 
-	if (CRYPTO_SESS_SYNC(crp->crp_session))
+	if (CRYPTO_SESS_SYNC(crp->crp_session)) {
+		KASSERT(crp->crp_etype == 0,
+		    ("%s: callback with error %d", __func__, crp->crp_etype));
 		return (0);
+	}
 
-	error = crp->crp_etype;
-	if (error == EAGAIN)
-		error = crypto_dispatch(crp);
-	mtx_lock(&as->as_lock);
-	if (error || (crp->crp_flags & CRYPTO_F_DONE))
+	if (crp->crp_etype == EAGAIN) {
+		crp->crp_etype = 0;
+		crp->crp_flags &= ~CRYPTO_F_DONE;
+		(void)crypto_dispatch(crp);
+	} else {
+		mtx_lock(&as->as_lock);
+		crp->crp_opaque = NULL;
 		wakeup(crp);
-	mtx_unlock(&as->as_lock);
+		mtx_unlock(&as->as_lock);
+	}
 
 	return (0);
 }
@@ -164,11 +169,12 @@ aes_encrypt_1(const struct krb5_key_state *ks, int buftype, void *buf,
 
 	if (!CRYPTO_SESS_SYNC(as->as_session_aes)) {
 		mtx_lock(&as->as_lock);
-		if (!error && !(crp->crp_flags & CRYPTO_F_DONE))
+		if (error == 0 && crp->crp_opaque != NULL)
 			error = msleep(crp, &as->as_lock, 0, "gssaes", 0);
 		mtx_unlock(&as->as_lock);
 	}
-
+	if (crp->crp_etype != 0)
+		panic("%s: crypto req failed: %d", __func__, crp->crp_etype);
 	crypto_freereq(crp);
 }
 
@@ -334,11 +340,13 @@ aes_checksum(const struct krb5_key_state *ks, int usage,
 
 	if (!CRYPTO_SESS_SYNC(as->as_session_sha1)) {
 		mtx_lock(&as->as_lock);
-		if (!error && !(crp->crp_flags & CRYPTO_F_DONE))
+		if (error == 0 && crp->crp_opaque != NULL)
 			error = msleep(crp, &as->as_lock, 0, "gssaes", 0);
 		mtx_unlock(&as->as_lock);
 	}
 
+	if (crp->crp_etype != 0)
+		panic("%s: crypto req failed: %d", __func__, crp->crp_etype);
 	crypto_freereq(crp);
 }

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