Patch "crypto: api - Add crypto_tfm_get" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    crypto: api - Add crypto_tfm_get

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     crypto-api-add-crypto_tfm_get.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 95daf6ee243e7f34ca304d96a1423eeecaf3210f
Author: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date:   Thu Apr 13 14:24:15 2023 +0800

    crypto: api - Add crypto_tfm_get
    
    [ Upstream commit ae131f4970f0778f35ed06aeb15bde2fbc1d9619 ]
    
    Add a crypto_tfm_get interface to allow tfm objects to be shared.
    They can still be freed in the usual way.
    
    This should only be done with tfm objects with no keys.  You must
    also not modify the tfm flags in any way once it becomes shared.
    
    Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
    Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
    Stable-dep-of: 1465036b10be ("llc: Improve setsockopt() handling of malformed user input")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/crypto/api.c b/crypto/api.c
index 64f2d365a8e94..c58774586d9fb 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -409,6 +409,7 @@ struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
 		goto out_err;
 
 	tfm->__crt_alg = alg;
+	refcount_set(&tfm->refcnt, 1);
 
 	err = crypto_init_ops(tfm, type, mask);
 	if (err)
@@ -508,6 +509,7 @@ void *crypto_create_tfm_node(struct crypto_alg *alg,
 	tfm = (struct crypto_tfm *)(mem + tfmsize);
 	tfm->__crt_alg = alg;
 	tfm->node = node;
+	refcount_set(&tfm->refcnt, 1);
 
 	err = frontend->init_tfm(tfm);
 	if (err)
@@ -620,6 +622,8 @@ void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
 	if (IS_ERR_OR_NULL(mem))
 		return;
 
+	if (!refcount_dec_and_test(&tfm->refcnt))
+		return;
 	alg = tfm->__crt_alg;
 
 	if (!tfm->exit && alg->cra_exit)
diff --git a/crypto/internal.h b/crypto/internal.h
index c08385571853e..521bc021c54bc 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -10,6 +10,7 @@
 
 #include <crypto/algapi.h>
 #include <linux/completion.h>
+#include <linux/err.h>
 #include <linux/jump_label.h>
 #include <linux/list.h>
 #include <linux/module.h>
@@ -166,5 +167,10 @@ static inline int crypto_is_test_larval(struct crypto_larval *larval)
 	return larval->alg.cra_driver_name[0];
 }
 
+static inline struct crypto_tfm *crypto_tfm_get(struct crypto_tfm *tfm)
+{
+	return refcount_inc_not_zero(&tfm->refcnt) ? tfm : ERR_PTR(-EOVERFLOW);
+}
+
 #endif	/* _CRYPTO_INTERNAL_H */
 
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index e3c4be29aaccb..d354a2a7ac5ff 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -642,6 +642,7 @@ int crypto_has_alg(const char *name, u32 type, u32 mask);
  */
 
 struct crypto_tfm {
+	refcount_t refcnt;
 
 	u32 crt_flags;