[bpf-next,v6,1/3] bpf: make common crypto API for TC/XDP programs

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index eb447b0a9423..0143ff6c93a1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1228,6 +1228,7 @@  int bpf_dynptr_check_size(u32 size);
 u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr);
 const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len);
 void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len);
+bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr);
 
 #ifdef CONFIG_BPF_JIT
 int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
diff --git a/include/linux/bpf_crypto.h b/include/linux/bpf_crypto.h
new file mode 100644
index 000000000000..e81bd8ab979c
--- /dev/null
+++ b/include/linux/bpf_crypto.h
@@ -0,0 +1,23 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+#ifndef _BPF_CRYPTO_H
+#define _BPF_CRYPTO_H
+
+struct bpf_crypto_type {
+	void *(*alloc_tfm)(const char *algo);
+	void (*free_tfm)(void *tfm);
+	int (*has_algo)(const char *algo);
+	int (*setkey)(void *tfm, const u8 *key, unsigned int keylen);
+	int (*setauthsize)(void *tfm, unsigned int authsize);
+	int (*encrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
+	int (*decrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
+	unsigned int (*ivsize)(void *tfm);
+	u32 (*get_flags)(void *tfm);
+	struct module *owner;
+	char name[14];
+};
+
+int bpf_crypto_register_type(const struct bpf_crypto_type *type);
+int bpf_crypto_unregister_type(const struct bpf_crypto_type *type);
+
+#endif /* _BPF_CRYPTO_H */
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index f526b7573e97..bcde762bb2c2 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -41,6 +41,9 @@  obj-$(CONFIG_BPF_SYSCALL) += bpf_struct_ops.o
 obj-$(CONFIG_BPF_SYSCALL) += cpumask.o
 obj-${CONFIG_BPF_LSM} += bpf_lsm.o
 endif
+ifeq ($(CONFIG_CRYPTO),y)
+obj-$(CONFIG_BPF_SYSCALL) += crypto.o
+endif
 obj-$(CONFIG_BPF_PRELOAD) += preload/
 
 obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
new file mode 100644
index 000000000000..46b4d263e472
--- /dev/null
+++ b/kernel/bpf/crypto.c
@@ -0,0 +1,364 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2023 Meta, Inc */
+#include <linux/bpf.h>
+#include <linux/bpf_crypto.h>
+#include <linux/bpf_mem_alloc.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
+#include <linux/filter.h>
+#include <linux/scatterlist.h>
+#include <linux/skbuff.h>
+#include <crypto/skcipher.h>
+
+struct bpf_crypto_type_list {
+	const struct bpf_crypto_type *type;
+	struct list_head list;
+};
+
+static LIST_HEAD(bpf_crypto_types);
+static DECLARE_RWSEM(bpf_crypto_types_sem);
+
+/**
+ * struct bpf_crypto_ctx - refcounted BPF crypto context structure
+ * @type:	The pointer to bpf crypto type
+ * @tfm:	The pointer to instance of crypto API struct.
+ * @rcu:	The RCU head used to free the crypto context with RCU safety.
+ * @usage:	Object reference counter. When the refcount goes to 0, the
+ *		memory is released back to the BPF allocator, which provides
+ *		RCU safety.
+ */
+struct bpf_crypto_ctx {
+	const struct bpf_crypto_type *type;
+	void *tfm;
+	struct rcu_head rcu;
+	refcount_t usage;
+};
+
+int bpf_crypto_register_type(const struct bpf_crypto_type *type)
+{
+	struct bpf_crypto_type_list *node;
+	int err = -EEXIST;
+
+	down_write(&bpf_crypto_types_sem);
+	list_for_each_entry(node, &bpf_crypto_types, list) {
+		if (!strcmp(node->type->name, type->name))
+			goto unlock;
+	}
+
+	node = kmalloc(sizeof(*node), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!node)
+		goto unlock;
+
+	node->type = type;
+	list_add(&node->list, &bpf_crypto_types);
+	err = 0;
+
+unlock:
+	up_write(&bpf_crypto_types_sem);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(bpf_crypto_register_type);
+
+int bpf_crypto_unregister_type(const struct bpf_crypto_type *type)
+{
+	struct bpf_crypto_type_list *node;
+	int err = -ENOENT;
+
+	down_write(&bpf_crypto_types_sem);
+	list_for_each_entry(node, &bpf_crypto_types, list) {
+		if (strcmp(node->type->name, type->name))
+			continue;
+
+		list_del(&node->list);
+		kfree(node);
+		err = 0;
+		break;
+	}
+	up_write(&bpf_crypto_types_sem);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(bpf_crypto_unregister_type);
+
+static const struct bpf_crypto_type *bpf_crypto_get_type(const char *name)
+{
+	const struct bpf_crypto_type *type = ERR_PTR(-ENOENT);
+	struct bpf_crypto_type_list *node;
+
+	down_read(&bpf_crypto_types_sem);
+	list_for_each_entry(node, &bpf_crypto_types, list) {
+		if (strcmp(node->type->name, name))
+			continue;
+
+		if (try_module_get(node->type->owner))
+			type = node->type;
+		break;
+	}
+	up_read(&bpf_crypto_types_sem);
+
+	return type;
+}
+
+__bpf_kfunc_start_defs();
+
+/**
+ * bpf_crypto_ctx_create() - Create a mutable BPF crypto context.
+ *
+ * Allocates a crypto context that can be used, acquired, and released by
+ * a BPF program. The crypto context returned by this function must either
+ * be embedded in a map as a kptr, or freed with bpf_crypto_ctx_release().
+ * As crypto API functions use GFP_KERNEL allocations, this function can
+ * only be used in sleepable BPF programs.
+ *
+ * bpf_crypto_ctx_create() allocates memory for crypto context.
+ * It may return NULL if no memory is available.
+ * @type__str: pointer to string representation of crypto type.
+ * @algo__str: pointer to string representation of algorithm.
+ * @pkey:      bpf_dynptr which holds cipher key to do crypto.
+ * @err:       integer to store error code when NULL is returned
+ */
+__bpf_kfunc struct bpf_crypto_ctx *
+bpf_crypto_ctx_create(const char *type__str, const char *algo__str,
+		      const struct bpf_dynptr_kern *pkey,
+		      unsigned int authsize, int *err)
+{
+	const struct bpf_crypto_type *type = bpf_crypto_get_type(type__str);
+	struct bpf_crypto_ctx *ctx;
+	const u8 *key;
+	u32 key_len;
+
+	//type = bpf_crypto_get_type(type__str);
+	if (IS_ERR(type)) {
+		*err = PTR_ERR(type);
+		return NULL;
+	}
+
+	if (!type->has_algo(algo__str)) {
+		*err = -EOPNOTSUPP;
+		goto err;
+	}
+
+	if (!authsize && type->setauthsize) {
+		*err = -EOPNOTSUPP;
+		goto err;
+	}
+
+	if (authsize && !type->setauthsize) {
+		*err = -EOPNOTSUPP;
+		goto err;
+	}
+
+	key_len = __bpf_dynptr_size(pkey);
+	if (!key_len) {
+		*err = -EINVAL;
+		goto err;
+	}
+	key = __bpf_dynptr_data(pkey, key_len);
+	if (!key) {
+		*err = -EINVAL;
+		goto err;
+	}
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx) {
+		*err = -ENOMEM;
+		goto err;
+	}
+
+	ctx->type = type;
+	ctx->tfm = type->alloc_tfm(algo__str);
+	if (IS_ERR(ctx->tfm)) {
+		*err = PTR_ERR(ctx->tfm);
+		ctx->tfm = NULL;
+		goto err;
+	}
+
+	if (authsize) {
+		*err = type->setauthsize(ctx->tfm, authsize;
+		if (*err)
+			goto err;
+	}
+
+	*err = type->setkey(ctx->tfm, key, key_len);
+	if (*err)
+		goto err;
+
+	refcount_set(&ctx->usage, 1);
+
+	return ctx;
+err:
+	if (ctx->tfm)
+		type->free_tfm(ctx->tfm);
+	kfree(ctx);
+	module_put(type->owner);
+
+	return NULL;
+}
+
+static void crypto_free_cb(struct rcu_head *head)
+{
+	struct bpf_crypto_ctx *ctx;
+
+	ctx = container_of(head, struct bpf_crypto_ctx, rcu);
+	ctx->type->free_tfm(ctx->tfm);
+	module_put(ctx->type->owner);
+	kfree(ctx);
+}
+
+/**
+ * bpf_crypto_ctx_acquire() - Acquire a reference to a BPF crypto context.
+ * @ctx: The BPF crypto context being acquired. The ctx must be a trusted
+ *	     pointer.
+ *
+ * Acquires a reference to a BPF crypto context. The context returned by this function
+ * must either be embedded in a map as a kptr, or freed with
+ * bpf_crypto_skcipher_ctx_release().
+ */
+__bpf_kfunc struct bpf_crypto_ctx *
+bpf_crypto_ctx_acquire(struct bpf_crypto_ctx *ctx)
+{
+	refcount_inc(&ctx->usage);
+	return ctx;
+}
+
+/**
+ * bpf_crypto_ctx_release() - Release a previously acquired BPF crypto context.
+ * @ctx: The crypto context being released.
+ *
+ * Releases a previously acquired reference to a BPF crypto context. When the final
+ * reference of the BPF crypto context has been released, it is subsequently freed in
+ * an RCU callback in the BPF memory allocator.
+ */
+__bpf_kfunc void bpf_crypto_ctx_release(struct bpf_crypto_ctx *ctx)
+{
+	if (refcount_dec_and_test(&ctx->usage))
+		call_rcu(&ctx->rcu, crypto_free_cb);
+}
+
+static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx,
+			    const struct bpf_dynptr_kern *src,
+			    struct bpf_dynptr_kern *dst,
+			    const struct bpf_dynptr_kern *iv,
+			    bool decrypt)
+{
+	u32 src_len, dst_len, iv_len;
+	const u8 *psrc;
+	u8 *pdst, *piv;
+	int err;
+
+	if (ctx->type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY)
+		return -EINVAL;
+
+	if (__bpf_dynptr_is_rdonly(dst))
+		return -EINVAL;
+
+	iv_len = __bpf_dynptr_size(iv);
+	src_len = __bpf_dynptr_size(src);
+	dst_len = __bpf_dynptr_size(dst);
+	if (!src_len || !dst_len)
+		return -EINVAL;
+
+	if (iv_len != ctx->type->ivsize(ctx->tfm))
+		return -EINVAL;
+
+	psrc = __bpf_dynptr_data(src, src_len);
+	if (!psrc)
+		return -EINVAL;
+	pdst = __bpf_dynptr_data_rw(dst, dst_len);
+	if (!pdst)
+		return -EINVAL;
+
+	piv = iv_len ? __bpf_dynptr_data_rw(iv, iv_len) : NULL;
+	if (iv_len && !piv)
+		return -EINVAL;
+
+	err = decrypt ? ctx->type->decrypt(ctx->tfm, psrc, pdst, src_len, piv)
+		      : ctx->type->encrypt(ctx->tfm, psrc, pdst, src_len, piv);
+
+	return err;
+}
+
+/**
+ * bpf_crypto_decrypt() - Decrypt buffer using configured context and IV provided.
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ * @src:	bpf_dynptr to the encrypted data. Must be a trusted pointer.
+ * @dst:	bpf_dynptr to the buffer where to store the result. Must be a trusted pointer.
+ * @iv:		bpf_dynptr to IV data to be used by decryptor.
+ *
+ * Decrypts provided buffer using IV data and the crypto context. Crypto context must be configured.
+ */
+__bpf_kfunc int bpf_crypto_decrypt(struct bpf_crypto_ctx *ctx,
+				   const struct bpf_dynptr_kern *src,
+				   struct bpf_dynptr_kern *dst,
+				   struct bpf_dynptr_kern *iv)
+{
+	return bpf_crypto_crypt(ctx, src, dst, iv, true);
+}
+
+/**
+ * bpf_crypto_encrypt() - Encrypt buffer using configured context and IV provided.
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ * @src:	bpf_dynptr to the plain data. Must be a trusted pointer.
+ * @dst:	bpf_dynptr to buffer where to store the result. Must be a trusted pointer.
+ * @iv:		bpf_dynptr to IV data to be used by decryptor.
+ *
+ * Encrypts provided buffer using IV data and the crypto context. Crypto context must be configured.
+ */
+__bpf_kfunc int bpf_crypto_encrypt(struct bpf_crypto_ctx *ctx,
+				   const struct bpf_dynptr_kern *src,
+				   struct bpf_dynptr_kern *dst,
+				   struct bpf_dynptr_kern *iv)
+{
+	return bpf_crypto_crypt(ctx, src, dst, iv, false);
+}
+
+__bpf_kfunc_end_defs();
+
+BTF_SET8_START(crypt_init_kfunc_btf_ids)
+BTF_ID_FLAGS(func, bpf_crypto_ctx_create, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_crypto_ctx_release, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_crypto_ctx_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS)
+BTF_SET8_END(crypt_init_kfunc_btf_ids)
+
+static const struct btf_kfunc_id_set crypt_init_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &crypt_init_kfunc_btf_ids,
+};
+
+BTF_SET8_START(crypt_kfunc_btf_ids)
+BTF_ID_FLAGS(func, bpf_crypto_decrypt, KF_RCU)
+BTF_ID_FLAGS(func, bpf_crypto_encrypt, KF_RCU)
+BTF_SET8_END(crypt_kfunc_btf_ids)
+
+static const struct btf_kfunc_id_set crypt_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &crypt_kfunc_btf_ids,
+};
+
+BTF_ID_LIST(bpf_crypto_dtor_ids)
+BTF_ID(struct, bpf_crypto_ctx)
+BTF_ID(func, bpf_crypto_ctx_release)
+
+static int __init crypto_kfunc_init(void)
+{
+	int ret;
+	const struct btf_id_dtor_kfunc bpf_crypto_dtors[] = {
+		{
+			.btf_id	      = bpf_crypto_dtor_ids[0],
+			.kfunc_btf_id = bpf_crypto_dtor_ids[1]
+		},
+	};
+
+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &crypt_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_ACT, &crypt_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &crypt_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC,
+					       &crypt_init_kfunc_set);
+	return  ret ?: register_btf_id_dtor_kfuncs(bpf_crypto_dtors,
+						   ARRAY_SIZE(bpf_crypto_dtors),
+						   THIS_MODULE);
+}
+
+late_initcall(crypto_kfunc_init);
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index b45a8381f9bd..b73314c0124e 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1436,7 +1436,7 @@  static const struct bpf_func_proto bpf_kptr_xchg_proto = {
 #define DYNPTR_SIZE_MASK	0xFFFFFF
 #define DYNPTR_RDONLY_BIT	BIT(31)
 
-static bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
+bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
 {
 	return ptr->size & DYNPTR_RDONLY_BIT;
 }
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8e7b6072e3f4..c54716966d5d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5162,6 +5162,7 @@  BTF_ID(struct, cgroup)
 #endif
 BTF_ID(struct, bpf_cpumask)
 BTF_ID(struct, task_struct)
+BTF_ID(struct, bpf_crypto_ctx)
 BTF_SET_END(rcu_protected_types)
 
 static bool rcu_protected_object(const struct btf *btf, u32 btf_id)