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[bpf-next,v9,0/4] BPF crypto API framework

Message ID 20240416204004.3942393-1-vadfed@meta.com
Headers show
Series BPF crypto API framework | expand

Message

Vadim Fedorenko April 16, 2024, 8:40 p.m. UTC 
This series introduces crypto kfuncs to make BPF programs able to
utilize kernel crypto subsystem. Crypto operations made pluggable to
avoid extensive growth of kernel when it's not needed. Only skcipher is
added within this series, but it can be easily extended to other types
of operations. No hardware offload supported as it needs sleepable
context which is not available for TX or XDP programs. At the same time
crypto context initialization kfunc can only run in sleepable context,
that's why it should be run separately and store the result in the map.

Selftests show the common way to implement crypto actions in BPF
programs. Benchmark is also added to have a baseline.

Vadim Fedorenko (4):
  bpf: make common crypto API for TC/XDP programs
  bpf: crypto: add skcipher to bpf crypto
  selftests: bpf: crypto skcipher algo selftests
  selftests: bpf: crypto: add benchmark for crypto functions

 MAINTAINERS                                   |   8 +
 crypto/Makefile                               |   3 +
 crypto/bpf_crypto_skcipher.c                  |  82 ++++
 include/linux/bpf.h                           |   1 +
 include/linux/bpf_crypto.h                    |  24 ++
 kernel/bpf/Makefile                           |   3 +
 kernel/bpf/crypto.c                           | 377 ++++++++++++++++++
 kernel/bpf/helpers.c                          |   2 +-
 kernel/bpf/verifier.c                         |   1 +
 tools/testing/selftests/bpf/Makefile          |   2 +
 tools/testing/selftests/bpf/bench.c           |   6 +
 .../selftests/bpf/benchs/bench_bpf_crypto.c   | 190 +++++++++
 tools/testing/selftests/bpf/config            |   5 +
 .../selftests/bpf/prog_tests/crypto_sanity.c  | 200 ++++++++++
 .../selftests/bpf/progs/crypto_basic.c        |  70 ++++
 .../selftests/bpf/progs/crypto_bench.c        | 111 ++++++
 .../selftests/bpf/progs/crypto_common.h       |  67 ++++
 .../selftests/bpf/progs/crypto_sanity.c       | 161 ++++++++
 .../selftests/bpf/progs/crypto_share.h        |  10 +
 19 files changed, 1322 insertions(+), 1 deletion(-)
 create mode 100644 crypto/bpf_crypto_skcipher.c
 create mode 100644 include/linux/bpf_crypto.h
 create mode 100644 kernel/bpf/crypto.c
 create mode 100644 tools/testing/selftests/bpf/benchs/bench_bpf_crypto.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/crypto_sanity.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_basic.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_bench.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_common.h
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_sanity.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_share.h

Comments

Martin KaFai Lau April 19, 2024, 6:57 p.m. UTC | #1 
On 4/16/24 1:40 PM, Vadim Fedorenko wrote:
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 5034c1b4ded7..acc479c13f52 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1265,6 +1265,7 @@ 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..a41e71d4e2d9
> --- /dev/null
> +++ b/include/linux/bpf_crypto.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Copyright (c) 2024 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);
> +	unsigned int (*statesize)(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 368c5d86b5b7..736bd22e5ce0 100644
> --- a/kernel/bpf/Makefile
> +++ b/kernel/bpf/Makefile
> @@ -44,6 +44,9 @@ 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..a76d80f37f55
> --- /dev/null
> +++ b/kernel/bpf/crypto.c
> @@ -0,0 +1,377 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2024 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;
> +};
> +
> +/* BPF crypto initialization parameters struct */
> +/**
> + * struct bpf_crypto_params - BPF crypto initialization parameters structure
> + * @type:	The string of crypto operation type.
> + * @algo:	The string of algorithm to initialize.
> + * @key:	The cipher key used to init crypto algorithm.
> + * @key_len:	The length of cipher key.
> + * @authsize:	The length of authentication tag used by algorithm.
> + */
> +struct bpf_crypto_params {
> +	char type[14];
> +	char algo[128];
> +	__u8 key[256];

It should have a two byte hole here. Add
	__u8 reserved[2];

and check for 0 in bpf_crypto_ctx_create() in case it could be reused later. The 
bpf_crypto_ctx_create() should not be called very often.

> +	__u32 key_len;
> +	__u32 authsize;

I don't think there is tail padding of this struct, so should be fine.

> +} __attribute__((aligned(8)));

Does it need aligned(8) here?

> +
> +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;
> +	u32 siv_len;
> +	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.
> + * @params: pointer to struct bpf_crypto_params which contains all the
> + *          details needed to initialise crypto context.
> + * @err:    integer to store error code when NULL is returned.
> + */
> +__bpf_kfunc struct bpf_crypto_ctx *
> +bpf_crypto_ctx_create(const struct bpf_crypto_params *params, int *err)

Add a "u32 params__sz" arg in case that the params struct will have addition.
Take a look at how opts__sz is checked in nf_conntrack_bpf.c.

> +{
> +	const struct bpf_crypto_type *type;
> +	struct bpf_crypto_ctx *ctx;
> +
> +	type = bpf_crypto_get_type(params->type);
> +	if (IS_ERR(type)) {
> +		*err = PTR_ERR(type);
> +		return NULL;
> +	}
> +
> +	if (!type->has_algo(params->algo)) {
> +		*err = -EOPNOTSUPP;
> +		goto err_module_put;
> +	}
> +
> +	if (!params->authsize && type->setauthsize) {
> +		*err = -EOPNOTSUPP;
> +		goto err_module_put;
> +	}
> +
> +	if (params->authsize && !type->setauthsize) {

nit. Together with the previous "if" test, replace them with one test like:

	if (!!params->authsize ^ !!type->setauthsize) {


> +		*err = -EOPNOTSUPP;
> +		goto err_module_put;
> +	}
> +
> +	if (!params->key_len) {

Also checks "|| params->key_len > sizeof(params->key)"

> +		*err = -EINVAL;
> +		goto err_module_put;
> +	}
> +
> +	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx) {
> +		*err = -ENOMEM;
> +		goto err_module_put;
> +	}
> +
> +	ctx->type = type;
> +	ctx->tfm = type->alloc_tfm(params->algo);
> +	if (IS_ERR(ctx->tfm)) {
> +		*err = PTR_ERR(ctx->tfm);
> +		goto err_free_ctx;
> +	}
> +
> +	if (params->authsize) {
> +		*err = type->setauthsize(ctx->tfm, params->authsize);
> +		if (*err)
> +			goto err_free_tfm;
> +	}
> +
> +	*err = type->setkey(ctx->tfm, params->key, params->key_len);
> +	if (*err)
> +		goto err_free_tfm;
> +
> +	if (type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY) {
> +		*err = -EINVAL;
> +		goto err_free_tfm;
> +	}
> +
> +	ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);
> +
> +	refcount_set(&ctx->usage, 1);
> +
> +	return ctx;
> +
> +err_free_tfm:
> +	type->free_tfm(ctx->tfm);
> +err_free_ctx:
> +	kfree(ctx);
> +err_module_put:
> +	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)
> +{
> +	if (!refcount_inc_not_zero(&ctx->usage))
> +		return NULL;
> +	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 *siv,
> +			    bool decrypt)
> +{
> +	u32 src_len, dst_len, siv_len;
> +	const u8 *psrc;
> +	u8 *pdst, *piv;
> +	int err;
> +
> +	if (__bpf_dynptr_is_rdonly(dst))
> +		return -EINVAL;
> +
> +	siv_len = __bpf_dynptr_size(siv);
> +	src_len = __bpf_dynptr_size(src);
> +	dst_len = __bpf_dynptr_size(dst);
> +	if (!src_len || !dst_len)
> +		return -EINVAL;
> +
> +	if (siv_len != ctx->siv_len)
> +		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 = siv_len ? __bpf_dynptr_data_rw(siv, siv_len) : NULL;

It has been a while. I don't remember if it has already been brought up before.

The "const struct bpf_dynptr_kern *siv" here is essentially an optional pointer. 
Allowing NULL is a more intuitive usage instead of passing a 0-len dynptr. The 
verifier needs some changes to take __nullable suffix for "struct 
bpf_dynptr_kern *siv__nullable". This could be a follow up to relax the 
restriction to allow NULL and not necessary in this set.

> +	if (siv_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;
> +}
Vadim Fedorenko April 20, 2024, 12:24 a.m. UTC | #2 
On 19/04/2024 19:57, Martin KaFai Lau wrote:
> On 4/16/24 1:40 PM, Vadim Fedorenko wrote:
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index 5034c1b4ded7..acc479c13f52 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -1265,6 +1265,7 @@ 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..a41e71d4e2d9
>> --- /dev/null
>> +++ b/include/linux/bpf_crypto.h
>> @@ -0,0 +1,24 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/* Copyright (c) 2024 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);
>> +    unsigned int (*statesize)(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 368c5d86b5b7..736bd22e5ce0 100644
>> --- a/kernel/bpf/Makefile
>> +++ b/kernel/bpf/Makefile
>> @@ -44,6 +44,9 @@ 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..a76d80f37f55
>> --- /dev/null
>> +++ b/kernel/bpf/crypto.c
>> @@ -0,0 +1,377 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/* Copyright (c) 2024 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;
>> +};
>> +
>> +/* BPF crypto initialization parameters struct */
>> +/**
>> + * struct bpf_crypto_params - BPF crypto initialization parameters 
>> structure
>> + * @type:    The string of crypto operation type.
>> + * @algo:    The string of algorithm to initialize.
>> + * @key:    The cipher key used to init crypto algorithm.
>> + * @key_len:    The length of cipher key.
>> + * @authsize:    The length of authentication tag used by algorithm.
>> + */
>> +struct bpf_crypto_params {
>> +    char type[14];
>> +    char algo[128];
>> +    __u8 key[256];
> 
> It should have a two byte hole here. Add
>      __u8 reserved[2];
> 
> and check for 0 in bpf_crypto_ctx_create() in case it could be reused 
> later. The bpf_crypto_ctx_create() should not be called very often.
> 

Sure, I'll add it to have algo, key and other fields aligned to 8 bytes.

>> +    __u32 key_len;
>> +    __u32 authsize;
> 
> I don't think there is tail padding of this struct, so should be fine.
> 
>> +} __attribute__((aligned(8)));
> 
> Does it need aligned(8) here?

Nope, looks like left over after uapi variant.

> 
>> +
>> +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;
>> +    u32 siv_len;
>> +    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.
>> + * @params: pointer to struct bpf_crypto_params which contains all the
>> + *          details needed to initialise crypto context.
>> + * @err:    integer to store error code when NULL is returned.
>> + */
>> +__bpf_kfunc struct bpf_crypto_ctx *
>> +bpf_crypto_ctx_create(const struct bpf_crypto_params *params, int *err)
> 
> Add a "u32 params__sz" arg in case that the params struct will have 
> addition.
> Take a look at how opts__sz is checked in nf_conntrack_bpf.c.
> 

nf_conntrack uses hard-coded value, while xfrm code uses
sizeof(struct bpf_xfrm_state_opts), which one is better?

>> +{
>> +    const struct bpf_crypto_type *type;
>> +    struct bpf_crypto_ctx *ctx;
>> +
>> +    type = bpf_crypto_get_type(params->type);
>> +    if (IS_ERR(type)) {
>> +        *err = PTR_ERR(type);
>> +        return NULL;
>> +    }
>> +
>> +    if (!type->has_algo(params->algo)) {
>> +        *err = -EOPNOTSUPP;
>> +        goto err_module_put;
>> +    }
>> +
>> +    if (!params->authsize && type->setauthsize) {
>> +        *err = -EOPNOTSUPP;
>> +        goto err_module_put;
>> +    }
>> +
>> +    if (params->authsize && !type->setauthsize) {
> 
> nit. Together with the previous "if" test, replace them with one test like:
> 
>      if (!!params->authsize ^ !!type->setauthsize) {
> 

yep

> 
>> +        *err = -EOPNOTSUPP;
>> +        goto err_module_put;
>> +    }
>> +
>> +    if (!params->key_len) {
> 
> Also checks "|| params->key_len > sizeof(params->key)"

Sure

>> +        *err = -EINVAL;
>> +        goto err_module_put;
>> +    }
>> +
>> +    ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
>> +    if (!ctx) {
>> +        *err = -ENOMEM;
>> +        goto err_module_put;
>> +    }
>> +
>> +    ctx->type = type;
>> +    ctx->tfm = type->alloc_tfm(params->algo);
>> +    if (IS_ERR(ctx->tfm)) {
>> +        *err = PTR_ERR(ctx->tfm);
>> +        goto err_free_ctx;
>> +    }
>> +
>> +    if (params->authsize) {
>> +        *err = type->setauthsize(ctx->tfm, params->authsize);
>> +        if (*err)
>> +            goto err_free_tfm;
>> +    }
>> +
>> +    *err = type->setkey(ctx->tfm, params->key, params->key_len);
>> +    if (*err)
>> +        goto err_free_tfm;
>> +
>> +    if (type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY) {
>> +        *err = -EINVAL;
>> +        goto err_free_tfm;
>> +    }
>> +
>> +    ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);
>> +
>> +    refcount_set(&ctx->usage, 1);
>> +
>> +    return ctx;
>> +
>> +err_free_tfm:
>> +    type->free_tfm(ctx->tfm);
>> +err_free_ctx:
>> +    kfree(ctx);
>> +err_module_put:
>> +    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)
>> +{
>> +    if (!refcount_inc_not_zero(&ctx->usage))
>> +        return NULL;
>> +    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 *siv,
>> +                bool decrypt)
>> +{
>> +    u32 src_len, dst_len, siv_len;
>> +    const u8 *psrc;
>> +    u8 *pdst, *piv;
>> +    int err;
>> +
>> +    if (__bpf_dynptr_is_rdonly(dst))
>> +        return -EINVAL;
>> +
>> +    siv_len = __bpf_dynptr_size(siv);
>> +    src_len = __bpf_dynptr_size(src);
>> +    dst_len = __bpf_dynptr_size(dst);
>> +    if (!src_len || !dst_len)
>> +        return -EINVAL;
>> +
>> +    if (siv_len != ctx->siv_len)
>> +        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 = siv_len ? __bpf_dynptr_data_rw(siv, siv_len) : NULL;
> 
> It has been a while. I don't remember if it has already been brought up 
> before.
> 
> The "const struct bpf_dynptr_kern *siv" here is essentially an optional 
> pointer. Allowing NULL is a more intuitive usage instead of passing a 
> 0-len dynptr. The verifier needs some changes to take __nullable suffix 
> for "struct bpf_dynptr_kern *siv__nullable". This could be a follow up 
> to relax the restriction to allow NULL and not necessary in this set.
>

I think we have already discussed and agreed to have follow up once this 
part is merged.


>> +    if (siv_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;
>> +}
> 
>