On 11/29, Vadim Fedorenko wrote:
> Add crypto API support to BPF to be able to decrypt or encrypt packets
> in TC/XDP BPF programs. Special care should be taken for initialization
> part of crypto algo because crypto alloc) doesn't work with preemtion
> disabled, it can be run only in sleepable BPF program. Also async crypto
> is not supported because of the very same issue - TC/XDP BPF programs
> are not sleepable.
>
> Signed-off-by: Vadim Fedorenko <vadfed@xxxxxxxx>
>
> ---
> v5 -> v6:
> - replace lskcipher with infrastructure to provide pluggable cipher
> types
> - add BPF skcipher as plug-in module in a separate patch
> v4 -> v5:
> - replace crypto API to use lskcipher (suggested by Herbert Xu)
> - remove SG list usage and provide raw buffers
> v3 -> v4:
> - reuse __bpf_dynptr_data and remove own implementation
> - use const __str to provide algorithm name
> - use kfunc macroses to avoid compilator warnings
> v2 -> v3:
> - fix kdoc issues
> v1 -> v2:
> - use kmalloc in sleepable func, suggested by Alexei
> - use __bpf_dynptr_is_rdonly() to check destination, suggested by Jakub
> - use __bpf_dynptr_data_ptr() for all dynptr accesses
> ---
> include/linux/bpf.h | 1 +
> include/linux/bpf_crypto.h | 23 +++
> kernel/bpf/Makefile | 3 +
> kernel/bpf/crypto.c | 364 +++++++++++++++++++++++++++++++++++++
> kernel/bpf/helpers.c | 2 +-
> kernel/bpf/verifier.c | 1 +
> 6 files changed, 393 insertions(+), 1 deletion(-)
> create mode 100644 include/linux/bpf_crypto.h
> create mode 100644 kernel/bpf/crypto.c
>
> 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);
Passing by comment: the line above probably shouldn't start with // ?
