On 12/1/23 5:06 PM, Vadim Fedorenko wrote:
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];
Does it have a macro (from crypto ?) that can be reused here instead of a
numeric constant?
+};
+
+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..a1e543d1d7fe
--- /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))
If I read patch 2 correctly, it is always built-in. I am not sure I understand
the module_put/get in this patch.
+ 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;
ctx is still not initialized. The error path will crash.
+ }
+
+ 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)
Considering bpf_crypto_ctx is rcu protected, the acquire may use "KF_ACQUIRE |
KF_RCU | KF_RET_NULL" such that the bpf_crypto_ctx_acquire(ctx_from_map_value)
will work and the user will prepare checking NULL from day one.
+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)
