[PATCH bpf-next v4 1/2] bpf: add skcipher API support to TC/XDP programs

[PATCH bpf-next v4 1/2] bpf: add skcipher API support to TC/XDP programs

[Vadim Fedorenko]

Add crypto API support to BPF to be able to decrypt or encrypt packets
in TC/XDP BPF programs. Only symmetric key ciphers are supported for
now. Special care should be taken for initialization part of crypto algo
because crypto_alloc_sync_skcipher() 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@meta.com>
---
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 +
 kernel/bpf/Makefile   |   3 +
 kernel/bpf/crypto.c   | 265 ++++++++++++++++++++++++++++++++++++++++++
 kernel/bpf/helpers.c  |   2 +-
 kernel/bpf/verifier.c |   1 +
 5 files changed, 271 insertions(+), 1 deletion(-)
 create mode 100644 kernel/bpf/crypto.c

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4001d11be151..77934ab7421d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1224,6 +1224,7 @@ 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/kernel/bpf/Makefile b/kernel/bpf/Makefile
index f526b7573e97..e14b5834c477 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_SKCIPHER),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..4fe1470ad4b8
--- /dev/null
+++ b/kernel/bpf/crypto.c
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2023 Meta, Inc */
+#include <linux/bpf.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_skcipher_ctx - refcounted BPF sync skcipher context structure
+ * @tfm:	The pointer to crypto_sync_skcipher 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_skcipher_ctx {
+	struct crypto_sync_skcipher *tfm;
+	struct rcu_head rcu;
+	refcount_t usage;
+};
+
+__bpf_kfunc_start_defs();
+
+/**
+ * bpf_crypto_skcipher_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_skcipher_ctx_release().
+ *
+ * bpf_crypto_skcipher_ctx_create() allocates memory using the BPF memory
+ * allocator, and will not block. It may return NULL if no memory is available.
+ * @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_skcipher_ctx *
+bpf_crypto_skcipher_ctx_create(const char *algo__str, const struct bpf_dynptr_kern *pkey,
+			       int *err)
+{
+	struct bpf_crypto_skcipher_ctx *ctx;
+	const u8 *key;
+	u32 key_len;
+
+	if (!crypto_has_skcipher(algo__str, CRYPTO_ALG_TYPE_SKCIPHER, CRYPTO_ALG_TYPE_MASK)) {
+		*err = -EOPNOTSUPP;
+		return NULL;
+	}
+
+	key_len = __bpf_dynptr_size(pkey);
+	if (!key_len) {
+		*err = -EINVAL;
+		return NULL;
+	}
+	key = __bpf_dynptr_data(pkey, key_len);
+	if (!key) {
+		*err = -EINVAL;
+		return NULL;
+	}
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx) {
+		*err = -ENOMEM;
+		return NULL;
+	}
+
+	ctx->tfm = crypto_alloc_sync_skcipher(algo__str, 0, 0);
+	if (IS_ERR(ctx->tfm)) {
+		*err = PTR_ERR(ctx->tfm);
+		ctx->tfm = NULL;
+		goto err;
+	}
+
+	*err = crypto_sync_skcipher_setkey(ctx->tfm, key, key_len);
+	if (*err)
+		goto err;
+
+	refcount_set(&ctx->usage, 1);
+
+	return ctx;
+err:
+	if (ctx->tfm)
+		crypto_free_sync_skcipher(ctx->tfm);
+	kfree(ctx);
+
+	return NULL;
+}
+
+static void crypto_free_sync_skcipher_cb(struct rcu_head *head)
+{
+	struct bpf_crypto_skcipher_ctx *ctx;
+
+	ctx = container_of(head, struct bpf_crypto_skcipher_ctx, rcu);
+	crypto_free_sync_skcipher(ctx->tfm);
+	kfree(ctx);
+}
+
+/**
+ * bpf_crypto_skcipher_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_skcipher_ctx *
+bpf_crypto_skcipher_ctx_acquire(struct bpf_crypto_skcipher_ctx *ctx)
+{
+	refcount_inc(&ctx->usage);
+	return ctx;
+}
+
+/**
+ * bpf_crypto_skcipher_ctx_release() - Release a previously acquired BPF crypto context.
+ * @ctx: The crypto context being released.
+ *
+ * Releases a previously acquired reference to a BPF cpumask. When the final
+ * reference of the BPF cpumask has been released, it is subsequently freed in
+ * an RCU callback in the BPF memory allocator.
+ */
+__bpf_kfunc void bpf_crypto_skcipher_ctx_release(struct bpf_crypto_skcipher_ctx *ctx)
+{
+	if (refcount_dec_and_test(&ctx->usage))
+		call_rcu(&ctx->rcu, crypto_free_sync_skcipher_cb);
+}
+
+static int bpf_crypto_skcipher_crypt(struct crypto_sync_skcipher *tfm,
+				     const struct bpf_dynptr_kern *src,
+				     struct bpf_dynptr_kern *dst,
+				     const struct bpf_dynptr_kern *iv,
+				     bool decrypt)
+{
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
+	struct scatterlist sgin, sgout;
+	u32 src_len, dst_len, iv_len;
+	const u8 *psrc;
+	u8 *pdst, *piv;
+	int err;
+
+	if (crypto_sync_skcipher_get_flags(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 != crypto_sync_skcipher_ivsize(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;
+
+	sg_init_one(&sgin, psrc, src_len);
+	sg_init_one(&sgout, pdst, dst_len);
+
+	skcipher_request_set_sync_tfm(req, tfm);
+	skcipher_request_set_callback(req, 0, NULL, NULL);
+	skcipher_request_set_crypt(req, &sgin, &sgout, src_len, piv);
+
+	err = decrypt ? crypto_skcipher_decrypt(req) : crypto_skcipher_encrypt(req);
+	skcipher_request_zero(req);
+
+	return err;
+}
+
+/**
+ * bpf_crypto_skcipher_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_skcipher_decrypt(struct bpf_crypto_skcipher_ctx *ctx,
+					    const struct bpf_dynptr_kern *src,
+					    struct bpf_dynptr_kern *dst,
+					    struct bpf_dynptr_kern *iv)
+{
+	return bpf_crypto_skcipher_crypt(ctx->tfm, src, dst, iv, true);
+}
+
+/**
+ * bpf_crypto_skcipher_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_skcipher_encrypt(struct bpf_crypto_skcipher_ctx *ctx,
+					    const struct bpf_dynptr_kern *src,
+					    struct bpf_dynptr_kern *dst,
+					    struct bpf_dynptr_kern *iv)
+{
+	return bpf_crypto_skcipher_crypt(ctx->tfm, src, dst, iv, false);
+}
+
+__bpf_kfunc_end_defs();
+
+BTF_SET8_START(crypt_skcipher_init_kfunc_btf_ids)
+BTF_ID_FLAGS(func, bpf_crypto_skcipher_ctx_create, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_crypto_skcipher_ctx_release, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_crypto_skcipher_ctx_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS)
+BTF_SET8_END(crypt_skcipher_init_kfunc_btf_ids)
+
+static const struct btf_kfunc_id_set crypt_skcipher_init_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &crypt_skcipher_init_kfunc_btf_ids,
+};
+
+BTF_SET8_START(crypt_skcipher_kfunc_btf_ids)
+BTF_ID_FLAGS(func, bpf_crypto_skcipher_decrypt, KF_RCU)
+BTF_ID_FLAGS(func, bpf_crypto_skcipher_encrypt, KF_RCU)
+BTF_SET8_END(crypt_skcipher_kfunc_btf_ids)
+
+static const struct btf_kfunc_id_set crypt_skcipher_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &crypt_skcipher_kfunc_btf_ids,
+};
+
+BTF_ID_LIST(crypto_skcipher_dtor_ids)
+BTF_ID(struct, bpf_crypto_skcipher_ctx)
+BTF_ID(func, bpf_crypto_skcipher_ctx_release)
+
+static int __init crypto_skcipher_kfunc_init(void)
+{
+	int ret;
+	const struct btf_id_dtor_kfunc crypto_skcipher_dtors[] = {
+		{
+			.btf_id	      = crypto_skcipher_dtor_ids[0],
+			.kfunc_btf_id = crypto_skcipher_dtor_ids[1]
+		},
+	};
+
+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &crypt_skcipher_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_ACT, &crypt_skcipher_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &crypt_skcipher_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC,
+					       &crypt_skcipher_init_kfunc_set);
+	return  ret ?: register_btf_id_dtor_kfuncs(crypto_skcipher_dtors,
+						   ARRAY_SIZE(crypto_skcipher_dtors),
+						   THIS_MODULE);
+}
+
+late_initcall(crypto_skcipher_kfunc_init);
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 03517db5cfb3..eb6ddc7e7fdc 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 9ae6eae13471..aac46e7f22ab 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5552,6 +5552,7 @@ BTF_ID(struct, cgroup)
 #endif
 BTF_ID(struct, bpf_cpumask)
 BTF_ID(struct, task_struct)
+BTF_ID(struct, bpf_crypto_skcipher_ctx)
 BTF_SET_END(rcu_protected_types)
 
 static bool rcu_protected_object(const struct btf *btf, u32 btf_id)
-- 
2.39.3

[PATCH bpf-next v4 2/2] selftests: bpf: crypto skcipher algo selftests

[Vadim Fedorenko]

Add simple tc hook selftests to show the way to work with new crypto
BPF API. Some weird structre and map are added to setup program to make
verifier happy about dynptr initialization from memory. Simple AES-ECB
algo is used to demonstrate encryption and decryption of fixed size
buffers.

Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
---
v3 -> v4:
- adjust selftests to use new syntax of helpers
- add tests for acquire and release
v2 -> v3:
- disable tests on s390 and aarch64 because of unknown Fatal exception
  in sg_init_one
v1 -> v2:
- add CONFIG_CRYPTO_AES and CONFIG_CRYPTO_ECB to selftest build config
  suggested by Daniel
---
 tools/testing/selftests/bpf/DENYLIST.aarch64  |   1 +
 tools/testing/selftests/bpf/DENYLIST.s390x    |   1 +
 tools/testing/selftests/bpf/config            |   3 +
 .../selftests/bpf/prog_tests/crypto_sanity.c  | 148 ++++++++++++++
 .../selftests/bpf/progs/crypto_common.h       |  69 +++++++
 .../selftests/bpf/progs/crypto_sanity.c       | 193 ++++++++++++++++++
 6 files changed, 415 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/crypto_sanity.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_common.h
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_sanity.c

diff --git a/tools/testing/selftests/bpf/DENYLIST.aarch64 b/tools/testing/selftests/bpf/DENYLIST.aarch64
index 5c2cc7e8c5d0..72c7ef3e5872 100644
--- a/tools/testing/selftests/bpf/DENYLIST.aarch64
+++ b/tools/testing/selftests/bpf/DENYLIST.aarch64
@@ -1,5 +1,6 @@
 bpf_cookie/multi_kprobe_attach_api               # kprobe_multi_link_api_subtest:FAIL:fentry_raw_skel_load unexpected error: -3
 bpf_cookie/multi_kprobe_link_api                 # kprobe_multi_link_api_subtest:FAIL:fentry_raw_skel_load unexpected error: -3
+crypto_sanity					 # sg_init_one has exception on aarch64
 exceptions					 # JIT does not support calling kfunc bpf_throw: -524
 fexit_sleep                                      # The test never returns. The remaining tests cannot start.
 kprobe_multi_bench_attach                        # needs CONFIG_FPROBE
diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
index 1a63996c0304..8ab7485bedb1 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -1,5 +1,6 @@
 # TEMPORARY
 # Alphabetical order
+crypto_sanity				 # sg_init_one has exception on s390					       (exceptions)
 exceptions				 # JIT does not support calling kfunc bpf_throw				       (exceptions)
 get_stack_raw_tp                         # user_stack corrupted user stack                                             (no backchain userspace)
 stacktrace_build_id                      # compare_map_keys stackid_hmap vs. stackmap err -2 errno 2                   (?)
diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
index 3ec5927ec3e5..81e521e9c0e9 100644
--- a/tools/testing/selftests/bpf/config
+++ b/tools/testing/selftests/bpf/config
@@ -14,6 +14,9 @@ CONFIG_CGROUP_BPF=y
 CONFIG_CRYPTO_HMAC=y
 CONFIG_CRYPTO_SHA256=y
 CONFIG_CRYPTO_USER_API_HASH=y
+CONFIG_CRYPTO_SKCIPHER=y
+CONFIG_CRYPTO_ECB=y
+CONFIG_CRYPTO_AES=y
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_INFO_BTF=y
 CONFIG_DEBUG_INFO_DWARF4=y
diff --git a/tools/testing/selftests/bpf/prog_tests/crypto_sanity.c b/tools/testing/selftests/bpf/prog_tests/crypto_sanity.c
new file mode 100644
index 000000000000..eb2cf7677797
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/crypto_sanity.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <linux/in6.h>
+
+#include "test_progs.h"
+#include "network_helpers.h"
+#include "crypto_sanity.skel.h"
+
+#define NS_TEST "crypto_sanity_ns"
+#define IPV6_IFACE_ADDR "face::1"
+#define UDP_TEST_PORT 7777
+static const char plain_text[] = "stringtoencrypt0";
+static const char crypted_data[] = "\x5B\x59\x39\xEA\xD9\x7A\x2D\xAD\xA7\xE0\x43" \
+				   "\x37\x8A\x77\x17\xB2";
+
+void test_crypto_sanity(void)
+{
+	LIBBPF_OPTS(bpf_tc_hook, qdisc_hook, .attach_point = BPF_TC_EGRESS);
+	LIBBPF_OPTS(bpf_tc_opts, tc_attach_enc);
+	LIBBPF_OPTS(bpf_tc_opts, tc_attach_dec);
+	LIBBPF_OPTS(bpf_test_run_opts, opts,
+		    .repeat = 1,
+	);
+	struct nstoken *nstoken = NULL;
+	struct crypto_sanity *skel;
+	struct sockaddr_in6 addr;
+	int sockfd, err, pfd;
+	socklen_t addrlen;
+
+	skel = crypto_sanity__open();
+	if (!ASSERT_OK_PTR(skel, "skel open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.crypto_accuire, true);
+
+	err = crypto_sanity__load(skel);
+	if (!ASSERT_ERR(err, "crypto_accuire unexpected load success"))
+		goto fail;
+
+	crypto_sanity__destroy(skel);
+
+	skel = crypto_sanity__open();
+	if (!ASSERT_OK_PTR(skel, "skel open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.crypto_accuire, false);
+
+	SYS(fail, "ip netns add %s", NS_TEST);
+	SYS(fail, "ip -net %s -6 addr add %s/128 dev lo nodad", NS_TEST, IPV6_IFACE_ADDR);
+	SYS(fail, "ip -net %s link set dev lo up", NS_TEST);
+
+	err = crypto_sanity__load(skel);
+	if (!ASSERT_OK(err, "crypto_sanity__load"))
+		goto fail;
+
+	nstoken = open_netns(NS_TEST);
+	if (!ASSERT_OK_PTR(nstoken, "open_netns"))
+		goto fail;
+
+	qdisc_hook.ifindex = if_nametoindex("lo");
+	if (!ASSERT_GT(qdisc_hook.ifindex, 0, "if_nametoindex lo"))
+		goto fail;
+
+	err = crypto_sanity__attach(skel);
+	if (!ASSERT_OK(err, "crypto_sanity__attach"))
+		goto fail;
+
+	pfd = bpf_program__fd(skel->progs.crypto_release);
+	if (!ASSERT_GT(pfd, 0, "crypto_release fd"))
+		goto fail;
+
+	err = bpf_prog_test_run_opts(pfd, &opts);
+	if (!ASSERT_OK(err, "crypto_release") ||
+	    !ASSERT_OK(opts.retval, "crypto_release retval"))
+		goto fail;
+
+	pfd = bpf_program__fd(skel->progs.skb_crypto_setup);
+	if (!ASSERT_GT(pfd, 0, "skb_crypto_setup fd"))
+		goto fail;
+
+	err = bpf_prog_test_run_opts(pfd, &opts);
+	if (!ASSERT_OK(err, "skb_crypto_setup") ||
+	    !ASSERT_OK(opts.retval, "skb_crypto_setup retval"))
+		goto fail;
+
+	if (!ASSERT_OK(skel->bss->status, "skb_crypto_setup status"))
+		goto fail;
+
+	err = bpf_tc_hook_create(&qdisc_hook);
+	if (!ASSERT_OK(err, "create qdisc hook"))
+		goto fail;
+
+	addrlen = sizeof(addr);
+	err = make_sockaddr(AF_INET6, IPV6_IFACE_ADDR, UDP_TEST_PORT,
+			    (void *)&addr, &addrlen);
+	if (!ASSERT_OK(err, "make_sockaddr"))
+		goto fail;
+
+	tc_attach_dec.prog_fd = bpf_program__fd(skel->progs.decrypt_sanity);
+	err = bpf_tc_attach(&qdisc_hook, &tc_attach_dec);
+	if (!ASSERT_OK(err, "attach decrypt filter"))
+		goto fail;
+
+	sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
+	if (!ASSERT_NEQ(sockfd, -1, "decrypt socket"))
+		goto fail;
+	err = sendto(sockfd, crypted_data, 16, 0, (void *)&addr, addrlen);
+	close(sockfd);
+	if (!ASSERT_EQ(err, 16, "decrypt send"))
+		goto fail;
+
+	bpf_tc_detach(&qdisc_hook, &tc_attach_dec);
+	if (!ASSERT_OK(skel->bss->status, "decrypt status"))
+		goto fail;
+	if (!ASSERT_STRNEQ(skel->bss->dst, plain_text, sizeof(plain_text), "decrypt"))
+		goto fail;
+
+	tc_attach_enc.prog_fd = bpf_program__fd(skel->progs.encrypt_sanity);
+	err = bpf_tc_attach(&qdisc_hook, &tc_attach_enc);
+	if (!ASSERT_OK(err, "attach encrypt filter"))
+		goto fail;
+
+	sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
+	if (!ASSERT_NEQ(sockfd, -1, "encrypt socket"))
+		goto fail;
+	err = sendto(sockfd, plain_text, 16, 0, (void *)&addr, addrlen);
+	close(sockfd);
+	if (!ASSERT_EQ(err, 16, "encrypt send"))
+		goto fail;
+
+	bpf_tc_detach(&qdisc_hook, &tc_attach_enc);
+	if (!ASSERT_OK(skel->bss->status, "encrypt status"))
+		goto fail;
+	if (!ASSERT_STRNEQ(skel->bss->dst, crypted_data, sizeof(crypted_data), "encrypt"))
+		goto fail;
+
+fail:
+	if (nstoken) {
+		bpf_tc_hook_destroy(&qdisc_hook);
+		close_netns(nstoken);
+	}
+	SYS_NOFAIL("ip netns del " NS_TEST " &> /dev/null");
+	crypto_sanity__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/crypto_common.h b/tools/testing/selftests/bpf/progs/crypto_common.h
new file mode 100644
index 000000000000..6874bc7b84dd
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/crypto_common.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#ifndef _CRYPTO_COMMON_H
+#define _CRYPTO_COMMON_H
+
+#include "errno.h"
+#include <stdbool.h>
+
+struct bpf_crypto_skcipher_ctx *bpf_crypto_skcipher_ctx_create(const char *algo__str,
+							       const struct bpf_dynptr *key,
+							       int *err) __ksym;
+struct bpf_crypto_skcipher_ctx *bpf_crypto_skcipher_ctx_acquire(struct bpf_crypto_skcipher_ctx *ctx) __ksym;
+void bpf_crypto_skcipher_ctx_release(struct bpf_crypto_skcipher_ctx *ctx) __ksym;
+int bpf_crypto_skcipher_encrypt(struct bpf_crypto_skcipher_ctx *ctx,
+				const struct bpf_dynptr *src, struct bpf_dynptr *dst,
+				struct bpf_dynptr *iv) __ksym;
+int bpf_crypto_skcipher_decrypt(struct bpf_crypto_skcipher_ctx *ctx,
+				const struct bpf_dynptr *src, struct bpf_dynptr *dst,
+				struct bpf_dynptr *iv) __ksym;
+
+struct __crypto_skcipher_ctx_value {
+	struct bpf_crypto_skcipher_ctx __kptr * ctx;
+};
+
+struct array_map {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, int);
+	__type(value, struct __crypto_skcipher_ctx_value);
+	__uint(max_entries, 1);
+} __crypto_skcipher_ctx_map SEC(".maps");
+
+static inline struct __crypto_skcipher_ctx_value *crypto_skcipher_ctx_value_lookup(void)
+{
+	u32 key = 0;
+
+	return bpf_map_lookup_elem(&__crypto_skcipher_ctx_map, &key);
+}
+
+static inline int crypto_skcipher_ctx_insert(struct bpf_crypto_skcipher_ctx *ctx)
+{
+	struct __crypto_skcipher_ctx_value local, *v;
+	struct bpf_crypto_skcipher_ctx *old;
+	u32 key = 0;
+	int err;
+
+	local.ctx = NULL;
+	err = bpf_map_update_elem(&__crypto_skcipher_ctx_map, &key, &local, 0);
+	if (err) {
+		bpf_crypto_skcipher_ctx_release(ctx);
+		return err;
+	}
+
+	v = bpf_map_lookup_elem(&__crypto_skcipher_ctx_map, &key);
+	if (!v) {
+		bpf_crypto_skcipher_ctx_release(ctx);
+		return -ENOENT;
+	}
+
+	old = bpf_kptr_xchg(&v->ctx, ctx);
+	if (old) {
+		bpf_crypto_skcipher_ctx_release(old);
+		return -EEXIST;
+	}
+
+	return 0;
+}
+
+#endif /* _CRYPTO_COMMON_H */
diff --git a/tools/testing/selftests/bpf/progs/crypto_sanity.c b/tools/testing/selftests/bpf/progs/crypto_sanity.c
new file mode 100644
index 000000000000..26fe9aff8b74
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/crypto_sanity.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_kfuncs.h"
+#include "crypto_common.h"
+
+#define UDP_TEST_PORT 7777
+unsigned char crypto_key[16] = "testtest12345678";
+const char crypto_algo[9] = "ecb(aes)";
+char dst[32] = {};
+int status;
+
+static int skb_dynptr_validate(struct __sk_buff *skb, struct bpf_dynptr *psrc)
+{
+	struct ipv6hdr ip6h;
+	struct udphdr udph;
+	u32 offset;
+
+	if (skb->protocol != __bpf_constant_htons(ETH_P_IPV6))
+		return -1;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN, &ip6h, sizeof(ip6h)))
+		return -1;
+
+	if (ip6h.nexthdr != IPPROTO_UDP)
+		return -1;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(ip6h), &udph, sizeof(udph)))
+		return -1;
+
+	if (udph.dest != __bpf_constant_htons(UDP_TEST_PORT))
+		return -1;
+
+	offset = ETH_HLEN + sizeof(ip6h) + sizeof(udph);
+	if (skb->len < offset + 16)
+		return -1;
+
+	bpf_dynptr_from_skb(skb, 0, psrc);
+	bpf_dynptr_adjust(psrc, offset, offset + 16);
+
+	return 0;
+}
+
+SEC("fentry.s/bpf_fentry_test1")
+int BPF_PROG(skb_crypto_setup)
+{
+	struct bpf_crypto_skcipher_ctx *cctx;
+	struct bpf_dynptr key = {};
+	int err = 0;
+
+	status = 0;
+
+	bpf_dynptr_from_mem(crypto_key, sizeof(crypto_key), 0, &key);
+	cctx = bpf_crypto_skcipher_ctx_create(crypto_algo, &key, &err);
+
+	if (!cctx) {
+		status = err;
+		return 0;
+	}
+
+	err = crypto_skcipher_ctx_insert(cctx);
+	if (err && err != -EEXIST)
+		status = err;
+
+	return 0;
+}
+
+SEC("fentry.s/bpf_fentry_test1")
+int BPF_PROG(crypto_release)
+{
+	struct bpf_crypto_skcipher_ctx *cctx;
+	struct bpf_dynptr key = {};
+	int err = 0;
+
+	status = 0;
+
+	bpf_dynptr_from_mem(crypto_key, sizeof(crypto_key), 0, &key);
+	cctx = bpf_crypto_skcipher_ctx_create(crypto_algo, &key, &err);
+
+	if (!cctx) {
+		status = err;
+		return 0;
+	}
+
+	bpf_crypto_skcipher_ctx_release(cctx);
+
+	return 0;
+}
+
+SEC("?fentry.s/bpf_fentry_test1")
+__failure __msg("Unreleased reference")
+int BPF_PROG(crypto_accuire)
+{
+	struct bpf_crypto_skcipher_ctx *cctx;
+	struct bpf_dynptr key = {};
+	int err = 0;
+
+	status = 0;
+
+	bpf_dynptr_from_mem(crypto_key, sizeof(crypto_key), 0, &key);
+	cctx = bpf_crypto_skcipher_ctx_create(crypto_algo, &key, &err);
+
+	if (!cctx) {
+		status = err;
+		return 0;
+	}
+
+	cctx = bpf_crypto_skcipher_ctx_acquire(cctx);
+	if (!cctx)
+		return -EINVAL;
+
+	bpf_crypto_skcipher_ctx_release(cctx);
+
+	return 0;
+}
+
+SEC("tc")
+int decrypt_sanity(struct __sk_buff *skb)
+{
+	struct __crypto_skcipher_ctx_value *v;
+	struct bpf_crypto_skcipher_ctx *ctx;
+	struct bpf_dynptr psrc, pdst, iv;
+	int err;
+
+	err = skb_dynptr_validate(skb, &psrc);
+	if (err < 0) {
+		status = err;
+		return TC_ACT_SHOT;
+	}
+
+	v = crypto_skcipher_ctx_value_lookup();
+	if (!v) {
+		status = -ENOENT;
+		return TC_ACT_SHOT;
+	}
+
+	ctx = v->ctx;
+	if (!ctx) {
+		status = -ENOENT;
+		return TC_ACT_SHOT;
+	}
+
+	bpf_dynptr_from_mem(dst, sizeof(dst), 0, &pdst);
+	bpf_dynptr_from_mem(dst, 0, 0, &iv);
+
+	status = bpf_crypto_skcipher_decrypt(ctx, &psrc, &pdst, &iv);
+
+	return TC_ACT_SHOT;
+}
+
+SEC("tc")
+int encrypt_sanity(struct __sk_buff *skb)
+{
+	struct __crypto_skcipher_ctx_value *v;
+	struct bpf_crypto_skcipher_ctx *ctx;
+	struct bpf_dynptr psrc, pdst, iv;
+	int err;
+
+	status = 0;
+
+	err = skb_dynptr_validate(skb, &psrc);
+	if (err < 0) {
+		status = err;
+		return TC_ACT_SHOT;
+	}
+
+	v = crypto_skcipher_ctx_value_lookup();
+	if (!v) {
+		status = -ENOENT;
+		return TC_ACT_SHOT;
+	}
+
+	ctx = v->ctx;
+	if (!ctx) {
+		status = -ENOENT;
+		return TC_ACT_SHOT;
+	}
+
+	bpf_dynptr_from_mem(dst, sizeof(dst), 0, &pdst);
+	bpf_dynptr_from_mem(dst, 0, 0, &iv);
+
+	status = bpf_crypto_skcipher_encrypt(ctx, &psrc, &pdst, &iv);
+
+	return TC_ACT_SHOT;
+}
+
+char __license[] SEC("license") = "GPL";
-- 
2.39.3

Re: [PATCH bpf-next v4 1/2] bpf: add skcipher API support to TC/XDP programs

[Herbert Xu]

Vadim Fedorenko <vadfed@meta.com> wrote:
> Add crypto API support to BPF to be able to decrypt or encrypt packets
> in TC/XDP BPF programs. Only symmetric key ciphers are supported for
> now. Special care should be taken for initialization part of crypto algo
> because crypto_alloc_sync_skcipher() 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@meta.com>

Please use the newly introduced lskcipher interface instead of
skcipher.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH bpf-next v4 1/2] bpf: add skcipher API support to TC/XDP programs

[Vadim Fedorenko]

On 16/11/2023 19:59, Herbert Xu wrote:
> Vadim Fedorenko <vadfed@meta.com> wrote:
>> Add crypto API support to BPF to be able to decrypt or encrypt packets
>> in TC/XDP BPF programs. Only symmetric key ciphers are supported for
>> now. Special care should be taken for initialization part of crypto algo
>> because crypto_alloc_sync_skcipher() 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@meta.com>
> 
> Please use the newly introduced lskcipher interface instead of
> skcipher.

Oh, sounds like we do have proper API to work with buffers directly!
Thanks for pointing to it, I'll send v5 soon.