Merge branch 'Dynamic pointers'

Joanne Koong says:

====================

This patchset implements the basics of dynamic pointers in bpf.

A dynamic pointer (struct bpf_dynptr) is a pointer that stores extra metadata
alongside the address it points to. This abstraction is useful in bpf given
that every memory access in a bpf program must be safe. The verifier and bpf
helper functions can use the metadata to enforce safety guarantees for things
such as dynamically sized strings and kernel heap allocations.

From the program side, the bpf_dynptr is an opaque struct and the verifier
will enforce that its contents are never written to by the program.
It can only be written to through specific bpf helper functions.

There are several uses cases for dynamic pointers in bpf programs. Some
examples include: dynamically sized ringbuf reservations without extra
memcpys, dynamic string parsing and memory comparisons, dynamic memory
allocations that can be persisted in maps, and dynamic + ergonomic parsing of
sk_buff and xdp_md packet data.

At a high-level, the patches are as follows:
1/6 - Adds verifier support for dynptrs
2/6 - Adds bpf_dynptr_from_mem (local dynptr)
3/6 - Adds dynptr support for ring buffers
4/6 - Adds bpf_dynptr_read and bpf_dynptr_write
5/6 - Adds dynptr data slices (ptr to the dynptr data)
6/6 - Tests to check that the verifier rejects invalid cases and passes valid ones

This is the first dynptr patchset in a larger series. The next series of
patches will add dynptrs that support dynamic memory allocations that can also
be persisted in maps, support for parsing packet data through dynptrs, convenience
helpers for using dynptrs as iterators, and more helper functions for interacting
with strings and memory dynamically.

Changelog:
----------
v5 -> v6:
v5:
https://lore.kernel.org/bpf/20220520044245.3305025-1-joannelkoong@gmail.com/
* enforce PTR_TO_MAP_VALUE for bpf_dynptr_from_mem data in check_helper_call
instead of using DYNPTR_TYPE_LOCAL when checking func arg compatiblity
* remove MEM_DYNPTR modifier

v4 -> v5:
v4:
https://lore.kernel.org/bpf/20220509224257.3222614-1-joannelkoong@gmail.com/
* Remove malloc dynptr; this will be part of the 2nd patchset while we
figure out memory accounting
* For data slices, only set the register's ref_obj_id to dynptr_id (Alexei)
* Tidying (eg remove "inline", move offset checking to "check_func_arg_reg_off")
(David)
* Add a few new test cases, remove malloc-only ones.

v3 -> v4:
v3:
https://lore.kernel.org/bpf/20220428211059.4065379-1-joannelkoong@gmail.com/
1/6 - Change mem ptr + size check to use more concise inequality expression
(David + Andrii)
2/6 - Add check for meta->uninit_dynptr_regno not already set (Andrii)
      Move DYNPTR_TYPE_FLAG_MASK to include/linux/bpf.h (Andrii)
3/6 - Remove four underscores for invoking BPF_CALL (Andrii)
      Add __BPF_TYPE_FLAG_MAX and use it for __BPF_TYPE_LAST_FLAG (Andrii)
4/6 - Fix capacity to be bpf_dynptr size value in check_off_len (Andrii)
      Change -EINVAL to -E2BIG if len + offset is out of bounds (Andrii)
5/6 - Add check for only 1 dynptr arg for dynptr data function (Andrii)
6/6 - For ringbuf map, set max_entries from userspace (Andrii)
      Use err ?: ... for interactring with dynptr APIs (Andrii)
      Define array_map2 for add_dynptr_to_map2 test where value is a struct
with an embedded dynptr
      Remove ref id from missing_put_callback message, since on different
environments, ref id is not always = 1

v2 -> v3:
v2:
https://lore.kernel.org/bpf/20220416063429.3314021-1-joannelkoong@gmail.com/
* Reorder patches (move ringbuffer patch to be right after the verifier +
* malloc
dynptr patchset)
* Remove local type dynptrs (Andrii + Alexei)
* Mark stack slot as STACK_MISC after any writes into a dynptr instead of
* explicitly prohibiting writes (Alexei)
* Pass number of slots, not memory size to is_spi_bounds_valid (Kumar)
* Check reference leaks by adding dynptr id to state->refs instead of checking
stack slots (Alexei)

v1 -> v2:
v1: https://lore.kernel.org/bpf/20220402015826.3941317-1-joannekoong@fb.com/
1/7 -
    * Remove ARG_PTR_TO_MAP_VALUE_UNINIT alias and use
      ARG_PTR_TO_MAP_VALUE | MEM_UNINIT directly (Andrii)
    * Drop arg_type_is_mem_ptr() wrapper function (Andrii)
2/7 -
    * Change name from MEM_RELEASE to OBJ_RELEASE (Andrii)
    * Use meta.release_ref instead of ref_obj_id != 0 to determine whether
      to release reference (Kumar)
    * Drop type_is_release_mem() wrapper function (Andrii)
3/7 -
    * Add checks for nested dynptrs edge-cases, which could lead to corrupt
    * writes of the dynptr stack variable.
    * Add u64 flags to bpf_dynptr_from_mem() and bpf_dynptr_alloc() (Andrii)
    * Rename from bpf_malloc/bpf_free to bpf_dynptr_alloc/bpf_dynptr_put
      (Alexei)
    * Support alloc flag __GFP_ZERO (Andrii)
    * Reserve upper 8 bits in dynptr size and offset fields instead of
      reserving just the upper 4 bits (Andrii)
    * Allow dynptr zero-slices (Andrii)
    * Use the highest bit for is_rdonly instead of the 28th bit (Andrii)
    * Rename check_* functions to is_* functions for better readability
      (Andrii)
    * Add comment for code that checks the spi bounds (Andrii)
4/7 -
    * Fix doc description for bpf_dynpt_read (Toke)
    * Move bpf_dynptr_check_off_len() from function patch 1 to here (Andrii)
5/7 -
    * When finding the id for the dynptr to associate the data slice with,
      look for dynptr arg instead of assuming it is BPF_REG_1.
6/7 -
    * Add __force when casting from unsigned long to void * (kernel test
    * robot)
    * Expand on docs for ringbuf dynptr APIs (Andrii)
7/7 -
    * Use table approach for defining test programs and error messages
    * (Andrii)
    * Print out full log if there’s an error (Andrii)
    * Use bpf_object__find_program_by_name() instead of specifying
      program name as a string (Andrii)
    * Add 6 extra cases: invalid_nested_dynptrs1, invalid_nested_dynptrs2,
      invalid_ref_mem1, invalid_ref_mem2, zero_slice_access,
      and test_alloc_zero_bytes
    * Add checking for edge cases (eg allocing with invalid flags)
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

4 files changed, 972 insertions, 0 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 56688bee20d9..f4009dbdf62d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5178,6 +5178,77 @@ union bpf_attr {
  *		Dynamically cast a *sk* pointer to a *mptcp_sock* pointer.
  *	Return
  *		*sk* if casting is valid, or **NULL** otherwise.
+ *
+ * long bpf_dynptr_from_mem(void *data, u32 size, u64 flags, struct bpf_dynptr *ptr)
+ *	Description
+ *		Get a dynptr to local memory *data*.
+ *
+ *		*data* must be a ptr to a map value.
+ *		The maximum *size* supported is DYNPTR_MAX_SIZE.
+ *		*flags* is currently unused.
+ *	Return
+ *		0 on success, -E2BIG if the size exceeds DYNPTR_MAX_SIZE,
+ *		-EINVAL if flags is not 0.
+ *
+ * long bpf_ringbuf_reserve_dynptr(void *ringbuf, u32 size, u64 flags, struct bpf_dynptr *ptr)
+ *	Description
+ *		Reserve *size* bytes of payload in a ring buffer *ringbuf*
+ *		through the dynptr interface. *flags* must be 0.
+ *
+ *		Please note that a corresponding bpf_ringbuf_submit_dynptr or
+ *		bpf_ringbuf_discard_dynptr must be called on *ptr*, even if the
+ *		reservation fails. This is enforced by the verifier.
+ *	Return
+ *		0 on success, or a negative error in case of failure.
+ *
+ * void bpf_ringbuf_submit_dynptr(struct bpf_dynptr *ptr, u64 flags)
+ *	Description
+ *		Submit reserved ring buffer sample, pointed to by *data*,
+ *		through the dynptr interface. This is a no-op if the dynptr is
+ *		invalid/null.
+ *
+ *		For more information on *flags*, please see
+ *		'bpf_ringbuf_submit'.
+ *	Return
+ *		Nothing. Always succeeds.
+ *
+ * void bpf_ringbuf_discard_dynptr(struct bpf_dynptr *ptr, u64 flags)
+ *	Description
+ *		Discard reserved ring buffer sample through the dynptr
+ *		interface. This is a no-op if the dynptr is invalid/null.
+ *
+ *		For more information on *flags*, please see
+ *		'bpf_ringbuf_discard'.
+ *	Return
+ *		Nothing. Always succeeds.
+ *
+ * long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset)
+ *	Description
+ *		Read *len* bytes from *src* into *dst*, starting from *offset*
+ *		into *src*.
+ *	Return
+ *		0 on success, -E2BIG if *offset* + *len* exceeds the length
+ *		of *src*'s data, -EINVAL if *src* is an invalid dynptr.
+ *
+ * long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len)
+ *	Description
+ *		Write *len* bytes from *src* into *dst*, starting from *offset*
+ *		into *dst*.
+ *	Return
+ *		0 on success, -E2BIG if *offset* + *len* exceeds the length
+ *		of *dst*'s data, -EINVAL if *dst* is an invalid dynptr or if *dst*
+ *		is a read-only dynptr.
+ *
+ * void *bpf_dynptr_data(struct bpf_dynptr *ptr, u32 offset, u32 len)
+ *	Description
+ *		Get a pointer to the underlying dynptr data.
+ *
+ *		*len* must be a statically known value. The returned data slice
+ *		is invalidated whenever the dynptr is invalidated.
+ *	Return
+ *		Pointer to the underlying dynptr data, NULL if the dynptr is
+ *		read-only, if the dynptr is invalid, or if the offset and length
+ *		is out of bounds.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5377,6 +5448,13 @@ union bpf_attr {
 	FN(kptr_xchg),			\
 	FN(map_lookup_percpu_elem),     \
 	FN(skc_to_mptcp_sock),		\
+	FN(dynptr_from_mem),		\
+	FN(ringbuf_reserve_dynptr),	\
+	FN(ringbuf_submit_dynptr),	\
+	FN(ringbuf_discard_dynptr),	\
+	FN(dynptr_read),		\
+	FN(dynptr_write),		\
+	FN(dynptr_data),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -6528,6 +6606,11 @@ struct bpf_timer {
 	__u64 :64;
 } __attribute__((aligned(8)));
 
+struct bpf_dynptr {
+	__u64 :64;
+	__u64 :64;
+} __attribute__((aligned(8)));
+
 struct bpf_sysctl {
 	__u32	write;		/* Sysctl is being read (= 0) or written (= 1).
 				 * Allows 1,2,4-byte read, but no write.
diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
new file mode 100644
index 000000000000..3c7aa82b98e2
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Facebook */
+
+#include <test_progs.h>
+#include "dynptr_fail.skel.h"
+#include "dynptr_success.skel.h"
+
+static size_t log_buf_sz = 1048576; /* 1 MB */
+static char obj_log_buf[1048576];
+
+static struct {
+	const char *prog_name;
+	const char *expected_err_msg;
+} dynptr_tests[] = {
+	/* failure cases */
+	{"ringbuf_missing_release1", "Unreleased reference id=1"},
+	{"ringbuf_missing_release2", "Unreleased reference id=2"},
+	{"ringbuf_missing_release_callback", "Unreleased reference id"},
+	{"use_after_invalid", "Expected an initialized dynptr as arg #3"},
+	{"ringbuf_invalid_api", "type=mem expected=alloc_mem"},
+	{"add_dynptr_to_map1", "invalid indirect read from stack"},
+	{"add_dynptr_to_map2", "invalid indirect read from stack"},
+	{"data_slice_out_of_bounds_ringbuf", "value is outside of the allowed memory range"},
+	{"data_slice_out_of_bounds_map_value", "value is outside of the allowed memory range"},
+	{"data_slice_use_after_release", "invalid mem access 'scalar'"},
+	{"data_slice_missing_null_check1", "invalid mem access 'mem_or_null'"},
+	{"data_slice_missing_null_check2", "invalid mem access 'mem_or_null'"},
+	{"invalid_helper1", "invalid indirect read from stack"},
+	{"invalid_helper2", "Expected an initialized dynptr as arg #3"},
+	{"invalid_write1", "Expected an initialized dynptr as arg #1"},
+	{"invalid_write2", "Expected an initialized dynptr as arg #3"},
+	{"invalid_write3", "Expected an initialized ringbuf dynptr as arg #1"},
+	{"invalid_write4", "arg 1 is an unacquired reference"},
+	{"invalid_read1", "invalid read from stack"},
+	{"invalid_read2", "cannot pass in dynptr at an offset"},
+	{"invalid_read3", "invalid read from stack"},
+	{"invalid_read4", "invalid read from stack"},
+	{"invalid_offset", "invalid write to stack"},
+	{"global", "type=map_value expected=fp"},
+	{"release_twice", "arg 1 is an unacquired reference"},
+	{"release_twice_callback", "arg 1 is an unacquired reference"},
+	{"dynptr_from_mem_invalid_api",
+		"Unsupported reg type fp for bpf_dynptr_from_mem data"},
+
+	/* success cases */
+	{"test_read_write", NULL},
+	{"test_data_slice", NULL},
+	{"test_ringbuf", NULL},
+};
+
+static void verify_fail(const char *prog_name, const char *expected_err_msg)
+{
+	LIBBPF_OPTS(bpf_object_open_opts, opts);
+	struct bpf_program *prog;
+	struct dynptr_fail *skel;
+	int err;
+
+	opts.kernel_log_buf = obj_log_buf;
+	opts.kernel_log_size = log_buf_sz;
+	opts.kernel_log_level = 1;
+
+	skel = dynptr_fail__open_opts(&opts);
+	if (!ASSERT_OK_PTR(skel, "dynptr_fail__open_opts"))
+		goto cleanup;
+
+	prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+		goto cleanup;
+
+	bpf_program__set_autoload(prog, true);
+
+	bpf_map__set_max_entries(skel->maps.ringbuf, getpagesize());
+
+	err = dynptr_fail__load(skel);
+	if (!ASSERT_ERR(err, "unexpected load success"))
+		goto cleanup;
+
+	if (!ASSERT_OK_PTR(strstr(obj_log_buf, expected_err_msg), "expected_err_msg")) {
+		fprintf(stderr, "Expected err_msg: %s\n", expected_err_msg);
+		fprintf(stderr, "Verifier output: %s\n", obj_log_buf);
+	}
+
+cleanup:
+	dynptr_fail__destroy(skel);
+}
+
+static void verify_success(const char *prog_name)
+{
+	struct dynptr_success *skel;
+	struct bpf_program *prog;
+	struct bpf_link *link;
+
+	skel = dynptr_success__open();
+	if (!ASSERT_OK_PTR(skel, "dynptr_success__open"))
+		return;
+
+	skel->bss->pid = getpid();
+
+	bpf_map__set_max_entries(skel->maps.ringbuf, getpagesize());
+
+	dynptr_success__load(skel);
+	if (!ASSERT_OK_PTR(skel, "dynptr_success__load"))
+		goto cleanup;
+
+	prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+		goto cleanup;
+
+	link = bpf_program__attach(prog);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+		goto cleanup;
+
+	usleep(1);
+
+	ASSERT_EQ(skel->bss->err, 0, "err");
+
+	bpf_link__destroy(link);
+
+cleanup:
+	dynptr_success__destroy(skel);
+}
+
+void test_dynptr(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(dynptr_tests); i++) {
+		if (!test__start_subtest(dynptr_tests[i].prog_name))
+			continue;
+
+		if (dynptr_tests[i].expected_err_msg)
+			verify_fail(dynptr_tests[i].prog_name,
+				    dynptr_tests[i].expected_err_msg);
+		else
+			verify_success(dynptr_tests[i].prog_name);
+	}
+}
diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
new file mode 100644
index 000000000000..d811cff73597
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -0,0 +1,588 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Facebook */
+
+#include <errno.h>
+#include <string.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct test_info {
+	int x;
+	struct bpf_dynptr ptr;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, struct bpf_dynptr);
+} array_map1 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, struct test_info);
+} array_map2 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u32);
+} array_map3 SEC(".maps");
+
+struct sample {
+	int pid;
+	long value;
+	char comm[16];
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+int err, val;
+
+static int get_map_val_dynptr(struct bpf_dynptr *ptr)
+{
+	__u32 key = 0, *map_val;
+
+	bpf_map_update_elem(&array_map3, &key, &val, 0);
+
+	map_val = bpf_map_lookup_elem(&array_map3, &key);
+	if (!map_val)
+		return -ENOENT;
+
+	bpf_dynptr_from_mem(map_val, sizeof(*map_val), 0, ptr);
+
+	return 0;
+}
+
+/* Every bpf_ringbuf_reserve_dynptr call must have a corresponding
+ * bpf_ringbuf_submit/discard_dynptr call
+ */
+SEC("?raw_tp/sys_nanosleep")
+int ringbuf_missing_release1(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, val, 0, &ptr);
+
+	/* missing a call to bpf_ringbuf_discard/submit_dynptr */
+
+	return 0;
+}
+
+SEC("?raw_tp/sys_nanosleep")
+int ringbuf_missing_release2(void *ctx)
+{
+	struct bpf_dynptr ptr1, ptr2;
+	struct sample *sample;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(*sample), 0, &ptr1);
+	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(*sample), 0, &ptr2);
+
+	sample = bpf_dynptr_data(&ptr1, 0, sizeof(*sample));
+	if (!sample) {
+		bpf_ringbuf_discard_dynptr(&ptr1, 0);
+		bpf_ringbuf_discard_dynptr(&ptr2, 0);
+		return 0;
+	}
+
+	bpf_ringbuf_submit_dynptr(&ptr1, 0);
+
+	/* missing a call to bpf_ringbuf_discard/submit_dynptr on ptr2 */
+
+	return 0;
+}
+
+static int missing_release_callback_fn(__u32 index, void *data)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, val, 0, &ptr);
+
+	/* missing a call to bpf_ringbuf_discard/submit_dynptr */
+
+	return 0;
+}
+
+/* Any dynptr initialized within a callback must have bpf_dynptr_put called */
+SEC("?raw_tp/sys_nanosleep")
+int ringbuf_missing_release_callback(void *ctx)
+{
+	bpf_loop(10, missing_release_callback_fn, NULL, 0);
+	return 0;
+}
+
+/* Can't call bpf_ringbuf_submit/discard_dynptr on a non-initialized dynptr */
+SEC("?raw_tp/sys_nanosleep")
+int ringbuf_release_uninit_dynptr(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	/* this should fail */
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/* A dynptr can't be used after it has been invalidated */
+SEC("?raw_tp/sys_nanosleep")
+int use_after_invalid(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	char read_data[64];
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(read_data), 0, &ptr);
+
+	bpf_dynptr_read(read_data, sizeof(read_data), &ptr, 0);
+
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	/* this should fail */
+	bpf_dynptr_read(read_data, sizeof(read_data), &ptr, 0);
+
+	return 0;
+}
+
+/* Can't call non-dynptr ringbuf APIs on a dynptr ringbuf sample */
+SEC("?raw_tp/sys_nanosleep")
+int ringbuf_invalid_api(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	struct sample *sample;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(*sample), 0, &ptr);
+	sample = bpf_dynptr_data(&ptr, 0, sizeof(*sample));
+	if (!sample)
+		goto done;
+
+	sample->pid = 123;
+
+	/* invalid API use. need to use dynptr API to submit/discard */
+	bpf_ringbuf_submit(sample, 0);
+
+done:
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+	return 0;
+}
+
+/* Can't add a dynptr to a map */
+SEC("?raw_tp/sys_nanosleep")
+int add_dynptr_to_map1(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	int key = 0;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, val, 0, &ptr);
+
+	/* this should fail */
+	bpf_map_update_elem(&array_map1, &key, &ptr, 0);
+
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/* Can't add a struct with an embedded dynptr to a map */
+SEC("?raw_tp/sys_nanosleep")
+int add_dynptr_to_map2(void *ctx)
+{
+	struct test_info x;
+	int key = 0;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, val, 0, &x.ptr);
+
+	/* this should fail */
+	bpf_map_update_elem(&array_map2, &key, &x, 0);
+
+	bpf_ringbuf_submit_dynptr(&x.ptr, 0);
+
+	return 0;
+}
+
+/* A data slice can't be accessed out of bounds */
+SEC("?raw_tp/sys_nanosleep")
+int data_slice_out_of_bounds_ringbuf(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	void *data;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 8, 0, &ptr);
+
+	data  = bpf_dynptr_data(&ptr, 0, 8);
+	if (!data)
+		goto done;
+
+	/* can't index out of bounds of the data slice */
+	val = *((char *)data + 8);
+
+done:
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+	return 0;
+}
+
+SEC("?raw_tp/sys_nanosleep")
+int data_slice_out_of_bounds_map_value(void *ctx)
+{
+	__u32 key = 0, map_val;
+	struct bpf_dynptr ptr;
+	void *data;
+
+	get_map_val_dynptr(&ptr);
+
+	data  = bpf_dynptr_data(&ptr, 0, sizeof(map_val));
+	if (!data)
+		return 0;
+
+	/* can't index out of bounds of the data slice */
+	val = *((char *)data + (sizeof(map_val) + 1));
+
+	return 0;
+}
+
+/* A data slice can't be used after it has been released */
+SEC("?raw_tp/sys_nanosleep")
+int data_slice_use_after_release(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	struct sample *sample;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(*sample), 0, &ptr);
+	sample = bpf_dynptr_data(&ptr, 0, sizeof(*sample));
+	if (!sample)
+		goto done;
+
+	sample->pid = 123;
+
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	/* this should fail */
+	val = sample->pid;
+
+	return 0;
+
+done:
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+	return 0;
+}
+
+/* A data slice must be first checked for NULL */
+SEC("?raw_tp/sys_nanosleep")
+int data_slice_missing_null_check1(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	void *data;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 8, 0, &ptr);
+
+	data  = bpf_dynptr_data(&ptr, 0, 8);
+
+	/* missing if (!data) check */
+
+	/* this should fail */
+	*(__u8 *)data = 3;
+
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+	return 0;
+}
+
+/* A data slice can't be dereferenced if it wasn't checked for null */
+SEC("?raw_tp/sys_nanosleep")
+int data_slice_missing_null_check2(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	__u64 *data1, *data2;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 16, 0, &ptr);
+
+	data1 = bpf_dynptr_data(&ptr, 0, 8);
+	data2 = bpf_dynptr_data(&ptr, 0, 8);
+	if (data1)
+		/* this should fail */
+		*data2 = 3;
+
+done:
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+	return 0;
+}
+
+/* Can't pass in a dynptr as an arg to a helper function that doesn't take in a
+ * dynptr argument
+ */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_helper1(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	get_map_val_dynptr(&ptr);
+
+	/* this should fail */
+	bpf_strncmp((const char *)&ptr, sizeof(ptr), "hello!");
+
+	return 0;
+}
+
+/* A dynptr can't be passed into a helper function at a non-zero offset */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_helper2(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	char read_data[64];
+
+	get_map_val_dynptr(&ptr);
+
+	/* this should fail */
+	bpf_dynptr_read(read_data, sizeof(read_data), (void *)&ptr + 8, 0);
+
+	return 0;
+}
+
+/* A bpf_dynptr is invalidated if it's been written into */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_write1(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	void *data;
+	__u8 x = 0;
+
+	get_map_val_dynptr(&ptr);
+
+	memcpy(&ptr, &x, sizeof(x));
+
+	/* this should fail */
+	data = bpf_dynptr_data(&ptr, 0, 1);
+
+	return 0;
+}
+
+/*
+ * A bpf_dynptr can't be used as a dynptr if it has been written into at a fixed
+ * offset
+ */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_write2(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	char read_data[64];
+	__u8 x = 0;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &ptr);
+
+	memcpy((void *)&ptr + 8, &x, sizeof(x));
+
+	/* this should fail */
+	bpf_dynptr_read(read_data, sizeof(read_data), &ptr, 0);
+
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/*
+ * A bpf_dynptr can't be used as a dynptr if it has been written into at a
+ * non-const offset
+ */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_write3(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	char stack_buf[16];
+	unsigned long len;
+	__u8 x = 0;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 8, 0, &ptr);
+
+	memcpy(stack_buf, &val, sizeof(val));
+	len = stack_buf[0] & 0xf;
+
+	memcpy((void *)&ptr + len, &x, sizeof(x));
+
+	/* this should fail */
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+static int invalid_write4_callback(__u32 index, void *data)
+{
+	*(__u32 *)data = 123;
+
+	return 0;
+}
+
+/* If the dynptr is written into in a callback function, it should
+ * be invalidated as a dynptr
+ */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_write4(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &ptr);
+
+	bpf_loop(10, invalid_write4_callback, &ptr, 0);
+
+	/* this should fail */
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/* A globally-defined bpf_dynptr can't be used (it must reside as a stack frame) */
+struct bpf_dynptr global_dynptr;
+SEC("?raw_tp/sys_nanosleep")
+int global(void *ctx)
+{
+	/* this should fail */
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 16, 0, &global_dynptr);
+
+	bpf_ringbuf_discard_dynptr(&global_dynptr, 0);
+
+	return 0;
+}
+
+/* A direct read should fail */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_read1(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &ptr);
+
+	/* this should fail */
+	val = *(int *)&ptr;
+
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/* A direct read at an offset should fail */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_read2(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	char read_data[64];
+
+	get_map_val_dynptr(&ptr);
+
+	/* this should fail */
+	bpf_dynptr_read(read_data, sizeof(read_data), (void *)&ptr + 1, 0);
+
+	return 0;
+}
+
+/* A direct read at an offset into the lower stack slot should fail */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_read3(void *ctx)
+{
+	struct bpf_dynptr ptr1, ptr2;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 16, 0, &ptr1);
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 16, 0, &ptr2);
+
+	/* this should fail */
+	memcpy(&val, (void *)&ptr1 + 8, sizeof(val));
+
+	bpf_ringbuf_discard_dynptr(&ptr1, 0);
+	bpf_ringbuf_discard_dynptr(&ptr2, 0);
+
+	return 0;
+}
+
+static int invalid_read4_callback(__u32 index, void *data)
+{
+	/* this should fail */
+	val = *(__u32 *)data;
+
+	return 0;
+}
+
+/* A direct read within a callback function should fail */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_read4(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &ptr);
+
+	bpf_loop(10, invalid_read4_callback, &ptr, 0);
+
+	bpf_ringbuf_submit_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/* Initializing a dynptr on an offset should fail */
+SEC("?raw_tp/sys_nanosleep")
+int invalid_offset(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	/* this should fail */
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 64, 0, &ptr + 1);
+
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+/* Can't release a dynptr twice */
+SEC("?raw_tp/sys_nanosleep")
+int release_twice(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 16, 0, &ptr);
+
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+
+	/* this second release should fail */
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+
+	return 0;
+}
+
+static int release_twice_callback_fn(__u32 index, void *data)
+{
+	/* this should fail */
+	bpf_ringbuf_discard_dynptr(data, 0);
+
+	return 0;
+}
+
+/* Test that releasing a dynptr twice, where one of the releases happens
+ * within a calback function, fails
+ */
+SEC("?raw_tp/sys_nanosleep")
+int release_twice_callback(void *ctx)
+{
+	struct bpf_dynptr ptr;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, 32, 0, &ptr);
+
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+
+	bpf_loop(10, release_twice_callback_fn, &ptr, 0);
+
+	return 0;
+}
+
+/* Reject unsupported local mem types for dynptr_from_mem API */
+SEC("?raw_tp/sys_nanosleep")
+int dynptr_from_mem_invalid_api(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	int x = 0;
+
+	/* this should fail */
+	bpf_dynptr_from_mem(&x, sizeof(x), 0, &ptr);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
new file mode 100644
index 000000000000..d67be48df4b2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Facebook */
+
+#include <string.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "errno.h"
+
+char _license[] SEC("license") = "GPL";
+
+int pid, err, val;
+
+struct sample {
+	int pid;
+	int seq;
+	long value;
+	char comm[16];
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u32);
+} array_map SEC(".maps");
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int test_read_write(void *ctx)
+{
+	char write_data[64] = "hello there, world!!";
+	char read_data[64] = {}, buf[64] = {};
+	struct bpf_dynptr ptr;
+	int i;
+
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(write_data), 0, &ptr);
+
+	/* Write data into the dynptr */
+	err = err ?: bpf_dynptr_write(&ptr, 0, write_data, sizeof(write_data));
+
+	/* Read the data that was written into the dynptr */
+	err = err ?: bpf_dynptr_read(read_data, sizeof(read_data), &ptr, 0);
+
+	/* Ensure the data we read matches the data we wrote */
+	for (i = 0; i < sizeof(read_data); i++) {
+		if (read_data[i] != write_data[i]) {
+			err = 1;
+			break;
+		}
+	}
+
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+	return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int test_data_slice(void *ctx)
+{
+	__u32 key = 0, val = 235, *map_val;
+	struct bpf_dynptr ptr;
+	__u32 map_val_size;
+	void *data;
+
+	map_val_size = sizeof(*map_val);
+
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	bpf_map_update_elem(&array_map, &key, &val, 0);
+
+	map_val = bpf_map_lookup_elem(&array_map, &key);
+	if (!map_val) {
+		err = 1;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(map_val, map_val_size, 0, &ptr);
+
+	/* Try getting a data slice that is out of range */
+	data = bpf_dynptr_data(&ptr, map_val_size + 1, 1);
+	if (data) {
+		err = 2;
+		return 0;
+	}
+
+	/* Try getting more bytes than available */
+	data = bpf_dynptr_data(&ptr, 0, map_val_size + 1);
+	if (data) {
+		err = 3;
+		return 0;
+	}
+
+	data = bpf_dynptr_data(&ptr, 0, sizeof(__u32));
+	if (!data) {
+		err = 4;
+		return 0;
+	}
+
+	*(__u32 *)data = 999;
+
+	err = bpf_probe_read_kernel(&val, sizeof(val), data);
+	if (err)
+		return 0;
+
+	if (val != *(int *)data)
+		err = 5;
+
+	return 0;
+}
+
+static int ringbuf_callback(__u32 index, void *data)
+{
+	struct sample *sample;
+
+	struct bpf_dynptr *ptr = (struct bpf_dynptr *)data;
+
+	sample = bpf_dynptr_data(ptr, 0, sizeof(*sample));
+	if (!sample)
+		err = 2;
+	else
+		sample->pid += index;
+
+	return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int test_ringbuf(void *ctx)
+{
+	struct bpf_dynptr ptr;
+	struct sample *sample;
+
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 0;
+
+	val = 100;
+
+	/* check that you can reserve a dynamic size reservation */
+	err = bpf_ringbuf_reserve_dynptr(&ringbuf, val, 0, &ptr);
+
+	sample = err ? NULL : bpf_dynptr_data(&ptr, 0, sizeof(*sample));
+	if (!sample) {
+		err = 1;
+		goto done;
+	}
+
+	sample->pid = 10;
+
+	/* Can pass dynptr to callback functions */
+	bpf_loop(10, ringbuf_callback, &ptr, 0);
+
+	if (sample->pid != 55)
+		err = 2;
+
+done:
+	bpf_ringbuf_discard_dynptr(&ptr, 0);
+	return 0;
+}