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>

11 files changed, 1636 insertions, 5 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a9b1875212f6..a7080c86fa76 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -392,10 +392,18 @@ enum bpf_type_flag {
 
 	MEM_UNINIT		= BIT(7 + BPF_BASE_TYPE_BITS),
 
+	/* DYNPTR points to memory local to the bpf program. */
+	DYNPTR_TYPE_LOCAL	= BIT(8 + BPF_BASE_TYPE_BITS),
+
+	/* DYNPTR points to a ringbuf record. */
+	DYNPTR_TYPE_RINGBUF	= BIT(9 + BPF_BASE_TYPE_BITS),
+
 	__BPF_TYPE_FLAG_MAX,
 	__BPF_TYPE_LAST_FLAG	= __BPF_TYPE_FLAG_MAX - 1,
 };
 
+#define DYNPTR_TYPE_FLAG_MASK	(DYNPTR_TYPE_LOCAL | DYNPTR_TYPE_RINGBUF)
+
 /* Max number of base types. */
 #define BPF_BASE_TYPE_LIMIT	(1UL << BPF_BASE_TYPE_BITS)
 
@@ -438,6 +446,7 @@ enum bpf_arg_type {
 	ARG_PTR_TO_CONST_STR,	/* pointer to a null terminated read-only string */
 	ARG_PTR_TO_TIMER,	/* pointer to bpf_timer */
 	ARG_PTR_TO_KPTR,	/* pointer to referenced kptr */
+	ARG_PTR_TO_DYNPTR,      /* pointer to bpf_dynptr. See bpf_type_flag for dynptr type */
 	__BPF_ARG_TYPE_MAX,
 
 	/* Extended arg_types. */
@@ -479,6 +488,7 @@ enum bpf_return_type {
 	RET_PTR_TO_TCP_SOCK_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_TCP_SOCK,
 	RET_PTR_TO_SOCK_COMMON_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_SOCK_COMMON,
 	RET_PTR_TO_ALLOC_MEM_OR_NULL	= PTR_MAYBE_NULL | MEM_ALLOC | RET_PTR_TO_ALLOC_MEM,
+	RET_PTR_TO_DYNPTR_MEM_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_ALLOC_MEM,
 	RET_PTR_TO_BTF_ID_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_BTF_ID,
 
 	/* This must be the last entry. Its purpose is to ensure the enum is
@@ -2225,6 +2235,9 @@ extern const struct bpf_func_proto bpf_ringbuf_reserve_proto;
 extern const struct bpf_func_proto bpf_ringbuf_submit_proto;
 extern const struct bpf_func_proto bpf_ringbuf_discard_proto;
 extern const struct bpf_func_proto bpf_ringbuf_query_proto;
+extern const struct bpf_func_proto bpf_ringbuf_reserve_dynptr_proto;
+extern const struct bpf_func_proto bpf_ringbuf_submit_dynptr_proto;
+extern const struct bpf_func_proto bpf_ringbuf_discard_dynptr_proto;
 extern const struct bpf_func_proto bpf_skc_to_tcp6_sock_proto;
 extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto;
 extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto;
@@ -2376,4 +2389,33 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
 			u32 **bin_buf, u32 num_args);
 void bpf_bprintf_cleanup(void);
 
+/* the implementation of the opaque uapi struct bpf_dynptr */
+struct bpf_dynptr_kern {
+	void *data;
+	/* Size represents the number of usable bytes of dynptr data.
+	 * If for example the offset is at 4 for a local dynptr whose data is
+	 * of type u64, the number of usable bytes is 4.
+	 *
+	 * The upper 8 bits are reserved. It is as follows:
+	 * Bits 0 - 23 = size
+	 * Bits 24 - 30 = dynptr type
+	 * Bit 31 = whether dynptr is read-only
+	 */
+	u32 size;
+	u32 offset;
+} __aligned(8);
+
+enum bpf_dynptr_type {
+	BPF_DYNPTR_TYPE_INVALID,
+	/* Points to memory that is local to the bpf program */
+	BPF_DYNPTR_TYPE_LOCAL,
+	/* Underlying data is a ringbuf record */
+	BPF_DYNPTR_TYPE_RINGBUF,
+};
+
+void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
+		     enum bpf_dynptr_type type, u32 offset, u32 size);
+void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);
+int bpf_dynptr_check_size(u32 size);
+
 #endif /* _LINUX_BPF_H */
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 1f1e7f2ea967..e8439f6cbe57 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -72,6 +72,18 @@ struct bpf_reg_state {
 
 		u32 mem_size; /* for PTR_TO_MEM | PTR_TO_MEM_OR_NULL */
 
+		/* For dynptr stack slots */
+		struct {
+			enum bpf_dynptr_type type;
+			/* A dynptr is 16 bytes so it takes up 2 stack slots.
+			 * We need to track which slot is the first slot
+			 * to protect against cases where the user may try to
+			 * pass in an address starting at the second slot of the
+			 * dynptr.
+			 */
+			bool first_slot;
+		} dynptr;
+
 		/* Max size from any of the above. */
 		struct {
 			unsigned long raw1;
@@ -88,6 +100,8 @@ struct bpf_reg_state {
 	 * for the purpose of tracking that it's freed.
 	 * For PTR_TO_SOCKET this is used to share which pointers retain the
 	 * same reference to the socket, to determine proper reference freeing.
+	 * For stack slots that are dynptrs, this is used to track references to
+	 * the dynptr to determine proper reference freeing.
 	 */
 	u32 id;
 	/* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned
@@ -174,9 +188,15 @@ enum bpf_stack_slot_type {
 	STACK_SPILL,      /* register spilled into stack */
 	STACK_MISC,	  /* BPF program wrote some data into this slot */
 	STACK_ZERO,	  /* BPF program wrote constant zero */
+	/* A dynptr is stored in this stack slot. The type of dynptr
+	 * is stored in bpf_stack_state->spilled_ptr.dynptr.type
+	 */
+	STACK_DYNPTR,
 };
 
 #define BPF_REG_SIZE 8	/* size of eBPF register in bytes */
+#define BPF_DYNPTR_SIZE		sizeof(struct bpf_dynptr_kern)
+#define BPF_DYNPTR_NR_SLOTS		(BPF_DYNPTR_SIZE / BPF_REG_SIZE)
 
 struct bpf_stack_state {
 	struct bpf_reg_state spilled_ptr;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 56688bee20d9..f4009dbdf62d 100644
--- a/include/uapi/linux/bpf.h
+++ b/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/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index bad96131a510..225806a02efb 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1412,6 +1412,169 @@ const struct bpf_func_proto bpf_kptr_xchg_proto = {
 	.arg2_btf_id  = BPF_PTR_POISON,
 };
 
+/* Since the upper 8 bits of dynptr->size is reserved, the
+ * maximum supported size is 2^24 - 1.
+ */
+#define DYNPTR_MAX_SIZE	((1UL << 24) - 1)
+#define DYNPTR_TYPE_SHIFT	28
+#define DYNPTR_SIZE_MASK	0xFFFFFF
+#define DYNPTR_RDONLY_BIT	BIT(31)
+
+static bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
+{
+	return ptr->size & DYNPTR_RDONLY_BIT;
+}
+
+static void bpf_dynptr_set_type(struct bpf_dynptr_kern *ptr, enum bpf_dynptr_type type)
+{
+	ptr->size |= type << DYNPTR_TYPE_SHIFT;
+}
+
+static u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr)
+{
+	return ptr->size & DYNPTR_SIZE_MASK;
+}
+
+int bpf_dynptr_check_size(u32 size)
+{
+	return size > DYNPTR_MAX_SIZE ? -E2BIG : 0;
+}
+
+void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
+		     enum bpf_dynptr_type type, u32 offset, u32 size)
+{
+	ptr->data = data;
+	ptr->offset = offset;
+	ptr->size = size;
+	bpf_dynptr_set_type(ptr, type);
+}
+
+void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr)
+{
+	memset(ptr, 0, sizeof(*ptr));
+}
+
+static int bpf_dynptr_check_off_len(struct bpf_dynptr_kern *ptr, u32 offset, u32 len)
+{
+	u32 size = bpf_dynptr_get_size(ptr);
+
+	if (len > size || offset > size - len)
+		return -E2BIG;
+
+	return 0;
+}
+
+BPF_CALL_4(bpf_dynptr_from_mem, void *, data, u32, size, u64, flags, struct bpf_dynptr_kern *, ptr)
+{
+	int err;
+
+	err = bpf_dynptr_check_size(size);
+	if (err)
+		goto error;
+
+	/* flags is currently unsupported */
+	if (flags) {
+		err = -EINVAL;
+		goto error;
+	}
+
+	bpf_dynptr_init(ptr, data, BPF_DYNPTR_TYPE_LOCAL, 0, size);
+
+	return 0;
+
+error:
+	bpf_dynptr_set_null(ptr);
+	return err;
+}
+
+const struct bpf_func_proto bpf_dynptr_from_mem_proto = {
+	.func		= bpf_dynptr_from_mem,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_UNINIT_MEM,
+	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL | MEM_UNINIT,
+};
+
+BPF_CALL_4(bpf_dynptr_read, void *, dst, u32, len, struct bpf_dynptr_kern *, src, u32, offset)
+{
+	int err;
+
+	if (!src->data)
+		return -EINVAL;
+
+	err = bpf_dynptr_check_off_len(src, offset, len);
+	if (err)
+		return err;
+
+	memcpy(dst, src->data + src->offset + offset, len);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_dynptr_read_proto = {
+	.func		= bpf_dynptr_read,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_UNINIT_MEM,
+	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
+	.arg3_type	= ARG_PTR_TO_DYNPTR,
+	.arg4_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_4(bpf_dynptr_write, struct bpf_dynptr_kern *, dst, u32, offset, void *, src, u32, len)
+{
+	int err;
+
+	if (!dst->data || bpf_dynptr_is_rdonly(dst))
+		return -EINVAL;
+
+	err = bpf_dynptr_check_off_len(dst, offset, len);
+	if (err)
+		return err;
+
+	memcpy(dst->data + dst->offset + offset, src, len);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_dynptr_write_proto = {
+	.func		= bpf_dynptr_write,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_DYNPTR,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
+	.arg4_type	= ARG_CONST_SIZE_OR_ZERO,
+};
+
+BPF_CALL_3(bpf_dynptr_data, struct bpf_dynptr_kern *, ptr, u32, offset, u32, len)
+{
+	int err;
+
+	if (!ptr->data)
+		return 0;
+
+	err = bpf_dynptr_check_off_len(ptr, offset, len);
+	if (err)
+		return 0;
+
+	if (bpf_dynptr_is_rdonly(ptr))
+		return 0;
+
+	return (unsigned long)(ptr->data + ptr->offset + offset);
+}
+
+const struct bpf_func_proto bpf_dynptr_data_proto = {
+	.func		= bpf_dynptr_data,
+	.gpl_only	= false,
+	.ret_type	= RET_PTR_TO_DYNPTR_MEM_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_DYNPTR,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_CONST_ALLOC_SIZE_OR_ZERO,
+};
+
 const struct bpf_func_proto bpf_get_current_task_proto __weak;
 const struct bpf_func_proto bpf_get_current_task_btf_proto __weak;
 const struct bpf_func_proto bpf_probe_read_user_proto __weak;
@@ -1460,12 +1623,26 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_ringbuf_discard_proto;
 	case BPF_FUNC_ringbuf_query:
 		return &bpf_ringbuf_query_proto;
+	case BPF_FUNC_ringbuf_reserve_dynptr:
+		return &bpf_ringbuf_reserve_dynptr_proto;
+	case BPF_FUNC_ringbuf_submit_dynptr:
+		return &bpf_ringbuf_submit_dynptr_proto;
+	case BPF_FUNC_ringbuf_discard_dynptr:
+		return &bpf_ringbuf_discard_dynptr_proto;
 	case BPF_FUNC_for_each_map_elem:
 		return &bpf_for_each_map_elem_proto;
 	case BPF_FUNC_loop:
 		return &bpf_loop_proto;
 	case BPF_FUNC_strncmp:
 		return &bpf_strncmp_proto;
+	case BPF_FUNC_dynptr_from_mem:
+		return &bpf_dynptr_from_mem_proto;
+	case BPF_FUNC_dynptr_read:
+		return &bpf_dynptr_read_proto;
+	case BPF_FUNC_dynptr_write:
+		return &bpf_dynptr_write_proto;
+	case BPF_FUNC_dynptr_data:
+		return &bpf_dynptr_data_proto;
 	default:
 		break;
 	}
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 311264ab80c4..ded4faeca192 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -475,3 +475,81 @@ const struct bpf_func_proto bpf_ringbuf_query_proto = {
 	.arg1_type	= ARG_CONST_MAP_PTR,
 	.arg2_type	= ARG_ANYTHING,
 };
+
+BPF_CALL_4(bpf_ringbuf_reserve_dynptr, struct bpf_map *, map, u32, size, u64, flags,
+	   struct bpf_dynptr_kern *, ptr)
+{
+	struct bpf_ringbuf_map *rb_map;
+	void *sample;
+	int err;
+
+	if (unlikely(flags)) {
+		bpf_dynptr_set_null(ptr);
+		return -EINVAL;
+	}
+
+	err = bpf_dynptr_check_size(size);
+	if (err) {
+		bpf_dynptr_set_null(ptr);
+		return err;
+	}
+
+	rb_map = container_of(map, struct bpf_ringbuf_map, map);
+
+	sample = __bpf_ringbuf_reserve(rb_map->rb, size);
+	if (!sample) {
+		bpf_dynptr_set_null(ptr);
+		return -EINVAL;
+	}
+
+	bpf_dynptr_init(ptr, sample, BPF_DYNPTR_TYPE_RINGBUF, 0, size);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_ringbuf_reserve_dynptr_proto = {
+	.func		= bpf_ringbuf_reserve_dynptr,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_CONST_MAP_PTR,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | MEM_UNINIT,
+};
+
+BPF_CALL_2(bpf_ringbuf_submit_dynptr, struct bpf_dynptr_kern *, ptr, u64, flags)
+{
+	if (!ptr->data)
+		return 0;
+
+	bpf_ringbuf_commit(ptr->data, flags, false /* discard */);
+
+	bpf_dynptr_set_null(ptr);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_ringbuf_submit_dynptr_proto = {
+	.func		= bpf_ringbuf_submit_dynptr,
+	.ret_type	= RET_VOID,
+	.arg1_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | OBJ_RELEASE,
+	.arg2_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_2(bpf_ringbuf_discard_dynptr, struct bpf_dynptr_kern *, ptr, u64, flags)
+{
+	if (!ptr->data)
+		return 0;
+
+	bpf_ringbuf_commit(ptr->data, flags, true /* discard */);
+
+	bpf_dynptr_set_null(ptr);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_ringbuf_discard_dynptr_proto = {
+	.func		= bpf_ringbuf_discard_dynptr,
+	.ret_type	= RET_VOID,
+	.arg1_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | OBJ_RELEASE,
+	.arg2_type	= ARG_ANYTHING,
+};
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 45153cbc2bd6..aedac2ac02b9 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -187,6 +187,9 @@ struct bpf_verifier_stack_elem {
 					  POISON_POINTER_DELTA))
 #define BPF_MAP_PTR(X)		((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
 
+static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx);
+static int release_reference(struct bpf_verifier_env *env, int ref_obj_id);
+
 static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
 {
 	return BPF_MAP_PTR(aux->map_ptr_state) == BPF_MAP_PTR_POISON;
@@ -259,6 +262,7 @@ struct bpf_call_arg_meta {
 	u32 ret_btf_id;
 	u32 subprogno;
 	struct bpf_map_value_off_desc *kptr_off_desc;
+	u8 uninit_dynptr_regno;
 };
 
 struct btf *btf_vmlinux;
@@ -581,6 +585,7 @@ static char slot_type_char[] = {
 	[STACK_SPILL]	= 'r',
 	[STACK_MISC]	= 'm',
 	[STACK_ZERO]	= '0',
+	[STACK_DYNPTR]	= 'd',
 };
 
 static void print_liveness(struct bpf_verifier_env *env,
@@ -596,6 +601,25 @@ static void print_liveness(struct bpf_verifier_env *env,
 		verbose(env, "D");
 }
 
+static int get_spi(s32 off)
+{
+	return (-off - 1) / BPF_REG_SIZE;
+}
+
+static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots)
+{
+	int allocated_slots = state->allocated_stack / BPF_REG_SIZE;
+
+	/* We need to check that slots between [spi - nr_slots + 1, spi] are
+	 * within [0, allocated_stack).
+	 *
+	 * Please note that the spi grows downwards. For example, a dynptr
+	 * takes the size of two stack slots; the first slot will be at
+	 * spi and the second slot will be at spi - 1.
+	 */
+	return spi - nr_slots + 1 >= 0 && spi < allocated_slots;
+}
+
 static struct bpf_func_state *func(struct bpf_verifier_env *env,
 				   const struct bpf_reg_state *reg)
 {
@@ -647,6 +671,132 @@ static void mark_verifier_state_scratched(struct bpf_verifier_env *env)
 	env->scratched_stack_slots = ~0ULL;
 }
 
+static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
+{
+	switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
+	case DYNPTR_TYPE_LOCAL:
+		return BPF_DYNPTR_TYPE_LOCAL;
+	case DYNPTR_TYPE_RINGBUF:
+		return BPF_DYNPTR_TYPE_RINGBUF;
+	default:
+		return BPF_DYNPTR_TYPE_INVALID;
+	}
+}
+
+static bool dynptr_type_refcounted(enum bpf_dynptr_type type)
+{
+	return type == BPF_DYNPTR_TYPE_RINGBUF;
+}
+
+static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
+				   enum bpf_arg_type arg_type, int insn_idx)
+{
+	struct bpf_func_state *state = func(env, reg);
+	enum bpf_dynptr_type type;
+	int spi, i, id;
+
+	spi = get_spi(reg->off);
+
+	if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS))
+		return -EINVAL;
+
+	for (i = 0; i < BPF_REG_SIZE; i++) {
+		state->stack[spi].slot_type[i] = STACK_DYNPTR;
+		state->stack[spi - 1].slot_type[i] = STACK_DYNPTR;
+	}
+
+	type = arg_to_dynptr_type(arg_type);
+	if (type == BPF_DYNPTR_TYPE_INVALID)
+		return -EINVAL;
+
+	state->stack[spi].spilled_ptr.dynptr.first_slot = true;
+	state->stack[spi].spilled_ptr.dynptr.type = type;
+	state->stack[spi - 1].spilled_ptr.dynptr.type = type;
+
+	if (dynptr_type_refcounted(type)) {
+		/* The id is used to track proper releasing */
+		id = acquire_reference_state(env, insn_idx);
+		if (id < 0)
+			return id;
+
+		state->stack[spi].spilled_ptr.id = id;
+		state->stack[spi - 1].spilled_ptr.id = id;
+	}
+
+	return 0;
+}
+
+static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
+{
+	struct bpf_func_state *state = func(env, reg);
+	int spi, i;
+
+	spi = get_spi(reg->off);
+
+	if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS))
+		return -EINVAL;
+
+	for (i = 0; i < BPF_REG_SIZE; i++) {
+		state->stack[spi].slot_type[i] = STACK_INVALID;
+		state->stack[spi - 1].slot_type[i] = STACK_INVALID;
+	}
+
+	/* Invalidate any slices associated with this dynptr */
+	if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
+		release_reference(env, state->stack[spi].spilled_ptr.id);
+		state->stack[spi].spilled_ptr.id = 0;
+		state->stack[spi - 1].spilled_ptr.id = 0;
+	}
+
+	state->stack[spi].spilled_ptr.dynptr.first_slot = false;
+	state->stack[spi].spilled_ptr.dynptr.type = 0;
+	state->stack[spi - 1].spilled_ptr.dynptr.type = 0;
+
+	return 0;
+}
+
+static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
+{
+	struct bpf_func_state *state = func(env, reg);
+	int spi = get_spi(reg->off);
+	int i;
+
+	if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS))
+		return true;
+
+	for (i = 0; i < BPF_REG_SIZE; i++) {
+		if (state->stack[spi].slot_type[i] == STACK_DYNPTR ||
+		    state->stack[spi - 1].slot_type[i] == STACK_DYNPTR)
+			return false;
+	}
+
+	return true;
+}
+
+static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
+				     enum bpf_arg_type arg_type)
+{
+	struct bpf_func_state *state = func(env, reg);
+	int spi = get_spi(reg->off);
+	int i;
+
+	if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS) ||
+	    !state->stack[spi].spilled_ptr.dynptr.first_slot)
+		return false;
+
+	for (i = 0; i < BPF_REG_SIZE; i++) {
+		if (state->stack[spi].slot_type[i] != STACK_DYNPTR ||
+		    state->stack[spi - 1].slot_type[i] != STACK_DYNPTR)
+			return false;
+	}
+
+	/* ARG_PTR_TO_DYNPTR takes any type of dynptr */
+	if (arg_type == ARG_PTR_TO_DYNPTR)
+		return true;
+
+	return state->stack[spi].spilled_ptr.dynptr.type == arg_to_dynptr_type(arg_type);
+}
+
 /* The reg state of a pointer or a bounded scalar was saved when
  * it was spilled to the stack.
  */
@@ -5400,6 +5550,11 @@ static bool arg_type_is_release(enum bpf_arg_type type)
 	return type & OBJ_RELEASE;
 }
 
+static bool arg_type_is_dynptr(enum bpf_arg_type type)
+{
+	return base_type(type) == ARG_PTR_TO_DYNPTR;
+}
+
 static int int_ptr_type_to_size(enum bpf_arg_type type)
 {
 	if (type == ARG_PTR_TO_INT)
@@ -5539,6 +5694,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 	[ARG_PTR_TO_CONST_STR]		= &const_str_ptr_types,
 	[ARG_PTR_TO_TIMER]		= &timer_types,
 	[ARG_PTR_TO_KPTR]		= &kptr_types,
+	[ARG_PTR_TO_DYNPTR]		= &stack_ptr_types,
 };
 
 static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
@@ -5628,8 +5784,13 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
 	bool fixed_off_ok = false;
 
 	switch ((u32)type) {
-	case SCALAR_VALUE:
 	/* Pointer types where reg offset is explicitly allowed: */
+	case PTR_TO_STACK:
+		if (arg_type_is_dynptr(arg_type) && reg->off % BPF_REG_SIZE) {
+			verbose(env, "cannot pass in dynptr at an offset\n");
+			return -EINVAL;
+		}
+		fallthrough;
 	case PTR_TO_PACKET:
 	case PTR_TO_PACKET_META:
 	case PTR_TO_MAP_KEY:
@@ -5639,7 +5800,7 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
 	case PTR_TO_MEM | MEM_ALLOC:
 	case PTR_TO_BUF:
 	case PTR_TO_BUF | MEM_RDONLY:
-	case PTR_TO_STACK:
+	case SCALAR_VALUE:
 		/* Some of the argument types nevertheless require a
 		 * zero register offset.
 		 */
@@ -5671,6 +5832,14 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
 	return __check_ptr_off_reg(env, reg, regno, fixed_off_ok);
 }
 
+static u32 stack_slot_get_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
+{
+	struct bpf_func_state *state = func(env, reg);
+	int spi = get_spi(reg->off);
+
+	return state->stack[spi].spilled_ptr.id;
+}
+
 static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			  struct bpf_call_arg_meta *meta,
 			  const struct bpf_func_proto *fn)
@@ -5725,7 +5894,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 
 skip_type_check:
 	if (arg_type_is_release(arg_type)) {
-		if (!reg->ref_obj_id && !register_is_null(reg)) {
+		if (arg_type_is_dynptr(arg_type)) {
+			struct bpf_func_state *state = func(env, reg);
+			int spi = get_spi(reg->off);
+
+			if (!is_spi_bounds_valid(state, spi, BPF_DYNPTR_NR_SLOTS) ||
+			    !state->stack[spi].spilled_ptr.id) {
+				verbose(env, "arg %d is an unacquired reference\n", regno);
+				return -EINVAL;
+			}
+		} else if (!reg->ref_obj_id && !register_is_null(reg)) {
 			verbose(env, "R%d must be referenced when passed to release function\n",
 				regno);
 			return -EINVAL;
@@ -5837,6 +6015,40 @@ skip_type_check:
 		bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
 
 		err = check_mem_size_reg(env, reg, regno, zero_size_allowed, meta);
+	} else if (arg_type_is_dynptr(arg_type)) {
+		if (arg_type & MEM_UNINIT) {
+			if (!is_dynptr_reg_valid_uninit(env, reg)) {
+				verbose(env, "Dynptr has to be an uninitialized dynptr\n");
+				return -EINVAL;
+			}
+
+			/* We only support one dynptr being uninitialized at the moment,
+			 * which is sufficient for the helper functions we have right now.
+			 */
+			if (meta->uninit_dynptr_regno) {
+				verbose(env, "verifier internal error: multiple uninitialized dynptr args\n");
+				return -EFAULT;
+			}
+
+			meta->uninit_dynptr_regno = regno;
+		} else if (!is_dynptr_reg_valid_init(env, reg, arg_type)) {
+			const char *err_extra = "";
+
+			switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
+			case DYNPTR_TYPE_LOCAL:
+				err_extra = "local ";
+				break;
+			case DYNPTR_TYPE_RINGBUF:
+				err_extra = "ringbuf ";
+				break;
+			default:
+				break;
+			}
+
+			verbose(env, "Expected an initialized %sdynptr as arg #%d\n",
+				err_extra, arg + 1);
+			return -EINVAL;
+		}
 	} else if (arg_type_is_alloc_size(arg_type)) {
 		if (!tnum_is_const(reg->var_off)) {
 			verbose(env, "R%d is not a known constant'\n",
@@ -5958,7 +6170,10 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 	case BPF_MAP_TYPE_RINGBUF:
 		if (func_id != BPF_FUNC_ringbuf_output &&
 		    func_id != BPF_FUNC_ringbuf_reserve &&
-		    func_id != BPF_FUNC_ringbuf_query)
+		    func_id != BPF_FUNC_ringbuf_query &&
+		    func_id != BPF_FUNC_ringbuf_reserve_dynptr &&
+		    func_id != BPF_FUNC_ringbuf_submit_dynptr &&
+		    func_id != BPF_FUNC_ringbuf_discard_dynptr)
 			goto error;
 		break;
 	case BPF_MAP_TYPE_STACK_TRACE:
@@ -6074,6 +6289,9 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 	case BPF_FUNC_ringbuf_output:
 	case BPF_FUNC_ringbuf_reserve:
 	case BPF_FUNC_ringbuf_query:
+	case BPF_FUNC_ringbuf_reserve_dynptr:
+	case BPF_FUNC_ringbuf_submit_dynptr:
+	case BPF_FUNC_ringbuf_discard_dynptr:
 		if (map->map_type != BPF_MAP_TYPE_RINGBUF)
 			goto error;
 		break;
@@ -6970,9 +7188,27 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 
 	regs = cur_regs(env);
 
+	if (meta.uninit_dynptr_regno) {
+		/* we write BPF_DW bits (8 bytes) at a time */
+		for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) {
+			err = check_mem_access(env, insn_idx, meta.uninit_dynptr_regno,
+					       i, BPF_DW, BPF_WRITE, -1, false);
+			if (err)
+				return err;
+		}
+
+		err = mark_stack_slots_dynptr(env, &regs[meta.uninit_dynptr_regno],
+					      fn->arg_type[meta.uninit_dynptr_regno - BPF_REG_1],
+					      insn_idx);
+		if (err)
+			return err;
+	}
+