Merge branch 'Introduce composable bpf types'

Hao Luo says:

====================
This patch set consists of two changes:

 - a cleanup of arg_type, ret_type and reg_type which try to make those
   types composable. (patch 1/9 - patch 6/9)
 - a bug fix that prevents bpf programs from writing kernel memory.
   (patch 7/9 - patch 9/9)

The purpose of the cleanup is to find a scalable way to express type
nullness and read-onliness. This patchset introduces two flags that
can be applied on all three types: PTR_MAYBE_NULL and MEM_RDONLY.
Previous types such as ARG_XXX_OR_NULL can now be written as

 ARG_XXX | PTR_MAYBE_NULL

Similarly, PTR_TO_RDONLY_BUF is now "PTR_TO_BUF | MEM_RDONLY".

Flags can be composed, as ARGs can be both MEM_RDONLY and MAYBE_NULL.

 ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY

Based on this new composable types, patch 7/9 applies MEM_RDONLY on
PTR_TO_MEM, in order to tag the returned memory from per_cpu_ptr as
read-only. Therefore fixing a previous bug that one can leverage
per_cpu_ptr to modify kernel memory within BPF programs.

Patch 8/9 generalizes the use of MEM_RDONLY further by tagging a set of
helper arguments ARG_PTR_TO_MEM with MEM_RDONLY. Some helper functions
may override their arguments, such as bpf_d_path, bpf_snprintf. In this
patch, we narrow the ARG_PTR_TO_MEM to be compatible with only a subset
of memory types. This prevents these helpers from writing read-only
memories. For the helpers that do not write its arguments, we add tag
MEM_RDONLY to allow taking a RDONLY memory as argument.

Changes since v1:
 - use %u to print base_type(type) instead of %lu. (Andrii, patch 3/9)
 - improve reg_type_str() by appending '_or_null' and prepending 'rdonly_'.
   use preallocated buffer in 'bpf_env'.
 - unified handling of the previous XXX_OR_NULL in adjust_ptr_min_max_vals
   (Andrii, patch 4/9)
 - move PTR_TO_MAP_KEY up to PTR_TO_MAP_VALUE so that we don't have
   to change to drivers that assume the numeric values of bpf_reg.
   (patch 4/9)
 - reintroduce the typo from previous commits in fixes tags (Andrii, patch 7/9)
 - extensive comments on the reason behind folding flags in
   check_reg_type (Andrii, patch 8/9)

Changes since RFC v2:
 - renamed BPF_BASE_TYPE to a more succinct name base_type and move its
   definition to bpf_verifier.h. Same for BPF_TYPE_FLAG. (Alexei)
 - made checking MEM_RDONLY in check_reg_type() universal (Alexei)
 - ran through majority of test_progs and fixed bugs in RFC v2:
   - fixed incorrect BPF_BASE_TYPE_MASK. The high bit of GENMASK should
     be BITS - 1, rather than BITS. patch 1/9.
   - fixed incorrect conditions when checking ARG_PTR_TO_MAP_VALUE in
     check_func_arg(). See patch 2/9.
   - fixed a bug where PTR_TO_BTF_ID may be combined with MEM_RDONLY,
     causing the check in check_mem_access() to fall through to the
     'else' branch. See check_helper_call() in patch 7/9.
 - fixed build failure on netronome driver. Entries in bpf_reg_type have
   been ordered. patch 4/9.
 - fixed build warnings of using '%d' to print base_type. patch 4/9
 - unify arg_type_may_be_null() and reg_type_may_be_null() into a single
   type_may_be_null().

Previous versions:

 v1:
   https://lwn.net/Articles/877938/

 RFC v2:
   https://lwn.net/Articles/877171/

 RFC v1:
   https://lore.kernel.org/bpf/20211109003052.3499225-1-haoluo@google.com/T/
   https://lore.kernel.org/bpf/20211109021624.1140446-8-haoluo@google.com/T/
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

15 files changed, 443 insertions, 335 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 965fffaf0308..26753139d5b4 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -297,6 +297,34 @@ bool bpf_map_meta_equal(const struct bpf_map *meta0,
 
 extern const struct bpf_map_ops bpf_map_offload_ops;
 
+/* bpf_type_flag contains a set of flags that are applicable to the values of
+ * arg_type, ret_type and reg_type. For example, a pointer value may be null,
+ * or a memory is read-only. We classify types into two categories: base types
+ * and extended types. Extended types are base types combined with a type flag.
+ *
+ * Currently there are no more than 32 base types in arg_type, ret_type and
+ * reg_types.
+ */
+#define BPF_BASE_TYPE_BITS	8
+
+enum bpf_type_flag {
+	/* PTR may be NULL. */
+	PTR_MAYBE_NULL		= BIT(0 + BPF_BASE_TYPE_BITS),
+
+	/* MEM is read-only. When applied on bpf_arg, it indicates the arg is
+	 * compatible with both mutable and immutable memory.
+	 */
+	MEM_RDONLY		= BIT(1 + BPF_BASE_TYPE_BITS),
+
+	__BPF_TYPE_LAST_FLAG	= MEM_RDONLY,
+};
+
+/* Max number of base types. */
+#define BPF_BASE_TYPE_LIMIT	(1UL << BPF_BASE_TYPE_BITS)
+
+/* Max number of all types. */
+#define BPF_TYPE_LIMIT		(__BPF_TYPE_LAST_FLAG | (__BPF_TYPE_LAST_FLAG - 1))
+
 /* function argument constraints */
 enum bpf_arg_type {
 	ARG_DONTCARE = 0,	/* unused argument in helper function */
@@ -308,13 +336,11 @@ enum bpf_arg_type {
 	ARG_PTR_TO_MAP_KEY,	/* pointer to stack used as map key */
 	ARG_PTR_TO_MAP_VALUE,	/* pointer to stack used as map value */
 	ARG_PTR_TO_UNINIT_MAP_VALUE,	/* pointer to valid memory used to store a map value */
-	ARG_PTR_TO_MAP_VALUE_OR_NULL,	/* pointer to stack used as map value or NULL */
 
 	/* the following constraints used to prototype bpf_memcmp() and other
 	 * functions that access data on eBPF program stack
 	 */
 	ARG_PTR_TO_MEM,		/* pointer to valid memory (stack, packet, map value) */
-	ARG_PTR_TO_MEM_OR_NULL, /* pointer to valid memory or NULL */
 	ARG_PTR_TO_UNINIT_MEM,	/* pointer to memory does not need to be initialized,
 				 * helper function must fill all bytes or clear
 				 * them in error case.
@@ -324,42 +350,65 @@ enum bpf_arg_type {
 	ARG_CONST_SIZE_OR_ZERO,	/* number of bytes accessed from memory or 0 */
 
 	ARG_PTR_TO_CTX,		/* pointer to context */
-	ARG_PTR_TO_CTX_OR_NULL,	/* pointer to context or NULL */
 	ARG_ANYTHING,		/* any (initialized) argument is ok */
 	ARG_PTR_TO_SPIN_LOCK,	/* pointer to bpf_spin_lock */
 	ARG_PTR_TO_SOCK_COMMON,	/* pointer to sock_common */
 	ARG_PTR_TO_INT,		/* pointer to int */
 	ARG_PTR_TO_LONG,	/* pointer to long */
 	ARG_PTR_TO_SOCKET,	/* pointer to bpf_sock (fullsock) */
-	ARG_PTR_TO_SOCKET_OR_NULL,	/* pointer to bpf_sock (fullsock) or NULL */
 	ARG_PTR_TO_BTF_ID,	/* pointer to in-kernel struct */
 	ARG_PTR_TO_ALLOC_MEM,	/* pointer to dynamically allocated memory */
-	ARG_PTR_TO_ALLOC_MEM_OR_NULL,	/* pointer to dynamically allocated memory or NULL */
 	ARG_CONST_ALLOC_SIZE_OR_ZERO,	/* number of allocated bytes requested */
 	ARG_PTR_TO_BTF_ID_SOCK_COMMON,	/* pointer to in-kernel sock_common or bpf-mirrored bpf_sock */
 	ARG_PTR_TO_PERCPU_BTF_ID,	/* pointer to in-kernel percpu type */
 	ARG_PTR_TO_FUNC,	/* pointer to a bpf program function */
-	ARG_PTR_TO_STACK_OR_NULL,	/* pointer to stack or NULL */
+	ARG_PTR_TO_STACK,	/* pointer to stack */
 	ARG_PTR_TO_CONST_STR,	/* pointer to a null terminated read-only string */
 	ARG_PTR_TO_TIMER,	/* pointer to bpf_timer */
 	__BPF_ARG_TYPE_MAX,
+
+	/* Extended arg_types. */
+	ARG_PTR_TO_MAP_VALUE_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_MAP_VALUE,
+	ARG_PTR_TO_MEM_OR_NULL		= PTR_MAYBE_NULL | ARG_PTR_TO_MEM,
+	ARG_PTR_TO_CTX_OR_NULL		= PTR_MAYBE_NULL | ARG_PTR_TO_CTX,
+	ARG_PTR_TO_SOCKET_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_SOCKET,
+	ARG_PTR_TO_ALLOC_MEM_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_ALLOC_MEM,
+	ARG_PTR_TO_STACK_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_STACK,
+
+	/* This must be the last entry. Its purpose is to ensure the enum is
+	 * wide enough to hold the higher bits reserved for bpf_type_flag.
+	 */
+	__BPF_ARG_TYPE_LIMIT	= BPF_TYPE_LIMIT,
 };
+static_assert(__BPF_ARG_TYPE_MAX <= BPF_BASE_TYPE_LIMIT);
 
 /* type of values returned from helper functions */
 enum bpf_return_type {
 	RET_INTEGER,			/* function returns integer */
 	RET_VOID,			/* function doesn't return anything */
 	RET_PTR_TO_MAP_VALUE,		/* returns a pointer to map elem value */
-	RET_PTR_TO_MAP_VALUE_OR_NULL,	/* returns a pointer to map elem value or NULL */
-	RET_PTR_TO_SOCKET_OR_NULL,	/* returns a pointer to a socket or NULL */
-	RET_PTR_TO_TCP_SOCK_OR_NULL,	/* returns a pointer to a tcp_sock or NULL */
-	RET_PTR_TO_SOCK_COMMON_OR_NULL,	/* returns a pointer to a sock_common or NULL */
-	RET_PTR_TO_ALLOC_MEM_OR_NULL,	/* returns a pointer to dynamically allocated memory or NULL */
-	RET_PTR_TO_BTF_ID_OR_NULL,	/* returns a pointer to a btf_id or NULL */
-	RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL, /* returns a pointer to a valid memory or a btf_id or NULL */
+	RET_PTR_TO_SOCKET,		/* returns a pointer to a socket */
+	RET_PTR_TO_TCP_SOCK,		/* returns a pointer to a tcp_sock */
+	RET_PTR_TO_SOCK_COMMON,		/* returns a pointer to a sock_common */
+	RET_PTR_TO_ALLOC_MEM,		/* returns a pointer to dynamically allocated memory */
 	RET_PTR_TO_MEM_OR_BTF_ID,	/* returns a pointer to a valid memory or a btf_id */
 	RET_PTR_TO_BTF_ID,		/* returns a pointer to a btf_id */
+	__BPF_RET_TYPE_MAX,
+
+	/* Extended ret_types. */
+	RET_PTR_TO_MAP_VALUE_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_MAP_VALUE,
+	RET_PTR_TO_SOCKET_OR_NULL	= PTR_MAYBE_NULL | RET_PTR_TO_SOCKET,
+	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 | 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
+	 * wide enough to hold the higher bits reserved for bpf_type_flag.
+	 */
+	__BPF_RET_TYPE_LIMIT	= BPF_TYPE_LIMIT,
 };
+static_assert(__BPF_RET_TYPE_MAX <= BPF_BASE_TYPE_LIMIT);
 
 /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
  * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
@@ -421,18 +470,15 @@ enum bpf_reg_type {
 	PTR_TO_CTX,		 /* reg points to bpf_context */
 	CONST_PTR_TO_MAP,	 /* reg points to struct bpf_map */
 	PTR_TO_MAP_VALUE,	 /* reg points to map element value */
-	PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
+	PTR_TO_MAP_KEY,		 /* reg points to a map element key */
 	PTR_TO_STACK,		 /* reg == frame_pointer + offset */
 	PTR_TO_PACKET_META,	 /* skb->data - meta_len */
 	PTR_TO_PACKET,		 /* reg points to skb->data */
 	PTR_TO_PACKET_END,	 /* skb->data + headlen */
 	PTR_TO_FLOW_KEYS,	 /* reg points to bpf_flow_keys */
 	PTR_TO_SOCKET,		 /* reg points to struct bpf_sock */
-	PTR_TO_SOCKET_OR_NULL,	 /* reg points to struct bpf_sock or NULL */
 	PTR_TO_SOCK_COMMON,	 /* reg points to sock_common */
-	PTR_TO_SOCK_COMMON_OR_NULL, /* reg points to sock_common or NULL */
 	PTR_TO_TCP_SOCK,	 /* reg points to struct tcp_sock */
-	PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */
 	PTR_TO_TP_BUFFER,	 /* reg points to a writable raw tp's buffer */
 	PTR_TO_XDP_SOCK,	 /* reg points to struct xdp_sock */
 	/* PTR_TO_BTF_ID points to a kernel struct that does not need
@@ -450,18 +496,25 @@ enum bpf_reg_type {
 	 * been checked for null. Used primarily to inform the verifier
 	 * an explicit null check is required for this struct.
 	 */
-	PTR_TO_BTF_ID_OR_NULL,
 	PTR_TO_MEM,		 /* reg points to valid memory region */
-	PTR_TO_MEM_OR_NULL,	 /* reg points to valid memory region or NULL */
-	PTR_TO_RDONLY_BUF,	 /* reg points to a readonly buffer */
-	PTR_TO_RDONLY_BUF_OR_NULL, /* reg points to a readonly buffer or NULL */
-	PTR_TO_RDWR_BUF,	 /* reg points to a read/write buffer */
-	PTR_TO_RDWR_BUF_OR_NULL, /* reg points to a read/write buffer or NULL */
+	PTR_TO_BUF,		 /* reg points to a read/write buffer */
 	PTR_TO_PERCPU_BTF_ID,	 /* reg points to a percpu kernel variable */
 	PTR_TO_FUNC,		 /* reg points to a bpf program function */
-	PTR_TO_MAP_KEY,		 /* reg points to a map element key */
 	__BPF_REG_TYPE_MAX,
+
+	/* Extended reg_types. */
+	PTR_TO_MAP_VALUE_OR_NULL	= PTR_MAYBE_NULL | PTR_TO_MAP_VALUE,
+	PTR_TO_SOCKET_OR_NULL		= PTR_MAYBE_NULL | PTR_TO_SOCKET,
+	PTR_TO_SOCK_COMMON_OR_NULL	= PTR_MAYBE_NULL | PTR_TO_SOCK_COMMON,
+	PTR_TO_TCP_SOCK_OR_NULL		= PTR_MAYBE_NULL | PTR_TO_TCP_SOCK,
+	PTR_TO_BTF_ID_OR_NULL		= PTR_MAYBE_NULL | PTR_TO_BTF_ID,
+
+	/* This must be the last entry. Its purpose is to ensure the enum is
+	 * wide enough to hold the higher bits reserved for bpf_type_flag.
+	 */
+	__BPF_REG_TYPE_LIMIT	= BPF_TYPE_LIMIT,
 };
+static_assert(__BPF_REG_TYPE_MAX <= BPF_BASE_TYPE_LIMIT);
 
 /* The information passed from prog-specific *_is_valid_access
  * back to the verifier.
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index ee931398f311..143401d4c9d9 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -18,6 +18,8 @@
  * that converting umax_value to int cannot overflow.
  */
 #define BPF_MAX_VAR_SIZ	(1 << 29)
+/* size of type_str_buf in bpf_verifier. */
+#define TYPE_STR_BUF_LEN 64
 
 /* Liveness marks, used for registers and spilled-regs (in stack slots).
  * Read marks propagate upwards until they find a write mark; they record that
@@ -484,6 +486,8 @@ struct bpf_verifier_env {
 	/* Same as scratched_regs but for stack slots */
 	u64 scratched_stack_slots;
 	u32 prev_log_len, prev_insn_print_len;
+	/* buffer used in reg_type_str() to generate reg_type string */
+	char type_str_buf[TYPE_STR_BUF_LEN];
 };
 
 __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log,
@@ -546,5 +550,18 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 			    struct bpf_attach_target_info *tgt_info);
 void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab);
 
+#define BPF_BASE_TYPE_MASK	GENMASK(BPF_BASE_TYPE_BITS - 1, 0)
+
+/* extract base type from bpf_{arg, return, reg}_type. */
+static inline u32 base_type(u32 type)
+{
+	return type & BPF_BASE_TYPE_MASK;
+}
+
+/* extract flags from an extended type. See bpf_type_flag in bpf.h. */
+static inline u32 type_flag(u32 type)
+{
+	return type & ~BPF_BASE_TYPE_MASK;
+}
 
 #endif /* _LINUX_BPF_VERIFIER_H */
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index a17de71abd2e..b3fddfb5bc84 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4940,10 +4940,12 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
 	/* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */
 	for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
 		const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
+		u32 type, flag;
 
-		if (ctx_arg_info->offset == off &&
-		    (ctx_arg_info->reg_type == PTR_TO_RDONLY_BUF_OR_NULL ||
-		     ctx_arg_info->reg_type == PTR_TO_RDWR_BUF_OR_NULL)) {
+		type = base_type(ctx_arg_info->reg_type);
+		flag = type_flag(ctx_arg_info->reg_type);
+		if (ctx_arg_info->offset == off && type == PTR_TO_BUF &&
+		    (flag & PTR_MAYBE_NULL)) {
 			info->reg_type = ctx_arg_info->reg_type;
 			return true;
 		}
@@ -5857,7 +5859,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
 				return -EINVAL;
 			}
 
-			reg->type = PTR_TO_MEM_OR_NULL;
+			reg->type = PTR_TO_MEM | PTR_MAYBE_NULL;
 			reg->id = ++env->id_gen;
 
 			continue;
@@ -6351,7 +6353,7 @@ const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
 	.func		= bpf_btf_find_by_name_kind,
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM,
+	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
 	.arg3_type	= ARG_ANYTHING,
 	.arg4_type	= ARG_ANYTHING,
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 43eb3501721b..514b4681a90a 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1789,7 +1789,7 @@ static const struct bpf_func_proto bpf_sysctl_set_new_value_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 34d6f91dec1c..01cfdf40c838 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -531,7 +531,7 @@ const struct bpf_func_proto bpf_strtol_proto = {
 	.func		= bpf_strtol,
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM,
+	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
 	.arg3_type	= ARG_ANYTHING,
 	.arg4_type	= ARG_PTR_TO_LONG,
@@ -559,7 +559,7 @@ const struct bpf_func_proto bpf_strtoul_proto = {
 	.func		= bpf_strtoul,
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM,
+	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
 	.arg3_type	= ARG_ANYTHING,
 	.arg4_type	= ARG_PTR_TO_LONG,
@@ -645,7 +645,7 @@ const struct bpf_func_proto bpf_event_output_data_proto =  {
 	.arg1_type      = ARG_PTR_TO_CTX,
 	.arg2_type      = ARG_CONST_MAP_PTR,
 	.arg3_type      = ARG_ANYTHING,
-	.arg4_type      = ARG_PTR_TO_MEM,
+	.arg4_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type      = ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -682,7 +682,7 @@ BPF_CALL_2(bpf_per_cpu_ptr, const void *, ptr, u32, cpu)
 const struct bpf_func_proto bpf_per_cpu_ptr_proto = {
 	.func		= bpf_per_cpu_ptr,
 	.gpl_only	= false,
-	.ret_type	= RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL,
+	.ret_type	= RET_PTR_TO_MEM_OR_BTF_ID | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg1_type	= ARG_PTR_TO_PERCPU_BTF_ID,
 	.arg2_type	= ARG_ANYTHING,
 };
@@ -695,7 +695,7 @@ BPF_CALL_1(bpf_this_cpu_ptr, const void *, percpu_ptr)
 const struct bpf_func_proto bpf_this_cpu_ptr_proto = {
 	.func		= bpf_this_cpu_ptr,
 	.gpl_only	= false,
-	.ret_type	= RET_PTR_TO_MEM_OR_BTF_ID,
+	.ret_type	= RET_PTR_TO_MEM_OR_BTF_ID | MEM_RDONLY,
 	.arg1_type	= ARG_PTR_TO_PERCPU_BTF_ID,
 };
 
@@ -1026,7 +1026,7 @@ const struct bpf_func_proto bpf_snprintf_proto = {
 	.arg1_type	= ARG_PTR_TO_MEM_OR_NULL,
 	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg3_type	= ARG_PTR_TO_CONST_STR,
-	.arg4_type	= ARG_PTR_TO_MEM_OR_NULL,
+	.arg4_type	= ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
diff --git a/kernel/bpf/map_iter.c b/kernel/bpf/map_iter.c
index 6a9542af4212..b0fa190b0979 100644
--- a/kernel/bpf/map_iter.c
+++ b/kernel/bpf/map_iter.c
@@ -174,9 +174,9 @@ static const struct bpf_iter_reg bpf_map_elem_reg_info = {
 	.ctx_arg_info_size	= 2,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__bpf_map_elem, key),
-		  PTR_TO_RDONLY_BUF_OR_NULL },
+		  PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
 		{ offsetof(struct bpf_iter__bpf_map_elem, value),
-		  PTR_TO_RDWR_BUF_OR_NULL },
+		  PTR_TO_BUF | PTR_MAYBE_NULL },
 	},
 };
 
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 9e0c10c6892a..638d7fd7b375 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -444,7 +444,7 @@ const struct bpf_func_proto bpf_ringbuf_output_proto = {
 	.func		= bpf_ringbuf_output,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_CONST_MAP_PTR,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 };
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index da07bdf71697..fa4505f9b611 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4773,7 +4773,7 @@ static const struct bpf_func_proto bpf_sys_bpf_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_ANYTHING,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 07d7d6124a18..ca5cd0de804c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -442,18 +442,6 @@ static bool reg_type_not_null(enum bpf_reg_type type)
 		type == PTR_TO_SOCK_COMMON;
 }
 
-static bool reg_type_may_be_null(enum bpf_reg_type type)
-{
-	return type == PTR_TO_MAP_VALUE_OR_NULL ||
-	       type == PTR_TO_SOCKET_OR_NULL ||
-	       type == PTR_TO_SOCK_COMMON_OR_NULL ||
-	       type == PTR_TO_TCP_SOCK_OR_NULL ||
-	       type == PTR_TO_BTF_ID_OR_NULL ||
-	       type == PTR_TO_MEM_OR_NULL ||
-	       type == PTR_TO_RDONLY_BUF_OR_NULL ||
-	       type == PTR_TO_RDWR_BUF_OR_NULL;
-}
-
 static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
 {
 	return reg->type == PTR_TO_MAP_VALUE &&
@@ -462,12 +450,14 @@ static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
 
 static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type)
 {
-	return type == PTR_TO_SOCKET ||
-		type == PTR_TO_SOCKET_OR_NULL ||
-		type == PTR_TO_TCP_SOCK ||
-		type == PTR_TO_TCP_SOCK_OR_NULL ||
-		type == PTR_TO_MEM ||
-		type == PTR_TO_MEM_OR_NULL;
+	return base_type(type) == PTR_TO_SOCKET ||
+		base_type(type) == PTR_TO_TCP_SOCK ||
+		base_type(type) == PTR_TO_MEM;
+}
+
+static bool type_is_rdonly_mem(u32 type)
+{
+	return type & MEM_RDONLY;
 }
 
 static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
@@ -475,14 +465,9 @@ static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
 	return type == ARG_PTR_TO_SOCK_COMMON;
 }
 
-static bool arg_type_may_be_null(enum bpf_arg_type type)
+static bool type_may_be_null(u32 type)
 {
-	return type == ARG_PTR_TO_MAP_VALUE_OR_NULL ||
-	       type == ARG_PTR_TO_MEM_OR_NULL ||
-	       type == ARG_PTR_TO_CTX_OR_NULL ||
-	       type == ARG_PTR_TO_SOCKET_OR_NULL ||
-	       type == ARG_PTR_TO_ALLOC_MEM_OR_NULL ||
-	       type == ARG_PTR_TO_STACK_OR_NULL;
+	return type & PTR_MAYBE_NULL;
 }
 
 /* Determine whether the function releases some resources allocated by another
@@ -542,39 +527,54 @@ static bool is_cmpxchg_insn(const struct bpf_insn *insn)
 	       insn->imm == BPF_CMPXCHG;
 }
 
-/* string representation of 'enum bpf_reg_type' */
-static const char * const reg_type_str[] = {
-	[NOT_INIT]		= "?",
-	[SCALAR_VALUE]		= "inv",
-	[PTR_TO_CTX]		= "ctx",
-	[CONST_PTR_TO_MAP]	= "map_ptr",
-	[PTR_TO_MAP_VALUE]	= "map_value",
-	[PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
-	[PTR_TO_STACK]		= "fp",
-	[PTR_TO_PACKET]		= "pkt",
-	[PTR_TO_PACKET_META]	= "pkt_meta",
-	[PTR_TO_PACKET_END]	= "pkt_end",
-	[PTR_TO_FLOW_KEYS]	= "flow_keys",
-	[PTR_TO_SOCKET]		= "sock",
-	[PTR_TO_SOCKET_OR_NULL] = "sock_or_null",
-	[PTR_TO_SOCK_COMMON]	= "sock_common",
-	[PTR_TO_SOCK_COMMON_OR_NULL] = "sock_common_or_null",
-	[PTR_TO_TCP_SOCK]	= "tcp_sock",
-	[PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
-	[PTR_TO_TP_BUFFER]	= "tp_buffer",
-	[PTR_TO_XDP_SOCK]	= "xdp_sock",
-	[PTR_TO_BTF_ID]		= "ptr_",
-	[PTR_TO_BTF_ID_OR_NULL]	= "ptr_or_null_",
-	[PTR_TO_PERCPU_BTF_ID]	= "percpu_ptr_",
-	[PTR_TO_MEM]		= "mem",
-	[PTR_TO_MEM_OR_NULL]	= "mem_or_null",
-	[PTR_TO_RDONLY_BUF]	= "rdonly_buf",
-	[PTR_TO_RDONLY_BUF_OR_NULL] = "rdonly_buf_or_null",
-	[PTR_TO_RDWR_BUF]	= "rdwr_buf",
-	[PTR_TO_RDWR_BUF_OR_NULL] = "rdwr_buf_or_null",
-	[PTR_TO_FUNC]		= "func",
-	[PTR_TO_MAP_KEY]	= "map_key",
-};
+/* string representation of 'enum bpf_reg_type'
+ *
+ * Note that reg_type_str() can not appear more than once in a single verbose()
+ * statement.
+ */
+static const char *reg_type_str(struct bpf_verifier_env *env,
+				enum bpf_reg_type type)
+{
+	char postfix[16] = {0}, prefix[16] = {0};
+	static const char * const str[] = {
+		[NOT_INIT]		= "?",
+		[SCALAR_VALUE]		= "inv",
+		[PTR_TO_CTX]		= "ctx",
+		[CONST_PTR_TO_MAP]	= "map_ptr",
+		[PTR_TO_MAP_VALUE]	= "map_value",
+		[PTR_TO_STACK]		= "fp",
+		[PTR_TO_PACKET]		= "pkt",
+		[PTR_TO_PACKET_META]	= "pkt_meta",
+		[PTR_TO_PACKET_END]	= "pkt_end",
+		[PTR_TO_FLOW_KEYS]	= "flow_keys",
+		[PTR_TO_SOCKET]		= "sock",
+		[PTR_TO_SOCK_COMMON]	= "sock_common",
+		[PTR_TO_TCP_SOCK]	= "tcp_sock",
+		[PTR_TO_TP_BUFFER]	= "tp_buffer",
+		[PTR_TO_XDP_SOCK]	= "xdp_sock",
+		[PTR_TO_BTF_ID]		= "ptr_",
+		[PTR_TO_PERCPU_BTF_ID]	= "percpu_ptr_",
+		[PTR_TO_MEM]		= "mem",
+		[PTR_TO_BUF]		= "buf",
+		[PTR_TO_FUNC]		= "func",
+		[PTR_TO_MAP_KEY]	= "map_key",
+	};
+
+	if (type & PTR_MAYBE_NULL) {
+		if (base_type(type) == PTR_TO_BTF_ID ||
+		    base_type(type) == PTR_TO_PERCPU_BTF_ID)
+			strncpy(postfix, "or_null_", 16);
+		else
+			strncpy(postfix, "_or_null", 16);
+	}
+
+	if (type & MEM_RDONLY)
+		strncpy(prefix, "rdonly_", 16);
+
+	snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s",
+		 prefix, str[base_type(type)], postfix);
+	return env->type_str_buf;
+}
 
 static char slot_type_char[] = {
 	[STACK_INVALID]	= '?',
@@ -680,7 +680,7 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 			continue;
 		verbose(env, " R%d", i);
 		print_liveness(env, reg->live);
-		verbose(env, "=%s", reg_type_str[t]);
+		verbose(env, "=%s", reg_type_str(env, t));
 		if (t == SCALAR_VALUE && reg->precise)
 			verbose(env, "P");
 		if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
@@ -688,9 +688,8 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 			/* reg->off should be 0 for SCALAR_VALUE */
 			verbose(env, "%lld", reg->var_off.value + reg->off);
 		} else {
-			if (t == PTR_TO_BTF_ID ||
-			    t == PTR_TO_BTF_ID_OR_NULL ||
-			    t == PTR_TO_PERCPU_BTF_ID)
+			if (base_type(t) == PTR_TO_BTF_ID ||
+			    base_type(t) == PTR_TO_PERCPU_BTF_ID)
 				verbose(env, "%s", kernel_type_name(reg->btf, reg->btf_id));
 			verbose(env, "(id=%d", reg->id);
 			if (reg_type_may_be_refcounted_or_null(t))
@@ -699,10 +698,9 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 				verbose(env, ",off=%d", reg->off);
 			if (type_is_pkt_pointer(t))
 				verbose(env, ",r=%d", reg->range);
-			else if (t == CONST_PTR_TO_MAP ||
-				 t == PTR_TO_MAP_KEY ||
-				 t == PTR_TO_MAP_VALUE ||
-				 t == PTR_TO_MAP_VALUE_OR_NULL)
+			else if (base_type(t) == CONST_PTR_TO_MAP ||
+				 base_type(t) == PTR_TO_MAP_KEY ||
+				 base_type(t) == PTR_TO_MAP_VALUE)
 				verbose(env, ",ks=%d,vs=%d",
 					reg->map_ptr->key_size,
 					reg->map_ptr->value_size);
@@ -774,7 +772,7 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 		if (is_spilled_reg(&state->stack[i])) {
 			reg = &state->stack[i].spilled_ptr;
 			t = reg->type;
-			verbose(env, "=%s", reg_type_str[t]);
+			verbose(env, "=%s", reg_type_str(env, t));
 			if (t == SCALAR_VALUE && reg->precise)
 				verbose(env, "P");
 			if (t == SCALAR_VALUE && tnum_is_const(reg->var_off))
@@ -1207,8 +1205,7 @@ static void mark_reg_known_zero(struct bpf_verifier_env *env,
 
 static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
 {
-	switch (reg->type) {
-	case PTR_TO_MAP_VALUE_OR_NULL: {
+	if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
 		const struct bpf_map *map = reg->map_ptr;
 
 		if (map->inner_map_meta) {
@@ -1227,32 +1224,10 @@ static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
 		} else {
 			reg->type = PTR_TO_MAP_VALUE;
 		}
-		break;
-	}
-	case PTR_TO_SOCKET_OR_NULL:
-		reg->type = PTR_TO_SOCKET;
-		break;
-	case PTR_TO_SOCK_COMMON_OR_NULL:
-		reg->type = PTR_TO_SOCK_COMMON;
-		break;
-	case PTR_TO_TCP_SOCK_OR_NULL:
-		reg->type = PTR_TO_TCP_SOCK;
-		break;
-	case PTR_TO_BTF_ID_OR_NULL:
-		reg->type = PTR_TO_BTF_ID;
-		break;
-	case PTR_TO_MEM_OR_NULL:
-		reg->type = PTR_TO_MEM;
-		break;
-	case PTR_TO_RDONLY_BUF_OR_NULL:
-		reg->type = PTR_TO_RDONLY_BUF;
-		break;
-	case PTR_TO_RDWR_BUF_OR_NULL:
-		reg->type = PTR_TO_RDWR_BUF;
-		break;
-	default:
-		WARN_ONCE(1, "unknown nullable register type");
+		return;
 	}
+
+	reg->type &= ~PTR_MAYBE_NULL;
 }
 
 static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
@@ -2108,7 +2083,7 @@ static int mark_reg_read(struct bpf_verifier_env *env,
 			break;
 		if (parent->live & REG_LIVE_DONE) {
 			verbose(env, "verifier BUG type %s var_off %lld off %d\n",
-				reg_type_str[parent->type],
+				reg_type_str(env, parent->type),
 				parent->var_off.value, parent->off);
 			return -EFAULT;
 		}
@@ -2773,9 +2748,8 @@ static int mark_chain_precision_stack(struct bpf_verifier_env *env, int spi)
 
 static bool is_spillable_regtype(enum bpf_reg_type type)
 {
-	switch (type) {
+	switch (base_type(type)) {
 	case PTR_TO_MAP_VALUE:
-	case PTR_TO_MAP_VALUE_OR_NULL:
 	case PTR_TO_STACK:
 	case PTR_TO_CTX:
 	case PTR_TO_PACKET:
@@ -2784,21 +2758,13 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
 	case PTR_TO_FLOW_KEYS:
 	case CONST_PTR_TO_MAP:
 	case PTR_TO_SOCKET:
-	case PTR_TO_SOCKET_OR_NULL:
 	case PTR_TO_SOCK_COMMON:
-	case PTR_TO_SOCK_COMMON_OR_NULL:
 	case PTR_TO_TCP_SOCK:
-	case PTR_TO_TCP_SOCK_OR_NULL:
 	case PTR_TO_XDP_SOCK:
 	case PTR_TO_BTF_ID:
-	case PTR_TO_BTF_ID_OR_NULL:
-	case PTR_TO_RDONLY_BUF:
-	case PTR_TO_RDONLY_BUF_OR_NULL:
-	case PTR_TO_RDWR_BUF:
-	case PTR_TO_RDWR_BUF_OR_NULL:
+	case PTR_TO_BUF:
 	case PTR_TO_PERCPU_BTF_ID:
 	case PTR_TO_MEM:
-	case PTR_TO_MEM_OR_NULL:
 	case PTR_TO_FUNC:
 	case PTR_TO_MAP_KEY:
 		return true;
@@ -3638,7 +3604,7 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off,
 		 */
 		*reg_type = info.reg_type;
 
-		if (*reg_type == PTR_TO_BTF_ID || *reg_type == PTR_TO_BTF_ID_OR_NULL) {
+		if (base_type(*reg_type) == PTR_TO_BTF_ID) {
 			*btf = info.btf;
 			*btf_id = info.btf_id;
 		} else {
@@ -3706,7 +3672,7 @@ static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
 	}
 
 	verbose(env, "R%d invalid %s access off=%d size=%d\n",
-		regno, reg_type_str[reg->type], off, size);
+		regno, reg_type_str(env, reg->type), off, size);
 
 	return -EACCES;
 }
@@ -4433,15 +4399,30 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 				mark_reg_unknown(env, regs, value_regno);
 			}
 		}
-	} else if (reg->type == PTR_TO_MEM) {
+	} else if (base_type(reg->type) == PTR_TO_MEM) {
+		bool rdonly_mem = type_is_rdonly_mem(reg->type);
+
+		if (type_may_be_null(reg->type)) {
+			verbose(env, "R%d invalid mem access '%s'\n", regno,
+				reg_type_str(env, reg->type));
+			return -EACCES;
+		}
+
+		if (t == BPF_WRITE && rdonly_mem) {
+			verbose(env, "R%d cannot write into %s\n",
+				regno, reg_type_str(env, reg->type));
+			return -EACCES;
+		}
+
 		if (t == BPF_WRITE && value_regno >= 0 &&
 		    is_pointer_value(env, value_regno)) {
 			verbose(env, "R%d leaks addr into mem\n", value_regno);
 			return -EACCES;
 		}
+
 		err = check_mem_region_access(env, regno, off, size,
 					      reg->mem_size, false);
-		if (!err && t == BPF_READ && value_regno >= 0)
+		if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem))
 			mark_reg_unknown(env, regs, value_regno);
 	} else if (reg->type == PTR_TO_CTX) {
 		enum bpf_reg_type reg_type = SCALAR_VALUE;
@@ -4471,7 +4452,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 			} else {
 				mark_reg_known_zero(env, regs,
 						    value_regno);
-				if (reg_type_may_be_null(reg_type))
+				if (type_may_be_null(reg_type))
 					regs[value_regno].id = ++env->id_gen;
 				/* A load of ctx field could have different
 				 * actual load size with the one encoded in the
@@ -4479,8 +4460,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 				 * a sub-register.
 				 */
 				regs[value_regno].subreg_def = DEF_NOT_SUBREG;
-				if (reg_type == PTR_TO_BTF_ID ||
-				    reg_type == PTR_TO_BTF_ID_OR_NULL) {
+				if (base_type(reg_type) == PTR_TO_BTF_ID) {
 					regs[value_regno].btf = btf;
 					regs[value_regno].btf_id = btf_id;
 				}
@@ -4533,7 +4513,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 	} else if (type_is_sk_pointer(reg->type)) {
 		if (t == BPF_WRITE) {
 			verbose(env, "R%d cannot write into %s\n",
-				regno, reg_type_str[reg->type]);
+				regno, reg_type_str(env, reg->type));
 			return -EACCES;
 		}
 		err = check_sock_access(env, insn_idx, regno, off, size, t);
@@ -4549,26 +4529,32 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 	} else if (reg->type == CONST_PTR_TO_MAP) {
 		err = check_ptr_to_map_access(env, regs, regno, off, size, t,
 					      value_regno);
-	} else if (reg->type == PTR_TO_RDONLY_BUF) {
-		if (t == BPF_WRITE) {
-			verbose(env, "R%d cannot write into %s\n",
-				regno, reg_type_str[reg->type]);
-			return -EACCES;
+	} else if (base_type(reg->type) == PTR_TO_BUF) {
+		bool rdonly_mem = type_is_rdonly_mem(reg->type);
+		const char *buf_info;
+		u32 *max_access;
+
+		if (rdonly_mem) {
+			if (t == BPF_WRITE) {
+				verbose(env, "R%d cannot write into %s\n",
+					regno, reg_type_str(env, reg->type));
+				return -EACCES;
+			}
+			buf_info = "rdonly";
+			max_access = &env->prog->aux->max_rdonly_access;
+		} else {
+			buf_info = "rdwr";
+			max_access = &env->prog->aux->max_rdwr_access;
 		}
+
 		err = check_buffer_access(env, reg, regno, off, size, false,
-					  "rdonly",
-					  &env->prog->aux->max_rdonly_access);
-		if (!err && value_regno >= 0)
-			mark_reg_unknown(env, regs, value_regno);
-	} else if (reg->type == PTR_TO_RDWR_BUF) {
-		err = check_buffer_access(env, reg, regno, off, size, false,
-					  "rdwr",
-					  &env->prog->aux->max_rdwr_access);
-		if (!err && t == BPF_READ && value_regno >= 0)
+					  buf_info, max_access);
+
+		if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
 			mark_reg_unknown(env, regs, value_regno);
 	} else {
 		verbose(env, "R%d invalid mem access '%s'\n", regno,
-			reg_type_str[reg->type]);
+			reg_type_str(env, reg->type));
 		return -EACCES;
 	}
 
@@ -4635,7 +4621,7 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i
 	    is_sk_reg(env, insn->dst_reg)) {
 		verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
 			insn->dst_reg,
-			reg_type_str[reg_state(env, insn->dst_reg)->type]);
+			reg_type_str(env, reg_state(env, insn->dst_reg)->type));
 		return -EACCES;
 	}
 
@@ -4812,8 +4798,10 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 				   struct bpf_call_arg_meta *meta)
 {
 	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
+	const char *buf_info;
+	u32 *max_access;
 
-	switch (reg->type) {
+	switch (base_type(reg->type)) {
 	case PTR_TO_PACKET:
 	case PTR_TO_PACKET_META:
 		return check_packet_access(env, regno, reg->off, access_size,
@@ -4832,18 +4820,20 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 		return check_mem_region_access(env, regno, reg->off,
 					       access_size, reg->mem_size,
 					       zero_size_allowed);
-	case PTR_TO_RDONLY_BUF:
-		if (meta && meta->raw_mode)
-			return -EACCES;
-		return check_buffer_access(env, reg, regno, reg->off,
-					   access_size, zero_size_allowed,
-					   "rdonly",
-					   &env->prog->aux->max_rdonly_access);
-	case PTR_TO_RDWR_BUF:
+	case PTR_TO_BUF:
+		if (type_is_rdonly_mem(reg->type)) {
+			if (meta && meta->raw_mode)
+				return -EACCES;
+
+			buf_info = "rdonly";
+			max_access = &env->prog->aux->max_rdonly_access;
+		} else {
+			buf_info = "rdwr";
+			max_access = &env->prog->aux->max_rdwr_access;
+		}
 		return check_buffer_access(env, reg, regno, reg->off,
 					   access_size, zero_size_allowed,
-					   "rdwr",
-					   &env->prog->aux->max_rdwr_access);
+					   buf_info, max_access);
 	case PTR_TO_STACK:
 		return check_stack_range_initialized(
 				env,
@@ -4855,9 +4845,9 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 		    register_is_null(reg))
 			return 0;
 
-		verbose(env, "R%d type=%s expected=%s\n", regno,
-			reg_type_str[reg->type],
-			reg_type_str[PTR_TO_STACK]);
+		verbose(env, "R%d type=%s ", regno,
+			reg_type_str(env, reg->type));
+		verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
 		return -EACCES;
 	}
 }
@@ -4868,7 +4858,7 @@ int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
 	if (register_is_null(reg))
 		return 0;
 
-	if (reg_type_may_be_null(reg->type)) {
+	if (type_may_be_null(reg->type)) {
 		/* Assuming that the register contains a value check if the memory
 		 * access is safe. Temporarily save and restore the register's state as
 		 * the conversion shouldn't be visible to a caller.
@@ -5016,9 +5006,8 @@ static int process_timer_func(struct bpf_verifier_env *env, int regno,
 
 static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
 {
-	return type == ARG_PTR_TO_MEM ||
-	       type == ARG_PTR_TO_MEM_OR_NULL ||
-	       type == ARG_PTR_TO_UNINIT_MEM;
+	return base_type(type) == ARG_PTR_TO_MEM ||
+	       base_type(type) == ARG_PTR_TO_UNINIT_MEM;
 }
 
 static bool arg_type_is_mem_size(enum bpf_arg_type type)
@@ -5123,8 +5112,7 @@ static const struct bpf_reg_types mem_types = {
 		PTR_TO_MAP_KEY,
 		PTR_TO_MAP_VALUE,
 		PTR_TO_MEM,
-		PTR_TO_RDONLY_BUF,
-		PTR_TO_RDWR_BUF,
+		PTR_TO_BUF,
 	},
 };
 
@@ -5155,31 +5143,26 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 	[ARG_PTR_TO_MAP_KEY]		= &map_key_value_types,
 	[ARG_PTR_TO_MAP_VALUE]		= &map_key_value_types,
 	[ARG_PTR_TO_UNINIT_MAP_VALUE]	= &map_key_value_types,
-	[ARG_PTR_TO_MAP_VALUE_OR_NULL]	= &map_key_value_types,
 	[ARG_CONST_SIZE]		= &scalar_types,
 	[ARG_CONST_SIZE_OR_ZERO]	= &scalar_types,
 	[ARG_CONST_ALLOC_SIZE_OR_ZERO]	= &scalar_types,
 	[ARG_CONST_MAP_PTR]		= &const_map_ptr_types,
 	[ARG_PTR_TO_CTX]		= &context_types,
-	[ARG_PTR_TO_CTX_OR_NULL]	= &context_types,
 	[ARG_PTR_TO_SOCK_COMMON]	= &sock_types,
 #ifdef CONFIG_NET
 	[ARG_PTR_TO_BTF_ID_SOCK_COMMON]	= &btf_id_sock_common_types,
 #endif
 	[ARG_PTR_TO_SOCKET]		= &fullsock_types,
-	[ARG_PTR_TO_SOCKET_OR_NULL]	= &fullsock_types,
 	[ARG_PTR_TO_BTF_ID]		= &btf_ptr_types,
 	[ARG_PTR_TO_SPIN_LOCK]		= &spin_lock_types,
 	[ARG_PTR_TO_MEM]		= &mem_types,
-	[ARG_PTR_TO_MEM_OR_NULL]	= &mem_types,
 	[ARG_PTR_TO_UNINIT_MEM]		= &mem_types,
 	[ARG_PTR_TO_ALLOC_MEM]		= &alloc_mem_types,
-	[ARG_PTR_TO_ALLOC_MEM_OR_NULL]	= &alloc_mem_types,
 	[ARG_PTR_TO_INT]		= &int_ptr_types,
 	[ARG_PTR_TO_LONG]		= &int_ptr_types,
 	[ARG_PTR_TO_PERCPU_BTF_ID]	= &percpu_btf_ptr_types,
 	[ARG_PTR_TO_FUNC]		= &func_ptr_types,
-	[ARG_PTR_TO_STACK_OR_NULL]	= &stack_ptr_types,
+	[ARG_PTR_TO_STACK]		= &stack_ptr_types,
 	[ARG_PTR_TO_CONST_STR]		= &const_str_ptr_types,
 	[ARG_PTR_TO_TIMER]		= &timer_types,
 };
@@ -5193,12 +5176,27 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
 	const struct bpf_reg_types *compatible;
 	int i, j;
 
-	compatible = compatible_reg_types[arg_type];
+	compatible = compatible_reg_types[base_type(arg_type)];
 	if (!compatible) {
 		verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
 		return -EFAULT;
 	}
 
+	/* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
+	 * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
+	 *
+	 * Same for MAYBE_NULL:
+	 *
+	 * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
+	 * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
+	 *
+	 * Therefore we fold these flags depending on the arg_type before comparison.
+	 */
+	if (arg_type & MEM_RDONLY)
+		type &= ~MEM_RDONLY;
+	if (arg_type & PTR_MAYBE_NULL)
+		type &= ~PTR_MAYBE_NULL;
+
 	for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
 		expected = compatible->types[i];
 		if (expected == NOT_INIT)
@@ -5208,14 +5206,14 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
 			goto found;
 	}
 
-	verbose(env, "R%d type=%s expected=", regno, reg_type_str[type]);
+	verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
 	for (j = 0; j + 1 < i; j++)
-		verbose(env, "%s, ", reg_type_str[compatible->types[j]]);
-	verbose(env, "%s\n", reg_type_str[compatible->types[j]]);
+		verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
+	verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
 	return -EACCES;
 
 found:
-	if (type == PTR_TO_BTF_ID) {
+	if (reg->type == PTR_TO_BTF_ID) {
 		if (!arg_btf_id) {
 			if (!compatible->btf_id) {
 				verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
@@ -5274,15 +5272,14 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		return -EACCES;
 	}
 
-	if (arg_type == ARG_PTR_TO_MAP_VALUE ||
-	    arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE ||
-	    arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) {
+	if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE ||
+	    base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) {
 		err = resolve_map_arg_type(env, meta, &arg_type);
 		if (err)
 			return err;
 	}
 
-	if (register_is_null(reg) && arg_type_may_be_null(arg_type))
+	if (register_is_null(reg) && type_may_be_null(arg_type))
 		/* A NULL register has a SCALAR_VALUE type, so skip
 		 * type checking.
 		 */
@@ -5351,10 +5348,11 @@ skip_type_check:
 		err = check_helper_mem_access(env, regno,
 					      meta->map_ptr->key_size, false,
 					      NULL);
-	} else if (arg_type == ARG_PTR_TO_MAP_VALUE ||
-		   (arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL &&
-		    !register_is_null(reg)) ||
-		   arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) {
+	} else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE ||
+		   base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) {
+		if (type_may_be_null(arg_type) && register_is_null(reg))
+			return 0;
+
 		/* bpf_map_xxx(..., map_ptr, ..., value) call:
 		 * check [value, value + map->value_size) validity
 		 */
@@ -6484,6 +6482,8 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 			     int *insn_idx_p)
 {
 	const struct bpf_func_proto *fn = NULL;
+	enum bpf_return_type ret_type;
+	enum bpf_type_flag ret_flag;
 	struct bpf_reg_state *regs;
 	struct bpf_call_arg_meta meta;
 	int insn_idx = *insn_idx_p;
@@ -6623,13 +6623,14 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 	regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
 
 	/* update return register (already marked as written above) */
-	if (fn->ret_type == RET_INTEGER) {
+	ret_type = fn->ret_type;
+	ret_flag = type_flag(fn->ret_type);
+	if (ret_type == RET_INTEGER) {
 		/* sets type to SCALAR_VALUE */
 		mark_reg_unknown(env, regs, BPF_REG_0);
-	} else if (fn->ret_type == RET_VOID) {
+	} else if (ret_type == RET_VOID) {
 		regs[BPF_REG_0].type = NOT_INIT;
-	} else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL ||
-		   fn->ret_type == RET_PTR_TO_MAP_VALUE) {
+	} else if (base_type(ret_type) == RET_PTR_TO_MAP_VALUE) {
 		/* There is no offset yet applied, variable or fixed */
 		mark_reg_known_zero(env, regs, BPF_REG_0);
 		/* remember map_ptr, so that check_map_access()
@@ -6643,28 +6644,25 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 		}
 		regs[BPF_REG_0].map_ptr = meta.map_ptr;
 		regs[BPF_REG_0].map_uid = meta.map_uid;
-		if (fn->ret_type == RET_PTR_TO_MAP_VALUE) {
-			regs[BPF_REG_0].type = PTR_TO_MAP_VALUE;
-			if (map_value_has_spin_lock(meta.map_ptr))
-				regs[BPF_REG_0].id = ++env->id_gen;
-		} else {
-			regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
+		regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
+		if (!type_may_be_null(ret_type) &&
+		    map_value_has_spin_lock(meta.map_ptr)) {
+			regs[BPF_REG_0].id = ++env->id_gen;
 		}
-	} else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) {
+	} else if (base_type(ret_type) == RET_PTR_TO_SOCKET) {
 		mark_reg_known_zero(env, regs, BPF_REG_0);
-		regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL;
-	} else if (fn->ret_type == RET_PTR_TO_SOCK_COMMON_OR_NULL) {
+		regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
+	} else if (base_type(ret_type) == RET_PTR_TO_SOCK_COMMON) {
 		mark_reg_known_zero(env, regs, BPF_REG_0);
-		regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON_OR_NULL;
-	} else if (fn->ret_type == RET_PTR_TO_TCP_SOCK_OR_NULL) {
+		regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
+	} else if (base_type(ret_type) == RET_PTR_TO_TCP_SOCK) {
 		mark_reg_known_zero(env, regs, BPF_REG_0);
-		regs[BPF_REG_0].type = PTR_TO_TCP_SOCK_OR_NULL;
-	} else if (fn->ret_type == RET_PTR_TO_ALLOC_MEM_OR_NULL) {
+		regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
+	} else if (base_type(ret_type) == RET_PTR_TO_ALLOC_MEM) {
 		mark_reg_known_zero(env, regs, BPF_REG_0);
-		regs[BPF_REG_0].type = PTR_TO_MEM_OR_NULL;
+		regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
 		regs[BPF_REG_0].mem_size = meta.mem_size;
-	} else if (fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL ||
-		   fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID) {
+	} else if (base_type(ret_type) == RET_PTR_TO_MEM_OR_BTF_ID) {
 		const struct btf_type *t;
 
 		mark_reg_known_zero(env, regs, BPF_REG_0);
@@ -6682,29 +6680,30 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 					tname, PTR_ERR(ret));
 				return -EINVAL;
 			}
-			regs[BPF_REG_0].type =
-				fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID ?
-				PTR_TO_MEM : PTR_TO_MEM_OR_NULL;
+			regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
 			regs[BPF_REG_0].mem_size = tsize;
 		} else {
-			regs[BPF_REG_0].type =
-				fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID ?
-				PTR_TO_BTF_ID : PTR_TO_BTF_ID_OR_NULL;
+			/* MEM_RDONLY may be carried from ret_flag, but it
+			 * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
+			 * it will confuse the check of PTR_TO_BTF_ID in
+			 * check_mem_access().
+			 */
+			ret_flag &= ~MEM_RDONLY;
+
+			regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
 			regs[BPF_REG_0].btf = meta.ret_btf;
 			regs[BPF_REG_0].btf_id = meta.ret_btf_id;
 		}
-	} else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL ||
-		   fn->ret_type == RET_PTR_TO_BTF_ID) {
+	} else if (base_type(ret_type) == RET_PTR_TO_BTF_ID) {
 		int ret_btf_id;
 
 		mark_reg_known_zero(env, regs, BPF_REG_0);
-		regs[BPF_REG_0].type = fn->ret_type == RET_PTR_TO_BTF_ID ?
-						     PTR_TO_BTF_ID :
-						     PTR_TO_BTF_ID_OR_NULL;
+		regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
 		ret_btf_id = *fn->ret_btf_id;
 		if (ret_btf_id == 0) {
-			verbose(env, "invalid return type %d of func %s#%d\n",
-				fn->ret_type, func_id_name(func_id), func_id);
+			verbose(env, "invalid return type %u of func %s#%d\n",
+				base_type(ret_type), func_id_name(func_id),
+				func_id);
 			return -EINVAL;
 		}
 		/* current BPF helper definitions are only coming from
@@ -6713,12 +6712,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
 		regs[BPF_REG_0].btf = btf_vmlinux;
 		regs[BPF_REG_0].btf_id = ret_btf_id;
 	} else {
-		verbose(env, "unknown return type %d of func %s#%d\n",
-			fn->ret_type, func_id_name(func_id), func_id);
+		verbose(env, "unknown return type %u of func %s#%d\n",
+			base_type(ret_type), func_id_name(func_id), func_id);
 		return -EINVAL;
 	}
 
-	if (reg_type_may_be_null(regs[BPF_REG_0].type))
+	if (type_may_be_null(regs[BPF_REG_0].type))
 		regs[BPF_REG_0].id = ++env->id_gen;
 
 	if (is_ptr_cast_function(func_id)) {
@@ -6927,25 +6926,25 @@ static bool check_reg_sane_offset(struct bpf_verifier_env *env,
 
 	if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
 		verbose(env, "math between %s pointer and %lld is not allowed\n",
-			reg_type_str[type], val);
+			reg_type_str(env, type), val);
 		return false;
 	}
 
 	if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
 		verbose(env, "%s pointer offset %d is not allowed\n",
-			reg_type_str[type], reg->off);
+			reg_type_str(env, type), reg->off);
 		return false;
 	}
 
 	if (smin == S64_MIN) {
 		verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
-			reg_type_str[type]);
+			reg_type_str(env, type));
 		return false;
 	}
 
 	if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
 		verbose(env, "value %lld makes %s pointer be out of bounds\n",
-			smin, reg_type_str[type]);
+			smin, reg_type_str(env, type));
 		return false;
 	}
 
@@ -7322,11 +7321,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 		return -EACCES;
 	}
 
-	switch (ptr_reg->type) {
-	case PTR_TO_MAP_VALUE_OR_NULL:
+	if (ptr_reg->type & PTR_MAYBE_NULL) {
 		verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
-			dst, reg_type_str[ptr_reg->type]);
+			dst, reg_type_str(env, ptr_reg->type));
 		return -EACCES;
+	}
+
+	switch (base_type(ptr_reg->type)) {
 	case CONST_PTR_TO_MAP:
 		/* smin_val represents the known value */
 		if (known && smin_val == 0 && opcode == BPF_ADD)
@@ -7334,14 +7335,11 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 		fallthrough;
 	case PTR_TO_PACKET_END:
 	case PTR_TO_SOCKET:
-	case PTR_TO_SOCKET_OR_NULL:
 	case PTR_TO_SOCK_COMMON:
-	case PTR_TO_SOCK_COMMON_OR_NULL:
 	case PTR_TO_TCP_SOCK:
-	case PTR_TO_TCP_SOCK_OR_NULL:
 	case PTR_TO_XDP_SOCK:
 		verbose(env, "R%d pointer arithmetic on %s prohibited\n",
-			dst, reg_type_str[ptr_reg->type]);
+			dst, reg_type_str(env, ptr_reg->type));
 		return -EACCES;
 	default:
 		break;
@@ -9060,7 +9058,7 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
 				 struct bpf_reg_state *reg, u32 id,
 				 bool is_null)
 {
-	if (reg_type_may_be_null(reg->type) && reg->id == id &&
+	if (type_may_be_null(reg->type) && reg->id == id &&
 	    !WARN_ON_ONCE(!reg->id)) {
 		/* Old offset (both fixed and variable parts) should
 		 * have been known-zero, because we don't allow pointer
@@ -9438,7 +9436,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
 	 */
 	if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K &&
 	    insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
-	    reg_type_may_be_null(dst_reg->type)) {
+	    type_may_be_null(dst_reg->type)) {
 		/* Mark all identical registers in each branch as either
 		 * safe or unknown depending R == 0 or R != 0 conditional.
 		 */
@@ -9493,7 +9491,7 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 		mark_reg_known_zero(env, regs, insn->dst_reg);
 
 		dst_reg->type = aux->btf_var.reg_type;
-		switch (dst_reg->type) {
+		switch (base_type(dst_reg->type)) {
 		case PTR_TO_MEM:
 			dst_reg->mem_size = aux->btf_var.mem_size;
 			break;
@@ -9692,7 +9690,7 @@ static int check_return_code(struct bpf_verifier_env *env)
 		/* enforce return zero from async callbacks like timer */
 		if (reg->type != SCALAR_VALUE) {
 			verbose(env, "In async callback the register R0 is not a known value (%s)\n",
-				reg_type_str[reg->type]);
+				reg_type_str(env, reg->type));
 			return -EINVAL;
 		}
 
@@ -9706,7 +9704,7 @@ static int check_return_code(struct bpf_verifier_env *env)
 	if (is_subprog) {
 		if (reg->type != SCALAR_VALUE) {
 			verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n",
-				reg_type_str[reg->type]);
+				reg_type_str(env, reg->type));
 			return -EINVAL;
 		}
 		return 0;
@@ -9770,7 +9768,7 @@ static int check_return_code(struct bpf_verifier_env *env)
 
 	if (reg->type != SCALAR_VALUE) {
 		verbose(env, "At program exit the register R0 is not a known value (%s)\n",
-			reg_type_str[reg->type]);
+			reg_type_str(env, reg->type));
 		return -EINVAL;
 	}
 
@@ -10627,7 +10625,7 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
 		return true;
 	if (rcur->type == NOT_INIT)
 		return false;
-	switch (rold->type) {
+	switch (base_type(rold->type)) {
 	case SCALAR_VALUE:
 		if (env->explore_alu_limits)
 			return false;
@@ -10649,6 +10647,22 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
 		}
 	case PTR_TO_MAP_KEY:
 	case PTR_TO_MAP_VALUE:
+		/* a PTR_TO_MAP_VALUE could be safe to use as a
+		 * PTR_TO_MAP_VALUE_OR_NULL into the same map.
+		 * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
+		 * checked, doing so could have affected others with the same
+		 * id, and we can't check for that because we lost the id when
+		 * we converted to a PTR_TO_MAP_VALUE.
+		 */
+		if (type_may_be_null(rold->type)) {
+			if (!type_may_be_null(rcur->type))
+				return false;
+			if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)))
+				return false;
+			/* Check our ids match any regs they're supposed to */
+			return check_ids(rold->id, rcur->id, idmap);
+		}
+
 		/* If the new min/max/var_off satisfy the old ones and
 		 * everything else matches, we are OK.
 		 * 'id' is not compared, since it's only used for maps with
@@ -10660,20 +10674,6 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
 		return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
 		       range_within(rold, rcur) &&
 		       tnum_in(rold->var_off, rcur->var_off);
-	case PTR_TO_MAP_VALUE_OR_NULL:
-		/* a PTR_TO_MAP_VALUE could be safe to use as a
-		 * PTR_TO_MAP_VALUE_OR_NULL into the same map.
-		 * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
-		 * checked, doing so could have affected others with the same
-		 * id, and we can't check for that because we lost the id when
-		 * we converted to a PTR_TO_MAP_VALUE.
-		 */
-		if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL)
-			return false;
-		if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)))
-			return false;
-		/* Check our ids match any regs they're supposed to */
-		return check_ids(rold->id, rcur->id, idmap);
 	case PTR_TO_PACKET_META:
 	case PTR_TO_PACKET:
 		if (rcur->type != rold->type)
@@ -10702,11 +10702,8 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
 	case PTR_TO_PACKET_END:
 	case PTR_TO_FLOW_KEYS:
 	case PTR_TO_SOCKET:
-	case PTR_TO_SOCKET_OR_NULL:
 	case PTR_TO_SOCK_COMMON:
-	case PTR_TO_SOCK_COMMON_OR_NULL:
 	case PTR_TO_TCP_SOCK:
-	case PTR_TO_TCP_SOCK_OR_NULL:
 	case PTR_TO_XDP_SOCK:
 		/* Only valid matches are exact, which memcmp() above
 		 * would have accepted
@@ -11232,17 +11229,13 @@ next:
 /* Return true if it's OK to have the same insn return a different type. */
 static bool reg_type_mismatch_ok(enum bpf_reg_type type)
 {
-	switch (type) {
+	switch (base_type(type)) {
 	case PTR_TO_CTX:
 	case PTR_TO_SOCKET:
-	case PTR_TO_SOCKET_OR_NULL:
 	case PTR_TO_SOCK_COMMON:
-	case PTR_TO_SOCK_COMMON_OR_NULL:
 	case PTR_TO_TCP_SOCK:
-	case PTR_TO_TCP_SOCK_OR_NULL:
 	case PTR_TO_XDP_SOCK:
 	case PTR_TO_BTF_ID:
-	case PTR_TO_BTF_ID_OR_NULL:
 		return false;
 	default:
 		return true;
@@ -11468,7 +11461,7 @@ static int do_check(struct bpf_verifier_env *env)
 			if (is_ctx_reg(env, insn->dst_reg)) {
 				verbose(env, "BPF_ST stores into R%d %s is not allowed\n",
 					insn->dst_reg,
-					reg_type_str[reg_state(env, insn->dst_reg)->type]);
+					reg_type_str(env, reg_state(env, insn->dst_reg)->type));
 				return -EACCES;
 			}
 
@@ -11721,7 +11714,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
 			err = -EINVAL;
 			goto err_put;
 		}
-		aux->btf_var.reg_type = PTR_TO_MEM;
+		aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
 		aux->btf_var.mem_size = tsize;
 	} else {
 		aux->btf_var.reg_type = PTR_TO_BTF_ID;
@@ -13621,7 +13614,7 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
 				mark_reg_known_zero(env, regs, i);
 			else if (regs[i].type == SCALAR_VALUE)
 				mark_reg_unknown(env, regs, i);
-			else if (regs[i].type == PTR_TO_MEM_OR_NULL) {
+			else if (base_type(regs[i].type) == PTR_TO_MEM) {
 				const u32 mem_size = regs[i].mem_size;
 
 				mark_reg_known_zero(env, regs, i);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index cea2ca6df949..21aa30644219 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -345,7 +345,7 @@ static const struct bpf_func_proto bpf_probe_write_user_proto = {
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_ANYTHING,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
@@ -394,7 +394,7 @@ static const struct bpf_func_proto bpf_trace_printk_proto = {
 	.func		= bpf_trace_printk,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM,
+	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
 };
 
@@ -450,9 +450,9 @@ static const struct bpf_func_proto bpf_trace_vprintk_proto = {
 	.func		= bpf_trace_vprintk,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM,
+	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
-	.arg3_type	= ARG_PTR_TO_MEM_OR_NULL,
+	.arg3_type	= ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -492,9 +492,9 @@ static const struct bpf_func_proto bpf_seq_printf_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID,
 	.arg1_btf_id	= &btf_seq_file_ids[0],
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
-	.arg4_type      = ARG_PTR_TO_MEM_OR_NULL,
+	.arg4_type      = ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg5_type      = ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -509,7 +509,7 @@ static const struct bpf_func_proto bpf_seq_write_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID,
 	.arg1_btf_id	= &btf_seq_file_ids[0],
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -533,7 +533,7 @@ static const struct bpf_func_proto bpf_seq_printf_btf_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID,
 	.arg1_btf_id	= &btf_seq_file_ids[0],
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -694,7 +694,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -1004,7 +1004,7 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_MEM,
 	.arg2_type	= ARG_CONST_SIZE,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -1334,7 +1334,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -1556,7 +1556,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -1610,7 +1610,7 @@ static const struct bpf_func_proto bpf_get_stack_proto_raw_tp = {
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 };
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 68d2cbf8331a..ea61dfe19c86 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -929,7 +929,7 @@ static struct bpf_iter_reg bpf_sk_storage_map_reg_info = {
 		{ offsetof(struct bpf_iter__bpf_sk_storage_map, sk),
 		  PTR_TO_BTF_ID_OR_NULL },
 		{ offsetof(struct bpf_iter__bpf_sk_storage_map, value),
-		  PTR_TO_RDWR_BUF_OR_NULL },
+		  PTR_TO_BUF | PTR_MAYBE_NULL },
 	},
 	.seq_info		= &iter_seq_info,
 };
diff --git a/net/core/filter.c b/net/core/filter.c
index 3f656391af7e..606ab5a98a1a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1712,7 +1712,7 @@ static const struct bpf_func_proto bpf_skb_store_bytes_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -2017,9 +2017,9 @@ static const struct bpf_func_proto bpf_csum_diff_proto = {
 	.gpl_only	= false,
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
-	.arg3_type	= ARG_PTR_TO_MEM_OR_NULL,
+	.arg3_type	= ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -2540,7 +2540,7 @@ static const struct bpf_func_proto bpf_redirect_neigh_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_ANYTHING,
-	.arg2_type      = ARG_PTR_TO_MEM_OR_NULL,
+	.arg2_type      = ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -4173,7 +4173,7 @@ static const struct bpf_func_proto bpf_skb_event_output_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -4187,7 +4187,7 @@ const struct bpf_func_proto bpf_skb_output_proto = {
 	.arg1_btf_id	= &bpf_skb_output_btf_ids[0],
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -4370,7 +4370,7 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_key_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -4396,7 +4396,7 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_opt_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
@@ -4566,7 +4566,7 @@ static const struct bpf_func_proto bpf_xdp_event_output_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -4580,7 +4580,7 @@ const struct bpf_func_proto bpf_xdp_output_proto = {
 	.arg1_btf_id	= &bpf_xdp_output_btf_ids[0],
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -5066,7 +5066,7 @@ const struct bpf_func_proto bpf_sk_setsockopt_proto = {
 	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -5100,7 +5100,7 @@ static const struct bpf_func_proto bpf_sock_addr_setsockopt_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -5134,7 +5134,7 @@ static const struct bpf_func_proto bpf_sock_ops_setsockopt_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -5309,7 +5309,7 @@ static const struct bpf_func_proto bpf_bind_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
@@ -5897,7 +5897,7 @@ static const struct bpf_func_proto bpf_lwt_in_push_encap_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -5907,7 +5907,7 @@ static const struct bpf_func_proto bpf_lwt_xmit_push_encap_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -5950,7 +5950,7 @@ static const struct bpf_func_proto bpf_lwt_seg6_store_bytes_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -6038,7 +6038,7 @@ static const struct bpf_func_proto bpf_lwt_seg6_action_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -6263,7 +6263,7 @@ static const struct bpf_func_proto bpf_skc_lookup_tcp_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6282,7 +6282,7 @@ static const struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6301,7 +6301,7 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6338,7 +6338,7 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_udp_proto = {
 	.pkt_access     = true,
 	.ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6361,7 +6361,7 @@ static const struct bpf_func_proto bpf_xdp_skc_lookup_tcp_proto = {
 	.pkt_access     = true,
 	.ret_type       = RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6384,7 +6384,7 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_tcp_proto = {
 	.pkt_access     = true,
 	.ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6403,7 +6403,7 @@ static const struct bpf_func_proto bpf_sock_addr_skc_lookup_tcp_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6422,7 +6422,7 @@ static const struct bpf_func_proto bpf_sock_addr_sk_lookup_tcp_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6441,7 +6441,7 @@ static const struct bpf_func_proto bpf_sock_addr_sk_lookup_udp_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6754,9 +6754,9 @@ static const struct bpf_func_proto bpf_tcp_check_syncookie_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -6823,9 +6823,9 @@ static const struct bpf_func_proto bpf_tcp_gen_syncookie_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -7054,7 +7054,7 @@ static const struct bpf_func_proto bpf_sock_ops_store_hdr_opt_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 4ca4b11f4e5f..9618ab6d7cc9 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1564,7 +1564,7 @@ static struct bpf_iter_reg sock_map_iter_reg = {
 	.ctx_arg_info_size	= 2,
 	.ctx_arg_info		= {
 		{ offsetof(struct bpf_iter__sockmap, key),
-		  PTR_TO_RDONLY_BUF_OR_NULL },
+		  PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
 		{ offsetof(struct bpf_iter__sockmap, sk),
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
index 79f6bd1e50d6..f6933b06daf8 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
@@ -8,6 +8,7 @@
 #include "test_ksyms_btf_null_check.skel.h"
 #include "test_ksyms_weak.skel.h"
 #include "test_ksyms_weak.lskel.h"
+#include "test_ksyms_btf_write_check.skel.h"
 
 static int duration;
 
@@ -137,6 +138,16 @@ cleanup:
 	test_ksyms_weak_lskel__destroy(skel);
 }
 
+static void test_write_check(void)
+{
+	struct test_ksyms_btf_write_check *skel;
+
+	skel = test_ksyms_btf_write_check__open_and_load();
+	ASSERT_ERR_PTR(skel, "unexpected load of a prog writing to ksym memory\n");
+
+	test_ksyms_btf_write_check__destroy(skel);
+}
+
 void test_ksyms_btf(void)
 {
 	int percpu_datasec;
@@ -167,4 +178,7 @@ void test_ksyms_btf(void)
 
 	if (test__start_subtest("weak_ksyms_lskel"))
 		test_weak_syms_lskel();
+
+	if (test__start_subtest("write_check"))
+		test_write_check();
 }
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
new file mode 100644
index 000000000000..2180c41cd890
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google */
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+
+extern const int bpf_prog_active __ksym; /* int type global var. */
+
+SEC("raw_tp/sys_enter")
+int handler(const void *ctx)
+{
+	int *active;
+	__u32 cpu;
+
+	cpu = bpf_get_smp_processor_id();
+	active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
+	if (active) {
+		/* Kernel memory obtained from bpf_{per,this}_cpu_ptr
+		 * is read-only, should _not_ pass verification.
+		 */
+		/* WRITE_ONCE */
+		*(volatile int *)active = -1;
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";