Merge branch 'Dynptr refactorings'

Kumar Kartikeya Dwivedi says:

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

This is part 1 of https://lore.kernel.org/bpf/20221018135920.726360-1-memxor@gmail.com.
This thread also gives some background on why the refactor is being done:
https://lore.kernel.org/bpf/CAEf4Bzb4beTHgVo+G+jehSj8oCeAjRbRcm6MRe=Gr+cajRBwEw@mail.gmail.com

As requested in patch 6 by Alexei, it only includes patches which
refactors the code, on top of which further fixes will be made in part
2. The refactor itself fixes another issue as a side effect. No
functional change is intended (except a few modified log messages).

Changelog:
----------
v1 -> v2
v1: https://lore.kernel.org/bpf/20221115000130.1967465-1-memxor@gmail.com

 * Address feedback from Joanne and David, add acks

Fixes v1 -> v1
Fixes v1: https://lore.kernel.org/bpf/20221018135920.726360-1-memxor@gmail.com

 * Collect acks from Joanne and David
 * Fix misc nits pointed out by Joanne, David
 * Split move of reg->off alignment check for dynptr into separate
   change (Alexei)
====================

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

3 files changed, 9 insertions, 11 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4920ac252754..3de24cfb7a3d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -775,7 +775,7 @@ enum bpf_reg_type {
 	PTR_TO_MEM,		 /* reg points to valid memory region */
 	PTR_TO_BUF,		 /* reg points to a read/write buffer */
 	PTR_TO_FUNC,		 /* reg points to a bpf program function */
-	PTR_TO_DYNPTR,		 /* reg points to a dynptr */
+	CONST_PTR_TO_DYNPTR,	 /* reg points to a const struct bpf_dynptr */
 	__BPF_REG_TYPE_MAX,
 
 	/* Extended reg_types. */
@@ -2828,7 +2828,7 @@ 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);
-u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr);
+u32 bpf_dynptr_get_size(const struct bpf_dynptr_kern *ptr);
 
 #ifdef CONFIG_BPF_LSM
 void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype);
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 70d06a99f0b8..df0cb825e0e3 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -615,11 +615,9 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
 			   enum bpf_arg_type arg_type);
 int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
 		   u32 regno, u32 mem_size);
-bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
-			      struct bpf_reg_state *reg);
-bool is_dynptr_type_expected(struct bpf_verifier_env *env,
-			     struct bpf_reg_state *reg,
-			     enum bpf_arg_type arg_type);
+struct bpf_call_arg_meta;
+int process_dynptr_func(struct bpf_verifier_env *env, int regno,
+			enum bpf_arg_type arg_type, struct bpf_call_arg_meta *meta);
 
 /* this lives here instead of in bpf.h because it needs to dereference tgt_prog */
 static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog,
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f89de51a45db..464ca3f01fe7 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5293,7 +5293,7 @@ union bpf_attr {
  *	Return
  *		Nothing. Always succeeds.
  *
- * long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset, u64 flags)
+ * long bpf_dynptr_read(void *dst, u32 len, const struct bpf_dynptr *src, u32 offset, u64 flags)
  *	Description
  *		Read *len* bytes from *src* into *dst*, starting from *offset*
  *		into *src*.
@@ -5303,7 +5303,7 @@ union bpf_attr {
  *		of *src*'s data, -EINVAL if *src* is an invalid dynptr or if
  *		*flags* is not 0.
  *
- * long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len, u64 flags)
+ * long bpf_dynptr_write(const struct bpf_dynptr *dst, u32 offset, void *src, u32 len, u64 flags)
  *	Description
  *		Write *len* bytes from *src* into *dst*, starting from *offset*
  *		into *dst*.
@@ -5313,7 +5313,7 @@ union bpf_attr {
  *		of *dst*'s data, -EINVAL if *dst* is an invalid dynptr or if *dst*
  *		is a read-only dynptr or if *flags* is not 0.
  *
- * void *bpf_dynptr_data(struct bpf_dynptr *ptr, u32 offset, u32 len)
+ * void *bpf_dynptr_data(const struct bpf_dynptr *ptr, u32 offset, u32 len)
  *	Description
  *		Get a pointer to the underlying dynptr data.
  *
@@ -5414,7 +5414,7 @@ union bpf_attr {
  *		Drain samples from the specified user ring buffer, and invoke
  *		the provided callback for each such sample:
  *
- *		long (\*callback_fn)(struct bpf_dynptr \*dynptr, void \*ctx);
+ *		long (\*callback_fn)(const struct bpf_dynptr \*dynptr, void \*ctx);
  *
  *		If **callback_fn** returns 0, the helper will continue to try
  *		and drain the next sample, up to a maximum of