bpf: treewide: Align kfunc signatures to prog point-of-view

Previously, kfunc declarations in bpf_kfuncs.h (and others) used "user
facing" types for kfuncs prototypes while the actual kfunc definitions
used "kernel facing" types. More specifically: bpf_dynptr vs
bpf_dynptr_kern, __sk_buff vs sk_buff, and xdp_md vs xdp_buff.

It wasn't an issue before, as the verifier allows aliased types.
However, since we are now generating kfunc prototypes in vmlinux.h (in
addition to keeping bpf_kfuncs.h around), this conflict creates
compilation errors.

Fix this conflict by using "user facing" types in kfunc definitions.
This results in more casts, but otherwise has no additional runtime
cost.

Note, similar to 5b268d1ebcdc ("bpf: Have bpf_rdonly_cast() take a const
pointer"), we also make kfuncs take const arguments where appropriate in
order to make the kfunc more permissive.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/b58346a63a0e66bc9b7504da751b526b0b189a67.1718207789.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

4 files changed, 53 insertions, 27 deletions

diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 2bee4af91e38..3c1de0e5c0bd 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -311,11 +311,15 @@ static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx,
  * Decrypts provided buffer using IV data and the crypto context. Crypto context must be configured.
  */
 __bpf_kfunc int bpf_crypto_decrypt(struct bpf_crypto_ctx *ctx,
-				   const struct bpf_dynptr_kern *src,
-				   const struct bpf_dynptr_kern *dst,
-				   const struct bpf_dynptr_kern *siv)
+				   const struct bpf_dynptr *src,
+				   const struct bpf_dynptr *dst,
+				   const struct bpf_dynptr *siv)
 {
-	return bpf_crypto_crypt(ctx, src, dst, siv, true);
+	const struct bpf_dynptr_kern *src_kern = (struct bpf_dynptr_kern *)src;
+	const struct bpf_dynptr_kern *dst_kern = (struct bpf_dynptr_kern *)dst;
+	const struct bpf_dynptr_kern *siv_kern = (struct bpf_dynptr_kern *)siv;
+
+	return bpf_crypto_crypt(ctx, src_kern, dst_kern, siv_kern, true);
 }
 
 /**
@@ -328,11 +332,15 @@ __bpf_kfunc int bpf_crypto_decrypt(struct bpf_crypto_ctx *ctx,
  * Encrypts provided buffer using IV data and the crypto context. Crypto context must be configured.
  */
 __bpf_kfunc int bpf_crypto_encrypt(struct bpf_crypto_ctx *ctx,
-				   const struct bpf_dynptr_kern *src,
-				   const struct bpf_dynptr_kern *dst,
-				   const struct bpf_dynptr_kern *siv)
+				   const struct bpf_dynptr *src,
+				   const struct bpf_dynptr *dst,
+				   const struct bpf_dynptr *siv)
 {
-	return bpf_crypto_crypt(ctx, src, dst, siv, false);
+	const struct bpf_dynptr_kern *src_kern = (struct bpf_dynptr_kern *)src;
+	const struct bpf_dynptr_kern *dst_kern = (struct bpf_dynptr_kern *)dst;
+	const struct bpf_dynptr_kern *siv_kern = (struct bpf_dynptr_kern *)siv;
+
+	return bpf_crypto_crypt(ctx, src_kern, dst_kern, siv_kern, false);
 }
 
 __bpf_kfunc_end_defs();
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 6f1abcb4b084..3ac521c48bba 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2459,9 +2459,10 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid)
  * provided buffer, with its contents containing the data, if unable to obtain
  * direct pointer)
  */
-__bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset,
+__bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr *p, u32 offset,
 				   void *buffer__opt, u32 buffer__szk)
 {
+	const struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
 	enum bpf_dynptr_type type;
 	u32 len = buffer__szk;
 	int err;
@@ -2543,9 +2544,11 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
  * provided buffer, with its contents containing the data, if unable to obtain
  * direct pointer)
  */
-__bpf_kfunc void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr_kern *ptr, u32 offset,
+__bpf_kfunc void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *p, u32 offset,
 					void *buffer__opt, u32 buffer__szk)
 {
+	const struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
+
 	if (!ptr->data || __bpf_dynptr_is_rdonly(ptr))
 		return NULL;
 
@@ -2571,11 +2574,12 @@ __bpf_kfunc void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr_kern *ptr, u32 o
 	 * will be copied out into the buffer and the user will need to call
 	 * bpf_dynptr_write() to commit changes.
 	 */
-	return bpf_dynptr_slice(ptr, offset, buffer__opt, buffer__szk);
+	return bpf_dynptr_slice(p, offset, buffer__opt, buffer__szk);
 }
 
-__bpf_kfunc int bpf_dynptr_adjust(struct bpf_dynptr_kern *ptr, u32 start, u32 end)
+__bpf_kfunc int bpf_dynptr_adjust(const struct bpf_dynptr *p, u32 start, u32 end)
 {
+	struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
 	u32 size;
 
 	if (!ptr->data || start > end)
@@ -2592,36 +2596,45 @@ __bpf_kfunc int bpf_dynptr_adjust(struct bpf_dynptr_kern *ptr, u32 start, u32 en
 	return 0;
 }
 
-__bpf_kfunc bool bpf_dynptr_is_null(struct bpf_dynptr_kern *ptr)
+__bpf_kfunc bool bpf_dynptr_is_null(const struct bpf_dynptr *p)
 {
+	struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
+
 	return !ptr->data;
 }
 
-__bpf_kfunc bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
+__bpf_kfunc bool bpf_dynptr_is_rdonly(const struct bpf_dynptr *p)
 {
+	struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
+
 	if (!ptr->data)
 		return false;
 
 	return __bpf_dynptr_is_rdonly(ptr);
 }
 
-__bpf_kfunc __u32 bpf_dynptr_size(const struct bpf_dynptr_kern *ptr)
+__bpf_kfunc __u32 bpf_dynptr_size(const struct bpf_dynptr *p)
 {
+	struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
+
 	if (!ptr->data)
 		return -EINVAL;
 
 	return __bpf_dynptr_size(ptr);
 }
 
-__bpf_kfunc int bpf_dynptr_clone(struct bpf_dynptr_kern *ptr,
-				 struct bpf_dynptr_kern *clone__uninit)
+__bpf_kfunc int bpf_dynptr_clone(const struct bpf_dynptr *p,
+				 struct bpf_dynptr *clone__uninit)
 {
+	struct bpf_dynptr_kern *clone = (struct bpf_dynptr_kern *)clone__uninit;
+	struct bpf_dynptr_kern *ptr = (struct bpf_dynptr_kern *)p;
+
 	if (!ptr->data) {
-		bpf_dynptr_set_null(clone__uninit);
+		bpf_dynptr_set_null(clone);
 		return -EINVAL;
 	}
 
-	*clone__uninit = *ptr;
+	*clone = *ptr;
 
 	return 0;
 }
@@ -2986,7 +2999,9 @@ late_initcall(kfunc_init);
  */
 const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len)
 {
-	return bpf_dynptr_slice(ptr, 0, NULL, len);
+	const struct bpf_dynptr *p = (struct bpf_dynptr *)ptr;
+
+	return bpf_dynptr_slice(p, 0, NULL, len);
 }
 
 /* Get a pointer to dynptr data up to len bytes for read write access. If
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index dcac6119d810..acc9dd830807 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10914,7 +10914,7 @@ enum {
 };
 
 BTF_ID_LIST(kf_arg_btf_ids)
-BTF_ID(struct, bpf_dynptr_kern)
+BTF_ID(struct, bpf_dynptr)
 BTF_ID(struct, bpf_list_head)
 BTF_ID(struct, bpf_list_node)
 BTF_ID(struct, bpf_rb_root)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index bc16e21a2a44..4b3fda456299 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1369,8 +1369,8 @@ __bpf_kfunc void bpf_key_put(struct bpf_key *bkey)
 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION
 /**
  * bpf_verify_pkcs7_signature - verify a PKCS#7 signature
- * @data_ptr: data to verify
- * @sig_ptr: signature of the data
+ * @data_p: data to verify
+ * @sig_p: signature of the data
  * @trusted_keyring: keyring with keys trusted for signature verification
  *
  * Verify the PKCS#7 signature *sig_ptr* against the supplied *data_ptr*
@@ -1378,10 +1378,12 @@ __bpf_kfunc void bpf_key_put(struct bpf_key *bkey)
  *
  * Return: 0 on success, a negative value on error.
  */
-__bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
-			       struct bpf_dynptr_kern *sig_ptr,
+__bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p,
+			       struct bpf_dynptr *sig_p,
 			       struct bpf_key *trusted_keyring)
 {
+	struct bpf_dynptr_kern *data_ptr = (struct bpf_dynptr_kern *)data_p;
+	struct bpf_dynptr_kern *sig_ptr = (struct bpf_dynptr_kern *)sig_p;
 	const void *data, *sig;
 	u32 data_len, sig_len;
 	int ret;
@@ -1444,7 +1446,7 @@ __bpf_kfunc_start_defs();
  * bpf_get_file_xattr - get xattr of a file
  * @file: file to get xattr from
  * @name__str: name of the xattr
- * @value_ptr: output buffer of the xattr value
+ * @value_p: output buffer of the xattr value
  *
  * Get xattr *name__str* of *file* and store the output in *value_ptr*.
  *
@@ -1453,8 +1455,9 @@ __bpf_kfunc_start_defs();
  * Return: 0 on success, a negative value on error.
  */
 __bpf_kfunc int bpf_get_file_xattr(struct file *file, const char *name__str,
-				   struct bpf_dynptr_kern *value_ptr)
+				   struct bpf_dynptr *value_p)
 {
+	struct bpf_dynptr_kern *value_ptr = (struct bpf_dynptr_kern *)value_p;
 	struct dentry *dentry;
 	u32 value_len;
 	void *value;