Merge branch 'introduce-kfuncs-for-memory-reads-into-dynptrs'

Mykyta Yatsenko says:

====================
Introduce kfuncs for memory reads into dynptrs

From: Mykyta Yatsenko <yatsenko@meta.com>

This patch adds new kfuncs that enable reading variable-length
user or kernel data directly into dynptrs.
These kfuncs provide a way to perform dynamically-sized reads
while maintaining memory safety. Unlike existing
`bpf_probe_read_{user|kernel}` APIs, which are limited to constant-sized
reads, these new kfuncs allow for more flexible data access.

v4 -> v5
 * Fix pointers annotations, use __user where necessary, cast where needed

v3 -> v4
 * Added pid filtering in selftests

v2 -> v3
 * Add KF_TRUSTED_ARGS for kfuncs that take pointer to task_struct
 as an argument
 * Remove checks for non-NULL task, where it was not necessary
 * Added comments on constants used in selftests, etc.

v1 -> v2
 * Renaming helper functions to use "user_str" instead of "user_data_str"
 suffix

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

Link: https://patch.msgid.link/20250512205348.191079-1-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3f0cc89c0622..83c56f40842b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1349,6 +1349,20 @@ u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr);
 const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len);
 void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len);
 bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr);
+int __bpf_dynptr_write(const struct bpf_dynptr_kern *dst, u32 offset,
+		       void *src, u32 len, u64 flags);
+void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *p, u32 offset,
+			    void *buffer__opt, u32 buffer__szk);
+
+static inline int bpf_dynptr_check_off_len(const struct bpf_dynptr_kern *ptr, u32 offset, u32 len)
+{
+	u32 size = __bpf_dynptr_size(ptr);
+
+	if (len > size || offset > size - len)
+		return -E2BIG;
+
+	return 0;
+}
 
 #ifdef CONFIG_BPF_JIT
 int bpf_trampoline_link_prog(struct bpf_tramp_link *link,