From: Florent Revest <revest@xxxxxxxxxx>
While eBPF programs can check whether a file is a socket by file->f_op
== &socket_file_ops, they cannot convert the void private_data pointer
to a struct socket BTF pointer. In order to do this a new helper
wrapping sock_from_file is added.
This is useful to tracing programs but also other program types
inheriting this set of helpers such as iterators or LSM programs.
Signed-off-by: Florent Revest <revest@xxxxxxxxxx>
---
include/uapi/linux/bpf.h | 7 +++++++
kernel/trace/bpf_trace.c | 20 ++++++++++++++++++++
scripts/bpf_helpers_doc.py | 4 ++++
tools/include/uapi/linux/bpf.h | 7 +++++++
4 files changed, 38 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 162999b12790..7d598f161dc0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3787,6 +3787,12 @@ union bpf_attr {
* *ARG_PTR_TO_BTF_ID* of type *task_struct*.
* Return
* Pointer to the current task.
+ *
+ * struct socket *bpf_sock_from_file(struct file *file)
+ * Description
+ * If the given file contains a socket, returns the associated socket.
+ * Return
+ * A pointer to a struct socket on success or NULL on failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3948,6 +3954,7 @@ union bpf_attr {
FN(task_storage_get), \
FN(task_storage_delete), \
FN(get_current_task_btf), \
+ FN(sock_from_file), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 02986c7b90eb..d87ca6f93c58 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1260,6 +1260,24 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = {
.arg5_type = ARG_ANYTHING,
};
+BPF_CALL_1(bpf_sock_from_file, struct file *, file)
+{
+ return (unsigned long) sock_from_file(file);
+}
+
+BTF_ID_LIST(bpf_sock_from_file_btf_ids)
+BTF_ID(struct, socket)
+BTF_ID(struct, file)
+
+static const struct bpf_func_proto bpf_sock_from_file_proto = {
+ .func = bpf_sock_from_file,
+ .gpl_only = false,
+ .ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
+ .ret_btf_id = &bpf_sock_from_file_btf_ids[0],
+ .arg1_type = ARG_PTR_TO_BTF_ID,
+ .arg1_btf_id = &bpf_sock_from_file_btf_ids[1],
+};
+
const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
@@ -1354,6 +1372,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_per_cpu_ptr_proto;
case BPF_FUNC_bpf_this_cpu_ptr:
return &bpf_this_cpu_ptr_proto;
+ case BPF_FUNC_sock_from_file:
+ return &bpf_sock_from_file_proto;
default:
return NULL;
}
diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
index 31484377b8b1..d609f20e8360 100755
--- a/scripts/bpf_helpers_doc.py
+++ b/scripts/bpf_helpers_doc.py
@@ -435,6 +435,8 @@ class PrinterHelpers(Printer):
'struct xdp_md',
'struct path',
'struct btf_ptr',
+ 'struct socket',
+ 'struct file',
]
known_types = {
'...',
@@ -478,6 +480,8 @@ class PrinterHelpers(Printer):
'struct task_struct',
'struct path',
'struct btf_ptr',
+ 'struct socket',
+ 'struct file',
}
mapped_types = {
'u8': '__u8',
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 162999b12790..7d598f161dc0 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3787,6 +3787,12 @@ union bpf_attr {
* *ARG_PTR_TO_BTF_ID* of type *task_struct*.
* Return
* Pointer to the current task.
+ *
+ * struct socket *bpf_sock_from_file(struct file *file)
+ * Description
+ * If the given file contains a socket, returns the associated socket.
+ * Return
+ * A pointer to a struct socket on success or NULL on failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3948,6 +3954,7 @@ union bpf_attr {
FN(task_storage_get), \
FN(task_storage_delete), \
FN(get_current_task_btf), \
+ FN(sock_from_file), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.29.2.299.gdc1121823c-goog
