From: Florent Revest <rev...@google.com>
eBPF programs can already check whether a file is a socket using
file->f_op == &socket_file_ops but they can not convert file->private_data
into a struct socket with BTF information. For that, we need a new
helper that is essentially just a wrapper for sock_from_file.
sock_from_file can set an err value but this is only set to -ENOTSOCK
when the return value is NULL so it's useless superfluous information.
Signed-off-by: Florent Revest <rev...@google.com>
---
include/uapi/linux/bpf.h | 7 +++++++
kernel/trace/bpf_trace.c | 22 ++++++++++++++++++++++
scripts/bpf_helpers_doc.py | 4 ++++
tools/include/uapi/linux/bpf.h | 7 +++++++
4 files changed, 40 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 162999b12790..6c96bf9c1f94 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 3530120fa280..d040d3ec8313 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1255,6 +1255,26 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = {
.arg5_type = ARG_ANYTHING,
};
+BPF_CALL_1(bpf_sock_from_file, struct file *, file)
+{
+ int err;
+
+ return (unsigned long) sock_from_file(file, &err);
+}
+
+BTF_ID_LIST(bpf_sock_from_file_btf_ids)
+BTF_ID(struct, socket)
+BTF_ID(struct, file)
+
+const struct bpf_func_proto bpf_sock_from_file_proto = {
+ .func = bpf_sock_from_file,
+ .gpl_only = true,
+ .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)
{
@@ -1349,6 +1369,8 @@ 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 6769caae142f..99068ec40315 100755
--- a/scripts/bpf_helpers_doc.py
+++ b/scripts/bpf_helpers_doc.py
@@ -434,6 +434,8 @@ class PrinterHelpers(Printer):
'struct xdp_md',
'struct path',
'struct btf_ptr',
+ 'struct socket',
+ 'struct file',
]
known_types = {
'...',
@@ -477,6 +479,8 @@ 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..6c96bf9c1f94 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
--
2.29.2.222.g5d2a92d10f8-goog
