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>
Acked-by: KP Singh <kpsingh@xxxxxxxxxx>
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
---
include/uapi/linux/bpf.h | 9 +++++++++
kernel/trace/bpf_trace.c | 20 ++++++++++++++++++++
scripts/bpf_helpers_doc.py | 4 ++++
tools/include/uapi/linux/bpf.h | 9 +++++++++
4 files changed, 42 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 1233f14f659f..30b477a26482 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3822,6 +3822,14 @@ union bpf_attr {
* The **hash_algo** is returned on success,
* **-EOPNOTSUP** if IMA is disabled or **-EINVAL** if
* invalid arguments are passed.
+ *
+ * struct socket *bpf_sock_from_file(struct file *file)
+ * Description
+ * If the given file represents a socket, returns the associated
+ * socket.
+ * Return
+ * A pointer to a struct socket on success or NULL if the file is
+ * not a socket.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3986,6 +3994,7 @@ union bpf_attr {
FN(bprm_opts_set), \
FN(ktime_get_coarse_ns), \
FN(ima_inode_hash), \
+ 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 23a390aac524..acbe76790996 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)
{
@@ -1356,6 +1374,8 @@ 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 8b829748d488..867ada23281c 100755
--- a/scripts/bpf_helpers_doc.py
+++ b/scripts/bpf_helpers_doc.py
@@ -437,6 +437,8 @@ class PrinterHelpers(Printer):
'struct path',
'struct btf_ptr',
'struct inode',
+ 'struct socket',
+ 'struct file',
]
known_types = {
'...',
@@ -482,6 +484,8 @@ class PrinterHelpers(Printer):
'struct path',
'struct btf_ptr',
'struct inode',
+ '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 1233f14f659f..30b477a26482 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3822,6 +3822,14 @@ union bpf_attr {
* The **hash_algo** is returned on success,
* **-EOPNOTSUP** if IMA is disabled or **-EINVAL** if
* invalid arguments are passed.
+ *
+ * struct socket *bpf_sock_from_file(struct file *file)
+ * Description
+ * If the given file represents a socket, returns the associated
+ * socket.
+ * Return
+ * A pointer to a struct socket on success or NULL if the file is
+ * not a socket.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3986,6 +3994,7 @@ union bpf_attr {
FN(bprm_opts_set), \
FN(ktime_get_coarse_ns), \
FN(ima_inode_hash), \
+ FN(sock_from_file), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.29.2.576.ga3fc446d84-goog
