This patch adds CRIB kfuncs for restoring data in skb.
bpf_restore_skb_rcv_queue() is used to create a new skb based on
the previously dumped skb information and add it to the tail of
the specified receive queue.
bpf_restore_skb_data() is used to restore data in the skb and
must be used after bpf_restore_skb_rcv_queue().
Signed-off-by: Juntong Deng <juntong.deng@xxxxxxxxxxx>
---
include/linux/bpf_crib.h | 13 +++++++
kernel/bpf/crib/bpf_crib.c | 3 ++
kernel/bpf/crib/bpf_restore.c | 67 +++++++++++++++++++++++++++++++++++
3 files changed, 83 insertions(+)
diff --git a/include/linux/bpf_crib.h b/include/linux/bpf_crib.h
index c073166e60a0..5b7d44642f80 100644
--- a/include/linux/bpf_crib.h
+++ b/include/linux/bpf_crib.h
@@ -46,4 +46,17 @@ struct bpf_iter_skb_data_kern {
unsigned int chunklen;
} __aligned(8);
+struct bpf_crib_skb_info {
+ int headerlen;
+ int len;
+ int size;
+ int tstamp;
+ int dev_scratch;
+ int protocol;
+ int csum;
+ int transport_header;
+ int network_header;
+ int mac_header;
+} __aligned(8);
+
#endif /* _BPF_CRIB_H */
diff --git a/kernel/bpf/crib/bpf_crib.c b/kernel/bpf/crib/bpf_crib.c
index 462ae1ab50e5..beada526021a 100644
--- a/kernel/bpf/crib/bpf_crib.c
+++ b/kernel/bpf/crib/bpf_crib.c
@@ -300,6 +300,9 @@ BTF_ID_FLAGS(func, bpf_iter_skb_data_get_chunk_len, KF_ITER_GETTER)
BTF_ID_FLAGS(func, bpf_iter_skb_data_get_offset, KF_ITER_GETTER)
BTF_ID_FLAGS(func, bpf_iter_skb_data_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_restore_skb_rcv_queue, KF_ACQUIRE | KF_TRUSTED_ARGS | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_restore_skb_data, KF_TRUSTED_ARGS)
+
BTF_KFUNCS_END(bpf_crib_kfuncs)
static int bpf_prog_run_crib(struct bpf_prog *prog,
diff --git a/kernel/bpf/crib/bpf_restore.c b/kernel/bpf/crib/bpf_restore.c
index 6bbb4b01e34b..7966c02e416e 100644
--- a/kernel/bpf/crib/bpf_restore.c
+++ b/kernel/bpf/crib/bpf_restore.c
@@ -7,7 +7,74 @@
*/
#include <linux/bpf_crib.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+
+extern struct sk_buff *bpf_skb_acquire(struct sk_buff *skb);
__bpf_kfunc_start_defs();
+/**
+ * bpf_restore_skb_rcv_queue() - Create a new skb based on the previously
+ * dumped skb information and add it to the tail of the specified queue to
+ * achieve restoring the skb
+ *
+ * Note that this function acquires a reference to struct sk_buff.
+ *
+ * @head: queue that needs to restore the skb
+ * @sk: struct sock where the queue is located.
+ * @skb_info: previously dumped skb information
+ *
+ * @returns a pointer to the skb if the restoration of the skb
+ * was successful, otherwise returns NULL.
+ */
+__bpf_kfunc struct sk_buff *
+bpf_restore_skb_rcv_queue(struct sk_buff_head *head, struct sock *sk,
+ struct bpf_crib_skb_info *skb_info)
+{
+ struct sk_buff *skb;
+
+ skb = alloc_skb(skb_info->size, GFP_KERNEL);
+ if (!skb)
+ return NULL;
+
+ skb_reserve(skb, skb_info->headerlen);
+ skb_put(skb, skb_info->len);
+
+ skb->tstamp = skb_info->tstamp;
+ skb->dev_scratch = skb_info->dev_scratch;
+ skb->protocol = skb_info->protocol;
+ skb->csum = skb_info->csum;
+ skb->transport_header = skb_info->transport_header;
+ skb->network_header = skb_info->network_header;
+ skb->mac_header = skb_info->mac_header;
+
+ lock_sock(sk);
+ skb_queue_tail(head, skb);
+ skb_set_owner_r(skb, sk);
+ release_sock(sk);
+
+ return bpf_skb_acquire(skb);
+}
+
+/**
+ * bpf_restore_skb_data() - Restore the data in skb
+ *
+ * @skb: skb that needs to restore data
+ * @offset: data offset in skb
+ * @data: data buffer
+ * @len: data length
+ *
+ * @returns the number of bytes of data restored if
+ * the restoration was successful, otherwise returns -1.
+ */
+__bpf_kfunc int bpf_restore_skb_data(struct sk_buff *skb, int offset, char *data, int len)
+{
+ if (offset + len > skb_headroom(skb) + skb->len)
+ return -1;
+
+ memcpy(skb->head + offset, data, len);
+ return len;
+}
+
__bpf_kfunc_end_defs();
--
2.39.2
