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Message-ID:
<AM6PR03MB5848E92F29EA82BE32F9BA2F99A42@AM6PR03MB5848.eurprd03.prod.outlook.com>
Date: Wed, 10 Jul 2024 19:40:56 +0100
From: Juntong Deng <juntong.deng@...look.com>
To: ast@...nel.org,
daniel@...earbox.net,
john.fastabend@...il.com,
martin.lau@...ux.dev,
eddyz87@...il.com,
song@...nel.org,
yonghong.song@...ux.dev,
kpsingh@...nel.org,
sdf@...ichev.me,
haoluo@...gle.com,
jolsa@...nel.org,
andrii@...nel.org,
avagin@...il.com,
snorcht@...il.com
Cc: bpf@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH 12/16] bpf/crib: Introduce skb_data open-coded iterator kfuncs
This patch adds open-coded iterator style skb data iterator kfuncs
bpf_iter_skb_data_{new,next,destroy} that iterates over all data in
the specified skb (struct sk_buff).
This iterator is designed for checkpointing, and thus iterates over
all data in the skb (starting with head), not just application-level
data (starting with data).
Each iteration (next) copies the data to the specified buffer and
updates the offset.
The skb_data iterator has two getters
bpf_iter_skb_data_get_offset()/bpf_iter_skb_data_get_chunk_len(),
which are used to get the offset/the size of the chunk read in the
current iteration.
The skb_data iterator has a setter bpf_iter_skb_data_set_buf(),
which is used to set the buffer and the size of the buffer for
dumping the skb data during iteration.
Signed-off-by: Juntong Deng <juntong.deng@...look.com>
---
include/linux/bpf_crib.h | 14 ++++
kernel/bpf/crib/bpf_checkpoint.c | 116 +++++++++++++++++++++++++++++++
kernel/bpf/crib/bpf_crib.c | 7 ++
3 files changed, 137 insertions(+)
diff --git a/include/linux/bpf_crib.h b/include/linux/bpf_crib.h
index e7cfa9c1ae6b..c073166e60a0 100644
--- a/include/linux/bpf_crib.h
+++ b/include/linux/bpf_crib.h
@@ -32,4 +32,18 @@ struct bpf_iter_skb_kern {
struct sk_buff *skb;
} __aligned(8);
+struct bpf_iter_skb_data {
+ __u64 __opaque[5];
+} __aligned(8);
+
+struct bpf_iter_skb_data_kern {
+ struct sk_buff *skb;
+ char *buf;
+ unsigned int buflen;
+ int offset;
+ unsigned int headerlen;
+ unsigned int size;
+ unsigned int chunklen;
+} __aligned(8);
+
#endif /* _BPF_CRIB_H */
diff --git a/kernel/bpf/crib/bpf_checkpoint.c b/kernel/bpf/crib/bpf_checkpoint.c
index c95844faecbc..5c56f1cbf3c8 100644
--- a/kernel/bpf/crib/bpf_checkpoint.c
+++ b/kernel/bpf/crib/bpf_checkpoint.c
@@ -241,4 +241,120 @@ __bpf_kfunc void bpf_iter_skb_destroy(struct bpf_iter_skb *it)
bpf_skb_release(kit->skb);
}
+/**
+ * bpf_iter_skb_data_new() - Initialize a new skb data iterator for a skb
+ * (sk_buff), used to iterates over all skb data in the specified skb
+ *
+ * @it: new bpf_iter_skb_data to be created
+ * @skb: a pointer to a sk_buff to be iterated over
+ * @buf: buffer for dumping skb data
+ * @buflen: buffer length
+ */
+__bpf_kfunc int bpf_iter_skb_data_new(struct bpf_iter_skb_data *it,
+ struct sk_buff *skb, char *buf, int buflen)
+{
+ struct bpf_iter_skb_data_kern *kit = (void *)it;
+
+ BUILD_BUG_ON(sizeof(struct bpf_iter_skb_data_kern) > sizeof(struct bpf_iter_skb_data));
+ BUILD_BUG_ON(__alignof__(struct bpf_iter_skb_data_kern) !=
+ __alignof__(struct bpf_iter_skb_data));
+
+ int headerlen = skb_headroom(skb);
+
+ kit->skb = skb;
+ kit->headerlen = headerlen;
+ kit->offset = 0;
+ kit->chunklen = 0;
+ kit->size = headerlen + skb->len;
+ kit->buf = buf;
+ kit->buflen = buflen;
+
+ return 0;
+}
+
+/**
+ * bpf_iter_skb_data_next() - Dumps the corresponding data in skb to
+ * the buffer based on the current offset and buffer size, and updates
+ * the offset after copying the data
+ *
+ * @it: bpf_iter_skb_data to be checked
+ *
+ * @returns a pointer to the buffer if further data is available,
+ * otherwise returns NULL
+ */
+__bpf_kfunc char *bpf_iter_skb_data_next(struct bpf_iter_skb_data *it)
+{
+ struct bpf_iter_skb_data_kern *kit = (void *)it;
+
+ if (!kit->buf || kit->buflen <= 0)
+ return NULL;
+
+ if (kit->offset >= kit->size)
+ return NULL;
+
+ kit->chunklen = (kit->offset + kit->buflen > kit->size) ?
+ kit->size - kit->offset : kit->buflen;
+
+ skb_copy_bits(kit->skb, kit->offset - kit->headerlen, kit->buf, kit->chunklen);
+
+ kit->offset += kit->chunklen;
+
+ return kit->buf;
+}
+
+/**
+ * bpf_iter_skb_data_set_buf() - Set the buffer for dumping the skb data
+ * during iteration
+ *
+ * @it: bpf_iter_skb_data to be set
+ * @buf: buffer
+ * @buflen: buffer length
+ */
+__bpf_kfunc void bpf_iter_skb_data_set_buf(struct bpf_iter_skb_data *it, char *buf, int buflen)
+{
+ struct bpf_iter_skb_data_kern *kit = (void *)it;
+
+ kit->buf = buf;
+ kit->buflen = buflen;
+}
+
+/**
+ * bpf_iter_skb_data_get_chunk_len() - get the size of the chunk read
+ * in the current iteration
+ *
+ * @it: bpf_iter_skb_data to be checked
+ *
+ * @returns read size in the current iteration
+ */
+__bpf_kfunc int bpf_iter_skb_data_get_chunk_len(struct bpf_iter_skb_data *it)
+{
+ struct bpf_iter_skb_data_kern *kit = (void *)it;
+
+ return kit->chunklen;
+}
+
+/**
+ * bpf_iter_skb_data_get_offset() - get the offset of the chunk read
+ * in the current iteration
+ *
+ * @it: bpf_iter_skb_data to be checked
+ *
+ * @returns offset in the current iteration
+ */
+__bpf_kfunc int bpf_iter_skb_data_get_offset(struct bpf_iter_skb_data *it)
+{
+ struct bpf_iter_skb_data_kern *kit = (void *)it;
+
+ return kit->offset - kit->chunklen;
+}
+
+/**
+ * bpf_iter_skb_destroy() - Destroy a bpf_iter_skb_data
+ *
+ * @it: bpf_iter_skb_data to be destroyed
+ */
+__bpf_kfunc void bpf_iter_skb_data_destroy(struct bpf_iter_skb_data *it)
+{
+}
+
__bpf_kfunc_end_defs();
diff --git a/kernel/bpf/crib/bpf_crib.c b/kernel/bpf/crib/bpf_crib.c
index fda34d8143f1..462ae1ab50e5 100644
--- a/kernel/bpf/crib/bpf_crib.c
+++ b/kernel/bpf/crib/bpf_crib.c
@@ -293,6 +293,13 @@ BTF_ID_FLAGS(func, bpf_iter_skb_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_iter_skb_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_skb_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_skb_data_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_iter_skb_data_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_skb_data_set_buf, KF_ITER_SETTER | KF_TRUSTED_ARGS)
+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_KFUNCS_END(bpf_crib_kfuncs)
static int bpf_prog_run_crib(struct bpf_prog *prog,
--
2.39.2
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