[PATCH v13 05/59] libceph: support sparse reads on msgr2 secure codepath

Jeff Layton
2022-04-06T00:22:10Z

Add a new init_sgs_pages helper that populates the scatterlist from
an arbitrary point in an array of pages.

Change setup_message_sgs to take an optional pointer to an array of
pages. If that's set, then the scatterlist will be set using that
array instead of the cursor.

When given a sparse read on a secure connection, decrypt the data
in-place rather than into the final destination, by passing it the
in_enc_pages array.

After decrypting, run the sparse_read state machine in a loop, copying
data from the decrypted pages until it's complete.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
net/ceph/messenger_v2.c | 119 ++++++++++++++++++++++++++++++++++++----
1 file changed, 109 insertions(+), 10 deletions(-)

diff --git a/net/ceph/messenger_v2.c b/net/ceph/messenger_v2.c
index d527777af584..3dcaee6f8903 100644
--- a/net/ceph/messenger_v2.c
+++ b/net/ceph/messenger_v2.c
@@ -963,12 +963,48 @@ static void init_sgs_cursor(struct scatterlist **sg,
}
}

+/**
+ * init_sgs_pages: set up scatterlist on an array of page pointers
+ * @sg: scatterlist to populate
+ * @pages: pointer to page array
+ * @dpos: position in the array to start (bytes)
+ * @dlen: len to add to sg (bytes)
+ * @pad: pointer to pad destination (if any)
+ *
+ * Populate the scatterlist from the page array, starting at an arbitrary
+ * byte in the array and running for a specified length.
+ */
+static void init_sgs_pages(struct scatterlist **sg, struct page **pages,
+ int dpos, int dlen, u8 *pad)
+{
+ int idx = dpos >> PAGE_SHIFT;
+ int off = offset_in_page(dpos);
+ int resid = dlen;
+
+ do {
+ int len = min(resid, (int)PAGE_SIZE - off);
+
+ sg_set_page(*sg, pages[idx], len, off);
+ *sg = sg_next(*sg);
+ off = 0;
+ ++idx;
+ resid -= len;
+ } while (resid);
+
+ if (need_padding(dlen)) {
+ sg_set_buf(*sg, pad, padding_len(dlen));
+ *sg = sg_next(*sg);
+ }
+}
+
static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
u8 *front_pad, u8 *middle_pad, u8 *data_pad,
- void *epilogue, bool add_tag)
+ void *epilogue, struct page **pages, int dpos,
+ bool add_tag)
{
struct ceph_msg_data_cursor cursor;
struct scatterlist *cur_sg;
+ int dlen = data_len(msg);
int sg_cnt;
int ret;

@@ -982,9 +1018,15 @@ static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
if (middle_len(msg))
sg_cnt += calc_sg_cnt(msg->middle->vec.iov_base,
middle_len(msg));
- if (data_len(msg)) {
- ceph_msg_data_cursor_init(&cursor, msg, data_len(msg));
- sg_cnt += calc_sg_cnt_cursor(&cursor);
+ if (dlen) {
+ if (pages) {
+ sg_cnt += calc_pages_for(dpos, dlen);
+ if (need_padding(dlen))
+ sg_cnt++;
+ } else {
+ ceph_msg_data_cursor_init(&cursor, msg, dlen);
+ sg_cnt += calc_sg_cnt_cursor(&cursor);
+ }
}

ret = sg_alloc_table(sgt, sg_cnt, GFP_NOIO);
@@ -998,9 +1040,13 @@ static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
if (middle_len(msg))
init_sgs(&cur_sg, msg->middle->vec.iov_base, middle_len(msg),
middle_pad);
- if (data_len(msg)) {
- ceph_msg_data_cursor_init(&cursor, msg, data_len(msg));
- init_sgs_cursor(&cur_sg, &cursor, data_pad);
+ if (dlen) {
+ if (pages) {
+ init_sgs_pages(&cur_sg, pages, dpos, dlen, data_pad);
+ } else {
+ ceph_msg_data_cursor_init(&cursor, msg, dlen);
+ init_sgs_cursor(&cur_sg, &cursor, data_pad);
+ }
}

WARN_ON(!sg_is_last(cur_sg));
@@ -1035,10 +1081,52 @@ static int decrypt_control_remainder(struct ceph_connection *con)
padded_len(rem_len) + CEPH_GCM_TAG_LEN);
}

+/* Process sparse read data that lives in a buffer */
+static int process_v2_sparse_read(struct ceph_connection *con, struct page **pages, int spos)
+{
+ struct ceph_msg_data_cursor *cursor = &con->v2.in_cursor;
+ int ret;
+
+ for (;;) {
+ char *buf = NULL;
+
+ ret = con->ops->sparse_read(con, cursor, &buf);
+ if (ret <= 0)
+ return ret;
+
+ dout("%s: sparse_read return %x buf %p\n", __func__, ret, buf);
+
+ do {
+ int idx = spos >> PAGE_SHIFT;
+ int soff = offset_in_page(spos);
+ struct page *spage = con->v2.in_enc_pages[idx];
+ int len = min_t(int, ret, PAGE_SIZE - soff);
+
+ if (buf) {
+ memcpy_from_page(buf, spage, soff, len);
+ buf += len;
+ } else {
+ struct bio_vec bv;
+
+ get_bvec_at(cursor, &bv);
+ len = min_t(int, len, bv.bv_len);
+ memcpy_page(bv.bv_page, bv.bv_offset,
+ spage, soff, len);
+ ceph_msg_data_advance(cursor, len);
+ }
+ spos += len;
+ ret -= len;
+ } while (ret);
+ }
+}
+
static int decrypt_tail(struct ceph_connection *con)
{
struct sg_table enc_sgt = {};
struct sg_table sgt = {};
+ struct page **pages = NULL;
+ bool sparse = con->in_msg->sparse_read;
+ int dpos = 0;
int tail_len;
int ret;

@@ -1049,9 +1137,14 @@ static int decrypt_tail(struct ceph_connection *con)
if (ret)
goto out;

+ if (sparse) {
+ dpos = padded_len(front_len(con->in_msg) + padded_len(middle_len(con->in_msg)));
+ pages = con->v2.in_enc_pages;
+ }
+
ret = setup_message_sgs(&sgt, con->in_msg, FRONT_PAD(con->v2.in_buf),
- MIDDLE_PAD(con->v2.in_buf), DATA_PAD(con->v2.in_buf),
- con->v2.in_buf, true);
+ MIDDLE_PAD(con->v2.in_buf), DATA_PAD(con->v2.in_buf),
+ con->v2.in_buf, pages, dpos, true);
if (ret)
goto out;

@@ -1061,6 +1154,12 @@ static int decrypt_tail(struct ceph_connection *con)
if (ret)
goto out;

+ if (sparse && data_len(con->in_msg)) {
+ ret = process_v2_sparse_read(con, con->v2.in_enc_pages, dpos);
+ if (ret)
+ goto out;
+ }
+
WARN_ON(!con->v2.in_enc_page_cnt);
ceph_release_page_vector(con->v2.in_enc_pages,
con->v2.in_enc_page_cnt);
@@ -1584,7 +1683,7 @@ static int prepare_message_secure(struct ceph_connection *con)

encode_epilogue_secure(con, false);
ret = setup_message_sgs(&sgt, con->out_msg, zerop, zerop, zerop,
- &con->v2.out_epil, false);
+ &con->v2.out_epil, NULL, 0, false);
if (ret)
goto out;

--
2.35.1