[PATCH 5.17 062/158] libceph: fix potential use-after-free on linger ping and resends

Greg Kroah-Hartman
2022-05-23T18:03:10Z

From: Ilya Dryomov <idryomov@gmail.com>

commit 75dbb685f4e8786c33ddef8279bab0eadfb0731f upstream.

request_reinit() is not only ugly as the comment rightfully suggests,
but also unsafe. Even though it is called with osdc->lock held for
write in all cases, resetting the OSD request refcount can still race
with handle_reply() and result in use-after-free. Taking linger ping
as an example:

handle_timeout thread handle_reply thread

down_read(&osdc->lock)
req = lookup_request(...)
...
finish_request(req) # unregisters
up_read(&osdc->lock)
__complete_request(req)
linger_ping_cb(req)

# req->r_kref == 2 because handle_reply still holds its ref

down_write(&osdc->lock)
send_linger_ping(lreq)
req = lreq->ping_req # same req
# cancel_linger_request is NOT
# called - handle_reply already
# unregistered
request_reinit(req)
WARN_ON(req->r_kref != 1) # fires
request_init(req)
kref_init(req->r_kref)

# req->r_kref == 1 after kref_init

ceph_osdc_put_request(req)
kref_put(req->r_kref)

# req->r_kref == 0 after kref_put, req is freed

<further req initialization/use> !!!

This happens because send_linger_ping() always (re)uses the same OSD
request for watch ping requests, relying on cancel_linger_request() to
unregister it from the OSD client and rip its messages out from the
messenger. send_linger() does the same for watch/notify registration
and watch reconnect requests. Unfortunately cancel_request() doesn't
guarantee that after it returns the OSD client would be completely done
with the OSD request -- a ref could still be held and the callback (if
specified) could still be invoked too.

The original motivation for request_reinit() was inability to deal with
allocation failures in send_linger() and send_linger_ping(). Switching
to using osdc->req_mempool (currently only used by CephFS) respects that
and allows us to get rid of request_reinit().

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/ceph/osd_client.h | 3
net/ceph/osd_client.c | 302 +++++++++++++++-------------------------
2 files changed, 122 insertions(+), 183 deletions(-)

--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -287,6 +287,9 @@ struct ceph_osd_linger_request {
rados_watcherrcb_t errcb;
void *data;

+ struct ceph_pagelist *request_pl;
+ struct page **notify_id_pages;
+
struct page ***preply_pages;
size_t *preply_len;
};
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -537,43 +537,6 @@ static void request_init(struct ceph_osd
target_init(&req->r_t);
}

-/*
- * This is ugly, but it allows us to reuse linger registration and ping
- * requests, keeping the structure of the code around send_linger{_ping}()
- * reasonable. Setting up a min_nr=2 mempool for each linger request
- * and dealing with copying ops (this blasts req only, watch op remains
- * intact) isn't any better.
- */
-static void request_reinit(struct ceph_osd_request *req)
-{
- struct ceph_osd_client *osdc = req->r_osdc;
- bool mempool = req->r_mempool;
- unsigned int num_ops = req->r_num_ops;
- u64 snapid = req->r_snapid;
- struct ceph_snap_context *snapc = req->r_snapc;
- bool linger = req->r_linger;
- struct ceph_msg *request_msg = req->r_request;
- struct ceph_msg *reply_msg = req->r_reply;
-
- dout("%s req %p\n", __func__, req);
- WARN_ON(kref_read(&req->r_kref) != 1);
- request_release_checks(req);
-
- WARN_ON(kref_read(&request_msg->kref) != 1);
- WARN_ON(kref_read(&reply_msg->kref) != 1);
- target_destroy(&req->r_t);
-
- request_init(req);
- req->r_osdc = osdc;
- req->r_mempool = mempool;
- req->r_num_ops = num_ops;
- req->r_snapid = snapid;
- req->r_snapc = snapc;
- req->r_linger = linger;
- req->r_request = request_msg;
- req->r_reply = reply_msg;
-}
-
struct ceph_osd_request *ceph_osdc_alloc_request(struct ceph_osd_client *osdc,
struct ceph_snap_context *snapc,
unsigned int num_ops,
@@ -918,14 +881,30 @@ EXPORT_SYMBOL(osd_req_op_xattr_init);
* @watch_opcode: CEPH_OSD_WATCH_OP_*
*/
static void osd_req_op_watch_init(struct ceph_osd_request *req, int which,
- u64 cookie, u8 watch_opcode)
+ u8 watch_opcode, u64 cookie, u32 gen)
{
struct ceph_osd_req_op *op;

op = osd_req_op_init(req, which, CEPH_OSD_OP_WATCH, 0);
op->watch.cookie = cookie;
op->watch.op = watch_opcode;
- op->watch.gen = 0;
+ op->watch.gen = gen;
+}
+
+/*
+ * prot_ver, timeout and notify payload (may be empty) should already be
+ * encoded in @request_pl
+ */
+static void osd_req_op_notify_init(struct ceph_osd_request *req, int which,
+ u64 cookie, struct ceph_pagelist *request_pl)
+{
+ struct ceph_osd_req_op *op;
+
+ op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY, 0);
+ op->notify.cookie = cookie;
+
+ ceph_osd_data_pagelist_init(&op->notify.request_data, request_pl);
+ op->indata_len = request_pl->length;
}

/*
@@ -2727,10 +2706,13 @@ static void linger_release(struct kref *
WARN_ON(!list_empty(&lreq->pending_lworks));
WARN_ON(lreq->osd);

- if (lreq->reg_req)
- ceph_osdc_put_request(lreq->reg_req);
- if (lreq->ping_req)
- ceph_osdc_put_request(lreq->ping_req);
+ if (lreq->request_pl)
+ ceph_pagelist_release(lreq->request_pl);
+ if (lreq->notify_id_pages)
+ ceph_release_page_vector(lreq->notify_id_pages, 1);
+
+ ceph_osdc_put_request(lreq->reg_req);
+ ceph_osdc_put_request(lreq->ping_req);
target_destroy(&lreq->t);
kfree(lreq);
}
@@ -2999,6 +2981,12 @@ static void linger_commit_cb(struct ceph
struct ceph_osd_linger_request *lreq = req->r_priv;

mutex_lock(&lreq->lock);
+ if (req != lreq->reg_req) {
+ dout("%s lreq %p linger_id %llu unknown req (%p != %p)\n",
+ __func__, lreq, lreq->linger_id, req, lreq->reg_req);
+ goto out;
+ }
+
dout("%s lreq %p linger_id %llu result %d\n", __func__, lreq,
lreq->linger_id, req->r_result);
linger_reg_commit_complete(lreq, req->r_result);
@@ -3022,6 +3010,7 @@ static void linger_commit_cb(struct ceph
}
}

+out:
mutex_unlock(&lreq->lock);
linger_put(lreq);
}
@@ -3044,6 +3033,12 @@ static void linger_reconnect_cb(struct c
struct ceph_osd_linger_request *lreq = req->r_priv;

mutex_lock(&lreq->lock);
+ if (req != lreq->reg_req) {
+ dout("%s lreq %p linger_id %llu unknown req (%p != %p)\n",
+ __func__, lreq, lreq->linger_id, req, lreq->reg_req);
+ goto out;
+ }
+
dout("%s lreq %p linger_id %llu result %d last_error %d\n", __func__,
lreq, lreq->linger_id, req->r_result, lreq->last_error);
if (req->r_result < 0) {
@@ -3053,46 +3048,64 @@ static void linger_reconnect_cb(struct c
}
}

+out:
mutex_unlock(&lreq->lock);
linger_put(lreq);
}

static void send_linger(struct ceph_osd_linger_request *lreq)
{
- struct ceph_osd_request *req = lreq->reg_req;
- struct ceph_osd_req_op *op = &req->r_ops[0];
+ struct ceph_osd_client *osdc = lreq->osdc;
+ struct ceph_osd_request *req;
+ int ret;

- verify_osdc_wrlocked(req->r_osdc);
+ verify_osdc_wrlocked(osdc);
+ mutex_lock(&lreq->lock);
dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);

- if (req->r_osd)
- cancel_linger_request(req);
+ if (lreq->reg_req) {
+ if (lreq->reg_req->r_osd)
+ cancel_linger_request(lreq->reg_req);
+ ceph_osdc_put_request(lreq->reg_req);
+ }
+
+ req = ceph_osdc_alloc_request(osdc, NULL, 1, true, GFP_NOIO);
+ BUG_ON(!req);

- request_reinit(req);
target_copy(&req->r_t, &lreq->t);
req->r_mtime = lreq->mtime;

- mutex_lock(&lreq->lock);
if (lreq->is_watch && lreq->committed) {
- WARN_ON(op->op != CEPH_OSD_OP_WATCH ||
- op->watch.cookie != lreq->linger_id);
- op->watch.op = CEPH_OSD_WATCH_OP_RECONNECT;
- op->watch.gen = ++lreq->register_gen;
+ osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_RECONNECT,
+ lreq->linger_id, ++lreq->register_gen);
dout("lreq %p reconnect register_gen %u\n", lreq,
- op->watch.gen);
+ req->r_ops[0].watch.gen);
req->r_callback = linger_reconnect_cb;
} else {
- if (!lreq->is_watch)
+ if (lreq->is_watch) {
+ osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_WATCH,
+ lreq->linger_id, 0);
+ } else {
lreq->notify_id = 0;
- else
- WARN_ON(op->watch.op != CEPH_OSD_WATCH_OP_WATCH);
+
+ refcount_inc(&lreq->request_pl->refcnt);
+ osd_req_op_notify_init(req, 0, lreq->linger_id,
+ lreq->request_pl);
+ ceph_osd_data_pages_init(
+ osd_req_op_data(req, 0, notify, response_data),
+ lreq->notify_id_pages, PAGE_SIZE, 0, false, false);
+ }
dout("lreq %p register\n", lreq);
req->r_callback = linger_commit_cb;
}
- mutex_unlock(&lreq->lock);
+
+ ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+ BUG_ON(ret);

req->r_priv = linger_get(lreq);
req->r_linger = true;
+ lreq->reg_req = req;
+ mutex_unlock(&lreq->lock);

submit_request(req, true);
}
@@ -3102,6 +3115,12 @@ static void linger_ping_cb(struct ceph_o
struct ceph_osd_linger_request *lreq = req->r_priv;

mutex_lock(&lreq->lock);
+ if (req != lreq->ping_req) {
+ dout("%s lreq %p linger_id %llu unknown req (%p != %p)\n",
+ __func__, lreq, lreq->linger_id, req, lreq->ping_req);
+ goto out;
+ }
+
dout("%s lreq %p linger_id %llu result %d ping_sent %lu last_error %d\n",
__func__, lreq, lreq->linger_id, req->r_result, lreq->ping_sent,
lreq->last_error);
@@ -3117,6 +3136,7 @@ static void linger_ping_cb(struct ceph_o
lreq->register_gen, req->r_ops[0].watch.gen);
}

+out:
mutex_unlock(&lreq->lock);
linger_put(lreq);
}
@@ -3124,8 +3144,8 @@ static void linger_ping_cb(struct ceph_o
static void send_linger_ping(struct ceph_osd_linger_request *lreq)
{
struct ceph_osd_client *osdc = lreq->osdc;
- struct ceph_osd_request *req = lreq->ping_req;
- struct ceph_osd_req_op *op = &req->r_ops[0];
+ struct ceph_osd_request *req;
+ int ret;

if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_PAUSERD)) {
dout("%s PAUSERD\n", __func__);
@@ -3137,19 +3157,26 @@ static void send_linger_ping(struct ceph
__func__, lreq, lreq->linger_id, lreq->ping_sent,
lreq->register_gen);

- if (req->r_osd)
- cancel_linger_request(req);
+ if (lreq->ping_req) {
+ if (lreq->ping_req->r_osd)
+ cancel_linger_request(lreq->ping_req);
+ ceph_osdc_put_request(lreq->ping_req);
+ }

- request_reinit(req);
- target_copy(&req->r_t, &lreq->t);
+ req = ceph_osdc_alloc_request(osdc, NULL, 1, true, GFP_NOIO);
+ BUG_ON(!req);

- WARN_ON(op->op != CEPH_OSD_OP_WATCH ||
- op->watch.cookie != lreq->linger_id ||
- op->watch.op != CEPH_OSD_WATCH_OP_PING);
- op->watch.gen = lreq->register_gen;
+ target_copy(&req->r_t, &lreq->t);
+ osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_PING, lreq->linger_id,
+ lreq->register_gen);
req->r_callback = linger_ping_cb;
+
+ ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
+ BUG_ON(ret);
+
req->r_priv = linger_get(lreq);
req->r_linger = true;
+ lreq->ping_req = req;

ceph_osdc_get_request(req);
account_request(req);
@@ -3165,12 +3192,6 @@ static void linger_submit(struct ceph_os

down_write(&osdc->lock);
linger_register(lreq);
- if (lreq->is_watch) {
- lreq->reg_req->r_ops[0].watch.cookie = lreq->linger_id;
- lreq->ping_req->r_ops[0].watch.cookie = lreq->linger_id;
- } else {
- lreq->reg_req->r_ops[0].notify.cookie = lreq->linger_id;
- }

calc_target(osdc, &lreq->t, false);
osd = lookup_create_osd(osdc, lreq->t.osd, true);
@@ -3202,9 +3223,9 @@ static void cancel_linger_map_check(stru
*/
static void __linger_cancel(struct ceph_osd_linger_request *lreq)
{
- if (lreq->is_watch && lreq->ping_req->r_osd)
+ if (lreq->ping_req && lreq->ping_req->r_osd)
cancel_linger_request(lreq->ping_req);
- if (lreq->reg_req->r_osd)
+ if (lreq->reg_req && lreq->reg_req->r_osd)
cancel_linger_request(lreq->reg_req);
cancel_linger_map_check(lreq);
unlink_linger(lreq->osd, lreq);
@@ -4653,43 +4674,6 @@ again:
}
EXPORT_SYMBOL(ceph_osdc_sync);

-static struct ceph_osd_request *
-alloc_linger_request(struct ceph_osd_linger_request *lreq)
-{
- struct ceph_osd_request *req;
-
- req = ceph_osdc_alloc_request(lreq->osdc, NULL, 1, false, GFP_NOIO);
- if (!req)
- return NULL;
-
- ceph_oid_copy(&req->r_base_oid, &lreq->t.base_oid);
- ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);
- return req;
-}
-
-static struct ceph_osd_request *
-alloc_watch_request(struct ceph_osd_linger_request *lreq, u8 watch_opcode)
-{
- struct ceph_osd_request *req;
-
- req = alloc_linger_request(lreq);
- if (!req)
- return NULL;
-
- /*
- * Pass 0 for cookie because we don't know it yet, it will be
- * filled in by linger_submit().
- */
- osd_req_op_watch_init(req, 0, 0, watch_opcode);
-
- if (ceph_osdc_alloc_messages(req, GFP_NOIO)) {
- ceph_osdc_put_request(req);
- return NULL;
- }
-
- return req;
-}
-
/*
* Returns a handle, caller owns a ref.
*/
@@ -4719,18 +4703,6 @@ ceph_osdc_watch(struct ceph_osd_client *
lreq->t.flags = CEPH_OSD_FLAG_WRITE;
ktime_get_real_ts64(&lreq->mtime);

- lreq->reg_req = alloc_watch_request(lreq, CEPH_OSD_WATCH_OP_WATCH);
- if (!lreq->reg_req) {
- ret = -ENOMEM;
- goto err_put_lreq;
- }
-
- lreq->ping_req = alloc_watch_request(lreq, CEPH_OSD_WATCH_OP_PING);
- if (!lreq->ping_req) {
- ret = -ENOMEM;
- goto err_put_lreq;
- }
-
linger_submit(lreq);
ret = linger_reg_commit_wait(lreq);
if (ret) {
@@ -4768,8 +4740,8 @@ int ceph_osdc_unwatch(struct ceph_osd_cl
ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);
req->r_flags = CEPH_OSD_FLAG_WRITE;
ktime_get_real_ts64(&req->r_mtime);
- osd_req_op_watch_init(req, 0, lreq->linger_id,
- CEPH_OSD_WATCH_OP_UNWATCH);
+ osd_req_op_watch_init(req, 0, CEPH_OSD_WATCH_OP_UNWATCH,
+ lreq->linger_id, 0);

ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
if (ret)
@@ -4855,35 +4827,6 @@ out_put_req:
}
EXPORT_SYMBOL(ceph_osdc_notify_ack);

-static int osd_req_op_notify_init(struct ceph_osd_request *req, int which,
- u64 cookie, u32 prot_ver, u32 timeout,
- void *payload, u32 payload_len)
-{
- struct ceph_osd_req_op *op;
- struct ceph_pagelist *pl;
- int ret;
-
- op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY, 0);
- op->notify.cookie = cookie;
-
- pl = ceph_pagelist_alloc(GFP_NOIO);
- if (!pl)
- return -ENOMEM;
-
- ret = ceph_pagelist_encode_32(pl, 1); /* prot_ver */
- ret |= ceph_pagelist_encode_32(pl, timeout);
- ret |= ceph_pagelist_encode_32(pl, payload_len);
- ret |= ceph_pagelist_append(pl, payload, payload_len);
- if (ret) {
- ceph_pagelist_release(pl);
- return -ENOMEM;
- }
-
- ceph_osd_data_pagelist_init(&op->notify.request_data, pl);
- op->indata_len = pl->length;
- return 0;
-}
-
/*
* @timeout: in seconds
*
@@ -4902,7 +4845,6 @@ int ceph_osdc_notify(struct ceph_osd_cli
size_t *preply_len)
{
struct ceph_osd_linger_request *lreq;
- struct page **pages;
int ret;

WARN_ON(!timeout);
@@ -4915,41 +4857,35 @@ int ceph_osdc_notify(struct ceph_osd_cli
if (!lreq)
return -ENOMEM;

- lreq->preply_pages = preply_pages;
- lreq->preply_len = preply_len;
-
- ceph_oid_copy(&lreq->t.base_oid, oid);
- ceph_oloc_copy(&lreq->t.base_oloc, oloc);
- lreq->t.flags = CEPH_OSD_FLAG_READ;
-
- lreq->reg_req = alloc_linger_request(lreq);
- if (!lreq->reg_req) {
+ lreq->request_pl = ceph_pagelist_alloc(GFP_NOIO);
+ if (!lreq->request_pl) {
ret = -ENOMEM;
goto out_put_lreq;
}

- /*
- * Pass 0 for cookie because we don't know it yet, it will be
- * filled in by linger_submit().
- */
- ret = osd_req_op_notify_init(lreq->reg_req, 0, 0, 1, timeout,
- payload, payload_len);
- if (ret)
+ ret = ceph_pagelist_encode_32(lreq->request_pl, 1); /* prot_ver */
+ ret |= ceph_pagelist_encode_32(lreq->request_pl, timeout);
+ ret |= ceph_pagelist_encode_32(lreq->request_pl, payload_len);
+ ret |= ceph_pagelist_append(lreq->request_pl, payload, payload_len);
+ if (ret) {
+ ret = -ENOMEM;
goto out_put_lreq;
+ }

/* for notify_id */
- pages = ceph_alloc_page_vector(1, GFP_NOIO);
- if (IS_ERR(pages)) {
- ret = PTR_ERR(pages);
+ lreq->notify_id_pages = ceph_alloc_page_vector(1, GFP_NOIO);
+ if (IS_ERR(lreq->notify_id_pages)) {
+ ret = PTR_ERR(lreq->notify_id_pages);
+ lreq->notify_id_pages = NULL;
goto out_put_lreq;
}
- ceph_osd_data_pages_init(osd_req_op_data(lreq->reg_req, 0, notify,
- response_data),
- pages, PAGE_SIZE, 0, false, true);

- ret = ceph_osdc_alloc_messages(lreq->reg_req, GFP_NOIO);
- if (ret)
- goto out_put_lreq;
+ lreq->preply_pages = preply_pages;
+ lreq->preply_len = preply_len;
+
+ ceph_oid_copy(&lreq->t.base_oid, oid);
+ ceph_oloc_copy(&lreq->t.base_oloc, oloc);
+ lreq->t.flags = CEPH_OSD_FLAG_READ;

linger_submit(lreq);
ret = linger_reg_commit_wait(lreq);