[PATCH 4.9 05/25] scsi: target: Fix XCOPY NAA identifier lookup

Greg Kroah-Hartman
2021-01-15T13:07:43Z

From: David Disseldorp <ddiss@suse.de>

[ Upstream commit 2896c93811e39d63a4d9b63ccf12a8fbc226e5e4 ]

When attempting to match EXTENDED COPY CSCD descriptors with corresponding
se_devices, target_xcopy_locate_se_dev_e4() currently iterates over LIO's
global devices list which includes all configured backstores.

This change ensures that only initiator-accessible backstores are
considered during CSCD descriptor lookup, according to the session's
se_node_acl LUN list.

To avoid LUN removal race conditions, device pinning is changed from being
configfs based to instead using the se_node_acl lun_ref.

Reference: CVE-2020-28374
Fixes: cbf031f425fd ("target: Add support for EXTENDED_COPY copy offload emulation")
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/target/target_core_xcopy.c | 119 +++++++++++++++++------------
drivers/target/target_core_xcopy.h | 1 +
2 files changed, 71 insertions(+), 49 deletions(-)

diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index 065669f9ca8cc..84e3bf1132fd5 100644
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -52,60 +52,83 @@ static int target_xcopy_gen_naa_ieee(struct se_device *dev, unsigned char *buf)
return 0;
}

-struct xcopy_dev_search_info {
- const unsigned char *dev_wwn;
- struct se_device *found_dev;
-};
-
+/**
+ * target_xcopy_locate_se_dev_e4_iter - compare XCOPY NAA device identifiers
+ *
+ * @se_dev: device being considered for match
+ * @dev_wwn: XCOPY requested NAA dev_wwn
+ * @return: 1 on match, 0 on no-match
+ */
static int target_xcopy_locate_se_dev_e4_iter(struct se_device *se_dev,
- void *data)
+ const unsigned char *dev_wwn)
{
- struct xcopy_dev_search_info *info = data;
unsigned char tmp_dev_wwn[XCOPY_NAA_IEEE_REGEX_LEN];
int rc;

- if (!se_dev->dev_attrib.emulate_3pc)
+ if (!se_dev->dev_attrib.emulate_3pc) {
+ pr_debug("XCOPY: emulate_3pc disabled on se_dev %p\n", se_dev);
return 0;
+ }

memset(&tmp_dev_wwn[0], 0, XCOPY_NAA_IEEE_REGEX_LEN);
target_xcopy_gen_naa_ieee(se_dev, &tmp_dev_wwn[0]);

- rc = memcmp(&tmp_dev_wwn[0], info->dev_wwn, XCOPY_NAA_IEEE_REGEX_LEN);
- if (rc != 0)
- return 0;
-
- info->found_dev = se_dev;
- pr_debug("XCOPY 0xe4: located se_dev: %p\n", se_dev);
-
- rc = target_depend_item(&se_dev->dev_group.cg_item);
+ rc = memcmp(&tmp_dev_wwn[0], dev_wwn, XCOPY_NAA_IEEE_REGEX_LEN);
if (rc != 0) {
- pr_err("configfs_depend_item attempt failed: %d for se_dev: %p\n",
- rc, se_dev);
- return rc;
+ pr_debug("XCOPY: skip non-matching: %*ph\n",
+ XCOPY_NAA_IEEE_REGEX_LEN, tmp_dev_wwn);
+ return 0;
}
+ pr_debug("XCOPY 0xe4: located se_dev: %p\n", se_dev);

- pr_debug("Called configfs_depend_item for se_dev: %p se_dev->se_dev_group: %p\n",
- se_dev, &se_dev->dev_group);
return 1;
}

-static int target_xcopy_locate_se_dev_e4(const unsigned char *dev_wwn,
- struct se_device **found_dev)
+static int target_xcopy_locate_se_dev_e4(struct se_session *sess,
+ const unsigned char *dev_wwn,
+ struct se_device **_found_dev,
+ struct percpu_ref **_found_lun_ref)
{
- struct xcopy_dev_search_info info;
- int ret;
-
- memset(&info, 0, sizeof(info));
- info.dev_wwn = dev_wwn;
-
- ret = target_for_each_device(target_xcopy_locate_se_dev_e4_iter, &info);
- if (ret == 1) {
- *found_dev = info.found_dev;
- return 0;
- } else {
- pr_debug_ratelimited("Unable to locate 0xe4 descriptor for EXTENDED_COPY\n");
- return -EINVAL;
+ struct se_dev_entry *deve;
+ struct se_node_acl *nacl;
+ struct se_lun *this_lun = NULL;
+ struct se_device *found_dev = NULL;
+
+ /* cmd with NULL sess indicates no associated $FABRIC_MOD */
+ if (!sess)
+ goto err_out;
+
+ pr_debug("XCOPY 0xe4: searching for: %*ph\n",
+ XCOPY_NAA_IEEE_REGEX_LEN, dev_wwn);
+
+ nacl = sess->se_node_acl;
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
+ struct se_device *this_dev;
+ int rc;
+
+ this_lun = rcu_dereference(deve->se_lun);
+ this_dev = rcu_dereference_raw(this_lun->lun_se_dev);
+
+ rc = target_xcopy_locate_se_dev_e4_iter(this_dev, dev_wwn);
+ if (rc) {
+ if (percpu_ref_tryget_live(&this_lun->lun_ref))
+ found_dev = this_dev;
+ break;
+ }
}
+ rcu_read_unlock();
+ if (found_dev == NULL)
+ goto err_out;
+
+ pr_debug("lun_ref held for se_dev: %p se_dev->se_dev_group: %p\n",
+ found_dev, &found_dev->dev_group);
+ *_found_dev = found_dev;
+ *_found_lun_ref = &this_lun->lun_ref;
+ return 0;
+err_out:
+ pr_debug_ratelimited("Unable to locate 0xe4 descriptor for EXTENDED_COPY\n");
+ return -EINVAL;
}

static int target_xcopy_parse_tiddesc_e4(struct se_cmd *se_cmd, struct xcopy_op *xop,
@@ -248,12 +271,16 @@ static int target_xcopy_parse_target_descriptors(struct se_cmd *se_cmd,

switch (xop->op_origin) {
case XCOL_SOURCE_RECV_OP:
- rc = target_xcopy_locate_se_dev_e4(xop->dst_tid_wwn,
- &xop->dst_dev);
+ rc = target_xcopy_locate_se_dev_e4(se_cmd->se_sess,
+ xop->dst_tid_wwn,
+ &xop->dst_dev,
+ &xop->remote_lun_ref);
break;
case XCOL_DEST_RECV_OP:
- rc = target_xcopy_locate_se_dev_e4(xop->src_tid_wwn,
- &xop->src_dev);
+ rc = target_xcopy_locate_se_dev_e4(se_cmd->se_sess,
+ xop->src_tid_wwn,
+ &xop->src_dev,
+ &xop->remote_lun_ref);
break;
default:
pr_err("XCOPY CSCD descriptor IDs not found in CSCD list - "
@@ -397,18 +424,12 @@ static int xcopy_pt_get_cmd_state(struct se_cmd *se_cmd)

static void xcopy_pt_undepend_remotedev(struct xcopy_op *xop)
{
- struct se_device *remote_dev;
-
if (xop->op_origin == XCOL_SOURCE_RECV_OP)
- remote_dev = xop->dst_dev;
+ pr_debug("putting dst lun_ref for %p\n", xop->dst_dev);
else
- remote_dev = xop->src_dev;
-
- pr_debug("Calling configfs_undepend_item for"
- " remote_dev: %p remote_dev->dev_group: %p\n",
- remote_dev, &remote_dev->dev_group.cg_item);
+ pr_debug("putting src lun_ref for %p\n", xop->src_dev);

- target_undepend_item(&remote_dev->dev_group.cg_item);
+ percpu_ref_put(xop->remote_lun_ref);
}

static void xcopy_pt_release_cmd(struct se_cmd *se_cmd)
diff --git a/drivers/target/target_core_xcopy.h b/drivers/target/target_core_xcopy.h
index 700a981c7b415..7db8d0c9223f8 100644
--- a/drivers/target/target_core_xcopy.h
+++ b/drivers/target/target_core_xcopy.h
@@ -19,6 +19,7 @@ struct xcopy_op {
struct se_device *dst_dev;
unsigned char dst_tid_wwn[XCOPY_NAA_IEEE_REGEX_LEN];
unsigned char local_dev_wwn[XCOPY_NAA_IEEE_REGEX_LEN];
+ struct percpu_ref *remote_lun_ref;

sector_t src_lba;
sector_t dst_lba;
--
2.27.0