In drivers/target/target_core_xcopy.c in the Linux kernel before 5.10.7,
insufficient identifier checking in the LIO SCSI target code can be used by
remote attackers to read or write files via directory traversal in an XCOPY
request, aka CID-2896c93811e3. For example, an attack can occur over a
network if the attacker has access to one iSCSI LUN. The attacker gains
control over file access because I/O operations are proxied via an
attacker-selected backstore.

It was discovered that the LIO SCSI target implementation in the Linux
kernel performed insufficient identifier checking in certain XCOPY
requests. An attacker with access to at least one LUN in a multiple
backstore environment could use this to expose sensitive information or
modify data.

XCOPY support is enabled by default, but can be disabled via:

echo 0 > /sys/kernel/config/target/core/<backstore>/<name>/attrib/emulate_3pc

or

targetcli /backstores/<backstore>/<name> set attribute emulate_3pc=0

.
This workaround does *not* affect XCOPY requests sent to tcmu-runner
based backstores.

sbeattie

MITIGATION XCOPY support is enabled by default, but can be disabled via: echo 0 > /sys/kernel/config/target/core/<backstore>/<name>/attrib/emulate_3pc or targetcli /backstores/<backstore>/<name> set attribute emulate_3pc=0 . This workaround does *not* affect XCOPY requests sent to tcmu-runner based backstores.