Add devmem_bind_rx_unregister_check and devmem_bind_tx_unregister_check to nl_netdev.py to verify that unregistering a netdevsim device while a netlink socket holds an active RX or TX devmem binding synchronously detaches the dma_buf attachment and cleanly closes the netlink socket without use-after-free or page faults.
Cc: Tariq Toukan <[email protected]> Cc: Kaifeng Wang <[email protected]> Signed-off-by: Mina Almasry <[email protected]> --- tools/testing/selftests/net/nl_netdev.py | 108 ++++++++++++++++++++++- 1 file changed, 105 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/net/nl_netdev.py b/tools/testing/selftests/net/nl_netdev.py index ceb44c8e1fec5..bad230ee9dcd2 100755 --- a/tools/testing/selftests/net/nl_netdev.py +++ b/tools/testing/selftests/net/nl_netdev.py @@ -6,10 +6,14 @@ Tests for the netdev netlink family. """ import errno +import fcntl +import mmap +import os +import struct from os import system -from lib.py import ksft_run, ksft_exit +from lib.py import ksft_run, ksft_exit, KsftSkipEx from lib.py import ksft_eq, ksft_ge, ksft_ne, ksft_raises, ksft_busy_wait -from lib.py import NetdevFamily, NetdevSimDev, NlError, defer, ip +from lib.py import EthtoolFamily, NetdevFamily, NetdevSimDev, NlError, defer, ip def empty_check(nf) -> None: @@ -366,6 +370,102 @@ def page_pool_stats_ifindex_check(nf) -> None: ksft_eq(cm.exception.nl_msg.extack['bad-attr'], '.info.id') +def _create_udmabuf(num_pages=64) -> int: + """Create a sealed memfd-backed udmabuf fd for devmem tests.""" + if not os.path.exists("/dev/udmabuf"): + raise KsftSkipEx("/dev/udmabuf is not available") + + size = num_pages * mmap.PAGESIZE + memfd = os.memfd_create("devmem-ksft", os.MFD_ALLOW_SEALING) + os.ftruncate(memfd, size) + fcntl.fcntl(memfd, 1033, 0x0002) # F_ADD_SEALS, F_SEAL_SHRINK + devfd = os.open("/dev/udmabuf", os.O_RDWR) + req = bytearray(struct.pack("IIQQ", memfd, 0, 0, size)) + dmabuf_fd = fcntl.ioctl(devfd, 0x40187542, req) # UDMABUF_CREATE + os.close(devfd) + os.close(memfd) + return dmabuf_fd + + +def _dmabuf_attached_devs(): + """Return attached device names from debugfs dma_buf/bufinfo if available.""" + path = "/sys/kernel/debug/dma_buf/bufinfo" + if not os.path.exists(path): + return None + with open(path, "r", encoding="utf-8") as f: + text = f.read() + attached = [] + in_attached = False + for line in text.splitlines(): + if line.strip() == "Attached Devices:": + in_attached = True + continue + if in_attached: + if line.startswith("\t") and line.strip(): + attached.append(line.strip()) + else: + in_attached = False + return attached + + +def devmem_bind_rx_unregister_check(_nf) -> None: + """Verify RX devmem bindings detach dma_buf synchronously on netdev unregister.""" + dmabuf_fd = _create_udmabuf() + nf_priv = NetdevFamily() + ef = EthtoolFamily() + nsimdev = NetdevSimDev(queue_count=2) + nsim = nsimdev.nsims[0] + + ip(f"link set dev {nsim.ifname} up") + ef.rings_set({"header": {"dev-index": nsim.ifindex}, + "tcp-data-split": "enabled"}) + nf_priv.bind_rx({ + "ifindex": nsim.ifindex, + "fd": dmabuf_fd, + "queues": [{"id": 1, "type": "rx"}], + }) + + attached = _dmabuf_attached_devs() + if attached is not None: + ksft_ge(len(attached), 1) + + nsimdev.remove() + + attached = _dmabuf_attached_devs() + if attached is not None: + ksft_eq(len(attached), 0) + + del nf_priv + os.close(dmabuf_fd) + + +def devmem_bind_tx_unregister_check(_nf) -> None: + """Verify TX devmem bindings detach cleanly on netdev unregister without UAF.""" + dmabuf_fd = _create_udmabuf() + nf_priv = NetdevFamily() + nsimdev = NetdevSimDev(queue_count=2) + nsim = nsimdev.nsims[0] + + ip(f"link set dev {nsim.ifname} up") + nf_priv.bind_tx({ + "ifindex": nsim.ifindex, + "fd": dmabuf_fd, + }) + + attached = _dmabuf_attached_devs() + if attached is not None: + ksft_ge(len(attached), 1) + + nsimdev.remove() + + attached = _dmabuf_attached_devs() + if attached is not None: + ksft_eq(len(attached), 0) + + del nf_priv + os.close(dmabuf_fd) + + def main() -> None: """ Ksft boiler plate main """ nf = NetdevFamily() @@ -379,7 +479,9 @@ def main() -> None: page_pool_check, page_pool_dump_ifindex, page_pool_ifindex_leak_check, - page_pool_stats_ifindex_check + page_pool_stats_ifindex_check, + devmem_bind_rx_unregister_check, + devmem_bind_tx_unregister_check ], args=(nf, )) ksft_exit() -- 2.56.0.385.gd3acb90ef8-goog
