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.
Add the dma-buf, udmabuf and devmem options the tests need to tools/testing/selftests/net/config. Cc: Tariq Toukan <[email protected]> Cc: Kaifeng Wang <[email protected]> Assisted-by: LLM Signed-off-by: Mina Almasry <[email protected]> Reviewed-by: Dragos Tatulea <[email protected]> --- v3: - Count attachments of the test's own dma-buf only, and skip instead of passing when debugfs bufinfo is not readable (Sashiko). - Close the netlink socket after removing the device, clean up with defer(), and skip on EOPNOTSUPP from bind-rx/bind-tx (Sashiko). - Replace the hardcoded UDMABUF_CREATE value with a helper that computes it for the running architecture (Sashiko, Dragos), and close the memfd and /dev/udmabuf fds on errors (Sashiko). - Add the needed options to tools/testing/selftests/net/config (Sashiko). --- tools/testing/selftests/net/config | 4 + tools/testing/selftests/net/nl_netdev.py | 125 ++++++++++++++++++++++- 2 files changed, 126 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config index 737e7e6327b37..1e21f0055a2c0 100644 --- a/tools/testing/selftests/net/config +++ b/tools/testing/selftests/net/config @@ -11,6 +11,7 @@ CONFIG_CRYPTO_ARIA=y CONFIG_CRYPTO_CHACHA20POLY1305=m CONFIG_CRYPTO_SHA1=y CONFIG_CRYPTO_SM4_GENERIC=y +CONFIG_DEBUG_FS=y CONFIG_DEBUG_INFO_BTF=y CONFIG_DEBUG_INFO_BTF_MODULES=n CONFIG_DUMMY=y @@ -76,6 +77,7 @@ CONFIG_NET_CLS_BPF=m CONFIG_NET_CLS_FLOWER=m CONFIG_NET_CLS_MATCHALL=m CONFIG_NET_CLS_U32=m +CONFIG_NET_DEVMEM=y CONFIG_NETDEVSIM=m CONFIG_NET_DROP_MONITOR=m CONFIG_NETFILTER=y @@ -120,6 +122,7 @@ CONFIG_OPENVSWITCH=m CONFIG_PAGE_POOL_STATS=y CONFIG_PSAMPLE=m CONFIG_RPS=y +CONFIG_SYNC_FILE=y CONFIG_SYN_COOKIES=y CONFIG_SYSCTL=y CONFIG_SYSFS=y @@ -131,6 +134,7 @@ CONFIG_TEST_BPF=m CONFIG_TLS=m CONFIG_TRACEPOINTS=y CONFIG_TUN=y +CONFIG_UDMABUF=y CONFIG_USER_NS=y CONFIG_VETH=y CONFIG_VLAN_8021Q=y diff --git a/tools/testing/selftests/net/nl_netdev.py b/tools/testing/selftests/net/nl_netdev.py index ceb44c8e1fec5..988878b71358c 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, KsftFailEx, 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 +370,119 @@ def page_pool_stats_ifindex_check(nf) -> None: ksft_eq(cm.exception.nl_msg.extack['bad-attr'], '.info.id') +def _udmabuf_create_ioctl() -> int: + """Return UDMABUF_CREATE, _IOW('u', 0x42, struct udmabuf_create).""" + machine = os.uname().machine + if machine.startswith(("alpha", "mips", "ppc", "powerpc", "sparc")): + ioc_write = 4 << 29 + elif machine.startswith("parisc"): + ioc_write = 2 << 30 + else: + ioc_write = 1 << 30 + return ioc_write | 24 << 16 | ord("u") << 8 | 0x42 + + +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) + try: + os.ftruncate(memfd, size) + fcntl.fcntl(memfd, fcntl.F_ADD_SEALS, fcntl.F_SEAL_SHRINK) + devfd = os.open("/dev/udmabuf", os.O_RDWR) + try: + req = bytearray(struct.pack("IIQQ", memfd, 0, 0, size)) + return fcntl.ioctl(devfd, _udmabuf_create_ioctl(), req) + finally: + os.close(devfd) + finally: + os.close(memfd) + + +def _dmabuf_attach_count(dmabuf_fd) -> int: + """Return the number of devices attached to dmabuf_fd, from debugfs.""" + path = "/sys/kernel/debug/dma_buf/bufinfo" + try: + with open(path, "r", encoding="utf-8") as f: + lines = f.read().splitlines() + except OSError as e: + raise KsftSkipEx(f"{path} is not readable: {e}") from e + + ino = os.fstat(dmabuf_fd).st_ino + found = False + for line in lines: + fields = line.split("\t") + if not found: + found = (len(fields) == 7 and fields[5].isdigit() and + int(fields[5]) == ino) + elif line.startswith("Total "): + return int(line.split()[1]) + raise KsftFailEx(f"dma-buf {ino} not found in {path}") + + +def _devmem_bind(bind, attrs) -> None: + """Run a devmem bind op, skip the test if the device can't do devmem.""" + try: + bind(attrs) + except NlError as e: + if e.error == errno.EOPNOTSUPP: + raise KsftSkipEx(f"devmem binding not supported: {e}") from e + raise + + +def devmem_bind_rx_unregister_check(_nf) -> None: + """Verify RX devmem bindings detach dma_buf synchronously on netdev unregister.""" + dmabuf_fd = _create_udmabuf() + defer(os.close, dmabuf_fd) + nf_priv = NetdevFamily() + defer(nf_priv.close) + nsimdev = NetdevSimDev(queue_count=2) + defer(nsimdev.remove) + nsim = nsimdev.nsims[0] + + ip(f"link set dev {nsim.ifname} up") + with EthtoolFamily() as ef: + ef.rings_set({"header": {"dev-index": nsim.ifindex}, + "tcp-data-split": "enabled"}) + _devmem_bind(nf_priv.bind_rx, { + "ifindex": nsim.ifindex, + "fd": dmabuf_fd, + "queues": [{"id": 1, "type": "rx"}], + }) + ksft_ge(_dmabuf_attach_count(dmabuf_fd), 1) + + nsimdev.remove() + ksft_eq(_dmabuf_attach_count(dmabuf_fd), 0) + + nf_priv.close() + + +def devmem_bind_tx_unregister_check(_nf) -> None: + """Verify TX devmem bindings detach cleanly on netdev unregister without UAF.""" + dmabuf_fd = _create_udmabuf() + defer(os.close, dmabuf_fd) + nf_priv = NetdevFamily() + defer(nf_priv.close) + nsimdev = NetdevSimDev(queue_count=2) + defer(nsimdev.remove) + nsim = nsimdev.nsims[0] + + ip(f"link set dev {nsim.ifname} up") + _devmem_bind(nf_priv.bind_tx, { + "ifindex": nsim.ifindex, + "fd": dmabuf_fd, + }) + ksft_ge(_dmabuf_attach_count(dmabuf_fd), 1) + + nsimdev.remove() + ksft_eq(_dmabuf_attach_count(dmabuf_fd), 0) + + nf_priv.close() + + def main() -> None: """ Ksft boiler plate main """ nf = NetdevFamily() @@ -379,7 +496,9 @@ 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() -- 2.56.0.176.g3575e65682-goog
