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[34.125.198.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22341c04d16sm8473865ad.190.2025.02.26.11.20.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Feb 2025 11:20:57 -0800 (PST) From: Li Li To: dualli@google.com, corbet@lwn.net, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, donald.hunter@gmail.com, gregkh@linuxfoundation.org, arve@android.com, tkjos@android.com, maco@android.com, joel@joelfernandes.org, brauner@kernel.org, cmllamas@google.com, surenb@google.com, omosnace@redhat.com, shuah@kernel.org, arnd@arndb.de, masahiroy@kernel.org, bagasdotme@gmail.com, horms@kernel.org, tweek@google.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, netdev@vger.kernel.org, selinux@vger.kernel.org, hridya@google.com Cc: smoreland@google.com, ynaffit@google.com, kernel-team@android.com Subject: [PATCH v15 0/3] binder: report txn errors via generic netlink Date: Wed, 26 Feb 2025 11:20:44 -0800 Message-ID: <20250226192047.734627-1-dualli@chromium.org> X-Mailer: git-send-email 2.48.1.658.g4767266eb4-goog Precedence: bulk X-Mailing-List: selinux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Li Li It's a known issue that neither the frozen processes nor the system administration process of the OS can correctly deal with failed binder transactions. The reason is that there's no reliable way for the user space administration process to fetch the binder errors from the kernel binder driver. Android is such an OS suffering from this issue. Since cgroup freezer was used to freeze user applications to save battery, innocent frozen apps have to be killed when they receive sync binder transactions or when their async binder buffer is running out. This patch introduces the Linux generic netlink messages into the binder driver so that the Linux/Android system administration process can listen to important events and take corresponding actions, like stopping a broken app from attacking the OS by sending huge amount of spamming binder transactiions. The 1st version uses a global generic netlink for all binder contexts, raising potential security concerns. There were a few other feedbacks like request to kernel docs and test code. The thread can be found at https://lore.kernel.org/lkml/20240812211844.4107494-1-dualli@chromium.org/ The 2nd version fixes those issues and has been tested on the latest version of AOSP. See https://r.android.com/3305462 for how userspace is going to use this feature and the test code. It can be found at https://lore.kernel.org/lkml/20241011064427.1565287-1-dualli@chromium.org/ The 3rd version replaces the handcrafted netlink source code with the netlink protocal specs in YAML. It also fixes the documentation issues. https://lore.kernel.org/lkml/20241021182821.1259487-1-dualli@chromium.org/ The 4th version just containsi trivial fixes, making the subject of the patch aligned with the subject of the cover letter. https://lore.kernel.org/lkml/20241021191233.1334897-1-dualli@chromium.org/ The 5th version incorporates the suggested fixes to the kernel doc and the init function. It also removes the unsupported uapi-header in YAML that contains "/" for subdirectory. https://lore.kernel.org/lkml/20241025075102.1785960-1-dualli@chromium.org/ The 6th version has some trivial kernel doc fixes, without modifying any other source code. https://lore.kernel.org/lkml/20241028101952.775731-1-dualli@chromium.org/ The 7th version breaks the binary struct netlink message into individual attributes to better support automatic error checking. Thanks Jakub for improving ynl-gen. https://lore.kernel.org/all/20241031092504.840708-1-dualli@chromium.org/ The 8th version solves the multi-genl-family issue by demuxing the messages based on a new context attribute. It also improves the YAML spec to be consistent with netlink tradition. A Huge 'Thank You' to Jakub who taught me a lot about the netlink protocol! https://lore.kernel.org/all/20241113193239.2113577-1-dualli@chromium.org/ The 9th version only contains a few trivial fixes, removing a redundant pr_err and unnecessary payload check. The ynl-gen patch to allow uapi header in sub-dirs has been merged so it's no longer included in this patch set. https://lore.kernel.org/all/20241209192247.3371436-1-dualli@chromium.org/ The 10th version renames binder genl to binder netlink, improves the readability of the kernel doc and uses more descriptive variable names. The function binder_add_device() is moved out to a new commit per request. It also fixes a warning about newline used in NL_SET_ERR_MSG. Thanks Carlos for his valuable suggestions! https://lore.kernel.org/all/20241212224114.888373-1-dualli@chromium.org/ The 11th version simplifies the yaml filename to avoid redundant words in variable names. This also makes binder netlink yaml more aligned with other existing netlink specs. Another trivial change is to use reverse xmas tree for function variables. https://lore.kernel.org/all/20241218203740.4081865-1-dualli@chromium.org/ The 12th version makes Documentation/admin-guide/binder_netlink.rst aligned with the binder netlink yaml change introduced in the 11th revision. It doesn't change any source code. https://lore.kernel.org/all/20241218212935.4162907-1-dualli@chromium.org/ The 13th version removes the unnecessary dependency to binder file ops. Now the netlink configuration is reset using sock_priv_destroy. It also requires CAP_NET_ADMIN to send commands to the driver. One of the patches ("binderfs: add new binder devices to binder_devices") has been merged to linux-next. To avoid conflict, switch to linux-next master branch and remove the merged one. Adding sock_priv into netlink spec results in CFI failure, which is fixed by the new trampoline patches. https://lore.kernel.org/all/20250115102950.563615-1-dualli@chromium.org/ The 14th version fix the code style issue by wrapping the sock priv in a separate struct, as suggested by Jakub. The other 2 patches are no longer included in this patchset as the equvilent fix has already been merged to upstream linux master branch, as well as net & net-next. This version has already been rebased to TOT of linux-next. https://lore.kernel.org/all/20250118080939.2835687-1-dualli@chromium.org/ The 15th version switches from unicast to multicast per feedback and feature requriements from binder users. With this change, multiple user space processes can listen to the binder reports from the kernel driver at the same time. To receive the multicast messages, those user space processs should query the mcast group id and join the mcast group. In the previous unicast solution, a portid is saved in the kernel driver to prevent unauthorized process to send commands to the kernel driver. In this multicast solution, this is replaced by a new "setup_report" permission in the "binder" class. Meanwhile, the sock_priv_destroy callback and CAP_NET_ADMIN restriction are no longer required in favor of the multicast solution and the new "setup_report" permission. v1: add a global binder genl socket for all contexts v2: change to per-context binder genl for security reason replace the new ioctl with a netlink command add corresponding doc Documentation/admin-guide/binder_genl.rst add user space test code in AOSP v3: use YNL spec (./tools/net/ynl/ynl-regen.sh) fix documentation index v4: change the subject of the patch and remove unsed #if 0 v5: improve the kernel doc and the init function remove unsupported uapi-header in YAML v6: fix some trivial kernel doc issues v7: break the binary struct binder_report into individual attributes v8: use multiplex netlink message in a unified netlink family improve the YAML spec to be consistent with netlink tradition v9: remove unnecessary check to netlink flags and message payloads v10: improve the readability of kernel doc and variable names v11: rename binder_netlinnk.yaml to binder.yaml use reverse xmas tree for function variables v12: make kernel doc aligned with source code v13: use sock_priv_destroy to cleanup netlink require CAP_NET_ADMIN to send netlink commands add trampolines in ynl-gen to fix CFI failure v14: wrap the sock priv in a separate struct v15: switch from unicast to multicast netlink message add a "setup_report" permission in the "binder" class add generic_netlink to binder_features Li Li (2): binder: report txn errors via generic netlink binder: generic netlink binder_features flag Thiébaud Weksteen (1): lsm, selinux: Add setup_report permission to binder Documentation/admin-guide/binder_netlink.rst | 108 +++++++++ Documentation/admin-guide/index.rst | 1 + Documentation/netlink/specs/binder.yaml | 116 +++++++++ drivers/android/Kconfig | 1 + drivers/android/Makefile | 2 +- drivers/android/binder.c | 229 +++++++++++++++++- drivers/android/binder_internal.h | 16 ++ drivers/android/binder_netlink.c | 46 ++++ drivers/android/binder_netlink.h | 23 ++ drivers/android/binder_trace.h | 35 +++ drivers/android/binderfs.c | 8 + include/linux/lsm_hook_defs.h | 1 + include/linux/security.h | 1 + include/uapi/linux/android/binder_netlink.h | 57 +++++ security/security.c | 13 + security/selinux/hooks.c | 7 + security/selinux/include/classmap.h | 3 +- .../filesystems/binderfs/binderfs_test.c | 1 + 18 files changed, 663 insertions(+), 5 deletions(-) create mode 100644 Documentation/admin-guide/binder_netlink.rst create mode 100644 Documentation/netlink/specs/binder.yaml create mode 100644 drivers/android/binder_netlink.c create mode 100644 drivers/android/binder_netlink.h create mode 100644 include/uapi/linux/android/binder_netlink.h base-commit: 8433c776e1eb1371f5cd40b5fd3a61f9c7b7f3ad