[PATCH v13 0/3] binder: report txn errors via generic netlink

[PATCH v13 0/3] binder: report txn errors via generic netlink

[Li Li]

From: Li Li <dualli@google.com>

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.

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

Li Li (3):
  tools: ynl-gen: add trampolines for sock-priv
  netdev-genl: run ynl-regen to fix CFI failure
  binder: report txn errors via generic netlink

 Documentation/admin-guide/binder_netlink.rst | 110 ++++++++
 Documentation/admin-guide/index.rst          |   1 +
 Documentation/netlink/specs/binder.yaml      | 113 ++++++++
 drivers/android/Kconfig                      |   1 +
 drivers/android/Makefile                     |   2 +-
 drivers/android/binder.c                     | 282 ++++++++++++++++++-
 drivers/android/binder_internal.h            |  20 ++
 drivers/android/binder_netlink.c             |  53 ++++
 drivers/android/binder_netlink.h             |  22 ++
 drivers/android/binder_trace.h               |  35 +++
 drivers/android/binderfs.c                   |   1 +
 include/uapi/linux/android/binder_netlink.h  |  55 ++++
 net/core/netdev-genl-gen.c                   |  14 +-
 tools/net/ynl/pyynl/ynl_gen_c.py             |  14 +-
 14 files changed, 714 insertions(+), 9 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: dab2734f8e9ecba609d66d1dd087a392a7774c04
-- 
2.48.0.rc2.279.g1de40edade-goog

[PATCH v13 1/3] tools: ynl-gen: add trampolines for sock-priv

[Li Li]

From: Li Li <dualli@google.com>

This fixes the CFI failure at genl-sk_priv_get().

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Li Li <dualli@google.com>
---
 tools/net/ynl/pyynl/ynl_gen_c.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index d3a7dfbcf929..9852ba6fd9c3 100755
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -2411,6 +2411,15 @@ def print_kernel_family_struct_src(family, cw):
     if not kernel_can_gen_family_struct(family):
         return
 
+    if 'sock-priv' in family.kernel_family:
+        # Generate "trampolines" to make CFI happy
+        cw.write_func("static void", f"__{family.c_name}_nl_sock_priv_init",
+                      [f"{family.c_name}_nl_sock_priv_init(priv);"], ["void *priv"])
+        cw.nl()
+        cw.write_func("static void", f"__{family.c_name}_nl_sock_priv_destroy",
+                      [f"{family.c_name}_nl_sock_priv_destroy(priv);"], ["void *priv"])
+        cw.nl()
+
     cw.block_start(f"struct genl_family {family.ident_name}_nl_family __ro_after_init =")
     cw.p('.name\t\t= ' + family.fam_key + ',')
     cw.p('.version\t= ' + family.ver_key + ',')
@@ -2428,9 +2437,8 @@ def print_kernel_family_struct_src(family, cw):
         cw.p(f'.n_mcgrps\t= ARRAY_SIZE({family.c_name}_nl_mcgrps),')
     if 'sock-priv' in family.kernel_family:
         cw.p(f'.sock_priv_size\t= sizeof({family.kernel_family["sock-priv"]}),')
-        # Force cast here, actual helpers take pointer to the real type.
-        cw.p(f'.sock_priv_init\t= (void *){family.c_name}_nl_sock_priv_init,')
-        cw.p(f'.sock_priv_destroy = (void *){family.c_name}_nl_sock_priv_destroy,')
+        cw.p(f'.sock_priv_init\t= __{family.c_name}_nl_sock_priv_init,')
+        cw.p(f'.sock_priv_destroy = __{family.c_name}_nl_sock_priv_destroy,')
     cw.block_end(';')
 
 
-- 
2.48.0.rc2.279.g1de40edade-goog

[PATCH v13 2/3] netdev-genl: run ynl-regen to fix CFI failure

[Li Li]

From: Li Li <dualli@google.com>

The ynl-gen tool has been updated to generate trampolines for sock-priv
to fix the CFI failure. Run ynl-regen to apply the fix to netdev-genl.

Signed-off-by: Li Li <dualli@google.com>
---
 net/core/netdev-genl-gen.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c
index a89cbd8d87c3..996ac6a449eb 100644
--- a/net/core/netdev-genl-gen.c
+++ b/net/core/netdev-genl-gen.c
@@ -197,6 +197,16 @@ static const struct genl_multicast_group netdev_nl_mcgrps[] = {
 	[NETDEV_NLGRP_PAGE_POOL] = { "page-pool", },
 };
 
+static void __netdev_nl_sock_priv_init(void *priv)
+{
+	netdev_nl_sock_priv_init(priv);
+}
+
+static void __netdev_nl_sock_priv_destroy(void *priv)
+{
+	netdev_nl_sock_priv_destroy(priv);
+}
+
 struct genl_family netdev_nl_family __ro_after_init = {
 	.name		= NETDEV_FAMILY_NAME,
 	.version	= NETDEV_FAMILY_VERSION,
@@ -208,6 +218,6 @@ struct genl_family netdev_nl_family __ro_after_init = {
 	.mcgrps		= netdev_nl_mcgrps,
 	.n_mcgrps	= ARRAY_SIZE(netdev_nl_mcgrps),
 	.sock_priv_size	= sizeof(struct list_head),
-	.sock_priv_init	= (void *)netdev_nl_sock_priv_init,
-	.sock_priv_destroy = (void *)netdev_nl_sock_priv_destroy,
+	.sock_priv_init	= __netdev_nl_sock_priv_init,
+	.sock_priv_destroy = __netdev_nl_sock_priv_destroy,
 };
-- 
2.48.0.rc2.279.g1de40edade-goog

[PATCH v13 3/3] binder: report txn errors via generic netlink

[Li Li]

From: Li Li <dualli@google.com>

Introduce 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 transactions.

The binder netlink sources and headers are automatically generated from
the corresponding binder netlink YAML spec. Don't modify them directly.

Signed-off-by: Li Li <dualli@google.com>
---
 Documentation/admin-guide/binder_netlink.rst | 110 ++++++++
 Documentation/admin-guide/index.rst          |   1 +
 Documentation/netlink/specs/binder.yaml      | 113 ++++++++
 drivers/android/Kconfig                      |   1 +
 drivers/android/Makefile                     |   2 +-
 drivers/android/binder.c                     | 282 ++++++++++++++++++-
 drivers/android/binder_internal.h            |  20 ++
 drivers/android/binder_netlink.c             |  53 ++++
 drivers/android/binder_netlink.h             |  22 ++
 drivers/android/binder_trace.h               |  35 +++
 drivers/android/binderfs.c                   |   1 +
 include/uapi/linux/android/binder_netlink.h  |  55 ++++
 12 files changed, 691 insertions(+), 4 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

diff --git a/Documentation/admin-guide/binder_netlink.rst b/Documentation/admin-guide/binder_netlink.rst
new file mode 100644
index 000000000000..53ac6fa8ba63
--- /dev/null
+++ b/Documentation/admin-guide/binder_netlink.rst
@@ -0,0 +1,110 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================================================
+Generic Netlink for the Android Binder Driver (Binder Netlink)
+==============================================================
+
+The Generic Netlink subsystem in the Linux kernel provides a generic way for
+the Linux kernel to communicate with the user space applications via binder
+driver. It is used to report binder transaction errors and warnings to user
+space administration process. The driver allows multiple binder devices and
+their corresponding binder contexts. Each context has an independent Generic
+Netlink for security reason. To prevent untrusted user applications from
+accessing the netlink data, the kernel driver uses unicast mode instead of
+multicast.
+
+Basically, the user space code uses the BINDER_CMD_REPORT_SETUP command to
+request what kind of binder transactions should be reported by the driver.
+The driver then echoes the attributes in a reply message to acknowledge the
+request. The BINDER_CMD_REPORT_SETUP command also registers the current
+user space process to receive the reports. When the user space process
+exits, the previous request will be reset automatically.
+
+Currently the driver reports these binder transaction errors and warnings.
+1. "FAILED" transactions that fail to reach the target process;
+2. "ASYNC_FROZEN" transactions that are delayed due to the target process
+being frozen by cgroup freezer; or
+3. "SPAM" transactions that are considered spamming according to existing
+logic in binder_alloc.c.
+
+When the specified binder transactions happen, the driver uses the
+BINDER_CMD_REPORT command to send a generic netlink message to the
+registered process, containing the payload defined in binder.yaml.
+
+More details about the flags, attributes and operations can be found at the
+the doc sections in Documentations/netlink/specs/binder.yaml and the
+kernel-doc comments of the new source code in binder.{h|c}.
+
+Using Binder Netlink
+--------------------
+
+The Binder Netlink can be used in the same way as any other generic netlink
+drivers. Userspace application uses a raw netlink socket to send commands
+to and receive packets from the kernel driver.
+
+.. note::
+    If the userspace application that talks to the driver exits, the kernel
+    driver will automatically reset the configuration to the default and
+    stop sending more reports, which would otherwise fail.
+
+Usage example (user space pseudo code):
+
+::
+    /*
+     * send() below is overloaded to pack netlink commands and attributes
+     * to nlattr/genlmsghdr/nlmsghdr and then send to the netlink socket.
+     *
+     * recv() below is overloaded to receive the raw netlink message from
+     * the netlink socket, parse nlmsghdr/genlmsghdr to find the netlink
+     * command and then return the nlattr payload.
+     */
+
+    // open netlink socket
+    int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
+
+    // bind netlink socket
+    bind(fd, struct socketaddr);
+
+    // get the family id of the binder netlink
+    send(fd, CTRL_CMD_GETFAMILY, CTRL_ATTR_FAMILY_NAME,
+            BINDER_FAMILY_NAME);
+    void *data = recv(CTRL_CMD_NEWFAMILY);
+    if (!has_nla_type(data, CTRL_ATTR_FAMILY_ID)) {
+        // Binder Netlink isn't available on this version of Linux kernel
+        return;
+    }
+    __u16 id = nla(data)[CTRL_ATTR_FAMILY_ID];
+
+    // enable per-context binder report
+    send(fd, id, BINDER_CMD_REPORT_SETUP, "binder", 0,
+            BINDER_FLAG_FAILED | BINDER_FLAG_DELAYED);
+
+    // confirm the per-context configuration
+    data = recv(fd, BINDER_CMD_REPLY);
+    char *context = nla(data)[BINDER_A_CMD_CONTEXT];
+    __u32 pid =  nla(data)[BINDER_A_CMD_PID];
+    __u32 flags = nla(data)[BINDER_A_CMD_FLAGS];
+
+    // set optional per-process report, overriding the per-context one
+    send(fd, id, BINDER_CMD_REPORT_SETUP, "binder", getpid(),
+            BINDER_FLAG_SPAM | BINDER_REPORT_OVERRIDE);
+
+    // confirm the optional per-process configuration
+    data = recv(fd, BINDER_CMD_REPLY);
+    context = nla(data)[BINDER_A_CMD_CONTEXT];
+    pid =  nla(data)[BINDER_A_CMD_PID];
+    flags = nla(data)[BINDER_A_CMD_FLAGS];
+
+    // wait and read all binder reports
+    while (running) {
+            data = recv(fd, BINDER_CMD_REPORT);
+            auto *attr = nla(data)[BINDER_A_REPORT_XXX];
+
+            // process binder report
+            do_something(*attr);
+    }
+
+    // clean up
+    send(fd, id, BINDER_CMD_REPORT_SETUP, 0, 0);
+    send(fd, id, BINDER_CMD_REPORT_SETUP, getpid(), 0);
+    close(fd);
diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
index c8af32a8f800..655f39ddf1cf 100644
--- a/Documentation/admin-guide/index.rst
+++ b/Documentation/admin-guide/index.rst
@@ -120,6 +120,7 @@ Block-layer and filesystem administration
    :maxdepth: 1
 
    bcache
+   binder_netlink
    binderfs
    blockdev/index
    cifs/index
diff --git a/Documentation/netlink/specs/binder.yaml b/Documentation/netlink/specs/binder.yaml
new file mode 100644
index 000000000000..b5c8bdfc2ae4
--- /dev/null
+++ b/Documentation/netlink/specs/binder.yaml
@@ -0,0 +1,113 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+
+name: binder
+protocol: genetlink
+uapi-header: linux/android/binder_netlink.h
+doc: Netlink protocol to report binder transaction errors and warnings.
+
+definitions:
+  -
+    type: flags
+    name: flag
+    doc: Define what kind of binder transactions should be reported.
+    entries: [ failed, async-frozen, spam, override ]
+
+attribute-sets:
+  -
+    name: cmd
+    doc: The supported attributes of "report-setup" command.
+    attributes:
+      -
+        name: context
+        type: string
+        doc: The binder context to enable binder netlink report.
+      -
+        name: pid
+        type: u32
+        doc: The binder proc to enable binder netlink report.
+      -
+        name: flags
+        type: u32
+        enum: flag
+        doc: What kind of binder transactions should be reported.
+  -
+    name: report
+    doc: The supported attributes of "report" command
+    attributes:
+      -
+        name: context
+        type: string
+        doc: The binder context where the binder netlink report happens.
+      -
+        name: err
+        type: u32
+        doc: Copy of binder_driver_return_protocol returned to the sender.
+      -
+        name: from_pid
+        type: u32
+        doc: Sender pid of the corresponding binder transaction.
+      -
+        name: from_tid
+        type: u32
+        doc: Sender tid of the corresponding binder transaction.
+      -
+        name: to_pid
+        type: u32
+        doc: Target pid of the corresponding binder transaction.
+      -
+        name: to_tid
+        type: u32
+        doc: Target tid of the corresponding binder transaction.
+      -
+        name: reply
+        type: u32
+        doc: 1 means the transaction is a reply, 0 otherwise.
+      -
+        name: flags
+        type: u32
+        doc: Copy of binder_transaction_data->flags.
+      -
+        name: code
+        type: u32
+        doc: Copy of binder_transaction_data->code.
+      -
+        name: data_size
+        type: u32
+        doc: Copy of binder_transaction_data->data_size.
+
+operations:
+  list:
+    -
+      name: report-setup
+      doc: Set flags from user space.
+      attribute-set: cmd
+      flags: [ admin-perm ]
+
+      do:
+        request: &params
+          attributes:
+            - context
+            - pid
+            - flags
+        reply: *params
+    -
+      name: report
+      doc: Send the requested reports to user space.
+      attribute-set: report
+
+      event:
+        attributes:
+          - context
+          - err
+          - from_pid
+          - from_tid
+          - to_pid
+          - to_tid
+          - reply
+          - flags
+          - code
+          - data_size
+
+kernel-family:
+  headers: [ "binder_internal.h" ]
+  sock-priv: struct binder_context *
diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig
index 07aa8ae0a058..e2fa620934e2 100644
--- a/drivers/android/Kconfig
+++ b/drivers/android/Kconfig
@@ -4,6 +4,7 @@ menu "Android"
 config ANDROID_BINDER_IPC
 	bool "Android Binder IPC Driver"
 	depends on MMU
+	depends on NET
 	default n
 	help
 	  Binder is used in Android for both communication between processes,
diff --git a/drivers/android/Makefile b/drivers/android/Makefile
index c9d3d0c99c25..b8874dba884e 100644
--- a/drivers/android/Makefile
+++ b/drivers/android/Makefile
@@ -2,5 +2,5 @@
 ccflags-y += -I$(src)			# needed for trace events
 
 obj-$(CONFIG_ANDROID_BINDERFS)		+= binderfs.o
-obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o binder_alloc.o
+obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o binder_alloc.o binder_netlink.o
 obj-$(CONFIG_ANDROID_BINDER_IPC_SELFTEST) += binder_alloc_selftest.o
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 76052006bd87..a5be7bca934e 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -72,6 +72,7 @@
 
 #include <linux/cacheflush.h>
 
+#include "binder_netlink.h"
 #include "binder_internal.h"
 #include "binder_trace.h"
 
@@ -2990,6 +2991,111 @@ static void binder_set_txn_from_error(struct binder_transaction *t, int id,
 	binder_thread_dec_tmpref(from);
 }
 
+/**
+ * binder_find_proc() - find the binder_proc by pid
+ * @pid:	the target process
+ *
+ * Returns the struct binder_proc if the pid is found, or NULL otherwise.
+ */
+static struct binder_proc *binder_find_proc(int pid)
+{
+	struct binder_proc *proc;
+
+	mutex_lock(&binder_procs_lock);
+	hlist_for_each_entry(proc, &binder_procs, proc_node) {
+		if (proc->pid == pid)
+			break;
+	}
+	mutex_unlock(&binder_procs_lock);
+
+	return proc;
+}
+
+/**
+ * binder_netlink_enabled() - check if binder netlink reports are enabled
+ * @proc:	the binder_proc to check
+ * @mask:	the categories of binder netlink reports
+ *
+ * Returns true if certain binder netlink reports are enabled for this binder
+ * proc (when per-process overriding takes effect) or context.
+ */
+static bool binder_netlink_enabled(struct binder_proc *proc, u32 mask)
+{
+	struct binder_context *context = proc->context;
+
+	if (!context->report_portid)
+		return false;
+
+	if (proc->report_flags & BINDER_FLAG_OVERRIDE)
+		return (proc->report_flags & mask) != 0;
+	else
+		return (context->report_flags & mask) != 0;
+}
+
+/**
+ * binder_netlink_report() - report one binder netlink event
+ * @context:	the binder context
+ * @err:	copy of binder_driver_return_protocol returned to the sender
+ * @pid:	sender process
+ * @tid:	sender thread
+ * @to_pid:	target process
+ * @to_tid:	target thread
+ * @reply:	whether the binder transaction is a reply
+ * @tr:		the binder transaction data
+ *
+ * Packs the report data into a binder netlink message and send it.
+ */
+static void binder_netlink_report(struct binder_context *context, u32 err,
+				  u32 pid, u32 tid, u32 to_pid, u32 to_tid,
+				  u32 reply,
+				  struct binder_transaction_data *tr)
+{
+	struct sk_buff *skb;
+	void *hdr;
+	int ret;
+
+	trace_binder_netlink_report(context->name, err, pid, tid, to_pid,
+				    to_tid, reply, tr);
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb) {
+		pr_err("Failed to alloc binder netlink message\n");
+		return;
+	}
+
+	hdr = genlmsg_put(skb, 0, atomic_inc_return(&context->report_seq),
+			  &binder_nl_family, 0, BINDER_CMD_REPORT);
+	if (!hdr)
+		goto free_skb;
+
+	if (nla_put_string(skb, BINDER_A_REPORT_CONTEXT, context->name) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_ERR, err) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_FROM_PID, pid) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_FROM_TID, tid) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_TO_PID, to_pid) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_TO_TID, to_tid) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_REPLY, reply) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_FLAGS, tr->flags) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_CODE, tr->code) ||
+	    nla_put_u32(skb, BINDER_A_REPORT_DATA_SIZE, tr->data_size))
+		goto cancel_skb;
+
+	genlmsg_end(skb, hdr);
+
+	ret = genlmsg_unicast(&init_net, skb, context->report_portid);
+	if (ret < 0)
+		pr_err("Failed to send binder netlink message to %d: %d\n",
+		       context->report_portid, ret);
+	return;
+
+cancel_skb:
+	pr_err("Failed to add attributes to binder netlink message\n");
+	genlmsg_cancel(skb, hdr);
+free_skb:
+	pr_err("Free binder netlink report message on error\n");
+	nlmsg_free(skb);
+}
+
 static void binder_transaction(struct binder_proc *proc,
 			       struct binder_thread *thread,
 			       struct binder_transaction_data *tr, int reply,
@@ -3683,10 +3789,17 @@ static void binder_transaction(struct binder_proc *proc,
 		return_error_line = __LINE__;
 		goto err_copy_data_failed;
 	}
-	if (t->buffer->oneway_spam_suspect)
+	if (t->buffer->oneway_spam_suspect) {
 		tcomplete->type = BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT;
-	else
+		if (binder_netlink_enabled(proc, BINDER_FLAG_SPAM))
+			binder_netlink_report(context, BR_ONEWAY_SPAM_SUSPECT,
+					      proc->pid, thread->pid,
+					      target_proc ? target_proc->pid : 0,
+					      target_thread ? target_thread->pid : 0,
+					      reply, tr);
+	} else {
 		tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE;
+	}
 	t->work.type = BINDER_WORK_TRANSACTION;
 
 	if (reply) {
@@ -3736,8 +3849,15 @@ static void binder_transaction(struct binder_proc *proc,
 		 * process and is put in a pending queue, waiting for the target
 		 * process to be unfrozen.
 		 */
-		if (return_error == BR_TRANSACTION_PENDING_FROZEN)
+		if (return_error == BR_TRANSACTION_PENDING_FROZEN) {
 			tcomplete->type = BINDER_WORK_TRANSACTION_PENDING;
+			if (binder_netlink_enabled(proc, BINDER_FLAG_ASYNC_FROZEN))
+				binder_netlink_report(context, return_error,
+						      proc->pid, thread->pid,
+						      target_proc ? target_proc->pid : 0,
+						      target_thread ? target_thread->pid : 0,
+						      reply, tr);
+		}
 		binder_enqueue_thread_work(thread, tcomplete);
 		if (return_error &&
 		    return_error != BR_TRANSACTION_PENDING_FROZEN)
@@ -3799,6 +3919,13 @@ static void binder_transaction(struct binder_proc *proc,
 		binder_dec_node_tmpref(target_node);
 	}
 
+	if (binder_netlink_enabled(proc, BINDER_FLAG_FAILED))
+		binder_netlink_report(context, return_error,
+				      proc->pid, thread->pid,
+				      target_proc ? target_proc->pid : 0,
+				      target_thread ? target_thread->pid : 0,
+				      reply, tr);
+
 	binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
 		     "%d:%d transaction %s to %d:%d failed %d/%d/%d, code %u size %lld-%lld line %d\n",
 		     proc->pid, thread->pid, reply ? "reply" :
@@ -6334,6 +6461,148 @@ binder_defer_work(struct binder_proc *proc, enum binder_deferred_state defer)
 	mutex_unlock(&binder_deferred_lock);
 }
 
+/**
+ * binder_nl_report_setup_doit() - netlink .doit handler
+ * @skb:	the metadata struct passed from netlink driver
+ * @info:	the generic netlink struct passed from netlink driver
+ *
+ * Implements the .doit function to process binder netlink commands.
+ */
+int binder_nl_report_setup_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct binder_context *context = NULL;
+	struct binder_context **sock_priv;
+	struct binder_device *device;
+	struct binder_proc *proc;
+	u32 flags, pid;
+	int ret = 0;
+	int portid;
+	void *hdr;
+
+	hlist_for_each_entry(device, &binder_devices, hlist) {
+		if (!nla_strcmp(info->attrs[BINDER_A_CMD_CONTEXT],
+				device->context.name)) {
+			context = &device->context;
+			break;
+		}
+	}
+
+	if (!context) {
+		NL_SET_ERR_MSG(info->extack, "Unknown binder context");
+		return -EINVAL;
+	}
+
+	sock_priv = genl_sk_priv_get(&binder_nl_family, NETLINK_CB(skb).sk);
+	if (IS_ERR(sock_priv)) {
+		NL_SET_ERR_MSG(info->extack, "Can't get sock priv");
+		return PTR_ERR(sock_priv);
+	}
+
+	if (*sock_priv && *sock_priv != context) {
+		NL_SET_ERR_MSG(info->extack, "Overloaded socket");
+		return -EINVAL;
+	}
+
+	portid = nlmsg_hdr(skb)->nlmsg_pid;
+	pid = nla_get_u32(info->attrs[BINDER_A_CMD_PID]);
+	flags = nla_get_u32(info->attrs[BINDER_A_CMD_FLAGS]);
+
+	mutex_lock(&context->report_lock);
+	if (context->report_portid && context->report_portid != portid) {
+		NL_SET_ERR_MSG_FMT(info->extack,
+				   "No permission to set flags from %d",
+				   portid);
+		ret = -EPERM;
+		goto err_exit;
+	}
+
+	if (!pid) {
+		/* Set the global flags for the whole binder context */
+		context->report_flags = flags;
+	} else {
+		/* Set the per-process flags */
+		proc = binder_find_proc(pid);
+		if (!proc) {
+			NL_SET_ERR_MSG_FMT(info->extack,
+					   "Invalid binder report pid %u",
+					   pid);
+			ret = -EINVAL;
+			goto err_exit;
+		}
+
+		proc->report_flags = flags;
+	}
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb) {
+		pr_err("Failed to alloc binder netlink reply message\n");
+		ret = -ENOMEM;
+		goto err_exit;
+	}
+
+	hdr = genlmsg_iput(skb, info);
+	if (!hdr)
+		goto free_skb;
+
+	if (nla_put_string(skb, BINDER_A_CMD_CONTEXT, context->name) ||
+	    nla_put_u32(skb, BINDER_A_CMD_PID, pid) ||
+	    nla_put_u32(skb, BINDER_A_CMD_FLAGS, flags))
+		goto cancel_skb;
+
+	genlmsg_end(skb, hdr);
+
+	if (genlmsg_reply(skb, info)) {
+		pr_err("Failed to send binder netlink reply message\n");
+		ret = -EFAULT;
+		goto err_exit;
+	}
+
+	context->report_portid = portid;
+	if (!(*sock_priv))
+		*sock_priv = context;
+	mutex_unlock(&context->report_lock);
+	return 0;
+
+cancel_skb:
+	pr_err("Failed to add reply attributes to binder netlink message\n");
+	genlmsg_cancel(skb, hdr);
+free_skb:
+	pr_err("Free binder netlink reply message on error\n");
+	nlmsg_free(skb);
+	ret = -EMSGSIZE;
+err_exit:
+	mutex_unlock(&context->report_lock);
+	return ret;
+}
+
+/**
+ * binder_nl_sock_priv_init() - netlink sock_priv_init handler
+ * @priv:	the per-socket private memory passed from netlink driver
+ *
+ * Implements the .sock_priv_init function to initialize sock_priv.
+ */
+void binder_nl_sock_priv_init(struct binder_context **priv)
+{
+}
+
+/**
+ * binder_nl_sock_priv_destroy() - netlink sock_priv_destroy handler
+ * @priv:	the per-socket private memory passed from netlink driver
+ *
+ * Implements the .sock_priv_destroy function to deinit sock_priv.
+ */
+void binder_nl_sock_priv_destroy(struct binder_context **priv)
+{
+	struct binder_context *context = *priv;
+
+	if (context) {
+		mutex_lock(&context->report_lock);
+		context->report_portid = 0;
+		context->report_flags = 0;
+		mutex_unlock(&context->report_lock);
+	}
+}
+
 static void print_binder_transaction_ilocked(struct seq_file *m,
 					     struct binder_proc *proc,
 					     const char *prefix,
@@ -6949,6 +7218,7 @@ static int __init init_binder_device(const char *name)
 	binder_device->context.binder_context_mgr_uid = INVALID_UID;
 	binder_device->context.name = name;
 	mutex_init(&binder_device->context.context_mgr_node_lock);
+	mutex_init(&binder_device->context.report_lock);
 
 	ret = misc_register(&binder_device->miscdev);
 	if (ret < 0) {
@@ -7013,6 +7283,12 @@ static int __init binder_init(void)
 	if (ret)
 		goto err_init_binder_device_failed;
 
+	ret = genl_register_family(&binder_nl_family);
+	if (ret) {
+		pr_err("Failed to register binder netlink family\n");
+		goto err_init_binder_device_failed;
+	}
+
 	return ret;
 
 err_init_binder_device_failed:
diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h
index e4eb8357989c..0e788247cf8a 100644
--- a/drivers/android/binder_internal.h
+++ b/drivers/android/binder_internal.h
@@ -12,15 +12,32 @@
 #include <linux/stddef.h>
 #include <linux/types.h>
 #include <linux/uidgid.h>
+#include <net/genetlink.h>
 #include <uapi/linux/android/binderfs.h>
 #include "binder_alloc.h"
 #include "dbitmap.h"
 
+/**
+ * struct binder_context - information about a binder domain
+ * @binder_context_mgr_node: the context manager
+ * @context_mgr_node_lock:   the lock protecting the above context manager node
+ * @binder_context_mgr_uid:  the uid of the above context manager
+ * @name:                    the name of the binder device
+ * @report_lock:             the lock protecting report_portid
+ * @report_portid:           the netlink socket to receive binder reports
+ * @report_flags:            the categories of binder transactions that would
+ *                           be reported (see enum binder_report_flag).
+ * @report_seq:              the seq number of the generic netlink report
+ */
 struct binder_context {
 	struct binder_node *binder_context_mgr_node;
 	struct mutex context_mgr_node_lock;
 	kuid_t binder_context_mgr_uid;
 	const char *name;
+	struct mutex report_lock; /* protect report_portid below */
+	u32 report_portid;
+	u32 report_flags;
+	atomic_t report_seq;
 };
 
 /**
@@ -414,6 +431,8 @@ struct binder_ref {
  * @binderfs_entry:       process-specific binderfs log file
  * @oneway_spam_detection_enabled: process enabled oneway spam detection
  *                        or not
+ * @report_flags:         the categories of binder transactions that would
+ *                        be reported (see enum binder_genl_flag).
  *
  * Bookkeeping structure for binder processes
  */
@@ -452,6 +471,7 @@ struct binder_proc {
 	spinlock_t outer_lock;
 	struct dentry *binderfs_entry;
 	bool oneway_spam_detection_enabled;
+	u32 report_flags;
 };
 
 /**
diff --git a/drivers/android/binder_netlink.c b/drivers/android/binder_netlink.c
new file mode 100644
index 000000000000..b9af337e5f68
--- /dev/null
+++ b/drivers/android/binder_netlink.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/binder.yaml */
+/* YNL-GEN kernel source */
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include "binder_netlink.h"
+
+#include <uapi/linux/android/binder_netlink.h>
+#include <binder_internal.h>
+
+/* BINDER_CMD_REPORT_SETUP - do */
+static const struct nla_policy binder_report_setup_nl_policy[BINDER_A_CMD_FLAGS + 1] = {
+	[BINDER_A_CMD_CONTEXT] = { .type = NLA_NUL_STRING, },
+	[BINDER_A_CMD_PID] = { .type = NLA_U32, },
+	[BINDER_A_CMD_FLAGS] = NLA_POLICY_MASK(NLA_U32, 0xf),
+};
+
+/* Ops table for binder */
+static const struct genl_split_ops binder_nl_ops[] = {
+	{
+		.cmd		= BINDER_CMD_REPORT_SETUP,
+		.doit		= binder_nl_report_setup_doit,
+		.policy		= binder_report_setup_nl_policy,
+		.maxattr	= BINDER_A_CMD_FLAGS,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+};
+
+static void __binder_nl_sock_priv_init(void *priv)
+{
+	binder_nl_sock_priv_init(priv);
+}
+
+static void __binder_nl_sock_priv_destroy(void *priv)
+{
+	binder_nl_sock_priv_destroy(priv);
+}
+
+struct genl_family binder_nl_family __ro_after_init = {
+	.name		= BINDER_FAMILY_NAME,
+	.version	= BINDER_FAMILY_VERSION,
+	.netnsok	= true,
+	.parallel_ops	= true,
+	.module		= THIS_MODULE,
+	.split_ops	= binder_nl_ops,
+	.n_split_ops	= ARRAY_SIZE(binder_nl_ops),
+	.sock_priv_size	= sizeof(struct binder_context *),
+	.sock_priv_init	= __binder_nl_sock_priv_init,
+	.sock_priv_destroy = __binder_nl_sock_priv_destroy,
+};
diff --git a/drivers/android/binder_netlink.h b/drivers/android/binder_netlink.h
new file mode 100644
index 000000000000..2250b9c6debf
--- /dev/null
+++ b/drivers/android/binder_netlink.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/binder.yaml */
+/* YNL-GEN kernel header */
+
+#ifndef _LINUX_BINDER_GEN_H
+#define _LINUX_BINDER_GEN_H
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include <uapi/linux/android/binder_netlink.h>
+#include <binder_internal.h>
+
+int binder_nl_report_setup_doit(struct sk_buff *skb, struct genl_info *info);
+
+extern struct genl_family binder_nl_family;
+
+void binder_nl_sock_priv_init(struct binder_context **priv);
+void binder_nl_sock_priv_destroy(struct binder_context **priv);
+
+#endif /* _LINUX_BINDER_GEN_H */
diff --git a/drivers/android/binder_trace.h b/drivers/android/binder_trace.h
index 16de1b9e72f7..6fb454bcd857 100644
--- a/drivers/android/binder_trace.h
+++ b/drivers/android/binder_trace.h
@@ -423,6 +423,41 @@ TRACE_EVENT(binder_return,
 			  "unknown")
 );
 
+TRACE_EVENT(binder_netlink_report,
+	TP_PROTO(const char *name, u32 err, u32 pid, u32 tid, u32 to_pid,
+		 u32 to_tid, u32 reply, struct binder_transaction_data *tr),
+	TP_ARGS(name, err, pid, tid, to_pid, to_tid, reply, tr),
+	TP_STRUCT__entry(
+		__field(const char *, name)
+		__field(u32, err)
+		__field(u32, pid)
+		__field(u32, tid)
+		__field(u32, to_pid)
+		__field(u32, to_tid)
+		__field(u32, reply)
+		__field(u32, flags)
+		__field(u32, code)
+		__field(binder_size_t, data_size)
+	),
+	TP_fast_assign(
+		__entry->name = name;
+		__entry->err = err;
+		__entry->pid = pid;
+		__entry->tid = tid;
+		__entry->to_pid = to_pid;
+		__entry->to_tid = to_tid;
+		__entry->reply = reply;
+		__entry->flags = tr->flags;
+		__entry->code = tr->code;
+		__entry->data_size = tr->data_size;
+	),
+	TP_printk("%s: %d %d:%d -> %d:%d %s flags=0x08%x code=%d %llu",
+		  __entry->name, __entry->err, __entry->pid, __entry->tid,
+		  __entry->to_pid, __entry->to_tid,
+		  __entry->reply ? "reply" : "",
+		  __entry->flags, __entry->code, __entry->data_size)
+);
+
 #endif /* _BINDER_TRACE_H */
 
 #undef TRACE_INCLUDE_PATH
diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index bc6bae76ccaf..452a86b931b5 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -174,6 +174,7 @@ static int binderfs_binder_device_create(struct inode *ref_inode,
 	device->miscdev.name = name;
 	device->miscdev.minor = minor;
 	mutex_init(&device->context.context_mgr_node_lock);
+	mutex_init(&device->context.report_lock);
 
 	req->major = MAJOR(binderfs_dev);
 	req->minor = minor;
diff --git a/include/uapi/linux/android/binder_netlink.h b/include/uapi/linux/android/binder_netlink.h
new file mode 100644
index 000000000000..d6504c267516
--- /dev/null
+++ b/include/uapi/linux/android/binder_netlink.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/binder.yaml */
+/* YNL-GEN uapi header */
+
+#ifndef _UAPI_LINUX_ANDROID_BINDER_NETLINK_H
+#define _UAPI_LINUX_ANDROID_BINDER_NETLINK_H
+
+#define BINDER_FAMILY_NAME	"binder"
+#define BINDER_FAMILY_VERSION	1
+
+/*
+ * Define what kind of binder transactions should be reported.
+ */
+enum binder_flag {
+	BINDER_FLAG_FAILED = 1,
+	BINDER_FLAG_ASYNC_FROZEN = 2,
+	BINDER_FLAG_SPAM = 4,
+	BINDER_FLAG_OVERRIDE = 8,
+};
+
+enum {
+	BINDER_A_CMD_CONTEXT = 1,
+	BINDER_A_CMD_PID,
+	BINDER_A_CMD_FLAGS,
+
+	__BINDER_A_CMD_MAX,
+	BINDER_A_CMD_MAX = (__BINDER_A_CMD_MAX - 1)
+};
+
+enum {
+	BINDER_A_REPORT_CONTEXT = 1,
+	BINDER_A_REPORT_ERR,
+	BINDER_A_REPORT_FROM_PID,
+	BINDER_A_REPORT_FROM_TID,
+	BINDER_A_REPORT_TO_PID,
+	BINDER_A_REPORT_TO_TID,
+	BINDER_A_REPORT_REPLY,
+	BINDER_A_REPORT_FLAGS,
+	BINDER_A_REPORT_CODE,
+	BINDER_A_REPORT_DATA_SIZE,
+
+	__BINDER_A_REPORT_MAX,
+	BINDER_A_REPORT_MAX = (__BINDER_A_REPORT_MAX - 1)
+};
+
+enum {
+	BINDER_CMD_REPORT_SETUP = 1,
+	BINDER_CMD_REPORT,
+
+	__BINDER_CMD_MAX,
+	BINDER_CMD_MAX = (__BINDER_CMD_MAX - 1)
+};
+
+#endif /* _UAPI_LINUX_ANDROID_BINDER_NETLINK_H */
-- 
2.48.0.rc2.279.g1de40edade-goog

Re: [PATCH v13 1/3] tools: ynl-gen: add trampolines for sock-priv

[Jakub Kicinski]

On Wed, 15 Jan 2025 02:29:48 -0800 Li Li wrote:
> From: Li Li <dualli@google.com>
> 
> This fixes the CFI failure at genl-sk_priv_get().
> 
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Li Li <dualli@google.com>

No, no, this is a fix. We'll try to send it to Linus tomorrow.

Re: [PATCH v13 1/3] tools: ynl-gen: add trampolines for sock-priv

[Li Li]

On Wed, Jan 15, 2025 at 8:13 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Wed, 15 Jan 2025 02:29:48 -0800 Li Li wrote:
> > From: Li Li <dualli@google.com>
> >
> > This fixes the CFI failure at genl-sk_priv_get().
> >
> > Suggested-by: Jakub Kicinski <kuba@kernel.org>
> > Signed-off-by: Li Li <dualli@google.com>
>
> No, no, this is a fix. We'll try to send it to Linus tomorrow.

Thank you for prioritizing the fix!

There's another trivial issue which I just realized after sending out the
patchset. When "sock-priv" is a pointer (like the example below), ynl-gen
generates ugly code and fails scripts/checkpatch.

Should I use typedef instead although it seems discouraged according to
https://www.kernel.org/doc/html/latest/process/coding-style.html?

YAML:
+  sock-priv: struct binder_context *

==>

Generated code:
+void binder_nl_sock_priv_init(struct binder_context * *priv);
                                                     ^^^ extra space
+void binder_nl_sock_priv_destroy(struct binder_context * *priv);
                                                        ^^^ extra space

Re: [PATCH v13 1/3] tools: ynl-gen: add trampolines for sock-priv

[Jakub Kicinski]

On Wed, 15 Jan 2025 08:44:37 -0800 Li Li wrote:
> On Wed, Jan 15, 2025 at 8:13 AM Jakub Kicinski <kuba@kernel.org> wrote:
> >
> > On Wed, 15 Jan 2025 02:29:48 -0800 Li Li wrote:  
> > > From: Li Li <dualli@google.com>
> > >
> > > This fixes the CFI failure at genl-sk_priv_get().
> > >
> > > Suggested-by: Jakub Kicinski <kuba@kernel.org>
> > > Signed-off-by: Li Li <dualli@google.com>  
> >
> > No, no, this is a fix. We'll try to send it to Linus tomorrow.  
> 
> Thank you for prioritizing the fix!
> 
> There's another trivial issue which I just realized after sending out the
> patchset. When "sock-priv" is a pointer (like the example below), ynl-gen
> generates ugly code and fails scripts/checkpatch.
> 
> Should I use typedef instead although it seems discouraged according to
> https://www.kernel.org/doc/html/latest/process/coding-style.html?
> 
> YAML:
> +  sock-priv: struct binder_context *

We can adjust that later, but I think cleanest fix may be to wrap the
priv in a separate struct, even if it only has one member.