Message-ID: <e21744a4-0155-40ec-b8c1-d81b14107c9f@leemhuis.info>
Date: Thu, 21 Aug 2025 10:49:09 +0200
From: Thorsten Leemhuis <linux@...mhuis.info>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Li Li <dualli@...gle.com>
Cc: Tiffany Yang <ynaffit@...gle.com>, John Stultz <jstultz@...gle.com>,
 Shai Barack <shayba@...gle.com>, Thiébaud Weksteen
 <tweek@...gle.com>, kernel-team@...roid.com, linux-kernel@...r.kernel.org,
 "David S. Miller" <davem@...emloft.net>,
 Joel Fernandes <joelagnelf@...dia.com>, Todd Kjos <tkjos@...roid.com>,
 Arve Hjønnevåg <arve@...roid.com>,
 Donald Hunter <donald.hunter@...il.com>,
 Christian Brauner <brauner@...nel.org>, Eric Dumazet <edumazet@...gle.com>,
 "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
 Martijn Coenen <maco@...roid.com>, Stephen Rothwell <sfr@...b.auug.org.au>,
 Linux Next Mailing List <linux-next@...r.kernel.org>,
 Jakub Kicinski <kuba@...nel.org>,
 Linux kernel regressions list <regressions@...ts.linux.dev>,
 Carlos Llamas <cmllamas@...gle.com>, Alice Ryhl <aliceryhl@...gle.com>,
 Suren Baghdasaryan <surenb@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>
Subject: Re: [PATCH v20 3/5] binder: introduce transaction reports via netlink

On 27.07.25 20:29, Carlos Llamas wrote:
> From: Li Li <dualli@...gle.com>
> 
> Introduce a generic netlink multicast event to report binder transaction
> failures to userspace. This allows subscribers to monitor these events
> and take appropriate actions, such as stopping a misbehaving application
> that is spamming a service with huge amount of transactions.
> 
> The multicast event contains full details of the failed transactions,
> including the sender/target PIDs, payload size and specific error code.
> This interface is defined using a YAML spec, from which the UAPI and
> kernel headers and source are auto-generated.

It seems to me like this patch (which showed up in -next today after
Greg merged it) caused a build error for me in my daily -next builds
for Fedora when building tools/net/ynl:

"""
make[1]: Entering directory '/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/lib'
gcc -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow   -c -MMD -c -o ynl.o ynl.c
        AR ynl.a
make[1]: Leaving directory '/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/lib'
make[1]: Entering directory '/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/generated'
        GEN binder-user.c
Traceback (most recent call last):
  File "/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/generated/../pyynl/ynl_gen_c.py", line 3673, in <module>
    main()
    ~~~~^^
  File "/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/generated/../pyynl/ynl_gen_c.py", line 3382, in main
    parsed = Family(args.spec, exclude_ops)
  File "/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/generated/../pyynl/ynl_gen_c.py", line 1205, in __init__
    super().__init__(file_name, exclude_ops=exclude_ops)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/pyynl/lib/nlspec.py", line 462, in __init__
    jsonschema.validate(self.yaml, schema)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/jsonschema/validators.py", line 1307, in validate
    raise error
jsonschema.exceptions.ValidationError: 'from_pid' does not match '^[0-9a-z-]+$'

Failed validating 'pattern' in schema['properties']['attribute-sets']['items']['properties']['attributes']['items']['properties']['name']:
    {'pattern': '^[0-9a-z-]+$', 'type': 'string'}

On instance['attribute-sets'][0]['attributes'][2]['name']:
    'from_pid'
make[1]: *** [Makefile:48: binder-user.c] Error 1
make[1]: Leaving directory '/home/kbuilder/ark-vanilla/linux-knurd42/tools/net/ynl/generated'
make: *** [Makefile:25: generated] Error 2
"""

This is from a local build while investigating the problem. For
the error logs from my rpm builds, see:
https://download.copr.fedorainfracloud.org/results/@kernel-vanilla/next/fedora-rawhide-x86_64/09453564-next-next-all/builder-live.log.gz

I could avoid the problem by reverting 5/5, 4/5, and this patch (3/5) 
from this series (I removed the former two to avoid conflicts).

Ciao, Thorsten

 
> Signed-off-by: Li Li <dualli@...gle.com>
> Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
> ---
>  Documentation/netlink/specs/binder.yaml     | 93 +++++++++++++++++++++
>  MAINTAINERS                                 |  1 +
>  drivers/android/Kconfig                     |  1 +
>  drivers/android/Makefile                    |  2 +-
>  drivers/android/binder.c                    | 85 ++++++++++++++++++-
>  drivers/android/binder_netlink.c            | 31 +++++++
>  drivers/android/binder_netlink.h            | 20 +++++
>  include/uapi/linux/android/binder_netlink.h | 37 ++++++++
>  8 files changed, 265 insertions(+), 5 deletions(-)
>  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/netlink/specs/binder.yaml b/Documentation/netlink/specs/binder.yaml
> new file mode 100644
> index 000000000000..140b77a6afee
> --- /dev/null
> +++ b/Documentation/netlink/specs/binder.yaml
> @@ -0,0 +1,93 @@
> +# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
> +#
> +# Copyright 2025 Google LLC
> +#
> +---
> +name: binder
> +protocol: genetlink
> +uapi-header: linux/android/binder_netlink.h
> +doc: Binder interface over generic netlink
> +
> +attribute-sets:
> +  -
> +    name: report
> +    doc: |
> +      Attributes included within a transaction failure report. The elements
> +      correspond directly with the specific transaction that failed, along
> +      with the error returned to the sender e.g. BR_DEAD_REPLY.
> +
> +    attributes:
> +      -
> +        name: error
> +        type: u32
> +        doc: The enum binder_driver_return_protocol returned to the sender.
> +      -
> +        name: context
> +        type: string
> +        doc: The binder context where the transaction occurred.
> +      -
> +        name: from_pid
> +        type: u32
> +        doc: The PID of the sender process.
> +      -
> +        name: from_tid
> +        type: u32
> +        doc: The TID of the sender thread.
> +      -
> +        name: to_pid
> +        type: u32
> +        doc: |
> +          The PID of the recipient process. This attribute may not be present
> +          if the target could not be determined.
> +      -
> +        name: to_tid
> +        type: u32
> +        doc: |
> +          The TID of the recipient thread. This attribute may not be present
> +          if the target could not be determined.
> +      -
> +        name: is_reply
> +        type: flag
> +        doc: When present, indicates the failed transaction is a reply.
> +      -
> +        name: flags
> +        type: u32
> +        doc: The bitmask of enum transaction_flags from the transaction.
> +      -
> +        name: code
> +        type: u32
> +        doc: The application-defined code from the transaction.
> +      -
> +        name: data_size
> +        type: u32
> +        doc: The transaction payload size in bytes.
> +
> +operations:
> +  list:
> +    -
> +      name: report
> +      doc: |
> +        A multicast event sent to userspace subscribers to notify them about
> +        binder transaction failures. The generated report provides the full
> +        details of the specific transaction that failed. The intention is for
> +        programs to monitor these events and react to the failures as needed.
> +
> +      attribute-set: report
> +      mcgrp: report
> +      event:
> +        attributes:
> +          - error
> +          - context
> +          - from_pid
> +          - from_tid
> +          - to_pid
> +          - to_tid
> +          - is_reply
> +          - flags
> +          - code
> +          - data_size
> +
> +mcast-groups:
> +  list:
> +    -
> +      name: report
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f8c8f682edf6..df8f6b31f2f8 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1769,6 +1769,7 @@ M:	Suren Baghdasaryan <surenb@...gle.com>
>  L:	linux-kernel@...r.kernel.org
>  S:	Supported
>  T:	git git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
> +F:	Documentation/netlink/specs/binder.yaml
>  F:	drivers/android/
>  
>  ANDROID GOLDFISH PIC DRIVER
> diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig
> index 5b3b8041f827..75af3cf472c8 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 c5d47be0276c..f422f91e026b 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_ALLOC_KUNIT_TEST)	+= tests/
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 95aa1fae53e2..0d37eca514f9 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -74,6 +74,7 @@
>  
>  #include <linux/cacheflush.h>
>  
> +#include "binder_netlink.h"
>  #include "binder_internal.h"
>  #include "binder_trace.h"
>  
> @@ -2993,6 +2994,67 @@ static void binder_set_txn_from_error(struct binder_transaction *t, int id,
>  	binder_thread_dec_tmpref(from);
>  }
>  
> +/**
> + * binder_netlink_report() - report a transaction failure via netlink
> + * @proc:	the binder proc sending the transaction
> + * @t:		the binder transaction that failed
> + * @data_size:	the user provided data size for the transaction
> + * @error:	enum binder_driver_return_protocol returned to sender
> + */
> +static void binder_netlink_report(struct binder_proc *proc,
> +				  struct binder_transaction *t,
> +				  u32 data_size,
> +				  u32 error)
> +{
> +	const char *context = proc->context->name;
> +	struct sk_buff *skb;
> +	void *hdr;
> +
> +	if (!genl_has_listeners(&binder_nl_family, &init_net,
> +				BINDER_NLGRP_REPORT))
> +		return;
> +
> +	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> +	if (!skb)
> +		return;
> +
> +	hdr = genlmsg_put(skb, 0, 0, &binder_nl_family, 0, BINDER_CMD_REPORT);
> +	if (!hdr)
> +		goto free_skb;
> +
> +	if (nla_put_u32(skb, BINDER_A_REPORT_ERROR, error) ||
> +	    nla_put_string(skb, BINDER_A_REPORT_CONTEXT, context) ||
> +	    nla_put_u32(skb, BINDER_A_REPORT_FROM_PID, t->from_pid) ||
> +	    nla_put_u32(skb, BINDER_A_REPORT_FROM_TID, t->from_tid))
> +		goto cancel_skb;
> +
> +	if (t->to_proc &&
> +	    nla_put_u32(skb, BINDER_A_REPORT_TO_PID, t->to_proc->pid))
> +		goto cancel_skb;
> +
> +	if (t->to_thread &&
> +	    nla_put_u32(skb, BINDER_A_REPORT_TO_TID, t->to_thread->pid))
> +		goto cancel_skb;
> +
> +	if (t->is_reply && nla_put_flag(skb, BINDER_A_REPORT_IS_REPLY))
> +		goto cancel_skb;
> +
> +	if (nla_put_u32(skb, BINDER_A_REPORT_FLAGS, t->flags) ||
> +	    nla_put_u32(skb, BINDER_A_REPORT_CODE, t->code) ||
> +	    nla_put_u32(skb, BINDER_A_REPORT_DATA_SIZE, data_size))
> +		goto cancel_skb;
> +
> +	genlmsg_end(skb, hdr);
> +	genlmsg_multicast(&binder_nl_family, skb, 0, BINDER_NLGRP_REPORT,
> +			  GFP_KERNEL);
> +	return;
> +
> +cancel_skb:
> +	genlmsg_cancel(skb, hdr);
> +free_skb:
> +	nlmsg_free(skb);
> +}
> +
>  static void binder_transaction(struct binder_proc *proc,
>  			       struct binder_thread *thread,
>  			       struct binder_transaction_data *tr, int reply,
> @@ -3679,10 +3741,13 @@ 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
> +		binder_netlink_report(proc, t, tr->data_size,
> +				      BR_ONEWAY_SPAM_SUSPECT);
> +	} else {
>  		tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE;
> +	}
>  
>  	if (reply) {
>  		binder_enqueue_thread_work(thread, tcomplete);
> @@ -3730,8 +3795,11 @@ 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;
> +			binder_netlink_report(proc, t, tr->data_size,
> +					      return_error);
> +		}
>  		binder_enqueue_thread_work(thread, tcomplete);
>  		if (return_error &&
>  		    return_error != BR_TRANSACTION_PENDING_FROZEN)
> @@ -3789,6 +3857,8 @@ static void binder_transaction(struct binder_proc *proc,
>  		binder_dec_node(target_node, 1, 0);
>  		binder_dec_node_tmpref(target_node);
>  	}
> +
> +	binder_netlink_report(proc, t, tr->data_size, return_error);
>  	kfree(t);
>  	binder_stats_deleted(BINDER_STAT_TRANSACTION);
>  err_alloc_t_failed:
> @@ -7067,12 +7137,19 @@ static int __init binder_init(void)
>  		}
>  	}
>  
> -	ret = init_binderfs();
> +	ret = genl_register_family(&binder_nl_family);
>  	if (ret)
>  		goto err_init_binder_device_failed;
>  
> +	ret = init_binderfs();
> +	if (ret)
> +		goto err_init_binderfs_failed;
> +
>  	return ret;
>  
> +err_init_binderfs_failed:
> +	genl_unregister_family(&binder_nl_family);
> +
>  err_init_binder_device_failed:
>  	hlist_for_each_entry_safe(device, tmp, &binder_devices, hlist) {
>  		misc_deregister(&device->miscdev);
> diff --git a/drivers/android/binder_netlink.c b/drivers/android/binder_netlink.c
> new file mode 100644
> index 000000000000..d05397a50ca6
> --- /dev/null
> +++ b/drivers/android/binder_netlink.c
> @@ -0,0 +1,31 @@
> +// 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>
> +
> +/* Ops table for binder */
> +static const struct genl_split_ops binder_nl_ops[] = {
> +};
> +
> +static const struct genl_multicast_group binder_nl_mcgrps[] = {
> +	[BINDER_NLGRP_REPORT] = { "report", },
> +};
> +
> +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),
> +	.mcgrps		= binder_nl_mcgrps,
> +	.n_mcgrps	= ARRAY_SIZE(binder_nl_mcgrps),
> +};
> diff --git a/drivers/android/binder_netlink.h b/drivers/android/binder_netlink.h
> new file mode 100644
> index 000000000000..882c7a6b537e
> --- /dev/null
> +++ b/drivers/android/binder_netlink.h
> @@ -0,0 +1,20 @@
> +/* 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>
> +
> +enum {
> +	BINDER_NLGRP_REPORT,
> +};
> +
> +extern struct genl_family binder_nl_family;
> +
> +#endif /* _LINUX_BINDER_GEN_H */
> diff --git a/include/uapi/linux/android/binder_netlink.h b/include/uapi/linux/android/binder_netlink.h
> new file mode 100644
> index 000000000000..b218f96d6668
> --- /dev/null
> +++ b/include/uapi/linux/android/binder_netlink.h
> @@ -0,0 +1,37 @@
> +/* 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
> +
> +enum {
> +	BINDER_A_REPORT_ERROR = 1,
> +	BINDER_A_REPORT_CONTEXT,
> +	BINDER_A_REPORT_FROM_PID,
> +	BINDER_A_REPORT_FROM_TID,
> +	BINDER_A_REPORT_TO_PID,
> +	BINDER_A_REPORT_TO_TID,
> +	BINDER_A_REPORT_IS_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 = 1,
> +
> +	__BINDER_CMD_MAX,
> +	BINDER_CMD_MAX = (__BINDER_CMD_MAX - 1)
> +};
> +
> +#define BINDER_MCGRP_REPORT	"report"
> +
> +#endif /* _UAPI_LINUX_ANDROID_BINDER_NETLINK_H */

Powered by blists - more mailing lists