media: rc: introduce BPF_PROG_LIRC_MODE2

Add support for BPF_PROG_LIRC_MODE2. This type of BPF program can call
rc_keydown() to reported decoded IR scancodes, or rc_repeat() to report
that the last key should be repeated.

The bpf program can be attached to using the bpf(BPF_PROG_ATTACH) syscall;
the target_fd must be the /dev/lircN device.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Sean Young 2018-05-27 12:24:09 +01:00 committed by Daniel Borkmann
parent 170a7e3ea0
commit f4364dcfc8
10 changed files with 479 additions and 3 deletions

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@ -25,6 +25,19 @@ config LIRC
passes raw IR to and from userspace, which is needed for
IR transmitting (aka "blasting") and for the lirc daemon.
config BPF_LIRC_MODE2
bool "Support for eBPF programs attached to lirc devices"
depends on BPF_SYSCALL
depends on RC_CORE=y
depends on LIRC
help
Allow attaching eBPF programs to a lirc device using the bpf(2)
syscall command BPF_PROG_ATTACH. This is supported for raw IR
receivers.
These eBPF programs can be used to decode IR into scancodes, for
IR protocols not supported by the kernel decoders.
menuconfig RC_DECODERS
bool "Remote controller decoders"
depends on RC_CORE

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@ -5,6 +5,7 @@ obj-y += keymaps/
obj-$(CONFIG_RC_CORE) += rc-core.o
rc-core-y := rc-main.o rc-ir-raw.o
rc-core-$(CONFIG_LIRC) += lirc_dev.o
rc-core-$(CONFIG_BPF_LIRC_MODE2) += bpf-lirc.o
obj-$(CONFIG_IR_NEC_DECODER) += ir-nec-decoder.o
obj-$(CONFIG_IR_RC5_DECODER) += ir-rc5-decoder.o
obj-$(CONFIG_IR_RC6_DECODER) += ir-rc6-decoder.o

313
drivers/media/rc/bpf-lirc.c Normal file
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@ -0,0 +1,313 @@
// SPDX-License-Identifier: GPL-2.0
// bpf-lirc.c - handles bpf
//
// Copyright (C) 2018 Sean Young <sean@mess.org>
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/bpf_lirc.h>
#include "rc-core-priv.h"
/*
* BPF interface for raw IR
*/
const struct bpf_prog_ops lirc_mode2_prog_ops = {
};
BPF_CALL_1(bpf_rc_repeat, u32*, sample)
{
struct ir_raw_event_ctrl *ctrl;
ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
rc_repeat(ctrl->dev);
return 0;
}
static const struct bpf_func_proto rc_repeat_proto = {
.func = bpf_rc_repeat,
.gpl_only = true, /* rc_repeat is EXPORT_SYMBOL_GPL */
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
};
/*
* Currently rc-core does not support 64-bit scancodes, but there are many
* known protocols with more than 32 bits. So, define the interface as u64
* as a future-proof.
*/
BPF_CALL_4(bpf_rc_keydown, u32*, sample, u32, protocol, u64, scancode,
u32, toggle)
{
struct ir_raw_event_ctrl *ctrl;
ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
rc_keydown(ctrl->dev, protocol, scancode, toggle != 0);
return 0;
}
static const struct bpf_func_proto rc_keydown_proto = {
.func = bpf_rc_keydown,
.gpl_only = true, /* rc_keydown is EXPORT_SYMBOL_GPL */
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_ANYTHING,
};
static const struct bpf_func_proto *
lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_rc_repeat:
return &rc_repeat_proto;
case BPF_FUNC_rc_keydown:
return &rc_keydown_proto;
case BPF_FUNC_map_lookup_elem:
return &bpf_map_lookup_elem_proto;
case BPF_FUNC_map_update_elem:
return &bpf_map_update_elem_proto;
case BPF_FUNC_map_delete_elem:
return &bpf_map_delete_elem_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_tail_call:
return &bpf_tail_call_proto;
case BPF_FUNC_get_prandom_u32:
return &bpf_get_prandom_u32_proto;
case BPF_FUNC_trace_printk:
if (capable(CAP_SYS_ADMIN))
return bpf_get_trace_printk_proto();
/* fall through */
default:
return NULL;
}
}
static bool lirc_mode2_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
/* We have one field of u32 */
return type == BPF_READ && off == 0 && size == sizeof(u32);
}
const struct bpf_verifier_ops lirc_mode2_verifier_ops = {
.get_func_proto = lirc_mode2_func_proto,
.is_valid_access = lirc_mode2_is_valid_access
};
#define BPF_MAX_PROGS 64
static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
{
struct bpf_prog_array __rcu *old_array;
struct bpf_prog_array *new_array;
struct ir_raw_event_ctrl *raw;
int ret;
if (rcdev->driver_type != RC_DRIVER_IR_RAW)
return -EINVAL;
ret = mutex_lock_interruptible(&ir_raw_handler_lock);
if (ret)
return ret;
raw = rcdev->raw;
if (!raw) {
ret = -ENODEV;
goto unlock;
}
if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) {
ret = -E2BIG;
goto unlock;
}
old_array = raw->progs;
ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
if (ret < 0)
goto unlock;
rcu_assign_pointer(raw->progs, new_array);
bpf_prog_array_free(old_array);
unlock:
mutex_unlock(&ir_raw_handler_lock);
return ret;
}
static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
{
struct bpf_prog_array __rcu *old_array;
struct bpf_prog_array *new_array;
struct ir_raw_event_ctrl *raw;
int ret;
if (rcdev->driver_type != RC_DRIVER_IR_RAW)
return -EINVAL;
ret = mutex_lock_interruptible(&ir_raw_handler_lock);
if (ret)
return ret;
raw = rcdev->raw;
if (!raw) {
ret = -ENODEV;
goto unlock;
}
old_array = raw->progs;
ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
/*
* Do not use bpf_prog_array_delete_safe() as we would end up
* with a dummy entry in the array, and the we would free the
* dummy in lirc_bpf_free()
*/
if (ret)
goto unlock;
rcu_assign_pointer(raw->progs, new_array);
bpf_prog_array_free(old_array);
unlock:
mutex_unlock(&ir_raw_handler_lock);
return ret;
}
void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
{
struct ir_raw_event_ctrl *raw = rcdev->raw;
raw->bpf_sample = sample;
if (raw->progs)
BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_sample, BPF_PROG_RUN);
}
/*
* This should be called once the rc thread has been stopped, so there can be
* no concurrent bpf execution.
*/
void lirc_bpf_free(struct rc_dev *rcdev)
{
struct bpf_prog **progs;
if (!rcdev->raw->progs)
return;
progs = rcu_dereference(rcdev->raw->progs)->progs;
while (*progs)
bpf_prog_put(*progs++);
bpf_prog_array_free(rcdev->raw->progs);
}
int lirc_prog_attach(const union bpf_attr *attr)
{
struct bpf_prog *prog;
struct rc_dev *rcdev;
int ret;
if (attr->attach_flags)
return -EINVAL;
prog = bpf_prog_get_type(attr->attach_bpf_fd,
BPF_PROG_TYPE_LIRC_MODE2);
if (IS_ERR(prog))
return PTR_ERR(prog);
rcdev = rc_dev_get_from_fd(attr->target_fd);
if (IS_ERR(rcdev)) {
bpf_prog_put(prog);
return PTR_ERR(rcdev);
}
ret = lirc_bpf_attach(rcdev, prog);
if (ret)
bpf_prog_put(prog);
put_device(&rcdev->dev);
return ret;
}
int lirc_prog_detach(const union bpf_attr *attr)
{
struct bpf_prog *prog;
struct rc_dev *rcdev;
int ret;
if (attr->attach_flags)
return -EINVAL;
prog = bpf_prog_get_type(attr->attach_bpf_fd,
BPF_PROG_TYPE_LIRC_MODE2);
if (IS_ERR(prog))
return PTR_ERR(prog);
rcdev = rc_dev_get_from_fd(attr->target_fd);
if (IS_ERR(rcdev)) {
bpf_prog_put(prog);
return PTR_ERR(rcdev);
}
ret = lirc_bpf_detach(rcdev, prog);
bpf_prog_put(prog);
put_device(&rcdev->dev);
return ret;
}
int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
{
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
struct bpf_prog_array __rcu *progs;
struct rc_dev *rcdev;
u32 cnt, flags = 0;
int ret;
if (attr->query.query_flags)
return -EINVAL;
rcdev = rc_dev_get_from_fd(attr->query.target_fd);
if (IS_ERR(rcdev))
return PTR_ERR(rcdev);
if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
ret = -EINVAL;
goto put;
}
ret = mutex_lock_interruptible(&ir_raw_handler_lock);
if (ret)
goto put;
progs = rcdev->raw->progs;
cnt = progs ? bpf_prog_array_length(progs) : 0;
if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
ret = -EFAULT;
goto unlock;
}
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
ret = -EFAULT;
goto unlock;
}
if (attr->query.prog_cnt != 0 && prog_ids && cnt)
ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
unlock:
mutex_unlock(&ir_raw_handler_lock);
put:
put_device(&rcdev->dev);
return ret;
}

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@ -20,6 +20,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/file.h>
#include <linux/idr.h>
#include <linux/poll.h>
#include <linux/sched.h>
@ -104,6 +105,12 @@ void ir_lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev)
TO_US(ev.duration), TO_STR(ev.pulse));
}
/*
* bpf does not care about the gap generated above; that exists
* for backwards compatibility
*/
lirc_bpf_run(dev, sample);
spin_lock_irqsave(&dev->lirc_fh_lock, flags);
list_for_each_entry(fh, &dev->lirc_fh, list) {
if (LIRC_IS_TIMEOUT(sample) && !fh->send_timeout_reports)
@ -816,4 +823,27 @@ void __exit lirc_dev_exit(void)
unregister_chrdev_region(lirc_base_dev, RC_DEV_MAX);
}
struct rc_dev *rc_dev_get_from_fd(int fd)
{
struct fd f = fdget(fd);
struct lirc_fh *fh;
struct rc_dev *dev;
if (!f.file)
return ERR_PTR(-EBADF);
if (f.file->f_op != &lirc_fops) {
fdput(f);
return ERR_PTR(-EINVAL);
}
fh = f.file->private_data;
dev = fh->rc;
get_device(&dev->dev);
fdput(f);
return dev;
}
MODULE_ALIAS("lirc_dev");

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@ -13,6 +13,7 @@
#define MAX_IR_EVENT_SIZE 512
#include <linux/slab.h>
#include <uapi/linux/bpf.h>
#include <media/rc-core.h>
/**
@ -57,6 +58,11 @@ struct ir_raw_event_ctrl {
/* raw decoder state follows */
struct ir_raw_event prev_ev;
struct ir_raw_event this_ev;
#ifdef CONFIG_BPF_LIRC_MODE2
u32 bpf_sample;
struct bpf_prog_array __rcu *progs;
#endif
struct nec_dec {
int state;
unsigned count;
@ -126,6 +132,9 @@ struct ir_raw_event_ctrl {
} imon;
};
/* Mutex for locking raw IR processing and handler change */
extern struct mutex ir_raw_handler_lock;
/* macros for IR decoders */
static inline bool geq_margin(unsigned d1, unsigned d2, unsigned margin)
{
@ -288,6 +297,7 @@ void ir_lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev);
void ir_lirc_scancode_event(struct rc_dev *dev, struct lirc_scancode *lsc);
int ir_lirc_register(struct rc_dev *dev);
void ir_lirc_unregister(struct rc_dev *dev);
struct rc_dev *rc_dev_get_from_fd(int fd);
#else
static inline int lirc_dev_init(void) { return 0; }
static inline void lirc_dev_exit(void) {}
@ -299,4 +309,15 @@ static inline int ir_lirc_register(struct rc_dev *dev) { return 0; }
static inline void ir_lirc_unregister(struct rc_dev *dev) { }
#endif
/*
* bpf interface
*/
#ifdef CONFIG_BPF_LIRC_MODE2
void lirc_bpf_free(struct rc_dev *dev);
void lirc_bpf_run(struct rc_dev *dev, u32 sample);
#else
static inline void lirc_bpf_free(struct rc_dev *dev) { }
static inline void lirc_bpf_run(struct rc_dev *dev, u32 sample) { }
#endif
#endif /* _RC_CORE_PRIV */

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@ -14,7 +14,7 @@
static LIST_HEAD(ir_raw_client_list);
/* Used to handle IR raw handler extensions */
static DEFINE_MUTEX(ir_raw_handler_lock);
DEFINE_MUTEX(ir_raw_handler_lock);
static LIST_HEAD(ir_raw_handler_list);
static atomic64_t available_protocols = ATOMIC64_INIT(0);
@ -621,9 +621,17 @@ void ir_raw_event_unregister(struct rc_dev *dev)
list_for_each_entry(handler, &ir_raw_handler_list, list)
if (handler->raw_unregister)
handler->raw_unregister(dev);
mutex_unlock(&ir_raw_handler_lock);
lirc_bpf_free(dev);
ir_raw_event_free(dev);
/*
* A user can be calling bpf(BPF_PROG_{QUERY|ATTACH|DETACH}), so
* ensure that the raw member is null on unlock; this is how
* "device gone" is checked.
*/
mutex_unlock(&ir_raw_handler_lock);
}
/*

29
include/linux/bpf_lirc.h Normal file
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@ -0,0 +1,29 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BPF_LIRC_H
#define _BPF_LIRC_H
#include <uapi/linux/bpf.h>
#ifdef CONFIG_BPF_LIRC_MODE2
int lirc_prog_attach(const union bpf_attr *attr);
int lirc_prog_detach(const union bpf_attr *attr);
int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
#else
static inline int lirc_prog_attach(const union bpf_attr *attr)
{
return -EINVAL;
}
static inline int lirc_prog_detach(const union bpf_attr *attr)
{
return -EINVAL;
}
static inline int lirc_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
return -EINVAL;
}
#endif
#endif /* _BPF_LIRC_H */

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@ -26,6 +26,9 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)
#ifdef CONFIG_CGROUP_BPF
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
#endif
#ifdef CONFIG_BPF_LIRC_MODE2
BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)

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@ -143,6 +143,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_RAW_TRACEPOINT,
BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
BPF_PROG_TYPE_LWT_SEG6LOCAL,
BPF_PROG_TYPE_LIRC_MODE2,
};
enum bpf_attach_type {
@ -162,6 +163,7 @@ enum bpf_attach_type {
BPF_CGROUP_INET6_POST_BIND,
BPF_CGROUP_UDP4_SENDMSG,
BPF_CGROUP_UDP6_SENDMSG,
BPF_LIRC_MODE2,
__MAX_BPF_ATTACH_TYPE
};
@ -2005,6 +2007,53 @@ union bpf_attr {
* direct packet access.
* Return
* 0 on success, or a negative error in case of failure.
*
* int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
* Description
* This helper is used in programs implementing IR decoding, to
* report a successfully decoded key press with *scancode*,
* *toggle* value in the given *protocol*. The scancode will be
* translated to a keycode using the rc keymap, and reported as
* an input key down event. After a period a key up event is
* generated. This period can be extended by calling either
* **bpf_rc_keydown** () again with the same values, or calling
* **bpf_rc_repeat** ().
*
* Some protocols include a toggle bit, in case the button was
* released and pressed again between consecutive scancodes.
*
* The *ctx* should point to the lirc sample as passed into
* the program.
*
* The *protocol* is the decoded protocol number (see
* **enum rc_proto** for some predefined values).
*
* This helper is only available is the kernel was compiled with
* the **CONFIG_BPF_LIRC_MODE2** configuration option set to
* "**y**".
*
* Return
* 0
*
* int bpf_rc_repeat(void *ctx)
* Description
* This helper is used in programs implementing IR decoding, to
* report a successfully decoded repeat key message. This delays
* the generation of a key up event for previously generated
* key down event.
*
* Some IR protocols like NEC have a special IR message for
* repeating last button, for when a button is held down.
*
* The *ctx* should point to the lirc sample as passed into
* the program.
*
* This helper is only available is the kernel was compiled with
* the **CONFIG_BPF_LIRC_MODE2** configuration option set to
* "**y**".
*
* Return
* 0
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -2083,7 +2132,9 @@ union bpf_attr {
FN(lwt_push_encap), \
FN(lwt_seg6_store_bytes), \
FN(lwt_seg6_adjust_srh), \
FN(lwt_seg6_action),
FN(lwt_seg6_action), \
FN(rc_repeat), \
FN(rc_keydown),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call

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@ -11,6 +11,7 @@
*/
#include <linux/bpf.h>
#include <linux/bpf_trace.h>
#include <linux/bpf_lirc.h>
#include <linux/btf.h>
#include <linux/syscalls.h>
#include <linux/slab.h>
@ -1582,6 +1583,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, true);
case BPF_LIRC_MODE2:
return lirc_prog_attach(attr);
default:
return -EINVAL;
}
@ -1654,6 +1657,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, false);
case BPF_LIRC_MODE2:
return lirc_prog_detach(attr);
default:
return -EINVAL;
}
@ -1703,6 +1708,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_CGROUP_SOCK_OPS:
case BPF_CGROUP_DEVICE:
break;
case BPF_LIRC_MODE2:
return lirc_prog_query(attr, uattr);
default:
return -EINVAL;
}