@@ -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
@@ -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
new file mode 100644
@@ -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;
+}
@@ -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");
@@ -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 */
@@ -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);
}
/*
new file mode 100644
@@ -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 */
@@ -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)
@@ -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 {
@@ -160,6 +161,7 @@ enum bpf_attach_type {
BPF_CGROUP_INET6_CONNECT,
BPF_CGROUP_INET4_POST_BIND,
BPF_CGROUP_INET6_POST_BIND,
+ BPF_LIRC_MODE2,
__MAX_BPF_ATTACH_TYPE
};
@@ -2004,6 +2006,53 @@ 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), \
@@ -2082,7 +2131,9 @@ 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
@@ -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>
@@ -1578,6 +1579,8 @@ 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;
}
@@ -1648,6 +1651,8 @@ 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;
}
@@ -1695,6 +1700,8 @@ 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;
}