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Subject[PATCH v1 2/4] media: bpf: allow raw IR decoder bpf programs to be used
Date
This implements attaching, detaching, querying and execution. The target
fd has to be the /dev/lircN device.

Signed-off-by: Sean Young <sean@mess.org>
---
drivers/media/rc/ir-bpf-decoder.c | 191 ++++++++++++++++++++++++++++++
drivers/media/rc/lirc_dev.c | 30 +++++
drivers/media/rc/rc-core-priv.h | 15 +++
drivers/media/rc/rc-ir-raw.c | 5 +
include/uapi/linux/bpf.h | 1 +
kernel/bpf/syscall.c | 7 ++
6 files changed, 249 insertions(+)

diff --git a/drivers/media/rc/ir-bpf-decoder.c b/drivers/media/rc/ir-bpf-decoder.c
index aaa5e208b1a5..651590a14772 100644
--- a/drivers/media/rc/ir-bpf-decoder.c
+++ b/drivers/media/rc/ir-bpf-decoder.c
@@ -91,3 +91,194 @@ const struct bpf_verifier_ops ir_decoder_verifier_ops = {
.get_func_proto = ir_decoder_func_proto,
.is_valid_access = ir_decoder_is_valid_access
};
+
+#define BPF_MAX_PROGS 64
+
+int rc_dev_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog, u32 flags)
+{
+ struct ir_raw_event_ctrl *raw;
+ struct bpf_prog_array __rcu *old_array;
+ struct bpf_prog_array *new_array;
+ int ret;
+
+ if (rcdev->driver_type != RC_DRIVER_IR_RAW)
+ return -EINVAL;
+
+ ret = mutex_lock_interruptible(&rcdev->lock);
+ if (ret)
+ return ret;
+
+ raw = rcdev->raw;
+
+ if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) {
+ ret = -E2BIG;
+ goto out;
+ }
+
+ old_array = raw->progs;
+ ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
+ if (ret < 0)
+ goto out;
+
+ rcu_assign_pointer(raw->progs, new_array);
+ bpf_prog_array_free(old_array);
+out:
+ mutex_unlock(&rcdev->lock);
+ return ret;
+}
+
+int rc_dev_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog, u32 flags)
+{
+ struct ir_raw_event_ctrl *raw;
+ struct bpf_prog_array __rcu *old_array;
+ struct bpf_prog_array *new_array;
+ int ret;
+
+ if (rcdev->driver_type != RC_DRIVER_IR_RAW)
+ return -EINVAL;
+
+ ret = mutex_lock_interruptible(&rcdev->lock);
+ if (ret)
+ return ret;
+
+ raw = rcdev->raw;
+
+ old_array = raw->progs;
+ ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
+ if (ret < 0) {
+ bpf_prog_array_delete_safe(old_array, prog);
+ } else {
+ rcu_assign_pointer(raw->progs, new_array);
+ bpf_prog_array_free(old_array);
+ }
+
+ bpf_prog_put(prog);
+ mutex_unlock(&rcdev->lock);
+ return 0;
+}
+
+void rc_dev_bpf_run(struct rc_dev *rcdev)
+{
+ struct ir_raw_event_ctrl *raw = rcdev->raw;
+
+ if (raw->progs)
+ BPF_PROG_RUN_ARRAY(raw->progs, &raw->prev_ev, BPF_PROG_RUN);
+}
+
+void rc_dev_bpf_put(struct rc_dev *rcdev)
+{
+ struct bpf_prog_array *progs = rcdev->raw->progs;
+ int i, size;
+
+ if (!progs)
+ return;
+
+ size = bpf_prog_array_length(progs);
+ for (i = 0; i < size; i++)
+ bpf_prog_put(progs->progs[i]);
+
+ bpf_prog_array_free(rcdev->raw->progs);
+}
+
+int rc_dev_prog_attach(const union bpf_attr *attr)
+{
+ struct bpf_prog *prog;
+ struct rc_dev *rcdev;
+ int ret;
+
+ if (attr->attach_flags & BPF_F_ALLOW_OVERRIDE)
+ return -EINVAL;
+
+ prog = bpf_prog_get_type(attr->attach_bpf_fd,
+ BPF_PROG_TYPE_RAWIR_DECODER);
+ 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 = rc_dev_bpf_attach(rcdev, prog, attr->attach_flags);
+ if (ret)
+ bpf_prog_put(prog);
+
+ put_device(&rcdev->dev);
+
+ return ret;
+}
+
+int rc_dev_prog_detach(const union bpf_attr *attr)
+{
+ struct bpf_prog *prog;
+ struct rc_dev *rcdev;
+ int ret;
+
+ if (attr->attach_flags & BPF_F_ALLOW_OVERRIDE)
+ return -EINVAL;
+
+ prog = bpf_prog_get_type(attr->attach_bpf_fd,
+ BPF_PROG_TYPE_RAWIR_DECODER);
+ 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 = rc_dev_bpf_detach(rcdev, prog, attr->attach_flags);
+
+ bpf_prog_put(prog);
+ put_device(&rcdev->dev);
+
+ return ret;
+}
+
+int rc_dev_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 *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 out;
+ }
+
+ ret = mutex_lock_interruptible(&rcdev->lock);
+ if (ret)
+ goto out;
+
+ 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 out;
+ }
+ if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ if (attr->query.prog_cnt != 0 && prog_ids && cnt)
+ ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
+
+out:
+ mutex_unlock(&rcdev->lock);
+ put_device(&rcdev->dev);
+
+ return ret;
+}
diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
index 24e9fbb80e81..65319f2ccc13 100644
--- a/drivers/media/rc/lirc_dev.c
+++ b/drivers/media/rc/lirc_dev.c
@@ -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>
@@ -28,6 +29,8 @@
#include "rc-core-priv.h"
#include <uapi/linux/lirc.h>

+#include <linux/bpf-rcdev.h>
+
#define LIRCBUF_SIZE 256

static dev_t lirc_base_dev;
@@ -816,4 +819,31 @@ 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 rc_dev *dev;
+ struct file *f;
+
+ f = fget_raw(fd);
+ if (!f)
+ return ERR_PTR(-EBADF);
+
+ if (!S_ISCHR(f->f_inode->i_mode) ||
+ imajor(f->f_inode) != MAJOR(lirc_base_dev)) {
+ fput(f);
+ return ERR_PTR(-EBADF);
+ }
+
+ dev = container_of(f->f_inode->i_cdev, struct rc_dev, lirc_cdev);
+ if (!dev->registered) {
+ fput(f);
+ return ERR_PTR(-ENODEV);
+ }
+
+ get_device(&dev->dev);
+ fput(f);
+
+ return dev;
+}
+
MODULE_ALIAS("lirc_dev");
diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index e0e6a17460f6..b6f24f369657 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -57,6 +57,9 @@ struct ir_raw_event_ctrl {
/* raw decoder state follows */
struct ir_raw_event prev_ev;
struct ir_raw_event this_ev;
+#ifdef CONFIG_IR_BPF_DECODER
+ struct bpf_prog_array *progs;
+#endif
struct nec_dec {
int state;
unsigned count;
@@ -288,6 +291,7 @@ 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 +303,15 @@ 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_IR_BPF_DECODER
+void rc_dev_bpf_put(struct rc_dev *dev);
+void rc_dev_bpf_run(struct rc_dev *dev);
+#else
+void rc_dev_bpf_put(struct rc_dev *dev) {}
+void rc_dev_bpf_run(struct rc_dev *dev) {}
+#endif
+
#endif /* _RC_CORE_PRIV */
diff --git a/drivers/media/rc/rc-ir-raw.c b/drivers/media/rc/rc-ir-raw.c
index 374f83105a23..efddd9c44466 100644
--- a/drivers/media/rc/rc-ir-raw.c
+++ b/drivers/media/rc/rc-ir-raw.c
@@ -8,6 +8,8 @@
#include <linux/mutex.h>
#include <linux/kmod.h>
#include <linux/sched.h>
+#include <linux/filter.h>
+#include <linux/bpf.h>
#include "rc-core-priv.h"

/* Used to keep track of IR raw clients, protected by ir_raw_handler_lock */
@@ -33,6 +35,7 @@ static int ir_raw_event_thread(void *data)
handler->decode(raw->dev, ev);
ir_lirc_raw_event(raw->dev, ev);
raw->prev_ev = ev;
+ rc_dev_bpf_run(raw->dev);
}
mutex_unlock(&ir_raw_handler_lock);

@@ -623,6 +626,8 @@ void ir_raw_event_unregister(struct rc_dev *dev)
handler->raw_unregister(dev);
mutex_unlock(&ir_raw_handler_lock);

+ rc_dev_bpf_put(dev);
+
ir_raw_event_free(dev);
}

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 6ad053e831c0..d9740599adf6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -155,6 +155,7 @@ enum bpf_attach_type {
BPF_CGROUP_INET6_CONNECT,
BPF_CGROUP_INET4_POST_BIND,
BPF_CGROUP_INET6_POST_BIND,
+ BPF_RAWIR_DECODER,
__MAX_BPF_ATTACH_TYPE
};

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 016ef9025827..63ecc1f2e1e3 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -27,6 +27,7 @@
#include <linux/timekeeping.h>
#include <linux/ctype.h>
#include <linux/nospec.h>
+#include <linux/bpf-rcdev.h>

#define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \
(map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -1556,6 +1557,8 @@ 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_RAWIR_DECODER:
+ return rc_dev_prog_attach(attr);
default:
return -EINVAL;
}
@@ -1626,6 +1629,8 @@ 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_RAWIR_DECODER:
+ return rc_dev_prog_detach(attr);
default:
return -EINVAL;
}
@@ -1673,6 +1678,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_CGROUP_SOCK_OPS:
case BPF_CGROUP_DEVICE:
break;
+ case BPF_RAWIR_DECODER:
+ return rc_dev_prog_query(attr, uattr);
default:
return -EINVAL;
}
--
2.17.0
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