root/net/wireless/debugfs.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * cfg80211 debugfs
 *
 * Copyright 2009       Luis R. Rodriguez <lrodriguez@atheros.com>
 * Copyright 2007       Johannes Berg <johannes@sipsolutions.net>
 * Copyright (C) 2023 Intel Corporation
 */

#include <linux/slab.h>
#include "core.h"
#include "debugfs.h"

#define DEBUGFS_READONLY_FILE(name, buflen, fmt, value...)              \
static ssize_t name## _read(struct file *file, char __user *userbuf,    \
                            size_t count, loff_t *ppos)                 \
{                                                                       \
        struct wiphy *wiphy = file->private_data;                       \
        char buf[buflen];                                               \
        int res;                                                        \
                                                                        \
        res = scnprintf(buf, buflen, fmt "\n", ##value);                \
        return simple_read_from_buffer(userbuf, count, ppos, buf, res); \
}                                                                       \
                                                                        \
static const struct file_operations name## _ops = {                     \
        .read = name## _read,                                           \
        .open = simple_open,                                            \
        .llseek = generic_file_llseek,                                  \
}

#define DEBUGFS_RADIO_READONLY_FILE(name, buflen, fmt, value...)        \
static ssize_t name## _read(struct file *file, char __user *userbuf,    \
                            size_t count, loff_t *ppos)                 \
{                                                                       \
        struct wiphy_radio_cfg *radio_cfg = file->private_data;         \
        char buf[buflen];                                               \
        int res;                                                        \
                                                                        \
        res = scnprintf(buf, buflen, fmt "\n", ##value);                \
        return simple_read_from_buffer(userbuf, count, ppos, buf, res); \
}                                                                       \
                                                                        \
static const struct file_operations name## _ops = {                     \
        .read = name## _read,                                           \
        .open = simple_open,                                            \
        .llseek = generic_file_llseek,                                  \
}

DEBUGFS_READONLY_FILE(rts_threshold, 20, "%d",
                      wiphy->rts_threshold);
DEBUGFS_READONLY_FILE(fragmentation_threshold, 20, "%d",
                      wiphy->frag_threshold);
DEBUGFS_READONLY_FILE(short_retry_limit, 20, "%d",
                      wiphy->retry_short);
DEBUGFS_READONLY_FILE(long_retry_limit, 20, "%d",
                      wiphy->retry_long);

DEBUGFS_RADIO_READONLY_FILE(radio_rts_threshold, 20, "%d",
                            radio_cfg->rts_threshold);

static int ht_print_chan(struct ieee80211_channel *chan,
                         char *buf, int buf_size, int offset)
{
        if (WARN_ON(offset > buf_size))
                return 0;

        if (chan->flags & IEEE80211_CHAN_DISABLED)
                return scnprintf(buf + offset,
                                 buf_size - offset,
                                 "%d Disabled\n",
                                 chan->center_freq);

        return scnprintf(buf + offset,
                         buf_size - offset,
                         "%d HT40 %c%c\n",
                         chan->center_freq,
                         (chan->flags & IEEE80211_CHAN_NO_HT40MINUS) ?
                                ' ' : '-',
                         (chan->flags & IEEE80211_CHAN_NO_HT40PLUS) ?
                                ' ' : '+');
}

static ssize_t ht40allow_map_read(struct file *file,
                                  char __user *user_buf,
                                  size_t count, loff_t *ppos)
{
        struct wiphy *wiphy = file->private_data;
        char *buf;
        unsigned int offset = 0, buf_size = PAGE_SIZE, i;
        enum nl80211_band band;
        struct ieee80211_supported_band *sband;
        ssize_t r;

        buf = kzalloc(buf_size, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        for (band = 0; band < NUM_NL80211_BANDS; band++) {
                sband = wiphy->bands[band];
                if (!sband)
                        continue;
                for (i = 0; i < sband->n_channels; i++)
                        offset += ht_print_chan(&sband->channels[i],
                                                buf, buf_size, offset);
        }

        r = simple_read_from_buffer(user_buf, count, ppos, buf, offset);

        kfree(buf);

        return r;
}

static const struct file_operations ht40allow_map_ops = {
        .read = ht40allow_map_read,
        .open = simple_open,
        .llseek = default_llseek,
};

#define DEBUGFS_ADD(name)                                               \
        debugfs_create_file(#name, 0444, phyd, &rdev->wiphy, &name## _ops)

#define DEBUGFS_RADIO_ADD(name, radio_idx)                              \
        debugfs_create_file(#name, 0444, radiod,                        \
                            &rdev->wiphy.radio_cfg[radio_idx],          \
                            &name## _ops)

void cfg80211_debugfs_rdev_add(struct cfg80211_registered_device *rdev)
{
        struct dentry *phyd = rdev->wiphy.debugfsdir;
        struct dentry *radiod;
        u8 i;

        DEBUGFS_ADD(rts_threshold);
        DEBUGFS_ADD(fragmentation_threshold);
        DEBUGFS_ADD(short_retry_limit);
        DEBUGFS_ADD(long_retry_limit);
        DEBUGFS_ADD(ht40allow_map);

        for (i = 0; i < rdev->wiphy.n_radio; i++) {
                radiod = rdev->wiphy.radio_cfg[i].radio_debugfsdir;
                DEBUGFS_RADIO_ADD(radio_rts_threshold, i);
        }
}

struct debugfs_read_work {
        struct wiphy_work work;
        ssize_t (*handler)(struct wiphy *wiphy,
                           struct file *file,
                           char *buf,
                           size_t count,
                           void *data);
        struct wiphy *wiphy;
        struct file *file;
        char *buf;
        size_t bufsize;
        void *data;
        ssize_t ret;
        struct completion completion;
};

static void wiphy_locked_debugfs_read_work(struct wiphy *wiphy,
                                           struct wiphy_work *work)
{
        struct debugfs_read_work *w = container_of(work, typeof(*w), work);

        w->ret = w->handler(w->wiphy, w->file, w->buf, w->bufsize, w->data);
        complete(&w->completion);
}

static void wiphy_locked_debugfs_read_cancel(struct dentry *dentry,
                                             void *data)
{
        struct debugfs_read_work *w = data;

        wiphy_work_cancel(w->wiphy, &w->work);
        complete(&w->completion);
}

ssize_t wiphy_locked_debugfs_read(struct wiphy *wiphy, struct file *file,
                                  char *buf, size_t bufsize,
                                  char __user *userbuf, size_t count,
                                  loff_t *ppos,
                                  ssize_t (*handler)(struct wiphy *wiphy,
                                                     struct file *file,
                                                     char *buf,
                                                     size_t bufsize,
                                                     void *data),
                                  void *data)
{
        struct debugfs_read_work work = {
                .handler = handler,
                .wiphy = wiphy,
                .file = file,
                .buf = buf,
                .bufsize = bufsize,
                .data = data,
                .ret = -ENODEV,
                .completion = COMPLETION_INITIALIZER_ONSTACK(work.completion),
        };
        struct debugfs_cancellation cancellation = {
                .cancel = wiphy_locked_debugfs_read_cancel,
                .cancel_data = &work,
        };

        /* don't leak stack data or whatever */
        memset(buf, 0, bufsize);

        wiphy_work_init(&work.work, wiphy_locked_debugfs_read_work);
        wiphy_work_queue(wiphy, &work.work);

        debugfs_enter_cancellation(file, &cancellation);
        wait_for_completion(&work.completion);
        debugfs_leave_cancellation(file, &cancellation);

        if (work.ret < 0)
                return work.ret;

        if (WARN_ON(work.ret > bufsize))
                return -EINVAL;

        return simple_read_from_buffer(userbuf, count, ppos, buf, work.ret);
}
EXPORT_SYMBOL_GPL(wiphy_locked_debugfs_read);

struct debugfs_write_work {
        struct wiphy_work work;
        ssize_t (*handler)(struct wiphy *wiphy,
                           struct file *file,
                           char *buf,
                           size_t count,
                           void *data);
        struct wiphy *wiphy;
        struct file *file;
        char *buf;
        size_t count;
        void *data;
        ssize_t ret;
        struct completion completion;
};

static void wiphy_locked_debugfs_write_work(struct wiphy *wiphy,
                                            struct wiphy_work *work)
{
        struct debugfs_write_work *w = container_of(work, typeof(*w), work);

        w->ret = w->handler(w->wiphy, w->file, w->buf, w->count, w->data);
        complete(&w->completion);
}

static void wiphy_locked_debugfs_write_cancel(struct dentry *dentry,
                                              void *data)
{
        struct debugfs_write_work *w = data;

        wiphy_work_cancel(w->wiphy, &w->work);
        complete(&w->completion);
}

ssize_t wiphy_locked_debugfs_write(struct wiphy *wiphy,
                                   struct file *file, char *buf, size_t bufsize,
                                   const char __user *userbuf, size_t count,
                                   ssize_t (*handler)(struct wiphy *wiphy,
                                                      struct file *file,
                                                      char *buf,
                                                      size_t count,
                                                      void *data),
                                   void *data)
{
        struct debugfs_write_work work = {
                .handler = handler,
                .wiphy = wiphy,
                .file = file,
                .buf = buf,
                .count = count,
                .data = data,
                .ret = -ENODEV,
                .completion = COMPLETION_INITIALIZER_ONSTACK(work.completion),
        };
        struct debugfs_cancellation cancellation = {
                .cancel = wiphy_locked_debugfs_write_cancel,
                .cancel_data = &work,
        };

        /* mostly used for strings so enforce NUL-termination for safety */
        if (count >= bufsize)
                return -EINVAL;

        memset(buf, 0, bufsize);

        if (copy_from_user(buf, userbuf, count))
                return -EFAULT;

        wiphy_work_init(&work.work, wiphy_locked_debugfs_write_work);
        wiphy_work_queue(wiphy, &work.work);

        debugfs_enter_cancellation(file, &cancellation);
        wait_for_completion(&work.completion);
        debugfs_leave_cancellation(file, &cancellation);

        return work.ret;
}
EXPORT_SYMBOL_GPL(wiphy_locked_debugfs_write);