linux/sound/core/info.c
Takashi Iwai 6809cd682b ALSA: info: Return error for invalid read/write
Currently the ALSA proc handler allows read or write even if the proc
file were write-only or read-only.  It's mostly harmless, does thing
but allocating memory and ignores the input/output.  But it doesn't
tell user about the invalid use, and it's confusing and inconsistent
in comparison with other proc files.

This patch adds some sanity checks and let the proc handler returning
an -EIO error when the invalid read/write is performed.

Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-11-08 14:37:26 +01:00

885 lines
20 KiB
C

/*
* Information interface for ALSA driver
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/init.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/info.h>
#include <linux/utsname.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <stdarg.h>
int snd_info_check_reserved_words(const char *str)
{
static char *reserved[] =
{
"version",
"meminfo",
"memdebug",
"detect",
"devices",
"oss",
"cards",
"timers",
"synth",
"pcm",
"seq",
NULL
};
char **xstr = reserved;
while (*xstr) {
if (!strcmp(*xstr, str))
return 0;
xstr++;
}
if (!strncmp(str, "card", 4))
return 0;
return 1;
}
static DEFINE_MUTEX(info_mutex);
struct snd_info_private_data {
struct snd_info_buffer *rbuffer;
struct snd_info_buffer *wbuffer;
struct snd_info_entry *entry;
void *file_private_data;
};
static int snd_info_version_init(void);
static void snd_info_disconnect(struct snd_info_entry *entry);
/*
*/
static struct snd_info_entry *snd_proc_root;
struct snd_info_entry *snd_seq_root;
EXPORT_SYMBOL(snd_seq_root);
#ifdef CONFIG_SND_OSSEMUL
struct snd_info_entry *snd_oss_root;
#endif
static int alloc_info_private(struct snd_info_entry *entry,
struct snd_info_private_data **ret)
{
struct snd_info_private_data *data;
if (!entry || !entry->p)
return -ENODEV;
if (!try_module_get(entry->module))
return -EFAULT;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data) {
module_put(entry->module);
return -ENOMEM;
}
data->entry = entry;
*ret = data;
return 0;
}
static bool valid_pos(loff_t pos, size_t count)
{
if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
return false;
if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
return false;
return true;
}
/*
* file ops for binary proc files
*/
static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
{
struct snd_info_private_data *data;
struct snd_info_entry *entry;
loff_t ret = -EINVAL, size;
data = file->private_data;
entry = data->entry;
mutex_lock(&entry->access);
if (entry->c.ops->llseek) {
offset = entry->c.ops->llseek(entry,
data->file_private_data,
file, offset, orig);
goto out;
}
size = entry->size;
switch (orig) {
case SEEK_SET:
break;
case SEEK_CUR:
offset += file->f_pos;
break;
case SEEK_END:
if (!size)
goto out;
offset += size;
break;
default:
goto out;
}
if (offset < 0)
goto out;
if (size && offset > size)
offset = size;
file->f_pos = offset;
ret = offset;
out:
mutex_unlock(&entry->access);
return ret;
}
static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
size_t count, loff_t * offset)
{
struct snd_info_private_data *data = file->private_data;
struct snd_info_entry *entry = data->entry;
size_t size;
loff_t pos;
pos = *offset;
if (!valid_pos(pos, count))
return -EIO;
if (pos >= entry->size)
return 0;
size = entry->size - pos;
size = min(count, size);
size = entry->c.ops->read(entry, data->file_private_data,
file, buffer, size, pos);
if ((ssize_t) size > 0)
*offset = pos + size;
return size;
}
static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer,
size_t count, loff_t * offset)
{
struct snd_info_private_data *data = file->private_data;
struct snd_info_entry *entry = data->entry;
ssize_t size = 0;
loff_t pos;
pos = *offset;
if (!valid_pos(pos, count))
return -EIO;
if (count > 0) {
size_t maxsize = entry->size - pos;
count = min(count, maxsize);
size = entry->c.ops->write(entry, data->file_private_data,
file, buffer, count, pos);
}
if (size > 0)
*offset = pos + size;
return size;
}
static unsigned int snd_info_entry_poll(struct file *file, poll_table *wait)
{
struct snd_info_private_data *data = file->private_data;
struct snd_info_entry *entry = data->entry;
unsigned int mask = 0;
if (entry->c.ops->poll)
return entry->c.ops->poll(entry,
data->file_private_data,
file, wait);
if (entry->c.ops->read)
mask |= POLLIN | POLLRDNORM;
if (entry->c.ops->write)
mask |= POLLOUT | POLLWRNORM;
return mask;
}
static long snd_info_entry_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct snd_info_private_data *data = file->private_data;
struct snd_info_entry *entry = data->entry;
if (!entry->c.ops->ioctl)
return -ENOTTY;
return entry->c.ops->ioctl(entry, data->file_private_data,
file, cmd, arg);
}
static int snd_info_entry_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file_inode(file);
struct snd_info_private_data *data;
struct snd_info_entry *entry;
data = file->private_data;
if (data == NULL)
return 0;
entry = data->entry;
if (!entry->c.ops->mmap)
return -ENXIO;
return entry->c.ops->mmap(entry, data->file_private_data,
inode, file, vma);
}
static int snd_info_entry_open(struct inode *inode, struct file *file)
{
struct snd_info_entry *entry = PDE_DATA(inode);
struct snd_info_private_data *data;
int mode, err;
mutex_lock(&info_mutex);
err = alloc_info_private(entry, &data);
if (err < 0)
goto unlock;
mode = file->f_flags & O_ACCMODE;
if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
((mode == O_WRONLY || mode == O_RDWR) && !entry->c.ops->write)) {
err = -ENODEV;
goto error;
}
if (entry->c.ops->open) {
err = entry->c.ops->open(entry, mode, &data->file_private_data);
if (err < 0)
goto error;
}
file->private_data = data;
mutex_unlock(&info_mutex);
return 0;
error:
kfree(data);
module_put(entry->module);
unlock:
mutex_unlock(&info_mutex);
return err;
}
static int snd_info_entry_release(struct inode *inode, struct file *file)
{
struct snd_info_private_data *data = file->private_data;
struct snd_info_entry *entry = data->entry;
if (entry->c.ops->release)
entry->c.ops->release(entry, file->f_flags & O_ACCMODE,
data->file_private_data);
module_put(entry->module);
kfree(data);
return 0;
}
static const struct file_operations snd_info_entry_operations =
{
.owner = THIS_MODULE,
.llseek = snd_info_entry_llseek,
.read = snd_info_entry_read,
.write = snd_info_entry_write,
.poll = snd_info_entry_poll,
.unlocked_ioctl = snd_info_entry_ioctl,
.mmap = snd_info_entry_mmap,
.open = snd_info_entry_open,
.release = snd_info_entry_release,
};
/*
* file ops for text proc files
*/
static ssize_t snd_info_text_entry_write(struct file *file,
const char __user *buffer,
size_t count, loff_t *offset)
{
struct seq_file *m = file->private_data;
struct snd_info_private_data *data = m->private;
struct snd_info_entry *entry = data->entry;
struct snd_info_buffer *buf;
loff_t pos;
size_t next;
int err = 0;
if (!entry->c.text.write)
return -EIO;
pos = *offset;
if (!valid_pos(pos, count))
return -EIO;
next = pos + count;
/* don't handle too large text inputs */
if (next > 16 * 1024)
return -EIO;
mutex_lock(&entry->access);
buf = data->wbuffer;
if (!buf) {
data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
if (!buf) {
err = -ENOMEM;
goto error;
}
}
if (next > buf->len) {
char *nbuf = krealloc(buf->buffer, PAGE_ALIGN(next),
GFP_KERNEL | __GFP_ZERO);
if (!nbuf) {
err = -ENOMEM;
goto error;
}
buf->buffer = nbuf;
buf->len = PAGE_ALIGN(next);
}
if (copy_from_user(buf->buffer + pos, buffer, count)) {
err = -EFAULT;
goto error;
}
buf->size = next;
error:
mutex_unlock(&entry->access);
if (err < 0)
return err;
*offset = next;
return count;
}
static int snd_info_seq_show(struct seq_file *seq, void *p)
{
struct snd_info_private_data *data = seq->private;
struct snd_info_entry *entry = data->entry;
if (!entry->c.text.read) {
return -EIO;
} else {
data->rbuffer->buffer = (char *)seq; /* XXX hack! */
entry->c.text.read(entry, data->rbuffer);
}
return 0;
}
static int snd_info_text_entry_open(struct inode *inode, struct file *file)
{
struct snd_info_entry *entry = PDE_DATA(inode);
struct snd_info_private_data *data;
int err;
mutex_lock(&info_mutex);
err = alloc_info_private(entry, &data);
if (err < 0)
goto unlock;
data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
if (!data->rbuffer) {
err = -ENOMEM;
goto error;
}
if (entry->size)
err = single_open_size(file, snd_info_seq_show, data,
entry->size);
else
err = single_open(file, snd_info_seq_show, data);
if (err < 0)
goto error;
mutex_unlock(&info_mutex);
return 0;
error:
kfree(data->rbuffer);
kfree(data);
module_put(entry->module);
unlock:
mutex_unlock(&info_mutex);
return err;
}
static int snd_info_text_entry_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
struct snd_info_private_data *data = m->private;
struct snd_info_entry *entry = data->entry;
if (data->wbuffer && entry->c.text.write)
entry->c.text.write(entry, data->wbuffer);
single_release(inode, file);
kfree(data->rbuffer);
if (data->wbuffer) {
kfree(data->wbuffer->buffer);
kfree(data->wbuffer);
}
module_put(entry->module);
kfree(data);
return 0;
}
static const struct file_operations snd_info_text_entry_ops =
{
.owner = THIS_MODULE,
.open = snd_info_text_entry_open,
.release = snd_info_text_entry_release,
.write = snd_info_text_entry_write,
.llseek = seq_lseek,
.read = seq_read,
};
static struct snd_info_entry *create_subdir(struct module *mod,
const char *name)
{
struct snd_info_entry *entry;
entry = snd_info_create_module_entry(mod, name, NULL);
if (!entry)
return NULL;
entry->mode = S_IFDIR | S_IRUGO | S_IXUGO;
if (snd_info_register(entry) < 0) {
snd_info_free_entry(entry);
return NULL;
}
return entry;
}
static struct snd_info_entry *
snd_info_create_entry(const char *name, struct snd_info_entry *parent);
int __init snd_info_init(void)
{
snd_proc_root = snd_info_create_entry("asound", NULL);
if (!snd_proc_root)
return -ENOMEM;
snd_proc_root->mode = S_IFDIR | S_IRUGO | S_IXUGO;
snd_proc_root->p = proc_mkdir("asound", NULL);
if (!snd_proc_root->p)
goto error;
#ifdef CONFIG_SND_OSSEMUL
snd_oss_root = create_subdir(THIS_MODULE, "oss");
if (!snd_oss_root)
goto error;
#endif
#if IS_ENABLED(CONFIG_SND_SEQUENCER)
snd_seq_root = create_subdir(THIS_MODULE, "seq");
if (!snd_seq_root)
goto error;
#endif
if (snd_info_version_init() < 0 ||
snd_minor_info_init() < 0 ||
snd_minor_info_oss_init() < 0 ||
snd_card_info_init() < 0 ||
snd_info_minor_register() < 0)
goto error;
return 0;
error:
snd_info_free_entry(snd_proc_root);
return -ENOMEM;
}
int __exit snd_info_done(void)
{
snd_info_free_entry(snd_proc_root);
return 0;
}
/*
* create a card proc file
* called from init.c
*/
int snd_info_card_create(struct snd_card *card)
{
char str[8];
struct snd_info_entry *entry;
if (snd_BUG_ON(!card))
return -ENXIO;
sprintf(str, "card%i", card->number);
entry = create_subdir(card->module, str);
if (!entry)
return -ENOMEM;
card->proc_root = entry;
return 0;
}
/* register all pending info entries */
static int snd_info_register_recursive(struct snd_info_entry *entry)
{
struct snd_info_entry *p;
int err;
if (!entry->p) {
err = snd_info_register(entry);
if (err < 0)
return err;
}
list_for_each_entry(p, &entry->children, list) {
err = snd_info_register_recursive(p);
if (err < 0)
return err;
}
return 0;
}
/*
* register the card proc file
* called from init.c
* can be called multiple times for reinitialization
*/
int snd_info_card_register(struct snd_card *card)
{
struct proc_dir_entry *p;
int err;
if (snd_BUG_ON(!card))
return -ENXIO;
err = snd_info_register_recursive(card->proc_root);
if (err < 0)
return err;
if (!strcmp(card->id, card->proc_root->name))
return 0;
if (card->proc_root_link)
return 0;
p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
if (!p)
return -ENOMEM;
card->proc_root_link = p;
return 0;
}
/*
* called on card->id change
*/
void snd_info_card_id_change(struct snd_card *card)
{
mutex_lock(&info_mutex);
if (card->proc_root_link) {
proc_remove(card->proc_root_link);
card->proc_root_link = NULL;
}
if (strcmp(card->id, card->proc_root->name))
card->proc_root_link = proc_symlink(card->id,
snd_proc_root->p,
card->proc_root->name);
mutex_unlock(&info_mutex);
}
/*
* de-register the card proc file
* called from init.c
*/
void snd_info_card_disconnect(struct snd_card *card)
{
if (!card)
return;
mutex_lock(&info_mutex);
proc_remove(card->proc_root_link);
card->proc_root_link = NULL;
if (card->proc_root)
snd_info_disconnect(card->proc_root);
mutex_unlock(&info_mutex);
}
/*
* release the card proc file resources
* called from init.c
*/
int snd_info_card_free(struct snd_card *card)
{
if (!card)
return 0;
snd_info_free_entry(card->proc_root);
card->proc_root = NULL;
return 0;
}
/**
* snd_info_get_line - read one line from the procfs buffer
* @buffer: the procfs buffer
* @line: the buffer to store
* @len: the max. buffer size
*
* Reads one line from the buffer and stores the string.
*
* Return: Zero if successful, or 1 if error or EOF.
*/
int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
{
int c = -1;
if (snd_BUG_ON(!buffer || !buffer->buffer))
return 1;
if (len <= 0 || buffer->stop || buffer->error)
return 1;
while (!buffer->stop) {
c = buffer->buffer[buffer->curr++];
if (buffer->curr >= buffer->size)
buffer->stop = 1;
if (c == '\n')
break;
if (len > 1) {
len--;
*line++ = c;
}
}
*line = '\0';
return 0;
}
EXPORT_SYMBOL(snd_info_get_line);
/**
* snd_info_get_str - parse a string token
* @dest: the buffer to store the string token
* @src: the original string
* @len: the max. length of token - 1
*
* Parses the original string and copy a token to the given
* string buffer.
*
* Return: The updated pointer of the original string so that
* it can be used for the next call.
*/
const char *snd_info_get_str(char *dest, const char *src, int len)
{
int c;
while (*src == ' ' || *src == '\t')
src++;
if (*src == '"' || *src == '\'') {
c = *src++;
while (--len > 0 && *src && *src != c) {
*dest++ = *src++;
}
if (*src == c)
src++;
} else {
while (--len > 0 && *src && *src != ' ' && *src != '\t') {
*dest++ = *src++;
}
}
*dest = 0;
while (*src == ' ' || *src == '\t')
src++;
return src;
}
EXPORT_SYMBOL(snd_info_get_str);
/*
* snd_info_create_entry - create an info entry
* @name: the proc file name
* @parent: the parent directory
*
* Creates an info entry with the given file name and initializes as
* the default state.
*
* Usually called from other functions such as
* snd_info_create_card_entry().
*
* Return: The pointer of the new instance, or %NULL on failure.
*/
static struct snd_info_entry *
snd_info_create_entry(const char *name, struct snd_info_entry *parent)
{
struct snd_info_entry *entry;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (entry == NULL)
return NULL;
entry->name = kstrdup(name, GFP_KERNEL);
if (entry->name == NULL) {
kfree(entry);
return NULL;
}
entry->mode = S_IFREG | S_IRUGO;
entry->content = SNDRV_INFO_CONTENT_TEXT;
mutex_init(&entry->access);
INIT_LIST_HEAD(&entry->children);
INIT_LIST_HEAD(&entry->list);
entry->parent = parent;
if (parent)
list_add_tail(&entry->list, &parent->children);
return entry;
}
/**
* snd_info_create_module_entry - create an info entry for the given module
* @module: the module pointer
* @name: the file name
* @parent: the parent directory
*
* Creates a new info entry and assigns it to the given module.
*
* Return: The pointer of the new instance, or %NULL on failure.
*/
struct snd_info_entry *snd_info_create_module_entry(struct module * module,
const char *name,
struct snd_info_entry *parent)
{
struct snd_info_entry *entry = snd_info_create_entry(name, parent);
if (entry)
entry->module = module;
return entry;
}
EXPORT_SYMBOL(snd_info_create_module_entry);
/**
* snd_info_create_card_entry - create an info entry for the given card
* @card: the card instance
* @name: the file name
* @parent: the parent directory
*
* Creates a new info entry and assigns it to the given card.
*
* Return: The pointer of the new instance, or %NULL on failure.
*/
struct snd_info_entry *snd_info_create_card_entry(struct snd_card *card,
const char *name,
struct snd_info_entry * parent)
{
struct snd_info_entry *entry = snd_info_create_entry(name, parent);
if (entry) {
entry->module = card->module;
entry->card = card;
}
return entry;
}
EXPORT_SYMBOL(snd_info_create_card_entry);
static void snd_info_disconnect(struct snd_info_entry *entry)
{
struct snd_info_entry *p;
if (!entry->p)
return;
list_for_each_entry(p, &entry->children, list)
snd_info_disconnect(p);
proc_remove(entry->p);
entry->p = NULL;
}
/**
* snd_info_free_entry - release the info entry
* @entry: the info entry
*
* Releases the info entry.
*/
void snd_info_free_entry(struct snd_info_entry * entry)
{
struct snd_info_entry *p, *n;
if (!entry)
return;
if (entry->p) {
mutex_lock(&info_mutex);
snd_info_disconnect(entry);
mutex_unlock(&info_mutex);
}
/* free all children at first */
list_for_each_entry_safe(p, n, &entry->children, list)
snd_info_free_entry(p);
list_del(&entry->list);
kfree(entry->name);
if (entry->private_free)
entry->private_free(entry);
kfree(entry);
}
EXPORT_SYMBOL(snd_info_free_entry);
/**
* snd_info_register - register the info entry
* @entry: the info entry
*
* Registers the proc info entry.
*
* Return: Zero if successful, or a negative error code on failure.
*/
int snd_info_register(struct snd_info_entry * entry)
{
struct proc_dir_entry *root, *p = NULL;
if (snd_BUG_ON(!entry))
return -ENXIO;
root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
mutex_lock(&info_mutex);
if (S_ISDIR(entry->mode)) {
p = proc_mkdir_mode(entry->name, entry->mode, root);
if (!p) {
mutex_unlock(&info_mutex);
return -ENOMEM;
}
} else {
const struct file_operations *ops;
if (entry->content == SNDRV_INFO_CONTENT_DATA)
ops = &snd_info_entry_operations;
else
ops = &snd_info_text_entry_ops;
p = proc_create_data(entry->name, entry->mode, root,
ops, entry);
if (!p) {
mutex_unlock(&info_mutex);
return -ENOMEM;
}
proc_set_size(p, entry->size);
}
entry->p = p;
mutex_unlock(&info_mutex);
return 0;
}
EXPORT_SYMBOL(snd_info_register);
/*
*/
static void snd_info_version_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
snd_iprintf(buffer,
"Advanced Linux Sound Architecture Driver Version k%s.\n",
init_utsname()->release);
}
static int __init snd_info_version_init(void)
{
struct snd_info_entry *entry;
entry = snd_info_create_module_entry(THIS_MODULE, "version", NULL);
if (entry == NULL)
return -ENOMEM;
entry->c.text.read = snd_info_version_read;
return snd_info_register(entry); /* freed in error path */
}