[PATCH v3 4/8] debugfs: convert to debugfs_file_get() and -put()

Nicolai Stange
2017-10-30T23:15:50Z

Convert all calls to the now obsolete debugfs_use_file_start() and
debugfs_use_file_finish() from the debugfs core itself to the new
debugfs_file_get() and debugfs_file_put() API.

Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private
data")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
---
fs/debugfs/file.c | 106 ++++++++++++++++++++++++++----------------------------
1 file changed, 50 insertions(+), 56 deletions(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 08511678b782..d3a972b45ff0 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -155,15 +155,12 @@ EXPORT_SYMBOL_GPL(debugfs_file_put);

static int open_proxy_open(struct inode *inode, struct file *filp)
{
- const struct dentry *dentry = F_DENTRY(filp);
+ struct dentry *dentry = F_DENTRY(filp);
const struct file_operations *real_fops = NULL;
- int srcu_idx, r;
+ int r = 0;

- r = debugfs_use_file_start(dentry, &srcu_idx);
- if (r) {
- r = -ENOENT;
- goto out;
- }
+ if (debugfs_file_get(dentry))
+ return -ENOENT;

real_fops = debugfs_real_fops(filp);
real_fops = fops_get(real_fops);
@@ -180,7 +177,7 @@ static int open_proxy_open(struct inode *inode, struct file *filp)
r = real_fops->open(inode, filp);

out:
- debugfs_use_file_finish(srcu_idx);
+ debugfs_file_put(dentry);
return r;
}

@@ -194,16 +191,16 @@ const struct file_operations debugfs_open_proxy_file_operations = {
#define FULL_PROXY_FUNC(name, ret_type, filp, proto, args) \
static ret_type full_proxy_ ## name(proto) \
{ \
- const struct dentry *dentry = F_DENTRY(filp); \
+ struct dentry *dentry = F_DENTRY(filp); \
const struct file_operations *real_fops = \
debugfs_real_fops(filp); \
- int srcu_idx; \
ret_type r; \
\
- r = debugfs_use_file_start(dentry, &srcu_idx); \
- if (likely(!r)) \
- r = real_fops->name(args); \
- debugfs_use_file_finish(srcu_idx); \
+ r = debugfs_file_get(dentry); \
+ if (unlikely(r)) \
+ return r; \
+ r = real_fops->name(args); \
+ debugfs_file_put(dentry); \
return r; \
}

@@ -228,18 +225,15 @@ FULL_PROXY_FUNC(unlocked_ioctl, long, filp,
static unsigned int full_proxy_poll(struct file *filp,
struct poll_table_struct *wait)
{
- const struct dentry *dentry = F_DENTRY(filp);
const struct file_operations *real_fops = debugfs_real_fops(filp);
- int srcu_idx;
+ struct dentry *dentry = F_DENTRY(filp);
unsigned int r = 0;

- if (debugfs_use_file_start(dentry, &srcu_idx)) {
- debugfs_use_file_finish(srcu_idx);
+ if (debugfs_file_get(dentry))
return POLLHUP;
- }

r = real_fops->poll(filp, wait);
- debugfs_use_file_finish(srcu_idx);
+ debugfs_file_put(dentry);
return r;
}

@@ -283,16 +277,13 @@ static void __full_proxy_fops_init(struct file_operations *proxy_fops,

static int full_proxy_open(struct inode *inode, struct file *filp)
{
- const struct dentry *dentry = F_DENTRY(filp);
+ struct dentry *dentry = F_DENTRY(filp);
const struct file_operations *real_fops = NULL;
struct file_operations *proxy_fops = NULL;
- int srcu_idx, r;
+ int r = 0;

- r = debugfs_use_file_start(dentry, &srcu_idx);
- if (r) {
- r = -ENOENT;
- goto out;
- }
+ if (debugfs_file_get(dentry))
+ return -ENOENT;

real_fops = debugfs_real_fops(filp);
real_fops = fops_get(real_fops);
@@ -330,7 +321,7 @@ static int full_proxy_open(struct inode *inode, struct file *filp)
kfree(proxy_fops);
fops_put(real_fops);
out:
- debugfs_use_file_finish(srcu_idx);
+ debugfs_file_put(dentry);
return r;
}

@@ -341,13 +332,14 @@ const struct file_operations debugfs_full_proxy_file_operations = {
ssize_t debugfs_attr_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
+ struct dentry *dentry = F_DENTRY(file);
ssize_t ret;
- int srcu_idx;

- ret = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!ret))
- ret = simple_attr_read(file, buf, len, ppos);
- debugfs_use_file_finish(srcu_idx);
+ ret = debugfs_file_get(dentry);
+ if (unlikely(ret))
+ return ret;
+ ret = simple_attr_read(file, buf, len, ppos);
+ debugfs_file_put(dentry);
return ret;
}
EXPORT_SYMBOL_GPL(debugfs_attr_read);
@@ -355,13 +347,14 @@ EXPORT_SYMBOL_GPL(debugfs_attr_read);
ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
+ struct dentry *dentry = F_DENTRY(file);
ssize_t ret;
- int srcu_idx;

- ret = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!ret))
- ret = simple_attr_write(file, buf, len, ppos);
- debugfs_use_file_finish(srcu_idx);
+ ret = debugfs_file_get(dentry);
+ if (unlikely(ret))
+ return ret;
+ ret = simple_attr_write(file, buf, len, ppos);
+ debugfs_file_put(dentry);
return ret;
}
EXPORT_SYMBOL_GPL(debugfs_attr_write);
@@ -795,14 +788,14 @@ ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf,
{
char buf[3];
bool val;
- int r, srcu_idx;
+ int r;
+ struct dentry *dentry = F_DENTRY(file);

- r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!r))
- val = *(bool *)file->private_data;
- debugfs_use_file_finish(srcu_idx);
- if (r)
+ r = debugfs_file_get(dentry);
+ if (unlikely(r))
return r;
+ val = *(bool *)file->private_data;
+ debugfs_file_put(dentry);

if (val)
buf[0] = 'Y';
@@ -820,8 +813,9 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,
char buf[32];
size_t buf_size;
bool bv;
- int r, srcu_idx;
+ int r;
bool *val = file->private_data;
+ struct dentry *dentry = F_DENTRY(file);

buf_size = min(count, (sizeof(buf)-1));
if (copy_from_user(buf, user_buf, buf_size))
@@ -829,12 +823,11 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,

buf[buf_size] = '\0';
if (strtobool(buf, &bv) == 0) {
- r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!r))
- *val = bv;
- debugfs_use_file_finish(srcu_idx);
- if (r)
+ r = debugfs_file_get(dentry);
+ if (unlikely(r))
return r;
+ *val = bv;
+ debugfs_file_put(dentry);
}

return count;
@@ -896,14 +889,15 @@ static ssize_t read_file_blob(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
struct debugfs_blob_wrapper *blob = file->private_data;
+ struct dentry *dentry = F_DENTRY(file);
ssize_t r;
- int srcu_idx;

- r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!r))
- r = simple_read_from_buffer(user_buf, count, ppos, blob->data,
- blob->size);
- debugfs_use_file_finish(srcu_idx);
+ r = debugfs_file_get(dentry);
+ if (unlikely(r))
+ return r;
+ r = simple_read_from_buffer(user_buf, count, ppos, blob->data,
+ blob->size);
+ debugfs_file_put(dentry);
return r;
}

--
2.13.6