O_TRUNC open shouldn't fail after file truncation
* take truncate logics into a helper (handle_truncate()) * rip it out of may_open() * call it from the only caller of may_open() that might pass O_TRUNC * and do that after we'd finished with opening. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
Родитель
85a17f552d
Коммит
7715b52122
109
fs/namei.c
109
fs/namei.c
|
|
@ -1444,69 +1444,52 @@ int may_open(struct path *path, int acc_mode, int flag)
|
|||
if (error)
|
||||
return error;
|
||||
|
||||
error = ima_path_check(path, acc_mode ?
|
||||
acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
|
||||
ACC_MODE(flag) & (MAY_READ | MAY_WRITE),
|
||||
IMA_COUNT_UPDATE);
|
||||
|
||||
if (error)
|
||||
return error;
|
||||
/*
|
||||
* An append-only file must be opened in append mode for writing.
|
||||
*/
|
||||
if (IS_APPEND(inode)) {
|
||||
error = -EPERM;
|
||||
if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
|
||||
goto err_out;
|
||||
return -EPERM;
|
||||
if (flag & O_TRUNC)
|
||||
goto err_out;
|
||||
return -EPERM;
|
||||
}
|
||||
|
||||
/* O_NOATIME can only be set by the owner or superuser */
|
||||
if (flag & O_NOATIME)
|
||||
if (!is_owner_or_cap(inode)) {
|
||||
error = -EPERM;
|
||||
goto err_out;
|
||||
}
|
||||
if (flag & O_NOATIME && !is_owner_or_cap(inode))
|
||||
return -EPERM;
|
||||
|
||||
/*
|
||||
* Ensure there are no outstanding leases on the file.
|
||||
*/
|
||||
error = break_lease(inode, flag);
|
||||
if (error)
|
||||
goto err_out;
|
||||
return error;
|
||||
|
||||
if (flag & O_TRUNC) {
|
||||
error = get_write_access(inode);
|
||||
if (error)
|
||||
goto err_out;
|
||||
return ima_path_check(path, acc_mode ?
|
||||
acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
|
||||
ACC_MODE(flag) & (MAY_READ | MAY_WRITE),
|
||||
IMA_COUNT_UPDATE);
|
||||
}
|
||||
|
||||
/*
|
||||
* Refuse to truncate files with mandatory locks held on them.
|
||||
*/
|
||||
error = locks_verify_locked(inode);
|
||||
if (!error)
|
||||
error = security_path_truncate(path, 0,
|
||||
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
|
||||
if (!error) {
|
||||
vfs_dq_init(inode);
|
||||
|
||||
error = do_truncate(dentry, 0,
|
||||
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
|
||||
NULL);
|
||||
}
|
||||
put_write_access(inode);
|
||||
if (error)
|
||||
goto err_out;
|
||||
} else
|
||||
if (flag & FMODE_WRITE)
|
||||
vfs_dq_init(inode);
|
||||
|
||||
return 0;
|
||||
err_out:
|
||||
ima_counts_put(path, acc_mode ?
|
||||
acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
|
||||
ACC_MODE(flag) & (MAY_READ | MAY_WRITE));
|
||||
static int handle_truncate(struct path *path)
|
||||
{
|
||||
struct inode *inode = path->dentry->d_inode;
|
||||
int error = get_write_access(inode);
|
||||
if (error)
|
||||
return error;
|
||||
/*
|
||||
* Refuse to truncate files with mandatory locks held on them.
|
||||
*/
|
||||
error = locks_verify_locked(inode);
|
||||
if (!error)
|
||||
error = security_path_truncate(path, 0,
|
||||
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
|
||||
if (!error) {
|
||||
error = do_truncate(path->dentry, 0,
|
||||
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
|
||||
NULL);
|
||||
}
|
||||
put_write_access(inode);
|
||||
return error;
|
||||
}
|
||||
|
||||
|
|
@ -1561,7 +1544,7 @@ static inline int open_to_namei_flags(int flag)
|
|||
return flag;
|
||||
}
|
||||
|
||||
static int open_will_write_to_fs(int flag, struct inode *inode)
|
||||
static int open_will_truncate(int flag, struct inode *inode)
|
||||
{
|
||||
/*
|
||||
* We'll never write to the fs underlying
|
||||
|
|
@ -1586,7 +1569,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
|
|||
struct path path, save;
|
||||
struct dentry *dir;
|
||||
int count = 0;
|
||||
int will_write;
|
||||
int will_truncate;
|
||||
int flag = open_to_namei_flags(open_flag);
|
||||
|
||||
/*
|
||||
|
|
@ -1752,28 +1735,48 @@ ok:
|
|||
* be avoided. Taking this mnt write here
|
||||
* ensures that (2) can not occur.
|
||||
*/
|
||||
will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode);
|
||||
if (will_write) {
|
||||
will_truncate = open_will_truncate(flag, nd.path.dentry->d_inode);
|
||||
if (will_truncate) {
|
||||
error = mnt_want_write(nd.path.mnt);
|
||||
if (error)
|
||||
goto exit;
|
||||
}
|
||||
error = may_open(&nd.path, acc_mode, flag);
|
||||
if (error) {
|
||||
if (will_write)
|
||||
if (will_truncate)
|
||||
mnt_drop_write(nd.path.mnt);
|
||||
goto exit;
|
||||
}
|
||||
filp = nameidata_to_filp(&nd, open_flag);
|
||||
if (IS_ERR(filp))
|
||||
if (IS_ERR(filp)) {
|
||||
ima_counts_put(&nd.path,
|
||||
acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC));
|
||||
if (will_truncate)
|
||||
mnt_drop_write(nd.path.mnt);
|
||||
if (nd.root.mnt)
|
||||
path_put(&nd.root);
|
||||
return filp;
|
||||
}
|
||||
|
||||
if (acc_mode & MAY_WRITE)
|
||||
vfs_dq_init(nd.path.dentry->d_inode);
|
||||
|
||||
if (will_truncate) {
|
||||
error = handle_truncate(&nd.path);
|
||||
if (error) {
|
||||
mnt_drop_write(nd.path.mnt);
|
||||
fput(filp);
|
||||
if (nd.root.mnt)
|
||||
path_put(&nd.root);
|
||||
return ERR_PTR(error);
|
||||
}
|
||||
}
|
||||
/*
|
||||
* It is now safe to drop the mnt write
|
||||
* because the filp has had a write taken
|
||||
* on its behalf.
|
||||
*/
|
||||
if (will_write)
|
||||
if (will_truncate)
|
||||
mnt_drop_write(nd.path.mnt);
|
||||
if (nd.root.mnt)
|
||||
path_put(&nd.root);
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче