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ovl: use vfs_get_link()

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Resulting in a complete removal of a function basically implementing the
inverse of vfs_readlink().

As a bonus, now the proper security hook is also called.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2016-10-04 14:40:45 +02:00
parent d60874cd58
commit 7764235bec
2 changed files with 7 additions and 49 deletions
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46
fs/overlayfs/copy_up.c
View File

@ -177,40 +177,6 @@ out_fput:
return error;
}
static char *ovl_read_symlink(struct dentry *realdentry)
{
int res;
char *buf;
struct inode *inode = realdentry->d_inode;
mm_segment_t old_fs;
res = -EINVAL;
if (!inode->i_op->readlink)
goto err;
res = -ENOMEM;
buf = (char *) __get_free_page(GFP_KERNEL);
if (!buf)
goto err;
old_fs = get_fs();
set_fs(get_ds());
/* The cast to a user pointer is valid due to the set_fs() */
res = inode->i_op->readlink(realdentry,
(char __user *)buf, PAGE_SIZE - 1);
set_fs(old_fs);
if (res < 0) {
free_page((unsigned long) buf);
goto err;
}
buf[res] = '\0';
return buf;
err:
return ERR_PTR(res);
}
static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
{
struct iattr attr = {
@ -342,18 +308,20 @@ out_cleanup:
int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
struct path *lowerpath, struct kstat *stat)
{
DEFINE_DELAYED_CALL(done);
struct dentry *workdir = ovl_workdir(dentry);
int err;
struct kstat pstat;
struct path parentpath;
struct dentry *lowerdentry = lowerpath->dentry;
struct dentry *upperdir;
struct dentry *upperdentry;
char *link = NULL;
const char *link = NULL;
if (WARN_ON(!workdir))
return -EROFS;
ovl_do_check_copy_up(lowerpath->dentry);
ovl_do_check_copy_up(lowerdentry);
ovl_path_upper(parent, &parentpath);
upperdir = parentpath.dentry;
@ -363,7 +331,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
return err;
if (S_ISLNK(stat->mode)) {
link = ovl_read_symlink(lowerpath->dentry);
link = vfs_get_link(lowerdentry, &done);
if (IS_ERR(link))
return PTR_ERR(link);
}
@ -388,9 +356,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
}
out_unlock:
unlock_rename(workdir, upperdir);
if (link)
free_page((unsigned long) link);
do_delayed_call(&done);
return err;
}

10
fs/overlayfs/inode.c
View File

@ -156,22 +156,14 @@ static const char *ovl_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
struct dentry *realdentry;
struct inode *realinode;
const struct cred *old_cred;
const char *p;
if (!dentry)
return ERR_PTR(-ECHILD);
realdentry = ovl_dentry_real(dentry);
realinode = realdentry->d_inode;
if (WARN_ON(!realinode->i_op->get_link))
return ERR_PTR(-EPERM);
old_cred = ovl_override_creds(dentry->d_sb);
p = realinode->i_op->get_link(realdentry, realinode, done);
p = vfs_get_link(ovl_dentry_real(dentry), done);
revert_creds(old_cred);
return p;
}