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Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

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Pull overlayfs updates from Miklos Szeredi:
 "This update contains fixes to the "use mounter's permission to access
  underlying layers" area, and miscellaneous other fixes and cleanups.

  No new features this time"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: use vfs_get_link()
  vfs: add vfs_get_link() helper
  ovl: use generic_readlink
  ovl: explain error values when removing acl from workdir
  ovl: Fix info leak in ovl_lookup_temp()
  ovl: during copy up, switch to mounter's creds early
  ovl: lookup: do getxattr with mounter's permission
  ovl: copy_up_xattr(): use strnlen
This commit is contained in:
Linus Torvalds
2016-10-14 17:23:33 -07:00
parent 5d89d9f502 7764235bec
commit 1a892b485f
6 changed files with 82 additions and 93 deletions
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67
fs/overlayfs/copy_up.c
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@@ -57,6 +57,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
ssize_t list_size, size, value_size = 0;
char *buf, *name, *value = NULL;
int uninitialized_var(error);
size_t slen;
if (!(old->d_inode->i_opflags & IOP_XATTR) ||
!(new->d_inode->i_opflags & IOP_XATTR))
@@ -79,7 +80,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
goto out;
}
for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
for (name = buf; list_size; name += slen) {
slen = strnlen(name, list_size) + 1;
/* underlying fs providing us with an broken xattr list? */
if (WARN_ON(slen > list_size)) {
error = -EIO;
break;
}
list_size -= slen;
if (ovl_is_private_xattr(name))
continue;
retry:
@@ -174,40 +184,6 @@ 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 = {
@@ -354,19 +330,20 @@ 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;
const struct cred *old_cred;
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;
@@ -376,13 +353,11 @@ 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);
}
old_cred = ovl_override_creds(dentry->d_sb);
err = -EIO;
if (lock_rename(workdir, upperdir) != NULL) {
pr_err("overlayfs: failed to lock workdir+upperdir\n");
@@ -403,19 +378,16 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
}
out_unlock:
unlock_rename(workdir, upperdir);
revert_creds(old_cred);
if (link)
free_page((unsigned long) link);
do_delayed_call(&done);
return err;
}
int ovl_copy_up(struct dentry *dentry)
{
int err;
int err = 0;
const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
err = 0;
while (!err) {
struct dentry *next;
struct dentry *parent;
@@ -447,6 +419,7 @@ int ovl_copy_up(struct dentry *dentry)
dput(parent);
dput(next);
}
revert_creds(old_cred);
return err;
}