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

Pull overlayfs update from Miklos Szeredi:
 "First of all, this fixes a regression in overlayfs introduced by the
  dentry hash salting.  I've moved the patch fixing this to the front of
  the queue, so if (god forbid) something needs to be bisected in
  overlayfs this regression won't interfere with that.

  The biggest part is preparation for selinux support, done by Vivek
  Goyal.  Essentially this makes all operations on underlying
  filesystems be done with credentials of mounter.  This makes
  everything nicely consistent.

  There are also fixes for a number of known and recently discovered
  non-standard behavior (thanks to Eryu Guan for testing and improving
  the test suites)"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (23 commits)
  ovl: simplify empty checking
  qstr: constify instances in overlayfs
  ovl: clear nlink on rmdir
  ovl: disallow overlayfs as upperdir
  ovl: fix warning
  ovl: remove duplicated include from super.c
  ovl: append MAY_READ when diluting write checks
  ovl: dilute permission checks on lower only if not special file
  ovl: fix POSIX ACL setting
  ovl: share inode for hard link
  ovl: store real inode pointer in ->i_private
  ovl: permission: return ECHILD instead of ENOENT
  ovl: update atime on upper
  ovl: fix sgid on directory
  ovl: simplify permission checking
  ovl: do not require mounter to have MAY_WRITE on lower
  ovl: do operations on underlying file system in mounter's context
  ovl: modify ovl_permission() to do checks on two inodes
  ovl: define ->get_acl() for overlay inodes
  ovl: move some common code in a function
  ...
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@torvalds
torvalds committed Jul 29, 2016
2 parents 0a7736d + 30c17eb commit e7b4f2d
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Showing 5 changed files with 445 additions and 236 deletions.
1 change: 1 addition & 0 deletions fs/overlayfs/copy_up.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -292,6 +292,7 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
goto out_cleanup;

ovl_dentry_update(dentry, newdentry);
ovl_inode_update(d_inode(dentry), d_inode(newdentry));
newdentry = NULL;

/*
Expand Down
226 changes: 132 additions & 94 deletions fs/overlayfs/dir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -138,9 +138,12 @@ static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
int err;
enum ovl_path_type type;
struct path realpath;
const struct cred *old_cred;

type = ovl_path_real(dentry, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
err = vfs_getattr(&realpath, stat);
revert_creds(old_cred);
if (err)
return err;

Expand All @@ -158,6 +161,22 @@ static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
return 0;
}

/* Common operations required to be done after creation of file on upper */
static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
struct dentry *newdentry, bool hardlink)
{
ovl_dentry_version_inc(dentry->d_parent);
ovl_dentry_update(dentry, newdentry);
if (!hardlink) {
ovl_inode_update(inode, d_inode(newdentry));
ovl_copyattr(newdentry->d_inode, inode);
} else {
WARN_ON(ovl_inode_real(inode, NULL) != d_inode(newdentry));
inc_nlink(inode);
}
d_instantiate(dentry, inode);
}

static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
struct kstat *stat, const char *link,
struct dentry *hardlink)
Expand All @@ -177,10 +196,7 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
if (err)
goto out_dput;

ovl_dentry_version_inc(dentry->d_parent);
ovl_dentry_update(dentry, newdentry);
ovl_copyattr(newdentry->d_inode, inode);
d_instantiate(dentry, inode);
ovl_instantiate(dentry, inode, newdentry, !!hardlink);
newdentry = NULL;
out_dput:
dput(newdentry);
Expand Down Expand Up @@ -291,23 +307,29 @@ static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
{
int err;
struct dentry *ret = NULL;
enum ovl_path_type type = ovl_path_type(dentry);
LIST_HEAD(list);

err = ovl_check_empty_dir(dentry, &list);
if (err)
if (err) {
ret = ERR_PTR(err);
else {
/*
* If no upperdentry then skip clearing whiteouts.
*
* Can race with copy-up, since we don't hold the upperdir
* mutex. Doesn't matter, since copy-up can't create a
* non-empty directory from an empty one.
*/
if (ovl_dentry_upper(dentry))
ret = ovl_clear_empty(dentry, &list);
goto out_free;
}

/*
* When removing an empty opaque directory, then it makes no sense to
* replace it with an exact replica of itself.
*
* If no upperdentry then skip clearing whiteouts.
*
* Can race with copy-up, since we don't hold the upperdir mutex.
* Doesn't matter, since copy-up can't create a non-empty directory
* from an empty one.
*/
if (OVL_TYPE_UPPER(type) && OVL_TYPE_MERGE(type))
ret = ovl_clear_empty(dentry, &list);

out_free:
ovl_cache_free(&list);

return ret;
Expand Down Expand Up @@ -347,7 +369,23 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
if (err)
goto out_dput2;

if (S_ISDIR(stat->mode)) {
/*
* mode could have been mutilated due to umask (e.g. sgid directory)
*/
if (!hardlink &&
!S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
struct iattr attr = {
.ia_valid = ATTR_MODE,
.ia_mode = stat->mode,
};
inode_lock(newdentry->d_inode);
err = notify_change(newdentry, &attr, NULL);
inode_unlock(newdentry->d_inode);
if (err)
goto out_cleanup;
}

if (!hardlink && S_ISDIR(stat->mode)) {
err = ovl_set_opaque(newdentry);
if (err)
goto out_cleanup;
Expand All @@ -363,10 +401,7 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
if (err)
goto out_cleanup;
}
ovl_dentry_version_inc(dentry->d_parent);
ovl_dentry_update(dentry, newdentry);
ovl_copyattr(newdentry->d_inode, inode);
d_instantiate(dentry, inode);
ovl_instantiate(dentry, inode, newdentry, !!hardlink);
newdentry = NULL;
out_dput2:
dput(upper);
Expand All @@ -382,66 +417,73 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
goto out_dput2;
}

static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
const char *link, struct dentry *hardlink)
static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
struct kstat *stat, const char *link,
struct dentry *hardlink)
{
int err;
struct inode *inode;
struct kstat stat = {
.mode = mode,
.rdev = rdev,
};

err = -ENOMEM;
inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
if (!inode)
goto out;
const struct cred *old_cred;
struct cred *override_cred;

err = ovl_copy_up(dentry->d_parent);
if (err)
goto out_iput;

if (!ovl_dentry_is_opaque(dentry)) {
err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
} else {
const struct cred *old_cred;
struct cred *override_cred;

old_cred = ovl_override_creds(dentry->d_sb);

err = -ENOMEM;
override_cred = prepare_creds();
if (override_cred) {
override_cred->fsuid = old_cred->fsuid;
override_cred->fsgid = old_cred->fsgid;
put_cred(override_creds(override_cred));
put_cred(override_cred);
return err;

err = ovl_create_over_whiteout(dentry, inode, &stat,
link, hardlink);
}
revert_creds(old_cred);
old_cred = ovl_override_creds(dentry->d_sb);
err = -ENOMEM;
override_cred = prepare_creds();
if (override_cred) {
override_cred->fsuid = inode->i_uid;
override_cred->fsgid = inode->i_gid;
put_cred(override_creds(override_cred));
put_cred(override_cred);

if (!ovl_dentry_is_opaque(dentry))
err = ovl_create_upper(dentry, inode, stat, link,
hardlink);
else
err = ovl_create_over_whiteout(dentry, inode, stat,
link, hardlink);
}
revert_creds(old_cred);
if (!err) {
struct inode *realinode = d_inode(ovl_dentry_upper(dentry));

if (!err)
inode = NULL;
out_iput:
iput(inode);
out:
WARN_ON(inode->i_mode != realinode->i_mode);
WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
}
return err;
}

static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
const char *link)
{
int err;
struct inode *inode;
struct kstat stat = {
.rdev = rdev,
};

err = ovl_want_write(dentry);
if (!err) {
err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
ovl_drop_write(dentry);
}
if (err)
goto out;

err = -ENOMEM;
inode = ovl_new_inode(dentry->d_sb, mode);
if (!inode)
goto out_drop_write;

inode_init_owner(inode, dentry->d_parent->d_inode, mode);
stat.mode = inode->i_mode;

err = ovl_create_or_link(dentry, inode, &stat, link, NULL);
if (err)
iput(inode);

out_drop_write:
ovl_drop_write(dentry);
out:
return err;
}

Expand Down Expand Up @@ -476,7 +518,7 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
struct dentry *new)
{
int err;
struct dentry *upper;
struct inode *inode;

err = ovl_want_write(old);
if (err)
Expand All @@ -486,8 +528,12 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
if (err)
goto out_drop_write;

upper = ovl_dentry_upper(old);
err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
inode = d_inode(old);
ihold(inode);

err = ovl_create_or_link(new, inode, NULL, NULL, ovl_dentry_upper(old));
if (err)
iput(inode);

out_drop_write:
ovl_drop_write(old);
Expand All @@ -511,24 +557,10 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
return -EROFS;

if (is_dir) {
if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
opaquedir = ovl_check_empty_and_clear(dentry);
err = PTR_ERR(opaquedir);
if (IS_ERR(opaquedir))
goto out;
} else {
LIST_HEAD(list);

/*
* When removing an empty opaque directory, then it
* makes no sense to replace it with an exact replica of
* itself. But emptiness still needs to be checked.
*/
err = ovl_check_empty_dir(dentry, &list);
ovl_cache_free(&list);
if (err)
goto out;
}
opaquedir = ovl_check_empty_and_clear(dentry);
err = PTR_ERR(opaquedir);
if (IS_ERR(opaquedir))
goto out;
}

err = ovl_lock_rename_workdir(workdir, upperdir);
Expand Down Expand Up @@ -633,6 +665,8 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
{
enum ovl_path_type type;
int err;
const struct cred *old_cred;


err = ovl_check_sticky(dentry);
if (err)
Expand All @@ -647,14 +681,18 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
goto out_drop_write;

type = ovl_path_type(dentry);
if (OVL_TYPE_PURE_UPPER(type)) {
err = ovl_remove_upper(dentry, is_dir);
} else {
const struct cred *old_cred = ovl_override_creds(dentry->d_sb);

old_cred = ovl_override_creds(dentry->d_sb);
if (OVL_TYPE_PURE_UPPER(type))
err = ovl_remove_upper(dentry, is_dir);
else
err = ovl_remove_and_whiteout(dentry, is_dir);

revert_creds(old_cred);
revert_creds(old_cred);
if (!err) {
if (is_dir)
clear_nlink(dentry->d_inode);
else
drop_nlink(dentry->d_inode);
}
out_drop_write:
ovl_drop_write(dentry);
Expand Down Expand Up @@ -760,8 +798,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
new_opaque = !OVL_TYPE_PURE_UPPER(new_type);

if (old_opaque || new_opaque)
old_cred = ovl_override_creds(old->d_sb);
old_cred = ovl_override_creds(old->d_sb);

if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
opaquedir = ovl_check_empty_and_clear(new);
Expand Down Expand Up @@ -891,8 +928,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
out_unlock:
unlock_rename(new_upperdir, old_upperdir);
out_revert_creds:
if (old_opaque || new_opaque)
revert_creds(old_cred);
revert_creds(old_cred);
out_drop_write:
ovl_drop_write(old);
out:
Expand All @@ -913,8 +949,10 @@ const struct inode_operations ovl_dir_inode_operations = {
.mknod = ovl_mknod,
.permission = ovl_permission,
.getattr = ovl_dir_getattr,
.setxattr = ovl_setxattr,
.setxattr = generic_setxattr,
.getxattr = ovl_getxattr,
.listxattr = ovl_listxattr,
.removexattr = ovl_removexattr,
.get_acl = ovl_get_acl,
.update_time = ovl_update_time,
};
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