Commit 1d88f183 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: fix xattr get and set with selinux 



inode_doinit_with_dentry() in SELinux wants to read the upper inode's xattr
to get security label, and ovl_xattr_get() calls ovl_dentry_real(), which
depends on dentry->d_inode, but d_inode is null and not initialized yet at
this point resulting in an Oops.

Fix by getting the upperdentry info from the inode directly in this case.

Reported-by: default avatarEryu Guan <eguan@redhat.com>
Fixes: 09d8b586 ("ovl: move __upperdentry to ovl_inode")
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent a59f97ff

fs/overlayfs/inode.c

+17 −15
Original line number Diff line number Diff line
@@ -202,37 +202,38 @@ bool ovl_is_private_xattr(const char *name) 
		       sizeof(OVL_XATTR_PREFIX) - 1) == 0;

}



int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,

		  size_t size, int flags)

int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,

		  const void *value, size_t size, int flags)

{

	int err;

	struct path realpath;

	enum ovl_path_type type = ovl_path_real(dentry, &realpath);

	struct dentry *upperdentry = ovl_i_dentry_upper(inode);

	struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);

	const struct cred *old_cred;



	err = ovl_want_write(dentry);

	if (err)

		goto out;



	if (!value && !OVL_TYPE_UPPER(type)) {

		err = vfs_getxattr(realpath.dentry, name, NULL, 0);

	if (!value && !upperdentry) {

		err = vfs_getxattr(realdentry, name, NULL, 0);

		if (err < 0)

			goto out_drop_write;

	}



	if (!upperdentry) {

		err = ovl_copy_up(dentry);

		if (err)

			goto out_drop_write;



	if (!OVL_TYPE_UPPER(type))

		ovl_path_upper(dentry, &realpath);

		realdentry = ovl_dentry_upper(dentry);

	}



	old_cred = ovl_override_creds(dentry->d_sb);

	if (value)

		err = vfs_setxattr(realpath.dentry, name, value, size, flags);

		err = vfs_setxattr(realdentry, name, value, size, flags);

	else {

		WARN_ON(flags != XATTR_REPLACE);

		err = vfs_removexattr(realpath.dentry, name);

		err = vfs_removexattr(realdentry, name);

	}

	revert_creds(old_cred);
@@ -242,12 +243,13 @@ out: 
	return err;

}



int ovl_xattr_get(struct dentry *dentry, const char *name,

int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,

		  void *value, size_t size)

{

	struct dentry *realdentry = ovl_dentry_real(dentry);

	ssize_t res;

	const struct cred *old_cred;

	struct dentry *realdentry =

		ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);



	old_cred = ovl_override_creds(dentry->d_sb);

	res = vfs_getxattr(realdentry, name, value, size);

fs/overlayfs/overlayfs.h

+4 −3
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); 
struct dentry *ovl_dentry_upper(struct dentry *dentry);

struct dentry *ovl_dentry_lower(struct dentry *dentry);

struct dentry *ovl_dentry_real(struct dentry *dentry);

struct dentry *ovl_i_dentry_upper(struct inode *inode);

struct inode *ovl_inode_upper(struct inode *inode);

struct inode *ovl_inode_lower(struct inode *inode);

struct inode *ovl_inode_real(struct inode *inode);
@@ -271,9 +272,9 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr); 
int ovl_getattr(const struct path *path, struct kstat *stat,

		u32 request_mask, unsigned int flags);

int ovl_permission(struct inode *inode, int mask);

int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,

		  size_t size, int flags);

int ovl_xattr_get(struct dentry *dentry, const char *name,

int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,

		  const void *value, size_t size, int flags);

int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,

		  void *value, size_t size);

ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);

struct posix_acl *ovl_get_acl(struct inode *inode, int type);

fs/overlayfs/super.c

+4 −4
Original line number Diff line number Diff line
@@ -692,7 +692,7 @@ ovl_posix_acl_xattr_get(const struct xattr_handler *handler, 
			struct dentry *dentry, struct inode *inode,

			const char *name, void *buffer, size_t size)

{

	return ovl_xattr_get(dentry, handler->name, buffer, size);

	return ovl_xattr_get(dentry, inode, handler->name, buffer, size);

}



static int __maybe_unused
@@ -742,7 +742,7 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler, 
			return err;

	}



	err = ovl_xattr_set(dentry, handler->name, value, size, flags);

	err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);

	if (!err)

		ovl_copyattr(ovl_inode_real(inode), inode);
@@ -772,7 +772,7 @@ static int ovl_other_xattr_get(const struct xattr_handler *handler, 
			       struct dentry *dentry, struct inode *inode,

			       const char *name, void *buffer, size_t size)

{

	return ovl_xattr_get(dentry, name, buffer, size);

	return ovl_xattr_get(dentry, inode, name, buffer, size);

}



static int ovl_other_xattr_set(const struct xattr_handler *handler,
@@ -780,7 +780,7 @@ static int ovl_other_xattr_set(const struct xattr_handler *handler, 
			       const char *name, const void *value,

			       size_t size, int flags)

{

	return ovl_xattr_set(dentry, name, value, size, flags);

	return ovl_xattr_set(dentry, inode, name, value, size, flags);

}



static const struct xattr_handler __maybe_unused

fs/overlayfs/util.c

+6 −1
Original line number Diff line number Diff line
@@ -157,9 +157,14 @@ struct dentry *ovl_dentry_real(struct dentry *dentry) 
	return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);

}



struct dentry *ovl_i_dentry_upper(struct inode *inode)

{

	return ovl_upperdentry_dereference(OVL_I(inode));

}



struct inode *ovl_inode_upper(struct inode *inode)

{

	struct dentry *upperdentry = ovl_upperdentry_dereference(OVL_I(inode));

	struct dentry *upperdentry = ovl_i_dentry_upper(inode);



	return upperdentry ? d_inode(upperdentry) : NULL;

}

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