Commit 514d793e authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

smb: client: allow creating symlinks via reparse points 



Add support for creating symlinks via IO_REPARSE_TAG_SYMLINK reparse
points in SMB2+.

These are fully supported by most SMB servers and documented in
MS-FSCC.  Also have the advantage of requiring fewer roundtrips as
their symlink targets can be parsed directly from CREATE responses on
STATUS_STOPPED_ON_SYMLINK errors.

Reported-by: default avatarkernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311260838.nx5mkj1j-lkp@intel.com/


Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 5408990a

fs/smb/client/cifsglob.h

+6 −0
Original line number Diff line number Diff line
@@ -574,6 +574,12 @@ struct smb_version_operations { 
	int (*parse_reparse_point)(struct cifs_sb_info *cifs_sb,

				   struct kvec *rsp_iov,

				   struct cifs_open_info_data *data);

	int (*create_reparse_symlink)(const unsigned int xid,

				      struct inode *inode,

				      struct dentry *dentry,

				      struct cifs_tcon *tcon,

				      const char *full_path,

				      const char *symname);

};



struct smb_version_values {

fs/smb/client/link.c

+10 −5
Original line number Diff line number Diff line
@@ -569,6 +569,7 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode, 
	int rc = -EOPNOTSUPP;

	unsigned int xid;

	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);

	struct TCP_Server_Info *server;

	struct tcon_link *tlink;

	struct cifs_tcon *pTcon;

	const char *full_path;
@@ -590,6 +591,7 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode, 
		goto symlink_exit;

	}

	pTcon = tlink_tcon(tlink);

	server = cifs_pick_channel(pTcon->ses);



	full_path = build_path_from_dentry(direntry, page);

	if (IS_ERR(full_path)) {
@@ -601,17 +603,20 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode, 
	cifs_dbg(FYI, "symname is %s\n", symname);



	/* BB what if DFS and this volume is on different share? BB */

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) {

		rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY

	else if (pTcon->unix_ext)

	} else if (pTcon->unix_ext) {

		rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,

					   cifs_sb->local_nls,

					   cifs_remap(cifs_sb));

#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */

	/* else

	   rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,

					cifs_sb_target->local_nls); */

	} else if (server->ops->create_reparse_symlink) {

		rc =  server->ops->create_reparse_symlink(xid, inode, direntry,

							  pTcon, full_path,

							  symname);

		goto symlink_exit;

	}



	if (rc == 0) {

		if (pTcon->posix_extensions) {

fs/smb/client/smb2ops.c

+70 −0
Original line number Diff line number Diff line
@@ -5247,6 +5247,72 @@ static int nfs_make_node(unsigned int xid, struct inode *inode, 
	return rc;

}



static int smb2_create_reparse_symlink(const unsigned int xid,

				       struct inode *inode,

				       struct dentry *dentry,

				       struct cifs_tcon *tcon,

				       const char *full_path,

				       const char *symname)

{

	struct reparse_symlink_data_buffer *buf = NULL;

	struct cifs_open_info_data data;

	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);

	struct inode *new;

	struct kvec iov;

	__le16 *path;

	char *sym;

	u16 len, plen;

	int rc = 0;



	sym = kstrdup(symname, GFP_KERNEL);

	if (!sym)

		return -ENOMEM;



	data = (struct cifs_open_info_data) {

		.reparse_point = true,

		.reparse = { .tag = IO_REPARSE_TAG_SYMLINK, },

		.symlink_target = sym,

	};



	path = cifs_convert_path_to_utf16(symname, cifs_sb);

	if (!path) {

		rc = -ENOMEM;

		goto out;

	}



	plen = 2 * UniStrnlen((wchar_t *)path, PATH_MAX);

	len = sizeof(*buf) + plen * 2;

	buf = kzalloc(len, GFP_KERNEL);

	if (!buf) {

		rc = -ENOMEM;

		goto out;

	}



	buf->ReparseTag = cpu_to_le32(IO_REPARSE_TAG_SYMLINK);

	buf->ReparseDataLength = cpu_to_le16(len - sizeof(struct reparse_data_buffer));

	buf->SubstituteNameOffset = cpu_to_le16(plen);

	buf->SubstituteNameLength = cpu_to_le16(plen);

	memcpy(&buf->PathBuffer[plen], path, plen);

	buf->PrintNameOffset = 0;

	buf->PrintNameLength = cpu_to_le16(plen);

	memcpy(buf->PathBuffer, path, plen);

	buf->Flags = cpu_to_le32(*symname != '/' ? SYMLINK_FLAG_RELATIVE : 0);



	iov.iov_base = buf;

	iov.iov_len = len;

	new = smb2_get_reparse_inode(&data, inode->i_sb, xid,

				     tcon, full_path, &iov);

	if (!IS_ERR(new))

		d_instantiate(dentry, new);

	else

		rc = PTR_ERR(new);

out:

	kfree(path);

	cifs_free_open_info(&data);

	kfree(buf);

	return rc;

}



static int smb2_make_node(unsigned int xid, struct inode *inode,

			  struct dentry *dentry, struct cifs_tcon *tcon,

			  const char *full_path, umode_t mode, dev_t dev)
@@ -5323,6 +5389,7 @@ struct smb_version_operations smb20_operations = { 
	.parse_reparse_point = smb2_parse_reparse_point,

	.query_mf_symlink = smb3_query_mf_symlink,

	.create_mf_symlink = smb3_create_mf_symlink,

	.create_reparse_symlink = smb2_create_reparse_symlink,

	.open = smb2_open_file,

	.set_fid = smb2_set_fid,

	.close = smb2_close_file,
@@ -5425,6 +5492,7 @@ struct smb_version_operations smb21_operations = { 
	.parse_reparse_point = smb2_parse_reparse_point,

	.query_mf_symlink = smb3_query_mf_symlink,

	.create_mf_symlink = smb3_create_mf_symlink,

	.create_reparse_symlink = smb2_create_reparse_symlink,

	.open = smb2_open_file,

	.set_fid = smb2_set_fid,

	.close = smb2_close_file,
@@ -5530,6 +5598,7 @@ struct smb_version_operations smb30_operations = { 
	.parse_reparse_point = smb2_parse_reparse_point,

	.query_mf_symlink = smb3_query_mf_symlink,

	.create_mf_symlink = smb3_create_mf_symlink,

	.create_reparse_symlink = smb2_create_reparse_symlink,

	.open = smb2_open_file,

	.set_fid = smb2_set_fid,

	.close = smb2_close_file,
@@ -5644,6 +5713,7 @@ struct smb_version_operations smb311_operations = { 
	.parse_reparse_point = smb2_parse_reparse_point,

	.query_mf_symlink = smb3_query_mf_symlink,

	.create_mf_symlink = smb3_create_mf_symlink,

	.create_reparse_symlink = smb2_create_reparse_symlink,

	.open = smb2_open_file,

	.set_fid = smb2_set_fid,

	.close = smb2_close_file,