smb: client: move most of reparse point handling code to common file

In preparation to add support for creating special files also via WSL
reparse points in next commits.

Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 320 insertions, 0 deletions

diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
new file mode 100644
index 000000000000..c405be47c84d
--- /dev/null
+++ b/fs/smb/client/reparse.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024 Paulo Alcantara <pc@manguebit.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+#include "cifsglob.h"
+#include "smb2proto.h"
+#include "cifsproto.h"
+#include "cifs_unicode.h"
+#include "cifs_debug.h"
+#include "reparse.h"
+
+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, sep = CIFS_DIR_SEP(cifs_sb);
+	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,
+	};
+
+	convert_delimiter(sym, sep);
+	path = cifs_convert_path_to_utf16(sym, 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);
+	if (*sym != sep)
+		buf->Flags = cpu_to_le32(SYMLINK_FLAG_RELATIVE);
+
+	convert_delimiter(sym, '/');
+	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 nfs_set_reparse_buf(struct reparse_posix_data *buf,
+			       mode_t mode, dev_t dev,
+			       struct kvec *iov)
+{
+	u64 type;
+	u16 len, dlen;
+
+	len = sizeof(*buf);
+
+	switch ((type = reparse_mode_nfs_type(mode))) {
+	case NFS_SPECFILE_BLK:
+	case NFS_SPECFILE_CHR:
+		dlen = sizeof(__le64);
+		break;
+	case NFS_SPECFILE_FIFO:
+	case NFS_SPECFILE_SOCK:
+		dlen = 0;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	buf->ReparseTag = cpu_to_le32(IO_REPARSE_TAG_NFS);
+	buf->Reserved = 0;
+	buf->InodeType = cpu_to_le64(type);
+	buf->ReparseDataLength = cpu_to_le16(len + dlen -
+					     sizeof(struct reparse_data_buffer));
+	*(__le64 *)buf->DataBuffer = cpu_to_le64(((u64)MAJOR(dev) << 32) |
+						 MINOR(dev));
+	iov->iov_base = buf;
+	iov->iov_len = len + dlen;
+	return 0;
+}
+
+int smb2_make_nfs_node(unsigned int xid, struct inode *inode,
+		       struct dentry *dentry, struct cifs_tcon *tcon,
+		       const char *full_path, umode_t mode, dev_t dev)
+{
+	struct cifs_open_info_data data;
+	struct reparse_posix_data *p;
+	struct inode *new;
+	struct kvec iov;
+	__u8 buf[sizeof(*p) + sizeof(__le64)];
+	int rc;
+
+	p = (struct reparse_posix_data *)buf;
+	rc = nfs_set_reparse_buf(p, mode, dev, &iov);
+	if (rc)
+		return rc;
+
+	data = (struct cifs_open_info_data) {
+		.reparse_point = true,
+		.reparse = { .tag = IO_REPARSE_TAG_NFS, .posix = p, },
+	};
+
+	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);
+	cifs_free_open_info(&data);
+	return rc;
+}
+
+/* See MS-FSCC 2.1.2.6 for the 'NFS' style reparse tags */
+static int parse_reparse_posix(struct reparse_posix_data *buf,
+			       struct cifs_sb_info *cifs_sb,
+			       struct cifs_open_info_data *data)
+{
+	unsigned int len;
+	u64 type;
+
+	switch ((type = le64_to_cpu(buf->InodeType))) {
+	case NFS_SPECFILE_LNK:
+		len = le16_to_cpu(buf->ReparseDataLength);
+		data->symlink_target = cifs_strndup_from_utf16(buf->DataBuffer,
+							       len, true,
+							       cifs_sb->local_nls);
+		if (!data->symlink_target)
+			return -ENOMEM;
+		convert_delimiter(data->symlink_target, '/');
+		cifs_dbg(FYI, "%s: target path: %s\n",
+			 __func__, data->symlink_target);
+		break;
+	case NFS_SPECFILE_CHR:
+	case NFS_SPECFILE_BLK:
+	case NFS_SPECFILE_FIFO:
+	case NFS_SPECFILE_SOCK:
+		break;
+	default:
+		cifs_dbg(VFS, "%s: unhandled inode type: 0x%llx\n",
+			 __func__, type);
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+static int parse_reparse_symlink(struct reparse_symlink_data_buffer *sym,
+				 u32 plen, bool unicode,
+				 struct cifs_sb_info *cifs_sb,
+				 struct cifs_open_info_data *data)
+{
+	unsigned int len;
+	unsigned int offs;
+
+	/* We handle Symbolic Link reparse tag here. See: MS-FSCC 2.1.2.4 */
+
+	offs = le16_to_cpu(sym->SubstituteNameOffset);
+	len = le16_to_cpu(sym->SubstituteNameLength);
+	if (offs + 20 > plen || offs + len + 20 > plen) {
+		cifs_dbg(VFS, "srv returned malformed symlink buffer\n");
+		return -EIO;
+	}
+
+	data->symlink_target = cifs_strndup_from_utf16(sym->PathBuffer + offs,
+						       len, unicode,
+						       cifs_sb->local_nls);
+	if (!data->symlink_target)
+		return -ENOMEM;
+
+	convert_delimiter(data->symlink_target, '/');
+	cifs_dbg(FYI, "%s: target path: %s\n", __func__, data->symlink_target);
+
+	return 0;
+}
+
+int parse_reparse_point(struct reparse_data_buffer *buf,
+			u32 plen, struct cifs_sb_info *cifs_sb,
+			bool unicode, struct cifs_open_info_data *data)
+{
+	data->reparse.buf = buf;
+
+	/* See MS-FSCC 2.1.2 */
+	switch (le32_to_cpu(buf->ReparseTag)) {
+	case IO_REPARSE_TAG_NFS:
+		return parse_reparse_posix((struct reparse_posix_data *)buf,
+					   cifs_sb, data);
+	case IO_REPARSE_TAG_SYMLINK:
+		return parse_reparse_symlink(
+			(struct reparse_symlink_data_buffer *)buf,
+			plen, unicode, cifs_sb, data);
+	case IO_REPARSE_TAG_LX_SYMLINK:
+	case IO_REPARSE_TAG_AF_UNIX:
+	case IO_REPARSE_TAG_LX_FIFO:
+	case IO_REPARSE_TAG_LX_CHR:
+	case IO_REPARSE_TAG_LX_BLK:
+		return 0;
+	default:
+		cifs_dbg(VFS, "%s: unhandled reparse tag: 0x%08x\n",
+			 __func__, le32_to_cpu(buf->ReparseTag));
+		return -EOPNOTSUPP;
+	}
+}
+
+int smb2_parse_reparse_point(struct cifs_sb_info *cifs_sb,
+			     struct kvec *rsp_iov,
+			     struct cifs_open_info_data *data)
+{
+	struct reparse_data_buffer *buf;
+	struct smb2_ioctl_rsp *io = rsp_iov->iov_base;
+	u32 plen = le32_to_cpu(io->OutputCount);
+
+	buf = (struct reparse_data_buffer *)((u8 *)io +
+					     le32_to_cpu(io->OutputOffset));
+	return parse_reparse_point(buf, plen, cifs_sb, true, data);
+}
+
+bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb,
+				 struct cifs_fattr *fattr,
+				 struct cifs_open_info_data *data)
+{
+	struct reparse_posix_data *buf = data->reparse.posix;
+	u32 tag = data->reparse.tag;
+
+	if (tag == IO_REPARSE_TAG_NFS && buf) {
+		switch (le64_to_cpu(buf->InodeType)) {
+		case NFS_SPECFILE_CHR:
+			fattr->cf_mode |= S_IFCHR;
+			fattr->cf_dtype = DT_CHR;
+			fattr->cf_rdev = reparse_nfs_mkdev(buf);
+			break;
+		case NFS_SPECFILE_BLK:
+			fattr->cf_mode |= S_IFBLK;
+			fattr->cf_dtype = DT_BLK;
+			fattr->cf_rdev = reparse_nfs_mkdev(buf);
+			break;
+		case NFS_SPECFILE_FIFO:
+			fattr->cf_mode |= S_IFIFO;
+			fattr->cf_dtype = DT_FIFO;
+			break;
+		case NFS_SPECFILE_SOCK:
+			fattr->cf_mode |= S_IFSOCK;
+			fattr->cf_dtype = DT_SOCK;
+			break;
+		case NFS_SPECFILE_LNK:
+			fattr->cf_mode |= S_IFLNK;
+			fattr->cf_dtype = DT_LNK;
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			return false;
+		}
+		return true;
+	}
+
+	switch (tag) {
+	case IO_REPARSE_TAG_LX_SYMLINK:
+		fattr->cf_mode |= S_IFLNK;
+		fattr->cf_dtype = DT_LNK;
+		break;
+	case IO_REPARSE_TAG_LX_FIFO:
+		fattr->cf_mode |= S_IFIFO;
+		fattr->cf_dtype = DT_FIFO;
+		break;
+	case IO_REPARSE_TAG_AF_UNIX:
+		fattr->cf_mode |= S_IFSOCK;
+		fattr->cf_dtype = DT_SOCK;
+		break;
+	case IO_REPARSE_TAG_LX_CHR:
+		fattr->cf_mode |= S_IFCHR;
+		fattr->cf_dtype = DT_CHR;
+		break;
+	case IO_REPARSE_TAG_LX_BLK:
+		fattr->cf_mode |= S_IFBLK;
+		fattr->cf_dtype = DT_BLK;
+		break;
+	case 0: /* SMB1 symlink */
+	case IO_REPARSE_TAG_SYMLINK:
+	case IO_REPARSE_TAG_NFS:
+		fattr->cf_mode |= S_IFLNK;
+		fattr->cf_dtype = DT_LNK;
+		break;
+	default:
+		return false;
+	}
+	return true;
+}