1 files changed, 348 insertions, 24 deletions

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 473ca803365..85cdbf831e7 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -28,6 +28,296 @@
 #include "cifsproto.h"
 #include "cifs_debug.h"
 #include "cifs_fs_sb.h"
+#include "md5.h"
+
+#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
+#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
+#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
+#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
+#define CIFS_MF_SYMLINK_FILE_SIZE \
+	(CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)
+
+#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
+#define CIFS_MF_SYMLINK_MD5_FORMAT \
+	"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n"
+#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) \
+	md5_hash[0],  md5_hash[1],  md5_hash[2],  md5_hash[3], \
+	md5_hash[4],  md5_hash[5],  md5_hash[6],  md5_hash[7], \
+	md5_hash[8],  md5_hash[9],  md5_hash[10], md5_hash[11],\
+	md5_hash[12], md5_hash[13], md5_hash[14], md5_hash[15]
+
+static int
+CIFSParseMFSymlink(const u8 *buf,
+		   unsigned int buf_len,
+		   unsigned int *_link_len,
+		   char **_link_str)
+{
+	int rc;
+	unsigned int link_len;
+	const char *md5_str1;
+	const char *link_str;
+	struct MD5Context md5_ctx;
+	u8 md5_hash[16];
+	char md5_str2[34];
+
+	if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
+		return -EINVAL;
+
+	md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
+	link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
+
+	rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
+	if (rc != 1)
+		return -EINVAL;
+
+	cifs_MD5_init(&md5_ctx);
+	cifs_MD5_update(&md5_ctx, (const u8 *)link_str, link_len);
+	cifs_MD5_final(md5_hash, &md5_ctx);
+
+	snprintf(md5_str2, sizeof(md5_str2),
+		 CIFS_MF_SYMLINK_MD5_FORMAT,
+		 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
+
+	if (strncmp(md5_str1, md5_str2, 17) != 0)
+		return -EINVAL;
+
+	if (_link_str) {
+		*_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
+		if (!*_link_str)
+			return -ENOMEM;
+	}
+
+	*_link_len = link_len;
+	return 0;
+}
+
+static int
+CIFSFormatMFSymlink(u8 *buf, unsigned int buf_len, const char *link_str)
+{
+	unsigned int link_len;
+	unsigned int ofs;
+	struct MD5Context md5_ctx;
+	u8 md5_hash[16];
+
+	if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
+		return -EINVAL;
+
+	link_len = strlen(link_str);
+
+	if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
+		return -ENAMETOOLONG;
+
+	cifs_MD5_init(&md5_ctx);
+	cifs_MD5_update(&md5_ctx, (const u8 *)link_str, link_len);
+	cifs_MD5_final(md5_hash, &md5_ctx);
+
+	snprintf(buf, buf_len,
+		 CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
+		 link_len,
+		 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
+
+	ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
+	memcpy(buf + ofs, link_str, link_len);
+
+	ofs += link_len;
+	if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
+		buf[ofs] = '\n';
+		ofs++;
+	}
+
+	while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
+		buf[ofs] = ' ';
+		ofs++;
+	}
+
+	return 0;
+}
+
+static int
+CIFSCreateMFSymLink(const int xid, struct cifsTconInfo *tcon,
+		    const char *fromName, const char *toName,
+		    const struct nls_table *nls_codepage, int remap)
+{
+	int rc;
+	int oplock = 0;
+	__u16 netfid = 0;
+	u8 *buf;
+	unsigned int bytes_written = 0;
+
+	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	rc = CIFSFormatMFSymlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
+	if (rc != 0) {
+		kfree(buf);
+		return rc;
+	}
+
+	rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
+			 CREATE_NOT_DIR, &netfid, &oplock, NULL,
+			 nls_codepage, remap);
+	if (rc != 0) {
+		kfree(buf);
+		return rc;
+	}
+
+	rc = CIFSSMBWrite(xid, tcon, netfid,
+			  CIFS_MF_SYMLINK_FILE_SIZE /* length */,
+			  0 /* offset */,
+			  &bytes_written, buf, NULL, 0);
+	CIFSSMBClose(xid, tcon, netfid);
+	kfree(buf);
+	if (rc != 0)
+		return rc;
+
+	if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
+		return -EIO;
+
+	return 0;
+}
+
+static int
+CIFSQueryMFSymLink(const int xid, struct cifsTconInfo *tcon,
+		   const unsigned char *searchName, char **symlinkinfo,
+		   const struct nls_table *nls_codepage, int remap)
+{
+	int rc;
+	int oplock = 0;
+	__u16 netfid = 0;
+	u8 *buf;
+	char *pbuf;
+	unsigned int bytes_read = 0;
+	int buf_type = CIFS_NO_BUFFER;
+	unsigned int link_len = 0;
+	FILE_ALL_INFO file_info;
+
+	rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
+			 CREATE_NOT_DIR, &netfid, &oplock, &file_info,
+			 nls_codepage, remap);
+	if (rc != 0)
+		return rc;
+
+	if (file_info.EndOfFile != CIFS_MF_SYMLINK_FILE_SIZE) {
+		CIFSSMBClose(xid, tcon, netfid);
+		/* it's not a symlink */
+		return -EINVAL;
+	}
+
+	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	pbuf = buf;
+
+	rc = CIFSSMBRead(xid, tcon, netfid,
+			 CIFS_MF_SYMLINK_FILE_SIZE /* length */,
+			 0 /* offset */,
+			 &bytes_read, &pbuf, &buf_type);
+	CIFSSMBClose(xid, tcon, netfid);
+	if (rc != 0) {
+		kfree(buf);
+		return rc;
+	}
+
+	rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, symlinkinfo);
+	kfree(buf);
+	if (rc != 0)
+		return rc;
+
+	return 0;
+}
+
+bool
+CIFSCouldBeMFSymlink(const struct cifs_fattr *fattr)
+{
+	if (!(fattr->cf_mode & S_IFREG))
+		/* it's not a symlink */
+		return false;
+
+	if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
+		/* it's not a symlink */
+		return false;
+
+	return true;
+}
+
+int
+CIFSCheckMFSymlink(struct cifs_fattr *fattr,
+		   const unsigned char *path,
+		   struct cifs_sb_info *cifs_sb, int xid)
+{
+	int rc;
+	int oplock = 0;
+	__u16 netfid = 0;
+	struct tcon_link *tlink;
+	struct cifsTconInfo *pTcon;
+	u8 *buf;
+	char *pbuf;
+	unsigned int bytes_read = 0;
+	int buf_type = CIFS_NO_BUFFER;
+	unsigned int link_len = 0;
+	FILE_ALL_INFO file_info;
+
+	if (!CIFSCouldBeMFSymlink(fattr))
+		/* it's not a symlink */
+		return 0;
+
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink))
+		return PTR_ERR(tlink);
+	pTcon = tlink_tcon(tlink);
+
+	rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
+			 CREATE_NOT_DIR, &netfid, &oplock, &file_info,
+			 cifs_sb->local_nls,
+			 cifs_sb->mnt_cifs_flags &
+				CIFS_MOUNT_MAP_SPECIAL_CHR);
+	if (rc != 0)
+		goto out;
+
+	if (file_info.EndOfFile != CIFS_MF_SYMLINK_FILE_SIZE) {
+		CIFSSMBClose(xid, pTcon, netfid);
+		/* it's not a symlink */
+		goto out;
+	}
+
+	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
+	if (!buf) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	pbuf = buf;
+
+	rc = CIFSSMBRead(xid, pTcon, netfid,
+			 CIFS_MF_SYMLINK_FILE_SIZE /* length */,
+			 0 /* offset */,
+			 &bytes_read, &pbuf, &buf_type);
+	CIFSSMBClose(xid, pTcon, netfid);
+	if (rc != 0) {
+		kfree(buf);
+		goto out;
+	}
+
+	rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
+	kfree(buf);
+	if (rc == -EINVAL) {
+		/* it's not a symlink */
+		rc = 0;
+		goto out;
+	}
+
+	if (rc != 0)
+		goto out;
+
+	/* it is a symlink */
+	fattr->cf_eof = link_len;
+	fattr->cf_mode &= ~S_IFMT;
+	fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
+	fattr->cf_dtype = DT_LNK;
+out:
+	cifs_put_tlink(tlink);
+	return rc;
+}
 
 int
 cifs_hardlink(struct dentry *old_file, struct inode *inode,
@@ -37,17 +327,17 @@ cifs_hardlink(struct dentry *old_file, struct inode *inode,
 	int xid;
 	char *fromName = NULL;
 	char *toName = NULL;
-	struct cifs_sb_info *cifs_sb_target;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+	struct tcon_link *tlink;
 	struct cifsTconInfo *pTcon;
 	struct cifsInodeInfo *cifsInode;
 
-	xid = GetXid();
-
-	cifs_sb_target = CIFS_SB(inode->i_sb);
-	pTcon = cifs_sb_target->tcon;
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink))
+		return PTR_ERR(tlink);
+	pTcon = tlink_tcon(tlink);
 
-/* No need to check for cross device links since server will do that
-   BB note DFS case in future though (when we may have to check) */
+	xid = GetXid();
 
 	fromName = build_path_from_dentry(old_file);
 	toName = build_path_from_dentry(direntry);
@@ -56,16 +346,15 @@ cifs_hardlink(struct dentry *old_file, struct inode *inode,
 		goto cifs_hl_exit;
 	}
 
-/*	if (cifs_sb_target->tcon->ses->capabilities & CAP_UNIX)*/
 	if (pTcon->unix_ext)
 		rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
-					    cifs_sb_target->local_nls,
-					    cifs_sb_target->mnt_cifs_flags &
+					    cifs_sb->local_nls,
+					    cifs_sb->mnt_cifs_flags &
 						CIFS_MOUNT_MAP_SPECIAL_CHR);
 	else {
 		rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
-					cifs_sb_target->local_nls,
-					cifs_sb_target->mnt_cifs_flags &
+					cifs_sb->local_nls,
+					cifs_sb->mnt_cifs_flags &
 						CIFS_MOUNT_MAP_SPECIAL_CHR);
 		if ((rc == -EIO) || (rc == -EINVAL))
 			rc = -EOPNOTSUPP;
@@ -101,6 +390,7 @@ cifs_hl_exit:
 	kfree(fromName);
 	kfree(toName);
 	FreeXid(xid);
+	cifs_put_tlink(tlink);
 	return rc;
 }
 
@@ -113,10 +403,19 @@ cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 	char *full_path = NULL;
 	char *target_path = NULL;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-	struct cifsTconInfo *tcon = cifs_sb->tcon;
+	struct tcon_link *tlink = NULL;
+	struct cifsTconInfo *tcon;
 
 	xid = GetXid();
 
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink)) {
+		rc = PTR_ERR(tlink);
+		tlink = NULL;
+		goto out;
+	}
+	tcon = tlink_tcon(tlink);
+
 	/*
 	 * For now, we just handle symlinks with unix extensions enabled.
 	 * Eventually we should handle NTFS reparse points, and MacOS
@@ -130,7 +429,8 @@ cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 	 * but there doesn't seem to be any harm in allowing the client to
 	 * read them.
 	 */
-	if (!(tcon->ses->capabilities & CAP_UNIX)) {
+	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
+	    && !(tcon->ses->capabilities & CAP_UNIX)) {
 		rc = -EACCES;
 		goto out;
 	}
@@ -141,8 +441,21 @@ cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 
 	cFYI(1, "Full path: %s inode = 0x%p", full_path, inode);
 
-	rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
-				     cifs_sb->local_nls);
+	rc = -EACCES;
+	/*
+	 * First try Minshall+French Symlinks, if configured
+	 * and fallback to UNIX Extensions Symlinks.
+	 */
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
+		rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
+					cifs_sb->local_nls,
+					cifs_sb->mnt_cifs_flags &
+						CIFS_MOUNT_MAP_SPECIAL_CHR);
+
+	if ((rc != 0) && (tcon->ses->capabilities & CAP_UNIX))
+		rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
+					     cifs_sb->local_nls);
+
 	kfree(full_path);
 out:
 	if (rc != 0) {
@@ -151,6 +464,8 @@ out:
 	}
 
 	FreeXid(xid);
+	if (tlink)
+		cifs_put_tlink(tlink);
 	nd_set_link(nd, target_path);
 	return NULL;
 }
@@ -160,29 +475,37 @@ cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 {
 	int rc = -EOPNOTSUPP;
 	int xid;
-	struct cifs_sb_info *cifs_sb;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+	struct tcon_link *tlink;
 	struct cifsTconInfo *pTcon;
 	char *full_path = NULL;
 	struct inode *newinode = NULL;
 
 	xid = GetXid();
 
-	cifs_sb = CIFS_SB(inode->i_sb);
-	pTcon = cifs_sb->tcon;
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink)) {
+		rc = PTR_ERR(tlink);
+		goto symlink_exit;
+	}
+	pTcon = tlink_tcon(tlink);
 
 	full_path = build_path_from_dentry(direntry);
-
 	if (full_path == NULL) {
 		rc = -ENOMEM;
-		FreeXid(xid);
-		return rc;
+		goto symlink_exit;
 	}
 
 	cFYI(1, "Full path: %s", full_path);
 	cFYI(1, "symname is %s", symname);
 
 	/* BB what if DFS and this volume is on different share? BB */
-	if (pTcon->unix_ext)
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
+		rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
+					 cifs_sb->local_nls,
+					 cifs_sb->mnt_cifs_flags &
+						CIFS_MOUNT_MAP_SPECIAL_CHR);
+	else if (pTcon->unix_ext)
 		rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 					   cifs_sb->local_nls);
 	/* else
@@ -208,8 +531,9 @@ cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 			d_instantiate(direntry, newinode);
 		}
 	}
-
+symlink_exit:
 	kfree(full_path);
+	cifs_put_tlink(tlink);
 	FreeXid(xid);
 	return rc;
 }