1 files changed, 348 insertions, 24 deletions

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 473ca8033656..85cdbf831e7b 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;
 }