CIFS: Fix symbolic links usage

Now we treat any reparse point as a symbolic link and map it to a Unix
one that is not true in a common case due to many reparse point types
supported by SMB servers.

Distinguish reparse point types into two groups:
1) that can be accessed directly through a reparse point
(junctions, deduplicated files, NFS symlinks);
2) that need to be processed manually (Windows symbolic links, DFS);

and map only Windows symbolic links to Unix ones.

Cc: <stable@vger.kernel.org>
Acked-by: Jeff Layton <jlayton@redhat.com>
Reported-and-tested-by: Joao Correia <joaomiguelcorreia@gmail.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 26b1c1d..cddb807 100644 (file)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -261,7 +261,7 @@ struct smb_version_operations {
        /* query path data from the server */
        int (*query_path_info)(const unsigned int, struct cifs_tcon *,
                               struct cifs_sb_info *, const char *,
-                              FILE_ALL_INFO *, bool *);
+                              FILE_ALL_INFO *, bool *, bool *);
        /* query file data from the server */
        int (*query_file_info)(const unsigned int, struct cifs_tcon *,
                               struct cifs_fid *, FILE_ALL_INFO *);

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 867b7cd..36f9ebb 100644 (file)
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -542,7 +542,8 @@ static int cifs_sfu_mode(struct cifs_fattr *fattr, const unsigned char *path,
 /* Fill a cifs_fattr struct with info from FILE_ALL_INFO */
 static void
 cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
-                      struct cifs_sb_info *cifs_sb, bool adjust_tz)
+                      struct cifs_sb_info *cifs_sb, bool adjust_tz,
+                      bool symlink)
 {
        struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
@@ -569,7 +570,11 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
        fattr->cf_createtime = le64_to_cpu(info->CreationTime);
 
        fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
-       if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
+
+       if (symlink) {
+               fattr->cf_mode = S_IFLNK;
+               fattr->cf_dtype = DT_LNK;
+       } else if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
                fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
                fattr->cf_dtype = DT_DIR;
                /*
@@ -578,10 +583,6 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
                 */
                if (!tcon->unix_ext)
                        fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;
-       } else if (fattr->cf_cifsattrs & ATTR_REPARSE) {
-               fattr->cf_mode = S_IFLNK;
-               fattr->cf_dtype = DT_LNK;
-               fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
        } else {
                fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
                fattr->cf_dtype = DT_REG;
@@ -626,7 +627,8 @@ cifs_get_file_info(struct file *filp)
        rc = server->ops->query_file_info(xid, tcon, &cfile->fid, &find_data);
        switch (rc) {
        case 0:
-               cifs_all_info_to_fattr(&fattr, &find_data, cifs_sb, false);
+               cifs_all_info_to_fattr(&fattr, &find_data, cifs_sb, false,
+                                      false);
                break;
        case -EREMOTE:
                cifs_create_dfs_fattr(&fattr, inode->i_sb);
@@ -673,6 +675,7 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
        bool adjust_tz = false;
        struct cifs_fattr fattr;
        struct cifs_search_info *srchinf = NULL;
+       bool symlink = false;
 
        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink))
@@ -702,12 +705,12 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
                }
                data = (FILE_ALL_INFO *)buf;
                rc = server->ops->query_path_info(xid, tcon, cifs_sb, full_path,
-                                                 data, &adjust_tz);
+                                                 data, &adjust_tz, &symlink);
        }
 
        if (!rc) {
-               cifs_all_info_to_fattr(&fattr, (FILE_ALL_INFO *)data, cifs_sb,
-                                      adjust_tz);
+               cifs_all_info_to_fattr(&fattr, data, cifs_sb, adjust_tz,
+                                      symlink);
        } else if (rc == -EREMOTE) {
                cifs_create_dfs_fattr(&fattr, sb);
                rc = 0;

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 53a75f3..5940eca 100644 (file)
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -134,22 +134,6 @@ out:
        dput(dentry);
 }
 
-/*
- * Is it possible that this directory might turn out to be a DFS referral
- * once we go to try and use it?
- */
-static bool
-cifs_dfs_is_possible(struct cifs_sb_info *cifs_sb)
-{
-#ifdef CONFIG_CIFS_DFS_UPCALL
-       struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
-
-       if (tcon->Flags & SMB_SHARE_IS_IN_DFS)
-               return true;
-#endif
-       return false;
-}
-
 static void
 cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
 {
@@ -159,27 +143,19 @@ cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
        if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
                fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
                fattr->cf_dtype = DT_DIR;
-               /*
-                * Windows CIFS servers generally make DFS referrals look
-                * like directories in FIND_* responses with the reparse
-                * attribute flag also set (since DFS junctions are
-                * reparse points). We must revalidate at least these
-                * directory inodes before trying to use them (if
-                * they are DFS we will get PATH_NOT_COVERED back
-                * when queried directly and can then try to connect
-                * to the DFS target)
-                */
-               if (cifs_dfs_is_possible(cifs_sb) &&
-                   (fattr->cf_cifsattrs & ATTR_REPARSE))
-                       fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
-       } else if (fattr->cf_cifsattrs & ATTR_REPARSE) {
-               fattr->cf_mode = S_IFLNK;
-               fattr->cf_dtype = DT_LNK;
        } else {
                fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
                fattr->cf_dtype = DT_REG;
        }
 
+       /*
+        * We need to revalidate it further to make a decision about whether it
+        * is a symbolic link, DFS referral or a reparse point with a direct
+        * access like junctions, deduplicated files, NFS symlinks.
+        */
+       if (fattr->cf_cifsattrs & ATTR_REPARSE)
+               fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
+
        /* non-unix readdir doesn't provide nlink */
        fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;
 

diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index 384cffe..5f5ba0d 100644 (file)
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -534,10 +534,12 @@ cifs_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
 static int
 cifs_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
                     struct cifs_sb_info *cifs_sb, const char *full_path,
-                    FILE_ALL_INFO *data, bool *adjustTZ)
+                    FILE_ALL_INFO *data, bool *adjustTZ, bool *symlink)
 {
        int rc;
 
+       *symlink = false;
+
        /* could do find first instead but this returns more info */
        rc = CIFSSMBQPathInfo(xid, tcon, full_path, data, 0 /* not legacy */,
                              cifs_sb->local_nls, cifs_sb->mnt_cifs_flags &
@@ -554,6 +556,23 @@ cifs_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
                                                CIFS_MOUNT_MAP_SPECIAL_CHR);
                *adjustTZ = true;
        }
+
+       if (!rc && (le32_to_cpu(data->Attributes) & ATTR_REPARSE)) {
+               int tmprc;
+               int oplock = 0;
+               __u16 netfid;
+
+               /* Need to check if this is a symbolic link or not */
+               tmprc = CIFSSMBOpen(xid, tcon, full_path, FILE_OPEN,
+                                   FILE_READ_ATTRIBUTES, 0, &netfid, &oplock,
+                                   NULL, cifs_sb->local_nls,
+                       cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+               if (tmprc == -EOPNOTSUPP)
+                       *symlink = true;
+               else
+                       CIFSSMBClose(xid, tcon, netfid);
+       }
+
        return rc;
 }
 

diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index 78ff88c..84c012a 100644 (file)
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -123,12 +123,13 @@ move_smb2_info_to_cifs(FILE_ALL_INFO *dst, struct smb2_file_all_info *src)
 int
 smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
                     struct cifs_sb_info *cifs_sb, const char *full_path,
-                    FILE_ALL_INFO *data, bool *adjust_tz)
+                    FILE_ALL_INFO *data, bool *adjust_tz, bool *symlink)
 {
        int rc;
        struct smb2_file_all_info *smb2_data;
 
        *adjust_tz = false;
+       *symlink = false;
 
        smb2_data = kzalloc(sizeof(struct smb2_file_all_info) + MAX_NAME * 2,
                            GFP_KERNEL);
@@ -136,9 +137,16 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
                return -ENOMEM;
 
        rc = smb2_open_op_close(xid, tcon, cifs_sb, full_path,
-                               FILE_READ_ATTRIBUTES, FILE_OPEN,
-                               OPEN_REPARSE_POINT, smb2_data,
-                               SMB2_OP_QUERY_INFO);
+                               FILE_READ_ATTRIBUTES, FILE_OPEN, 0,
+                               smb2_data, SMB2_OP_QUERY_INFO);
+       if (rc == -EOPNOTSUPP) {
+               *symlink = true;
+               /* Failed on a symbolic link - query a reparse point info */
+               rc = smb2_open_op_close(xid, tcon, cifs_sb, full_path,
+                                       FILE_READ_ATTRIBUTES, FILE_OPEN,
+                                       OPEN_REPARSE_POINT, smb2_data,
+                                       SMB2_OP_QUERY_INFO);
+       }
        if (rc)
                goto out;
 

diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 313813e..b4eea10 100644 (file)
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -61,7 +61,7 @@ extern void move_smb2_info_to_cifs(FILE_ALL_INFO *dst,
 extern int smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
                                struct cifs_sb_info *cifs_sb,
                                const char *full_path, FILE_ALL_INFO *data,
-                               bool *adjust_tz);
+                               bool *adjust_tz, bool *symlink);
 extern int smb2_set_path_size(const unsigned int xid, struct cifs_tcon *tcon,
                              const char *full_path, __u64 size,
                              struct cifs_sb_info *cifs_sb, bool set_alloc);