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Subject[PATCH 3.12 102/212] CIFS: Fix symbolic links usage
Date
3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pavel Shilovsky <piastry@etersoft.ru>

commit eb85d94bdd91fb4dbea4ee465d4349cbea4eaaca upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/cifs/cifsglob.h | 2 +-
fs/cifs/inode.c | 23 +++++++++++++----------
fs/cifs/readdir.c | 40 ++++++++--------------------------------
fs/cifs/smb1ops.c | 21 ++++++++++++++++++++-
fs/cifs/smb2inode.c | 16 ++++++++++++----
fs/cifs/smb2proto.h | 2 +-
6 files changed, 55 insertions(+), 49 deletions(-)

--- 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 *);
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -542,7 +542,8 @@ static int cifs_sfu_mode(struct cifs_fat
/* 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->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
*/
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
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
}
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;
--- 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
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;

--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -534,10 +534,12 @@ cifs_is_path_accessible(const unsigned i
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
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;
}

--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -123,12 +123,13 @@ move_smb2_info_to_cifs(FILE_ALL_INFO *ds
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
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;

--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -61,7 +61,7 @@ extern void move_smb2_info_to_cifs(FILE_
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);



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