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CIFS: Fix symbolic links usage
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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: <[email protected]>
Acked-by: Jeff Layton <[email protected]>
Reported-and-tested-by: Joao Correia <[email protected]>
Signed-off-by: Pavel Shilovsky <[email protected]>
Signed-off-by: Steve French <[email protected]>
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@piastry @smfrench
piastry authored and smfrench committed Nov 11, 2013
1 parent 6c86ae2 commit eb85d94
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Showing 6 changed files with 55 additions and 49 deletions.
2 changes: 1 addition & 1 deletion fs/cifs/cifsglob.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 *);
Expand Down
23 changes: 13 additions & 10 deletions fs/cifs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand All @@ -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;
/*
Expand All @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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))
Expand Down Expand Up @@ -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;
Expand Down
40 changes: 8 additions & 32 deletions fs/cifs/readdir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -134,22 +134,6 @@ cifs_prime_dcache(struct dentry *parent, struct qstr *name,
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)
{
Expand All @@ -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;

Expand Down
21 changes: 20 additions & 1 deletion fs/cifs/smb1ops.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 &
Expand All @@ -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;
}

Expand Down
16 changes: 12 additions & 4 deletions fs/cifs/smb2inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -123,22 +123,30 @@ 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);
if (smb2_data == NULL)
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;

Expand Down
2 changes: 1 addition & 1 deletion fs/cifs/smb2proto.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down

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