1 files changed, 147 insertions, 155 deletions

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index c68a056f27f..58df174deb1 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -18,6 +18,7 @@
 #include <linux/slab.h>
 #include <linux/vfs.h>
 #include <linux/fs.h>
+#include <linux/inet.h>
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifsfs.h"
@@ -48,58 +49,74 @@ void cifs_dfs_release_automount_timer(void)
 }
 
 /**
- * cifs_get_share_name	-	extracts share name from UNC
- * @node_name:	pointer to UNC string
+ * cifs_build_devname - build a devicename from a UNC and optional prepath
+ * @nodename:	pointer to UNC string
+ * @prepath:	pointer to prefixpath (or NULL if there isn't one)
  *
- * Extracts sharename form full UNC.
- * i.e. strips from UNC trailing path that is not part of share
- * name and fixup missing '\' in the begining of DFS node refferal
- * if necessary.
- * Returns pointer to share name on success or ERR_PTR on error.
- * Caller is responsible for freeing returned string.
+ * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
+ * big enough to hold the final thing. Copy the UNC from the nodename, and
+ * concatenate the prepath onto the end of it if there is one.
+ *
+ * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
+ * for freeing the returned string.
  */
-static char *cifs_get_share_name(const char *node_name)
+static char *
+cifs_build_devname(char *nodename, const char *prepath)
 {
-	int len;
-	char *UNC;
-	char *pSep;
-
-	len = strlen(node_name);
-	UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
-			 GFP_KERNEL);
-	if (!UNC)
-		return ERR_PTR(-ENOMEM);
+	size_t pplen;
+	size_t unclen;
+	char *dev;
+	char *pos;
+
+	/* skip over any preceding delimiters */
+	nodename += strspn(nodename, "\\");
+	if (!*nodename)
+		return ERR_PTR(-EINVAL);
 
-	/* get share name and server name */
-	if (node_name[1] != '\\') {
-		UNC[0] = '\\';
-		strncpy(UNC+1, node_name, len);
-		len++;
-		UNC[len] = 0;
-	} else {
-		strncpy(UNC, node_name, len);
-		UNC[len] = 0;
-	}
+	/* get length of UNC and set pos to last char */
+	unclen = strlen(nodename);
+	pos = nodename + unclen - 1;
 
-	/* find server name end */
-	pSep = memchr(UNC+2, '\\', len-2);
-	if (!pSep) {
-		cERROR(1, "%s: no server name end in node name: %s",
-			__func__, node_name);
-		kfree(UNC);
-		return ERR_PTR(-EINVAL);
+	/* trim off any trailing delimiters */
+	while (*pos == '\\') {
+		--pos;
+		--unclen;
 	}
 
-	/* find sharename end */
-	pSep++;
-	pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
-	if (pSep) {
-		/* trim path up to sharename end
-		 * now we have share name in UNC */
-		*pSep = 0;
+	/* allocate a buffer:
+	 * +2 for preceding "//"
+	 * +1 for delimiter between UNC and prepath
+	 * +1 for trailing NULL
+	 */
+	pplen = prepath ? strlen(prepath) : 0;
+	dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	pos = dev;
+	/* add the initial "//" */
+	*pos = '/';
+	++pos;
+	*pos = '/';
+	++pos;
+
+	/* copy in the UNC portion from referral */
+	memcpy(pos, nodename, unclen);
+	pos += unclen;
+
+	/* copy the prefixpath remainder (if there is one) */
+	if (pplen) {
+		*pos = '/';
+		++pos;
+		memcpy(pos, prepath, pplen);
+		pos += pplen;
 	}
 
-	return UNC;
+	/* NULL terminator */
+	*pos = '\0';
+
+	convert_delimiter(dev, '/');
+	return dev;
 }
 
 
@@ -123,6 +140,7 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 {
 	int rc;
 	char *mountdata = NULL;
+	const char *prepath = NULL;
 	int md_len;
 	char *tkn_e;
 	char *srvIP = NULL;
@@ -132,7 +150,10 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 	if (sb_mountdata == NULL)
 		return ERR_PTR(-EINVAL);
 
-	*devname = cifs_get_share_name(ref->node_name);
+	if (strlen(fullpath) - ref->path_consumed)
+		prepath = fullpath + ref->path_consumed;
+
+	*devname = cifs_build_devname(ref->node_name, prepath);
 	if (IS_ERR(*devname)) {
 		rc = PTR_ERR(*devname);
 		*devname = NULL;
@@ -141,16 +162,19 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 
 	rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
 	if (rc < 0) {
-		cERROR(1, "%s: Failed to resolve server part of %s to IP: %d",
-			  __func__, *devname, rc);
+		cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
+			 __func__, *devname, rc);
 		goto compose_mount_options_err;
 	}
-	/* md_len = strlen(...) + 12 for 'sep+prefixpath='
-	 * assuming that we have 'unc=' and 'ip=' in
-	 * the original sb_mountdata
+
+	/*
+	 * In most cases, we'll be building a shorter string than the original,
+	 * but we do have to assume that the address in the ip= option may be
+	 * much longer than the original. Add the max length of an address
+	 * string to the length of the original string to allow for worst case.
 	 */
-	md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12;
-	mountdata = kzalloc(md_len+1, GFP_KERNEL);
+	md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
+	mountdata = kzalloc(md_len + 1, GFP_KERNEL);
 	if (mountdata == NULL) {
 		rc = -ENOMEM;
 		goto compose_mount_options_err;
@@ -194,29 +218,9 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 		strncat(mountdata, &sep, 1);
 	strcat(mountdata, "ip=");
 	strcat(mountdata, srvIP);
-	strncat(mountdata, &sep, 1);
-	strcat(mountdata, "unc=");
-	strcat(mountdata, *devname);
-
-	/* find & copy prefixpath */
-	tkn_e = strchr(ref->node_name + 2, '\\');
-	if (tkn_e == NULL) {
-		/* invalid unc, missing share name*/
-		rc = -EINVAL;
-		goto compose_mount_options_err;
-	}
-
-	tkn_e = strchr(tkn_e + 1, '\\');
-	if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
-		strncat(mountdata, &sep, 1);
-		strcat(mountdata, "prefixpath=");
-		if (tkn_e)
-			strcat(mountdata, tkn_e + 1);
-		strcat(mountdata, fullpath + ref->path_consumed);
-	}
 
-	/*cFYI(1, "%s: parent mountdata: %s", __func__,sb_mountdata);*/
-	/*cFYI(1, "%s: submount mountdata: %s", __func__, mountdata );*/
+	/*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
+	/*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
 
 compose_mount_options_out:
 	kfree(srvIP);
@@ -225,6 +229,8 @@ compose_mount_options_out:
 compose_mount_options_err:
 	kfree(mountdata);
 	mountdata = ERR_PTR(rc);
+	kfree(*devname);
+	*devname = NULL;
 	goto compose_mount_options_out;
 }
 
@@ -255,65 +261,34 @@ static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
 
 }
 
-static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
-				struct list_head *mntlist)
-{
-	/* stolen from afs code */
-	int err;
-
-	mntget(newmnt);
-	err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist);
-	switch (err) {
-	case 0:
-		path_put(&nd->path);
-		nd->path.mnt = newmnt;
-		nd->path.dentry = dget(newmnt->mnt_root);
-		schedule_delayed_work(&cifs_dfs_automount_task,
-				      cifs_dfs_mountpoint_expiry_timeout);
-		break;
-	case -EBUSY:
-		/* someone else made a mount here whilst we were busy */
-		while (d_mountpoint(nd->path.dentry) &&
-		       follow_down(&nd->path))
-			;
-		err = 0;
-	default:
-		mntput(newmnt);
-		break;
-	}
-	return err;
-}
-
 static void dump_referral(const struct dfs_info3_param *ref)
 {
-	cFYI(1, "DFS: ref path: %s", ref->path_name);
-	cFYI(1, "DFS: node path: %s", ref->node_name);
-	cFYI(1, "DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type);
-	cFYI(1, "DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
-				ref->path_consumed);
+	cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
+	cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
+	cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
+		 ref->flags, ref->server_type);
+	cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
+		 ref->ref_flag, ref->path_consumed);
 }
 
-
-static void*
-cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
+/*
+ * Create a vfsmount that we can automount
+ */
+static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
 {
 	struct dfs_info3_param *referrals = NULL;
 	unsigned int num_referrals = 0;
 	struct cifs_sb_info *cifs_sb;
-	struct cifsSesInfo *ses;
-	char *full_path = NULL;
-	int xid, i;
-	int rc = 0;
-	struct vfsmount *mnt = ERR_PTR(-ENOENT);
+	struct cifs_ses *ses;
+	char *full_path;
+	unsigned int xid;
+	int i;
+	int rc;
+	struct vfsmount *mnt;
 	struct tcon_link *tlink;
 
-	cFYI(1, "in %s", __func__);
-	BUG_ON(IS_ROOT(dentry));
-
-	xid = GetXid();
-
-	dput(nd->path.dentry);
-	nd->path.dentry = dget(dentry);
+	cifs_dbg(FYI, "in %s\n", __func__);
+	BUG_ON(IS_ROOT(mntpt));
 
 	/*
 	 * The MSDFS spec states that paths in DFS referral requests and
@@ -321,66 +296,83 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 	 * the double backslashes usually used in the UNC. This function
 	 * gives us the latter, so we must adjust the result.
 	 */
-	full_path = build_path_from_dentry(dentry);
-	if (full_path == NULL) {
-		rc = -ENOMEM;
-		goto out_err;
-	}
+	mnt = ERR_PTR(-ENOMEM);
+	full_path = build_path_from_dentry(mntpt);
+	if (full_path == NULL)
+		goto cdda_exit;
 
-	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
+	cifs_sb = CIFS_SB(mntpt->d_inode->i_sb);
 	tlink = cifs_sb_tlink(cifs_sb);
 	if (IS_ERR(tlink)) {
-		rc = PTR_ERR(tlink);
-		goto out_err;
+		mnt = ERR_CAST(tlink);
+		goto free_full_path;
 	}
 	ses = tlink_tcon(tlink)->ses;
 
+	xid = get_xid();
 	rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
 		&num_referrals, &referrals,
 		cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+	free_xid(xid);
 
 	cifs_put_tlink(tlink);
 
+	mnt = ERR_PTR(-ENOENT);
 	for (i = 0; i < num_referrals; i++) {
 		int len;
-		dump_referral(referrals+i);
+		dump_referral(referrals + i);
 		/* connect to a node */
 		len = strlen(referrals[i].node_name);
 		if (len < 2) {
-			cERROR(1, "%s: Net Address path too short: %s",
-					__func__, referrals[i].node_name);
-			rc = -EINVAL;
-			goto out_err;
+			cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
+				 __func__, referrals[i].node_name);
+			mnt = ERR_PTR(-EINVAL);
+			break;
 		}
 		mnt = cifs_dfs_do_refmount(cifs_sb,
 				full_path, referrals + i);
-		cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
-					referrals[i].node_name, mnt);
-
-		/* complete mount procedure if we accured submount */
+		cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
+			 __func__, referrals[i].node_name, mnt);
 		if (!IS_ERR(mnt))
-			break;
+			goto success;
 	}
 
-	/* we need it cause for() above could exit without valid submount */
-	rc = PTR_ERR(mnt);
-	if (IS_ERR(mnt))
-		goto out_err;
-
-	rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
+	/* no valid submounts were found; return error from get_dfs_path() by
+	 * preference */
+	if (rc != 0)
+		mnt = ERR_PTR(rc);
 
-out:
-	FreeXid(xid);
+success:
 	free_dfs_info_array(referrals, num_referrals);
+free_full_path:
 	kfree(full_path);
-	cFYI(1, "leaving %s" , __func__);
-	return ERR_PTR(rc);
-out_err:
-	path_put(&nd->path);
-	goto out;
+cdda_exit:
+	cifs_dbg(FYI, "leaving %s\n" , __func__);
+	return mnt;
+}
+
+/*
+ * Attempt to automount the referral
+ */
+struct vfsmount *cifs_dfs_d_automount(struct path *path)
+{
+	struct vfsmount *newmnt;
+
+	cifs_dbg(FYI, "in %s\n", __func__);
+
+	newmnt = cifs_dfs_do_automount(path->dentry);
+	if (IS_ERR(newmnt)) {
+		cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
+		return newmnt;
+	}
+
+	mntget(newmnt); /* prevent immediate expiration */
+	mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
+	schedule_delayed_work(&cifs_dfs_automount_task,
+			      cifs_dfs_mountpoint_expiry_timeout);
+	cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
+	return newmnt;
 }
 
 const struct inode_operations cifs_dfs_referral_inode_operations = {
-	.follow_link = cifs_dfs_follow_mountpoint,
 };
-