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Commit 1bfe73c2 authored by Igor Mammedov's avatar Igor Mammedov Committed by Steve French
Browse files

Remote DFS root support. 



Allows to mount share on a server that returns -EREMOTE
 at the tree connect stage or at the check on a full path
 accessibility.

Signed-off-by: default avatarIgor Mammedov <niallain@gmail.com>
Acked-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 85a6dac5

fs/cifs/connect.c

+120 −32
Original line number Diff line number Diff line
@@ -2214,9 +2214,56 @@ is_path_accessible(int xid, struct cifsTconInfo *tcon, 
	return rc;

}



static void

cleanup_volume_info(struct smb_vol **pvolume_info)

{

	struct smb_vol *volume_info;



	if (!pvolume_info && !*pvolume_info)

		return;



	volume_info = *pvolume_info;

	kzfree(volume_info->password);

	kfree(volume_info->UNC);

	kfree(volume_info->prepath);

	kfree(volume_info);

	*pvolume_info = NULL;

	return;

}



/* build_path_to_root returns full path to root when

 * we do not have an exiting connection (tcon) */

static char *

build_unc_path_to_root(const struct smb_vol *volume_info,

		const struct cifs_sb_info *cifs_sb)

{

	char *full_path;



	int unc_len = strnlen(volume_info->UNC, MAX_TREE_SIZE + 1);

	full_path = kmalloc(unc_len + cifs_sb->prepathlen + 1, GFP_KERNEL);

	if (full_path == NULL)

		return ERR_PTR(-ENOMEM);



	strncpy(full_path, volume_info->UNC, unc_len);

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {

		int i;

		for (i = 0; i < unc_len; i++) {

			if (full_path[i] == '\\')

				full_path[i] = '/';

		}

	}



	if (cifs_sb->prepathlen)

		strncpy(full_path + unc_len, cifs_sb->prepath,

				cifs_sb->prepathlen);



	full_path[unc_len + cifs_sb->prepathlen] = 0; /* add trailing null */

	return full_path;

}



int

cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,

	   char *mount_data, const char *devname)

		char *mount_data_global, const char *devname)

{

	int rc = 0;

	int xid;
@@ -2225,6 +2272,13 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
	struct cifsTconInfo *tcon = NULL;

	struct TCP_Server_Info *srvTcp = NULL;

	char   *full_path;

	struct dfs_info3_param *referrals = NULL;

	unsigned int num_referrals = 0;



	char *mount_data = mount_data_global;



try_mount_again:

	full_path = NULL;



	xid = GetXid();
@@ -2371,11 +2425,9 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
				}

			}



			/* check for null share name ie connect to dfs root */

			if ((strchr(volume_info->UNC + 3, '\\') == NULL)

			    && (strchr(volume_info->UNC + 3, '/') == NULL)) {

				/* rc = connect_to_dfs_path(...) */

				cFYI(1, ("DFS root not supported"));

				cERROR(1, ("Missing share name"));

				rc = -ENODEV;

				goto mount_fail_check;

			} else {
@@ -2392,7 +2444,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
				}

			}

			if (rc)

				goto mount_fail_check;

				goto remote_path_check;

			tcon->seal = volume_info->seal;

			write_lock(&cifs_tcp_ses_lock);

			list_add(&tcon->tcon_list, &pSesInfo->tcon_list);
@@ -2417,19 +2469,9 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
	/* BB FIXME fix time_gran to be larger for LANMAN sessions */

	sb->s_time_gran = 100;



mount_fail_check:

	/* on error free sesinfo and tcon struct if needed */

	if (rc) {

		/* If find_unc succeeded then rc == 0 so we can not end */

		/* up accidently freeing someone elses tcon struct */

		if (tcon)

			cifs_put_tcon(tcon);

		else if (pSesInfo)

			cifs_put_smb_ses(pSesInfo);

		else

			cifs_put_tcp_session(srvTcp);

		goto out;

	}

	if (rc)

		goto remote_path_check;



	cifs_sb->tcon = tcon;



	/* do not care if following two calls succeed - informational */
@@ -2461,7 +2503,9 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
		cifs_sb->rsize = min(cifs_sb->rsize,

			       (tcon->ses->server->maxBuf - MAX_CIFS_HDR_SIZE));



	if (!rc && cifs_sb->prepathlen) {

remote_path_check:

	/* check if a whole path (including prepath) is not remote */

	if (!rc && cifs_sb->prepathlen && tcon) {

		/* build_path_to_root works only when we have a valid tcon */

		full_path = cifs_build_path_to_root(cifs_sb);

		if (full_path == NULL) {
@@ -2469,13 +2513,66 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
			goto mount_fail_check;

		}

		rc = is_path_accessible(xid, tcon, cifs_sb, full_path);

		if (rc) {

			cERROR(1, ("Path %s in not accessible: %d",

						full_path, rc));

		if (rc != -EREMOTE) {

			kfree(full_path);

			goto mount_fail_check;

		}

		kfree(full_path);

	}



	/* get referral if needed */

	if (rc == -EREMOTE) {

		/* convert forward to back slashes in prepath here if needed */

		if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0)

			convert_delimiter(cifs_sb->prepath,

					CIFS_DIR_SEP(cifs_sb));

		full_path = build_unc_path_to_root(volume_info, cifs_sb);

		if (IS_ERR(full_path)) {

			rc = PTR_ERR(full_path);

			goto mount_fail_check;

		}



		cFYI(1, ("Getting referral for: %s", full_path));

		rc = get_dfs_path(xid, pSesInfo , full_path + 1,

			cifs_sb->local_nls, &num_referrals, &referrals,

			cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);

		if (!rc && num_referrals > 0) {

			char *fake_devname = NULL;



			if (mount_data != mount_data_global)

				kfree(mount_data);

			mount_data = cifs_compose_mount_options(

					cifs_sb->mountdata, full_path + 1,

					referrals, &fake_devname);

			kfree(fake_devname);

			free_dfs_info_array(referrals, num_referrals);



			if (tcon)

				cifs_put_tcon(tcon);

			else if (pSesInfo)

				cifs_put_smb_ses(pSesInfo);



			cleanup_volume_info(&volume_info);

			FreeXid(xid);

			kfree(full_path);

			goto try_mount_again;

		}

	}



mount_fail_check:

	/* on error free sesinfo and tcon struct if needed */

	if (rc) {

		if (mount_data != mount_data_global)

			kfree(mount_data);

		/* If find_unc succeeded then rc == 0 so we can not end */

		/* up accidently freeing someone elses tcon struct */

		if (tcon)

			cifs_put_tcon(tcon);

		else if (pSesInfo)

			cifs_put_smb_ses(pSesInfo);

		else

			cifs_put_tcp_session(srvTcp);

		goto out;

	}



	/* volume_info->password is freed above when existing session found
@@ -2484,16 +2581,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
	password will be freed at unmount time) */

out:

	/* zero out password before freeing */

	if (volume_info) {

		if (volume_info->password != NULL) {

			memset(volume_info->password, 0,

				strlen(volume_info->password));

			kfree(volume_info->password);

		}

		kfree(volume_info->UNC);

		kfree(volume_info->prepath);

		kfree(volume_info);

	}

	cleanup_volume_info(&volume_info);

	FreeXid(xid);

	return rc;

}