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Commit d9deef0a authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: fix composing of mount options for DFS referrals 



With the change to ignore the unc= and prefixpath= mount options, there
is no longer any need to add them to the options string when mounting.
By the same token, we now need to build a device name that includes the
prefixpath when mounting.

To make things neater, the delimiters on the devicename are changed
to '/' since that's preferred when mounting anyway.

v2: fix some comments and don't bother looking at whether there is
    a prepath in the ref->node_name when deciding whether to pass
    a prepath to cifs_build_devname.

v3: rebase on top of potential buffer overrun fix for stable

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 9c9c29e1

fs/cifs/cifs_dfs_ref.c

+71 −70
Original line number Diff line number Diff line
@@ -49,58 +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 beginning 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;

	size_t pplen;

	size_t unclen;

	char *dev;

	char *pos;



	/* skip over any preceding delimiters */

	nodename += strspn(nodename, "\\");

	if (!*nodename)

		return ERR_PTR(-EINVAL);



	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);

	/* get length of UNC and set pos to last char */

	unclen = strlen(nodename);

	pos = nodename + unclen - 1;



	/* 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;

	/* trim off any trailing delimiters */

	while (*pos == '\\') {

		--pos;

		--unclen;

	}



	/* find server name end */

	pSep = memchr(UNC+2, '\\', len-2);

	if (!pSep) {

		cifs_dbg(VFS, "%s: no server name end in node name: %s\n",

			 __func__, node_name);

		kfree(UNC);

		return ERR_PTR(-EINVAL);

	}

	/* 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);



	/* 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;

	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;

}
@@ -124,6 +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;
@@ -133,7 +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;
@@ -147,12 +167,13 @@ char *cifs_compose_mount_options(const char *sb_mountdata, 
		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 +

			INET6_ADDRSTRLEN;

	md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;

	mountdata = kzalloc(md_len + 1, GFP_KERNEL);

	if (mountdata == NULL) {

		rc = -ENOMEM;
@@ -197,26 +218,6 @@ 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);

	}



	/*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/

	/*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/

fs/cifs/dns_resolve.c

+2 −2
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ 


/**

 * dns_resolve_server_name_to_ip - Resolve UNC server name to ip address.

 * @unc: UNC path specifying the server

 * @unc: UNC path specifying the server (with '/' as delimiter)

 * @ip_addr: Where to return the IP address.

 *

 * The IP address will be returned in string form, and the caller is
@@ -64,7 +64,7 @@ dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) 
	hostname = unc + 2;



	/* Search for server name delimiter */

	sep = memchr(hostname, '\\', len);

	sep = memchr(hostname, '/', len);

	if (sep)

		len = sep - hostname;

	else