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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: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
master
Jeff Layton 8 years ago
committed by Steve French
parent
commit
d9deef0a3f
  1. 141
      fs/cifs/cifs_dfs_ref.c
  2. 4
      fs/cifs/dns_resolve.c

141
fs/cifs/cifs_dfs_ref.c

@ -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;
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) {
cifs_dbg(VFS, "%s: no server name end in node name: %s\n",
__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;
}
@ -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;
@ -147,13 +167,14 @@ 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;
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;
@ -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 );*/

4
fs/cifs/dns_resolve.c

@ -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

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