[PATCH] mount.cifs: allow mounts to ipv6 capable servers (try #2)

[Jeff Layton-2]

The current name resolution scheme in mount.cifs is IPv4 only. Expand
it to be protocol-independent. Also take advantage of the fact that
getaddrinfo() returns a list of addresses and have mount.cifs try each
in turn until it hits one that's reachable and allows the socket to
connect.

This is the second attempt at this patch. The first one had a possible
NULL pointer dereference that could occur if the user specified the
address.

Signed-off-by: Jeff Layton <jlayton@...>
---
 source3/client/mount.cifs.c |  223 +++++++++++++++++++++++-------------------
 1 files changed, 122 insertions(+), 101 deletions(-)

diff --git a/source3/client/mount.cifs.c b/source3/client/mount.cifs.c
index da2f98b..32064dd 100644
--- a/source3/client/mount.cifs.c
+++ b/source3/client/mount.cifs.c
@@ -80,6 +80,11 @@
 #define MOUNT_PASSWD_SIZE 64
 #define DOMAIN_SIZE 64
 
+/* maximum length of IPv6 address. e.g:
+ * FEDC:BA98:7654:3210:FEDC:BA98:7654:3210/128
+ */
+#define MAX_ADDRESS_LEN 43
+
 const char *thisprogram;
 int verboseflag = 0;
 static int got_password = 0;
@@ -189,12 +194,6 @@ static char * getusername(void) {
  return username;
 }
 
-static char * parse_cifs_url(char * unc_name)
-{
- printf("\nMounting cifs URL not implemented yet. Attempt to mount %s\n",unc_name);
- return NULL;
-}
-
 static int open_cred_file(char * file_name)
 {
  char * line_buf;
@@ -494,7 +493,7 @@ static int parse_options(char ** optionsp, int * filesys_flags)
  } else if (strncmp(data, "ip", 2) == 0) {
  if (!value || !*value) {
  printf("target ip address argument missing");
- } else if (strnlen(value, 35) < 35) {
+ } else if (strnlen(value, MAX_ADDRESS_LEN) <= MAX_ADDRESS_LEN) {
  if(verboseflag)
  printf("ip address %s override specified\n",value);
  got_ip = 1;
@@ -882,23 +881,23 @@ static void replace_char(char *string, char from, char to, int maxlen)
 }
 
 /* Note that caller frees the returned buffer if necessary */
-static char * parse_server(char ** punc_name)
+static struct addrinfo *
+parse_server(char ** punc_name)
 {
  char * unc_name = *punc_name;
  int length = strnlen(unc_name, MAX_UNC_LEN);
  char * share;
- char * ipaddress_string = NULL;
- struct hostent * host_entry = NULL;
- struct in_addr server_ipaddr;
+ struct addrinfo *addrlist;
+ int rc;
 
  if(length > (MAX_UNC_LEN - 1)) {
  printf("mount error: UNC name too long");
  return NULL;
  }
- if (strncasecmp("cifs://",unc_name,7) == 0)
- return parse_cifs_url(unc_name+7);
- if (strncasecmp("smb://",unc_name,6) == 0) {
- return parse_cifs_url(unc_name+6);
+ if ((strncasecmp("cifs://", unc_name, 7) == 0) ||
+    (strncasecmp("smb://", unc_name, 6) == 0)) {
+ printf("\nMounting cifs URL not implemented yet. Attempt to mount %s\n", unc_name);
+ return NULL;
  }
 
  if(length < 3) {
@@ -939,7 +938,12 @@ continue_unc_parsing:
  *share = 0;  /* temporarily terminate the string */
  share += 1;
  if(got_ip == 0) {
- host_entry = gethostbyname(unc_name);
+ rc = getaddrinfo(unc_name, NULL, NULL, &addrlist);
+ if (rc != 0) {
+ printf("mount error: could not resolve address for %s: %s\n",
+ unc_name, gai_strerror(rc));
+ addrlist = NULL;
+ }
  }
  *(share - 1) = '/'; /* put delimiter back */
 
@@ -954,23 +958,9 @@ continue_unc_parsing:
  printf("ip address specified explicitly\n");
  return NULL;
  }
- if(host_entry == NULL) {
- printf("mount error: could not find target server. TCP name %s not found\n", unc_name);
- return NULL;
- } else {
- /* BB should we pass an alternate version of the share name as Unicode */
- /* BB what about ipv6? BB */
- /* BB add retries with alternate servers in list */
+ /* BB should we pass an alternate version of the share name as Unicode */
 
- memcpy(&server_ipaddr.s_addr, host_entry->h_addr, 4);
-
- ipaddress_string = inet_ntoa(server_ipaddr);                                                                                    
- if(ipaddress_string == NULL) {
- printf("mount error: could not get valid ip address for target server\n");
- return NULL;
- }
- return ipaddress_string;
- }
+ return addrlist;
  } else {
  /* BB add code to find DFS root (send null path on get DFS Referral to specified server here */
  printf("Mounting the DFS root for a particular server not implemented yet\n");
@@ -1034,10 +1024,11 @@ int main(int argc, char ** argv)
  int flags = MS_MANDLOCK; /* no need to set legacy MS_MGC_VAL */
  char * orgoptions = NULL;
  char * share_name = NULL;
- char * ipaddr = NULL;
+ const char * ipaddr = NULL;
  char * uuid = NULL;
  char * mountpoint = NULL;
  char * options = NULL;
+ char * optionstail;
  char * resolved_path = NULL;
  char * temp;
  char * dev_name;
@@ -1050,10 +1041,14 @@ int main(int argc, char ** argv)
  int optlen = 0;
  int orgoptlen = 0;
  size_t options_size = 0;
+ size_t current_len;
  int retry = 0; /* set when we have to retry mount with uppercase */
+ struct addrinfo *addrhead = NULL, *addr;
  struct stat statbuf;
  struct utsname sysinfo;
  struct mntent mountent;
+ struct sockaddr_in *addr4;
+ struct sockaddr_in6 *addr6;
  FILE * pmntfile;
 
  /* setlocale(LC_ALL, "");
@@ -1245,8 +1240,8 @@ int main(int argc, char ** argv)
                 rc = EX_USAGE;
  goto mount_exit;
  }
- ipaddr = parse_server(&share_name);
- if((ipaddr == NULL) && (got_ip == 0)) {
+ addrhead = addr = parse_server(&share_name);
+ if((addrhead == NULL) && (got_ip == 0)) {
  printf("No ip address specified and hostname not found\n");
  rc = EX_USAGE;
  goto mount_exit;
@@ -1310,7 +1305,6 @@ int main(int argc, char ** argv)
  }
  /* FIXME launch daemon (handles dfs name resolution and credential change)
    remember to clear parms and overwrite password field before launching */
-mount_retry:
  if(orgoptions) {
  optlen = strlen(orgoptions);
  orgoptlen = optlen;
@@ -1325,10 +1319,10 @@ mount_retry:
  }
  if(user_name)
  optlen += strlen(user_name) + 6;
- if(ipaddr)
- optlen += strlen(ipaddr) + 4;
+ optlen += MAX_ADDRESS_LEN + 4;
  if(mountpassword)
  optlen += strlen(mountpassword) + 6;
+mount_retry:
  SAFE_FREE(options);
  options_size = optlen + 10 + DOMAIN_SIZE;
  options = (char *)malloc(options_size /* space for commas in password */ + 8 /* space for domain=  , domain name itself was counted as part of the length username string above */);
@@ -1338,18 +1332,12 @@ mount_retry:
  exit(EX_SYSERR);
  }
 
- options[0] = 0;
- strlcpy(options,"unc=",options_size);
+ strlcpy(options, "unc=", options_size);
  strlcat(options,share_name,options_size);
  /* scan backwards and reverse direction of slash */
  temp = strrchr(options, '/');
  if(temp > options + 6)
  *temp = '\\';
- if(ipaddr) {
- strlcat(options,",ip=",options_size);
- strlcat(options,ipaddr,options_size);
- }
-
  if(user_name) {
  /* check for syntax like user=domain\user */
  if(got_domain == 0)
@@ -1391,11 +1379,42 @@ mount_retry:
  /* convert all '\\' to '/' in share portion so that /proc/mounts looks pretty */
  replace_char(dev_name, '\\', '/', strlen(share_name));
 
- if(mount(dev_name, mountpoint, "cifs", flags, options)) {
- /* remember to kill daemon on error */
+ if (!got_ip && addr) {
+ strlcat(options, ",ip=", options_size);
+ current_len = strnlen(options, options_size);
+ optionstail = options + current_len;
+ switch (addr->ai_addr->sa_family) {
+ case AF_INET6:
+ addr6 = (struct sockaddr_in6 *) addr->ai_addr;
+ ipaddr = inet_ntop(AF_INET6, &addr6->sin6_addr, optionstail,
+   options_size - current_len);
+ break;
+ case AF_INET:
+ addr4 = (struct sockaddr_in *) addr->ai_addr;
+ ipaddr = inet_ntop(AF_INET, &addr4->sin_addr, optionstail,
+   options_size - current_len);
+ break;
+ }
+
+ /* if the address looks bogus, try the next one */
+ if (!ipaddr) {
+ addr = addr->ai_next;
+ if (addr)
+ goto mount_retry;
+ rc = EX_SYSERR;
+ goto mount_exit;
+ }
+ }
+
+ if (mount(dev_name, mountpoint, "cifs", flags, options)) {
  switch (errno) {
- case 0:
- printf("mount failed but no error number set\n");
+ case ECONNREFUSED:
+ case EHOSTUNREACH:
+ if (addr) {
+ addr = addr->ai_next;
+ if (addr)
+ goto mount_retry;
+ }
  break;
  case ENODEV:
  printf("mount error: cifs filesystem not supported by the system\n");
@@ -1410,64 +1429,64 @@ mount_retry:
  goto mount_retry;
  }
  }
- default:
- printf("mount error %d = %s\n",errno,strerror(errno));
  }
+ printf("mount error(%d): %s\n", errno, strerror(errno));
  printf("Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)\n");
  rc = EX_FAIL;
- } else {
- atexit(unlock_mtab);
- rc = lock_mtab();
- if (rc) {
- printf("cannot lock mtab");
- goto mount_exit;
- }
- pmntfile = setmntent(MOUNTED, "a+");
- if (!pmntfile) {
- printf("could not update mount table\n");
- unlock_mtab();
- rc = EX_FILEIO;
- goto mount_exit;
- }
- mountent.mnt_fsname = dev_name;
- mountent.mnt_dir = mountpoint;
- mountent.mnt_type = CONST_DISCARD(char *,"cifs");
- mountent.mnt_opts = (char *)malloc(220);
- if(mountent.mnt_opts) {
- char * mount_user = getusername();
- memset(mountent.mnt_opts,0,200);
- if(flags & MS_RDONLY)
- strlcat(mountent.mnt_opts,"ro",220);
- else
- strlcat(mountent.mnt_opts,"rw",220);
- if(flags & MS_MANDLOCK)
- strlcat(mountent.mnt_opts,",mand",220);
- if(flags & MS_NOEXEC)
- strlcat(mountent.mnt_opts,",noexec",220);
- if(flags & MS_NOSUID)
- strlcat(mountent.mnt_opts,",nosuid",220);
- if(flags & MS_NODEV)
- strlcat(mountent.mnt_opts,",nodev",220);
- if(flags & MS_SYNCHRONOUS)
- strlcat(mountent.mnt_opts,",sync",220);
- if(mount_user) {
- if(getuid() != 0) {
- strlcat(mountent.mnt_opts,
- ",user=", 220);
- strlcat(mountent.mnt_opts,
- mount_user, 220);
- }
+ goto mount_exit;
+ }
+
+ atexit(unlock_mtab);
+ rc = lock_mtab();
+ if (rc) {
+ printf("cannot lock mtab");
+ goto mount_exit;
+ }
+ pmntfile = setmntent(MOUNTED, "a+");
+ if (!pmntfile) {
+ printf("could not update mount table\n");
+ unlock_mtab();
+ rc = EX_FILEIO;
+ goto mount_exit;
+ }
+ mountent.mnt_fsname = dev_name;
+ mountent.mnt_dir = mountpoint;
+ mountent.mnt_type = CONST_DISCARD(char *,"cifs");
+ mountent.mnt_opts = (char *)malloc(220);
+ if(mountent.mnt_opts) {
+ char * mount_user = getusername();
+ memset(mountent.mnt_opts,0,200);
+ if(flags & MS_RDONLY)
+ strlcat(mountent.mnt_opts,"ro",220);
+ else
+ strlcat(mountent.mnt_opts,"rw",220);
+ if(flags & MS_MANDLOCK)
+ strlcat(mountent.mnt_opts,",mand",220);
+ if(flags & MS_NOEXEC)
+ strlcat(mountent.mnt_opts,",noexec",220);
+ if(flags & MS_NOSUID)
+ strlcat(mountent.mnt_opts,",nosuid",220);
+ if(flags & MS_NODEV)
+ strlcat(mountent.mnt_opts,",nodev",220);
+ if(flags & MS_SYNCHRONOUS)
+ strlcat(mountent.mnt_opts,",sync",220);
+ if(mount_user) {
+ if(getuid() != 0) {
+ strlcat(mountent.mnt_opts,
+ ",user=", 220);
+ strlcat(mountent.mnt_opts,
+ mount_user, 220);
  }
  }
- mountent.mnt_freq = 0;
- mountent.mnt_passno = 0;
- rc = addmntent(pmntfile,&mountent);
- endmntent(pmntfile);
- unlock_mtab();
- SAFE_FREE(mountent.mnt_opts);
- if (rc)
- rc = EX_FILEIO;
  }
+ mountent.mnt_freq = 0;
+ mountent.mnt_passno = 0;
+ rc = addmntent(pmntfile,&mountent);
+ endmntent(pmntfile);
+ unlock_mtab();
+ SAFE_FREE(mountent.mnt_opts);
+ if (rc)
+ rc = EX_FILEIO;
 mount_exit:
  if(mountpassword) {
  int len = strlen(mountpassword);
@@ -1475,6 +1494,8 @@ mount_exit:
  SAFE_FREE(mountpassword);
  }
 
+ if (addrhead)
+ freeaddrinfo(addrhead);
  SAFE_FREE(options);
  SAFE_FREE(orgoptions);
  SAFE_FREE(resolved_path);
--
1.5.5.1

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[Jeff Layton-2]

On Mon, 10 Nov 2008 12:45:35 -0500
Jeff Layton <jlayton@...> wrote:

> The current name resolution scheme in mount.cifs is IPv4 only. Expand
> it to be protocol-independent. Also take advantage of the fact that
> getaddrinfo() returns a list of addresses and have mount.cifs try each
> in turn until it hits one that's reachable and allows the socket to
> connect.
>
> This is the second attempt at this patch. The first one had a possible
> NULL pointer dereference that could occur if the user specified the
> address.
>
> Signed-off-by: Jeff Layton <jlayton@...>
> ---
>  source3/client/mount.cifs.c |  223 +++++++++++++++++++++++-------------------
>  1 files changed, 122 insertions(+), 101 deletions(-)
>

I've gone ahead and pushed a slight variant of this to master,
v3-3-test and v3-2-test. I left it out of v3-0-test since it's a pretty
big change and the later branches have diverged quite a bit from it.

Cheers,
--
Jeff Layton <jlayton@...>
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[Jeremy Allison]

On Fri, Dec 12, 2008 at 07:14:24AM -0500, Jeff Layton wrote:

> On Mon, 10 Nov 2008 12:45:35 -0500
> Jeff Layton <jlayton@...> wrote:
>
> > The current name resolution scheme in mount.cifs is IPv4 only. Expand
> > it to be protocol-independent. Also take advantage of the fact that
> > getaddrinfo() returns a list of addresses and have mount.cifs try each
> > in turn until it hits one that's reachable and allows the socket to
> > connect.
> >
> > This is the second attempt at this patch. The first one had a possible
> > NULL pointer dereference that could occur if the user specified the
> > address.
> >
> > Signed-off-by: Jeff Layton <jlayton@...>
> > ---
> >  source3/client/mount.cifs.c |  223 +++++++++++++++++++++++-------------------
> >  1 files changed, 122 insertions(+), 101 deletions(-)
> >
>
> I've gone ahead and pushed a slight variant of this to master,
> v3-3-test and v3-2-test. I left it out of v3-0-test since it's a pretty
> big change and the later branches have diverged quite a bit from it.

That's correct, 3.0.x doesn't support IPv6 at all.

Jeremy.
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