cifs: Allow binding to local IP address.

When using multi-homed machines, it's nice to be able to specify
the local IP to use for outbound connections.  This patch gives
cifs the ability to bind to a particular IP address.

   Usage:  mount -t cifs -o srcaddr=192.168.1.50,user=foo, ...
   Usage:  mount -t cifs -o srcaddr=2002::100:1,user=foo, ...

Acked-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Dr. David Holder <david.holder@erion.co.uk>
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index b7431afdd76d57fb17ef70385428dd5c132020f2..1b6ddd6f760f34c58a6b43c293d46c0033349996 100644 (file)
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -36,6 +36,7 @@
 #include <linux/kthread.h>
 #include <linux/freezer.h>
 #include <linux/smp_lock.h>
+#include <net/ipv6.h>
 #include "cifsfs.h"
 #include "cifspdu.h"
 #define DECLARE_GLOBALS_HERE
@@ -367,6 +368,8 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)
 {
        struct cifs_sb_info *cifs_sb = CIFS_SB(m->mnt_sb);
        struct cifsTconInfo *tcon = cifs_sb->tcon;
+       struct sockaddr *srcaddr;
+       srcaddr = (struct sockaddr *)&tcon->ses->server->srcaddr;
 
        seq_printf(s, ",unc=%s", tcon->treeName);
        if (tcon->ses->userName)
@@ -374,6 +377,22 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)
        if (tcon->ses->domainName)
                seq_printf(s, ",domain=%s", tcon->ses->domainName);
 
+       if (srcaddr->sa_family != AF_UNSPEC) {
+               struct sockaddr_in *saddr4;
+               struct sockaddr_in6 *saddr6;
+               saddr4 = (struct sockaddr_in *)srcaddr;
+               saddr6 = (struct sockaddr_in6 *)srcaddr;
+               if (srcaddr->sa_family == AF_INET6)
+                       seq_printf(s, ",srcaddr=%pI6c",
+                                  &saddr6->sin6_addr);
+               else if (srcaddr->sa_family == AF_INET)
+                       seq_printf(s, ",srcaddr=%pI4",
+                                  &saddr4->sin_addr.s_addr);
+               else
+                       seq_printf(s, ",srcaddr=BAD-AF:%i",
+                                  (int)(srcaddr->sa_family));
+       }
+
        seq_printf(s, ",uid=%d", cifs_sb->mnt_uid);
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_UID)
                seq_printf(s, ",forceuid");

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index c68f31cf455061b91c605e92085ad0d556f62210..6ef0efaf68d430eaf83446353e57c07da6461ca5 100644 (file)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -139,6 +139,7 @@ struct TCP_Server_Info {
                struct sockaddr_in sockAddr;
                struct sockaddr_in6 sockAddr6;
        } addr;
+       struct sockaddr_storage srcaddr; /* locally bind to this IP */
        wait_queue_head_t response_q;
        wait_queue_head_t request_q; /* if more than maxmpx to srvr must block*/
        struct list_head pending_mid_q;

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c99760a523bfe8256aa19eee65134d4090b88350..fa884520fb84a9c5c588385f0d799da5ea9a3765 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -105,6 +105,7 @@ struct smb_vol {
        bool sockopt_tcp_nodelay:1;
        unsigned short int port;
        char *prepath;
+       struct sockaddr_storage srcaddr; /* allow binding to a local IP */
        struct nls_table *local_nls;
 };
 
@@ -1046,6 +1047,22 @@ cifs_parse_mount_options(char *options, const char *devname,
                                                    "long\n");
                                return 1;
                        }
+               } else if (strnicmp(data, "srcaddr", 7) == 0) {
+                       vol->srcaddr.ss_family = AF_UNSPEC;
+
+                       if (!value || !*value) {
+                               printk(KERN_WARNING "CIFS: srcaddr value"
+                                      " not specified.\n");
+                               return 1;       /* needs_arg; */
+                       }
+                       i = cifs_convert_address((struct sockaddr *)&vol->srcaddr,
+                                                value, strlen(value));
+                       if (i < 0) {
+                               printk(KERN_WARNING "CIFS:  Could not parse"
+                                      " srcaddr: %s\n",
+                                      value);
+                               return 1;
+                       }
                } else if (strnicmp(data, "prefixpath", 10) == 0) {
                        if (!value || !*value) {
                                printk(KERN_WARNING
@@ -1374,8 +1391,36 @@ cifs_parse_mount_options(char *options, const char *devname,
        return 0;
 }
 
+/** Returns true if srcaddr isn't specified and rhs isn't
+ * specified, or if srcaddr is specified and
+ * matches the IP address of the rhs argument.
+ */
+static bool
+srcip_matches(struct sockaddr *srcaddr, struct sockaddr *rhs)
+{
+       switch (srcaddr->sa_family) {
+       case AF_UNSPEC:
+               return (rhs->sa_family == AF_UNSPEC);
+       case AF_INET: {
+               struct sockaddr_in *saddr4 = (struct sockaddr_in *)srcaddr;
+               struct sockaddr_in *vaddr4 = (struct sockaddr_in *)rhs;
+               return (saddr4->sin_addr.s_addr == vaddr4->sin_addr.s_addr);
+       }
+       case AF_INET6: {
+               struct sockaddr_in6 *saddr6 = (struct sockaddr_in6 *)srcaddr;
+               struct sockaddr_in6 *vaddr6 = (struct sockaddr_in6 *)&rhs;
+               return ipv6_addr_equal(&saddr6->sin6_addr, &vaddr6->sin6_addr);
+       }
+       default:
+               WARN_ON(1);
+               return false; /* don't expect to be here */
+       }
+}
+
+
 static bool
-match_address(struct TCP_Server_Info *server, struct sockaddr *addr)
+match_address(struct TCP_Server_Info *server, struct sockaddr *addr,
+             struct sockaddr *srcaddr)
 {
        struct sockaddr_in *addr4 = (struct sockaddr_in *)addr;
        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)addr;
@@ -1402,6 +1447,9 @@ match_address(struct TCP_Server_Info *server, struct sockaddr *addr)
                break;
        }
 
+       if (!srcip_matches(srcaddr, (struct sockaddr *)&server->srcaddr))
+               return false;
+
        return true;
 }
 
@@ -1469,7 +1517,8 @@ cifs_find_tcp_session(struct sockaddr *addr, struct smb_vol *vol)
                if (server->tcpStatus == CifsNew)
                        continue;
 
-               if (!match_address(server, addr))
+               if (!match_address(server, addr,
+                                  (struct sockaddr *)&vol->srcaddr))
                        continue;
 
                if (!match_security(server, vol))
@@ -1584,6 +1633,8 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
         * no need to spinlock this init of tcpStatus or srv_count
         */
        tcp_ses->tcpStatus = CifsNew;
+       memcpy(&tcp_ses->srcaddr, &volume_info->srcaddr,
+              sizeof(tcp_ses->srcaddr));
        ++tcp_ses->srv_count;
 
        if (addr.ss_family == AF_INET6) {
@@ -1999,6 +2050,33 @@ static void rfc1002mangle(char *target, char *source, unsigned int length)
 
 }
 
+static int
+bind_socket(struct TCP_Server_Info *server)
+{
+       int rc = 0;
+       if (server->srcaddr.ss_family != AF_UNSPEC) {
+               /* Bind to the specified local IP address */
+               struct socket *socket = server->ssocket;
+               rc = socket->ops->bind(socket,
+                                      (struct sockaddr *) &server->srcaddr,
+                                      sizeof(server->srcaddr));
+               if (rc < 0) {
+                       struct sockaddr_in *saddr4;
+                       struct sockaddr_in6 *saddr6;
+                       saddr4 = (struct sockaddr_in *)&server->srcaddr;
+                       saddr6 = (struct sockaddr_in6 *)&server->srcaddr;
+                       if (saddr6->sin6_family == AF_INET6)
+                               cERROR(1, "cifs: "
+                                      "Failed to bind to: %pI6c, error: %d\n",
+                                      &saddr6->sin6_addr, rc);
+                       else
+                               cERROR(1, "cifs: "
+                                      "Failed to bind to: %pI4, error: %d\n",
+                                      &saddr4->sin_addr.s_addr, rc);
+               }
+       }
+       return rc;
+}
 
 static int
 ipv4_connect(struct TCP_Server_Info *server)
@@ -2024,6 +2102,10 @@ ipv4_connect(struct TCP_Server_Info *server)
                cifs_reclassify_socket4(socket);
        }
 
+       rc = bind_socket(server);
+       if (rc < 0)
+               return rc;
+
        /* user overrode default port */
        if (server->addr.sockAddr.sin_port) {
                rc = socket->ops->connect(socket, (struct sockaddr *)
@@ -2186,6 +2268,10 @@ ipv6_connect(struct TCP_Server_Info *server)
                cifs_reclassify_socket6(socket);
        }
 
+       rc = bind_socket(server);
+       if (rc < 0)
+               return rc;
+
        /* user overrode default port */
        if (server->addr.sockAddr6.sin6_port) {
                rc = socket->ops->connect(socket,