[Qemu-devel] [PATCH 1/1] Add ifname support to -netdev tap and bridge when using helper

[Shaun Reitan]

Hi, I've modified the qemu source to add support for specifying a ifname 
when using -netdev tap or -netdev bridge with a helper. Currently this 
is not supported and all interface names are named tap0, tap1, ...

Hopfully i'm submitting this correctly, if not I appologize. Also, my C 
is a bit rusty... well it was never great to begin with :)

--
Shaun Reitan
NDCHost.com


> From 9af8c88781d63637822c6edea1f83e98199a570b Mon Sep 17 00:00:00 2001
From: Shaun Reitan <address@hidden>
Date: Mon, 15 Jan 2018 17:40:38 -0800
Subject: [PATCH 1/4] Add support for setting a TAP interface name

Signed-off-by: Shaun Reitan <address@hidden>
---
 qemu-bridge-helper.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c
index 5396fbf..7b01cd5 100644
--- a/qemu-bridge-helper.c
+++ b/qemu-bridge-helper.c
@@ -57,7 +57,7 @@ typedef QSIMPLEQ_HEAD(ACLList, ACLRule) ACLList;
 static void usage(void)
 {
     fprintf(stderr,
- "Usage: qemu-bridge-helper [--use-vnet] --br=bridge --fd=unixfd\n");
+ "Usage: qemu-bridge-helper [--use-vnet] --br=bridge --fd=unixfd 
[--ifname=name]\n");
 }

 static int parse_acl_file(const char *filename, ACLList *acl_list)
@@ -223,6 +223,7 @@ int main(int argc, char **argv)
     int use_vnet = 0;
     int mtu;
     const char *bridge = NULL;
+ const char *ifname = NULL;
     char iface[IFNAMSIZ];
     int index;
     ACLRule *acl_rule;
@@ -249,6 +250,8 @@ int main(int argc, char **argv)
             bridge = &argv[index][5];
         } else if (strncmp(argv[index], "--fd=", 5) == 0) {
             unixfd = atoi(&argv[index][5]);
+ } else if (strncmp(argv[index], "--ifname=", 9) == 0) {
+ ifname = &argv[index][9];
         } else {
             usage();
             return EXIT_FAILURE;
@@ -320,7 +323,11 @@ int main(int argc, char **argv)

     /* request a tap device, disable PI, and add vnet header support if
      * requested and it's available. */
- prep_ifreq(&ifr, "tap%d");
+ if (ifname == NULL) {
+ prep_ifreq(&ifr, "tap%d");
+ } else {
+ prep_ifreq(&ifr, ifname);
+ }
     ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
     if (use_vnet && has_vnet_hdr(fd)) {
         ifr.ifr_flags |= IFF_VNET_HDR;
--
2.9.5


> From 35a24821d437d1955c00dc64f7cd82d24e31ecda Mon Sep 17 00:00:00 2001
From: Shaun Reitan <address@hidden>
Date: Mon, 15 Jan 2018 17:42:32 -0800
Subject: [PATCH 2/4] Add ifname to NetdevBridgeOptions

Signed-off-by: Shaun Reitan <address@hidden>
---
 qapi/net.json | 1 +
 1 file changed, 1 insertion(+)

diff --git a/qapi/net.json b/qapi/net.json
index 4beff5d..5b5b281 100644
--- a/qapi/net.json
+++ b/qapi/net.json
@@ -402,6 +402,7 @@
 { 'struct': 'NetdevBridgeOptions',
   'data': {
     '*br': 'str',
+ '*ifname': 'str',
     '*helper': 'str' } }

 ##
--
2.9.5


> From 92bbc897a04628358e6d698d70c5a257a912b67c Mon Sep 17 00:00:00 2001
From: Shaun Reitan <address@hidden>
Date: Mon, 15 Jan 2018 17:43:24 -0800
Subject: [PATCH 3/4] Add ifname support to -netdev bridge options

Signed-off-by: Shaun Reitan <address@hidden>
---
 qemu-options.hx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qemu-options.hx b/qemu-options.hx
index 678181c..81cbc3c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1961,7 +1961,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
     " use 'queues=n' to specify the number of queues to be created for 
multiqueue TAP\n"
     " use 'poll-us=n' to speciy the maximum number of microseconds that 
could be\n"
     " spent on busy polling for vhost net\n"
- "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
+ "-netdev bridge,id=str[,br=bridge][,helper=helper][,ifname=name]\n"
     " configure a host TAP network backend with ID 'str' that is\n"
     " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
     " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
--
2.9.5


> From 797ca0174430ffd0dc8c5a36ce86380816ff2eee Mon Sep 17 00:00:00 2001
From: Shaun Reitan <address@hidden>
Date: Mon, 15 Jan 2018 17:43:42 -0800
Subject: [PATCH 4/4] Add ability to set ifname when using -netdev bridge 
and
 -netdev tap when using a helper

Signed-off-by: Shaun Reitan <address@hidden>
---
 net/tap.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/net/tap.c b/net/tap.c
index 979e622..1180094 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -472,7 +472,7 @@ static int recv_fd(int c)
 }

 static int net_bridge_run_helper(const char *helper, const char 
*bridge,
- Error **errp)
+ const char *ifname, Error **errp)
 {
     sigset_t oldmask, mask;
     int pid, status;
@@ -499,7 +499,8 @@ static int net_bridge_run_helper(const char *helper, 
const char *bridge,
         int open_max = sysconf(_SC_OPEN_MAX), i;
         char fd_buf[6+10];
         char br_buf[6+IFNAMSIZ] = {0};
- char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) + 15];
+ char ifname_buf[10+IFNAMSIZ];
+ char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) + 
sizeof(ifname_buf) + 15];

         for (i = 3; i < open_max; i++) {
             if (i != sv[1]) {
@@ -516,8 +517,12 @@ static int net_bridge_run_helper(const char 
*helper, const char *bridge,
                 snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", 
bridge);
             }

- snprintf(helper_cmd, sizeof(helper_cmd), "%s %s %s %s",
- helper, "--use-vnet", fd_buf, br_buf);
+ if (strstr(helper, "--ifname=") == NULL && ifname != NULL) {
+ snprintf(ifname_buf, sizeof(ifname_buf), "%s%s", "--ifname=", ifname);
+ }
+
+ snprintf(helper_cmd, sizeof(helper_cmd), "%s %s %s %s %s",
+ helper, "--use-vnet", fd_buf, br_buf, ifname_buf);

             parg = args;
             *parg++ = (char *)"sh";
@@ -536,6 +541,12 @@ static int net_bridge_run_helper(const char 
*helper, const char *bridge,
             *parg++ = (char *)"--use-vnet";
             *parg++ = fd_buf;
             *parg++ = br_buf;
+
+ if (ifname != NULL) {
+ snprintf(ifname_buf, sizeof(ifname_buf), "%s%s", "--ifname=", ifname);
+ *parg++ = ifname_buf;
+ }
+
             *parg++ = NULL;

             execv(helper, args);
@@ -586,7 +597,7 @@ int net_init_bridge(const Netdev *netdev, const char 
*name,
     helper = bridge->has_helper ? bridge->helper : 
DEFAULT_BRIDGE_HELPER;
     br = bridge->has_br ? bridge->br : DEFAULT_BRIDGE_INTERFACE;

- fd = net_bridge_run_helper(helper, br, errp);
+ fd = net_bridge_run_helper(helper, br, bridge->ifname, errp);
     if (fd == -1) {
         return -1;
     }
@@ -854,16 +865,17 @@ free_fail:
         g_free(vhost_fds);
         return -1;
     } else if (tap->has_helper) {
- if (tap->has_ifname || tap->has_script || tap->has_downscript ||
- tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
- error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
- "queues=, and vhostfds= are invalid with helper=");
+ if (tap->has_script || tap->has_downscript || tap->has_vnet_hdr ||
+ tap->has_queues || tap->has_vhostfds) {
+ error_setg(errp, "script=, downscript=, vnet_hdr=, queues=, and "
+ "vhostfds= are invalid with helper=");
             return -1;
         }

         fd = net_bridge_run_helper(tap->helper,
                                    tap->has_br ?
                                    tap->br : DEFAULT_BRIDGE_INTERFACE,
+ tap->ifname,
                                    errp);
         if (fd == -1) {
             return -1;
--
2.9.5