This makes a few changes to allow ifname to be specified when using
qemu-bridge-helper with both the bridge and tap network interfaces. It adds
the --ifname option to qemu-bridge-helper, removes the restriction that ifname
cannot be specified with helper for the tap interface, and adds logic to
specify the --ifname option when exec'ing the helper.
Signed-off-by: Mike Lovell <m...@dev-zero.net>
---
This feature was originally requested by Mario De Chenno on the qemu-devel
mailing list. Seems pretty simple and figured it was something I could throw
together pretty quickly. I have tested the following combinations of invoking
qemu (where qbr is qemu-bridge-helper)
qemu-system-x86_64 -net nic -net tap,helper="qbr --br=test1"
qemu-system-x86_64 -net nic -net tap,helper="qbr --br=test1",ifname=vm1
qemu-system-x86_64 -net nic -net tap,helper=qbr
qemu-system-x86_64 -net nic -net tap,helper=qbr,ifname=vm1
qemu-system-x86_64 -net nic -net bridge,helper=qbr
qemu-system-x86_64 -net nic -net bridge,helper=qbr,ifname=vm1
qemu-system-x86_64 -net nic -net bridge,helper=qbr,ifname=vm1,br=test1
qemu-system-x86_64 -net nic -net bridge,helper=qbr,br=test1
net/tap.c | 39 ++++++++++++++++++++++++++++-----------
qapi-schema.json | 3 ++-
qemu-bridge-helper.c | 10 +++++++---
3 files changed, 37 insertions(+), 15 deletions(-)
diff --git a/net/tap.c b/net/tap.c
index a88ae8f..cfb5bff 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -417,11 +417,13 @@ static int recv_fd(int c)
return len;
}
-static int net_bridge_run_helper(const char *helper, const char *bridge)
+static int net_bridge_run_helper(const char *helper,
+ const char *bridge,
+ const char *ifname)
{
sigset_t oldmask, mask;
int pid, status;
- char *args[5];
+ char *args[6];
char **parg;
int sv[2];
@@ -439,7 +441,9 @@ 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] = {0};
+ char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) +
+ sizeof(ifname_buf) + 15];
for (i = 0; i < open_max; i++) {
if (i != STDIN_FILENO &&
@@ -459,8 +463,13 @@ 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";
@@ -473,12 +482,17 @@ static int net_bridge_run_helper(const char *helper,
const char *bridge)
/* assume helper is just the executable path name */
snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
+ if (ifname != NULL) {
+ snprintf(ifname_buf, sizeof(ifname_buf), "%s%s" ,
+ "--ifname=", ifname);
+ }
parg = args;
*parg++ = (char *)helper;
*parg++ = (char *)"--use-vnet";
*parg++ = fd_buf;
*parg++ = br_buf;
+ *parg++ = ifname_buf;
*parg++ = NULL;
execv(helper, args);
@@ -517,7 +531,7 @@ int net_init_bridge(const NetClientOptions *opts, const
char *name,
NetClientState *peer)
{
const NetdevBridgeOptions *bridge;
- const char *helper, *br;
+ const char *helper, *br, *ifname;
TAPState *s;
int fd, vnet_hdr;
@@ -527,8 +541,9 @@ int net_init_bridge(const NetClientOptions *opts, const
char *name,
helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
br = bridge->has_br ? bridge->br : DEFAULT_BRIDGE_INTERFACE;
+ ifname = bridge->has_ifname ? bridge->ifname : NULL;
- fd = net_bridge_run_helper(helper, br);
+ fd = net_bridge_run_helper(helper, br, ifname);
if (fd == -1) {
return -1;
}
@@ -622,14 +637,16 @@ int net_init_tap(const NetClientOptions *opts, const char
*name,
model = "tap";
} else if (tap->has_helper) {
- if (tap->has_ifname || tap->has_script || tap->has_downscript ||
- tap->has_vnet_hdr) {
- error_report("ifname=, script=, downscript=, and vnet_hdr= "
+ if (tap->has_script || tap->has_downscript || tap->has_vnet_hdr) {
+ error_report("script=, downscript=, and vnet_hdr= "
"are invalid with helper=");
return -1;
}
- fd = net_bridge_run_helper(tap->helper, DEFAULT_BRIDGE_INTERFACE);
+ const char *ifname;
+ ifname = tap->has_ifname ? tap->ifname : NULL;
+ fd = net_bridge_run_helper(tap->helper, DEFAULT_BRIDGE_INTERFACE,
+ ifname);
if (fd == -1) {
return -1;
}
diff --git a/qapi-schema.json b/qapi-schema.json
index f9dbdae..feaac9e 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2432,7 +2432,8 @@
{ 'type': 'NetdevBridgeOptions',
'data': {
'*br': 'str',
- '*helper': 'str' } }
+ '*helper': 'str',
+ '*ifname': 'str' } }
##
# @NetdevHubPortOptions
diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c
index 652eec9..c1d1519 100644
--- a/qemu-bridge-helper.c
+++ b/qemu-bridge-helper.c
@@ -67,7 +67,8 @@ 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] [--ifname=name] "
+ "--br=bridge --fd=unixfd\n");
}
static int parse_acl_file(const char *filename, ACLList *acl_list)
@@ -239,6 +240,7 @@ int main(int argc, char **argv)
ACLList acl_list;
int access_allowed, access_denied;
int ret = EXIT_SUCCESS;
+ const char *ifname = NULL;
#ifdef CONFIG_LIBCAP
/* if we're run from an suid binary, immediately drop privileges
preserving
@@ -259,6 +261,8 @@ 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;
@@ -329,8 +333,8 @@ 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");
+ * requested and it's available. use ifname if provided for tap name. */
+ prep_ifreq(&ifr, ifname != NULL ? ifname : "tap%d");
ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
if (use_vnet && has_vnet_hdr(fd)) {
ifr.ifr_flags |= IFF_VNET_HDR;
