Quoting Stéphane Graber (stgra...@ubuntu.com):
> On Mon, Jul 21, 2014 at 07:27:02PM +0000, Serge Hallyn wrote:
> > Rather than always using eth0. Otherwise unpriv containers cannot have
> > multiple lxc.network.type = veth's without manually setting
> > lxc.network.name =.
> >
> > Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
> > ---
> > src/lxc/lxc_user_nic.c | 31 ++++++++++++++++++++++++++-----
> > 1 file changed, 26 insertions(+), 5 deletions(-)
> >
> > diff --git a/src/lxc/lxc_user_nic.c b/src/lxc/lxc_user_nic.c
> > index 1105b3d..75e4851 100644
> > --- a/src/lxc/lxc_user_nic.c
> > +++ b/src/lxc/lxc_user_nic.c
> > @@ -470,7 +470,7 @@ again:
> > goto again;
> > }
> >
> > -static int rename_in_ns(int pid, char *oldname, char *newname)
> > +static int rename_in_ns(int pid, char *oldname, char **newnamep)
> > {
> > char nspath[MAXPATHLEN];
> > int fd = -1, ofd = -1, ret;
> > @@ -495,8 +495,29 @@ static int rename_in_ns(int pid, char *oldname, char
> > *newname)
> > goto out_err;
> > }
> > close(fd); fd = -1;
> > - if ((ret = lxc_netdev_rename_by_name(oldname, newname)) < 0) {
> > - fprintf(stderr, "Error %d renaming netdev %s to %s in
> > container\n", ret, oldname, newname);
> > +
> > + if (!*newnamep) {
> > + int i = 0;
> > + char nicname[10];
> > + while (i < 100) {
> > + ret = snprintf(nicname, 10, "eth%d", i);
> > + if (ret < 0 || ret >= 10)
> > + return -1;
> > + if (if_nametoindex(nicname) == 0)
> > + break;
> > + i++;
> > + }
> > + if (i == 100) {
> > + fprintf(stderr, "too many nics in container\n");
> > + return -1;
> > + }
> > + *newnamep = strdup(nicname);
> > + if (!*newnamep)
> > + return -1;
> > + }
>
> As I said on IRC, are you sure we can't somehow get rid of all of that
> code and just somehow pass 'eth%d' to the kernel through netlink which
> will then make it use the next available ethX device (we already use
> that trick for privileged networking).
From 01950a5f05c6a9d1a6aed05c993ba2d1952c65a9 Mon Sep 17 00:00:00 2001
From: Serge Hallyn <serge.hal...@ubuntu.com>
Date: Mon, 21 Jul 2014 16:36:44 -0500
Subject: [PATCH 1/1] unprivileged containers: use next available nic name if
unspecified
Rather than always using eth0. Otherwise unpriv containers cannot have
multiple lxc.network.type = veth's without manually setting
lxc.network.name =.
Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
---
src/lxc/lxc_user_nic.c | 35 +++++++++++++++++++++++++++--------
1 file changed, 27 insertions(+), 8 deletions(-)
diff --git a/src/lxc/lxc_user_nic.c b/src/lxc/lxc_user_nic.c
index 1105b3d..5a1f6db 100644
--- a/src/lxc/lxc_user_nic.c
+++ b/src/lxc/lxc_user_nic.c
@@ -470,10 +470,13 @@ again:
goto again;
}
-static int rename_in_ns(int pid, char *oldname, char *newname)
+#define VETH_DEF_NAME "eth%d"
+
+static int rename_in_ns(int pid, char *oldname, char **newnamep)
{
char nspath[MAXPATHLEN];
- int fd = -1, ofd = -1, ret;
+ int fd = -1, ofd = -1, ret, ifindex;
+ bool grab_newname = false;
ret = snprintf(nspath, MAXPATHLEN, "/proc/%d/ns/net", getpid());
if (ret < 0 || ret >= MAXPATHLEN)
@@ -495,10 +498,28 @@ static int rename_in_ns(int pid, char *oldname, char
*newname)
goto out_err;
}
close(fd); fd = -1;
- if ((ret = lxc_netdev_rename_by_name(oldname, newname)) < 0) {
- fprintf(stderr, "Error %d renaming netdev %s to %s in
container\n", ret, oldname, newname);
+ if (!*newnamep) {
+ grab_newname = true;
+ *newnamep = VETH_DEF_NAME;
+ if (!(ifindex = if_nametoindex(oldname))) {
+ fprintf(stderr, "failed to get netdev index\n");
+ goto out_err;
+ }
+ }
+ if ((ret = lxc_netdev_rename_by_name(oldname, *newnamep)) < 0) {
+ fprintf(stderr, "Error %d renaming netdev %s to %s in
container\n", ret, oldname, *newnamep);
goto out_err;
}
+ if (grab_newname) {
+ char ifname[IFNAMSIZ], *namep = ifname;
+ if (!if_indextoname(ifindex, namep)) {
+ fprintf(stderr, "Failed to get new netdev name\n");
+ goto out_err;
+ }
+ *newnamep = strdup(namep);
+ if (!*newnamep)
+ goto out_err;
+ }
if (setns(ofd, 0) < 0) {
fprintf(stderr, "Error returning to original netns\n");
close(ofd);
@@ -566,7 +587,7 @@ int main(int argc, char *argv[])
char *me;
char *nicname = alloca(40);
char *cnic = NULL; // created nic name in container is returned here.
- char *vethname;
+ char *vethname = NULL;
int pid;
if ((me = get_username()) == NULL) {
@@ -578,8 +599,6 @@ int main(int argc, char *argv[])
usage(argv[0], true);
if (argc >= 5)
vethname = argv[4];
- else
- vethname = "eth0";
errno = 0;
pid = (int) strtol(argv[1], NULL, 10);
@@ -614,7 +633,7 @@ int main(int argc, char *argv[])
}
// Now rename the link
- if (rename_in_ns(pid, cnic, vethname) < 0) {
+ if (rename_in_ns(pid, cnic, &vethname) < 0) {
fprintf(stderr, "Failed to rename the link\n");
exit(1);
}
--
1.9.1
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