Currently, netconsole has two methods of configuration - module
parameter and configfs. The former interface allows for netconsole
activation earlier during boot (by specifying the module parameter on
the kernel command line), so it is preferred for debugging issues which
arise before userspace is up/the configfs interface can be used. The
module parameter syntax requires specifying the egress interface name.
This requirement makes it hard to use for a couple reasons:
- The egress interface name can be hard or impossible to predict. For
example, installing a new network card in a system can change the
interface names assigned by the kernel.
- When constructing the module parameter, one may have trouble
determining the original (kernel-assigned) name of the interface
(which is the name that should be given to netconsole) if some stable
interface naming scheme is in effect. A human can usually look at
kernel logs to determine the original name, but this is very painful
if automation is constructing the parameter.
For these reasons, allow selection of the egress interface via MAC
address when configuring netconsole using the module parameter. Update
the netconsole documentation with an example of the new syntax.
Selection of egress interface by MAC address via configfs is far less
interesting (since when this interface can be used, one should be able
to easily convert between MAC address and interface name), so it is left
unimplemented.
Signed-off-by: Uday Shankar <ushankar@xxxxxxxxxxxxxxx>
Reviewed-by: Breno Leitao <leitao@xxxxxxxxxx>
Tested-by: Breno Leitao <leitao@xxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
---
Documentation/networking/netconsole.rst | 6 +++-
include/linux/netpoll.h | 6 ++++
net/core/netpoll.c | 51 +++++++++++++++++++++++++--------
3 files changed, 50 insertions(+), 13 deletions(-)
diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst
index ae82a6337a8d8a07a0d691e2da170f6cf70ae86f..ec740ba127976bf9c978d7b2811fb1735c1a004e 100644
--- a/Documentation/networking/netconsole.rst
+++ b/Documentation/networking/netconsole.rst
@@ -47,7 +47,7 @@ following format::
r if present, prepend kernel version (release) to the message
src-port source for UDP packets (defaults to 6665)
src-ip source IP to use (interface address)
- dev network interface (eth0)
+ dev network interface name (eth0) or MAC address
tgt-port port for logging agent (6666)
tgt-ip IP address for logging agent
tgt-macaddr ethernet MAC address for logging agent (broadcast)
@@ -64,6 +64,10 @@ or using IPv6::
insmod netconsole netconsole=@/,@fd00:1:2:3::1/
+or using a MAC address to select the egress interface::
+
+ linux netconsole=4444@10.0.0.1/22:33:44:55:66:77,9353@10.0.0.2/12:34:56:78:9a:bc
+
It also supports logging to multiple remote agents by specifying
parameters for the multiple agents separated by semicolons and the
complete string enclosed in "quotes", thusly::
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index f6e8abe0b1f19a34a35ec976c127be468d863028..0477208ed9ffa5cc57b072dce35f0789169fc37b 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -25,7 +25,13 @@ union inet_addr {
struct netpoll {
struct net_device *dev;
netdevice_tracker dev_tracker;
+ /*
+ * Either dev_name or dev_mac can be used to specify the local
+ * interface - dev_name is used if it is a nonempty string, else
+ * dev_mac is used.
+ */
char dev_name[IFNAMSIZ];
+ u8 dev_mac[ETH_ALEN];
const char *name;
union inet_addr local_ip, remote_ip;
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 8a0df2b274a88213f4ca4632ecbb66d74ac960a9..976202d10297a6d7687b8251561ae73c64118f57 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -502,7 +502,8 @@ void netpoll_print_options(struct netpoll *np)
np_info(np, "local IPv6 address %pI6c\n", &np->local_ip.in6);
else
np_info(np, "local IPv4 address %pI4\n", &np->local_ip.ip);
- np_info(np, "interface '%s'\n", np->dev_name);
+ np_info(np, "interface name '%s'\n", np->dev_name);
+ np_info(np, "local ethernet address '%pM'\n", np->dev_mac);
np_info(np, "remote port %d\n", np->remote_port);
if (np->ipv6)
np_info(np, "remote IPv6 address %pI6c\n", &np->remote_ip.in6);
@@ -572,11 +573,18 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
cur++;
if (*cur != ',') {
- /* parse out dev name */
+ /* parse out dev_name or dev_mac */
if ((delim = strchr(cur, ',')) == NULL)
goto parse_failed;
*delim = 0;
- strscpy(np->dev_name, cur, sizeof(np->dev_name));
+
+ np->dev_name[0] = '\0';
+ eth_broadcast_addr(np->dev_mac);
+ if (!strchr(cur, ':'))
+ strscpy(np->dev_name, cur, sizeof(np->dev_name));
+ else if (!mac_pton(cur, np->dev_mac))
+ goto parse_failed;
+
cur = delim;
}
cur++;
@@ -690,27 +698,45 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
}
EXPORT_SYMBOL_GPL(__netpoll_setup);
+/*
+ * Returns a pointer to a string representation of the identifier used
+ * to select the egress interface for the given netpoll instance. buf
+ * must be a buffer of length at least MAC_ADDR_STR_LEN + 1.
+ */
+static char *egress_dev(struct netpoll *np, char *buf)
+{
+ if (np->dev_name[0])
+ return np->dev_name;
+
+ snprintf(buf, MAC_ADDR_STR_LEN, "%pM", np->dev_mac);
+ return buf;
+}
+
int netpoll_setup(struct netpoll *np)
{
+ struct net *net = current->nsproxy->net_ns;
+ char buf[MAC_ADDR_STR_LEN + 1];
struct net_device *ndev = NULL;
bool ip_overwritten = false;
struct in_device *in_dev;
int err;
rtnl_lock();
- if (np->dev_name[0]) {
- struct net *net = current->nsproxy->net_ns;
+ if (np->dev_name[0])
ndev = __dev_get_by_name(net, np->dev_name);
- }
+ else if (is_valid_ether_addr(np->dev_mac))
+ ndev = dev_getbyhwaddr(net, ARPHRD_ETHER, np->dev_mac);
+
if (!ndev) {
- np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
+ np_err(np, "%s doesn't exist, aborting\n", egress_dev(np, buf));
err = -ENODEV;
goto unlock;
}
netdev_hold(ndev, &np->dev_tracker, GFP_KERNEL);
if (netdev_master_upper_dev_get(ndev)) {
- np_err(np, "%s is a slave device, aborting\n", np->dev_name);
+ np_err(np, "%s is a slave device, aborting\n",
+ egress_dev(np, buf));
err = -EBUSY;
goto put;
}
@@ -718,7 +744,8 @@ int netpoll_setup(struct netpoll *np)
if (!netif_running(ndev)) {
unsigned long atmost;
- np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
+ np_info(np, "device %s not up yet, forcing it\n",
+ egress_dev(np, buf));
err = dev_open(ndev, NULL);
@@ -752,7 +779,7 @@ int netpoll_setup(struct netpoll *np)
if (!ifa) {
put_noaddr:
np_err(np, "no IP address for %s, aborting\n",
- np->dev_name);
+ egress_dev(np, buf));
err = -EDESTADDRREQ;
goto put;
}
@@ -783,13 +810,13 @@ int netpoll_setup(struct netpoll *np)
}
if (err) {
np_err(np, "no IPv6 address for %s, aborting\n",
- np->dev_name);
+ egress_dev(np, buf));
goto put;
} else
np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
#else
np_err(np, "IPv6 is not supported %s, aborting\n",
- np->dev_name);
+ egress_dev(np, buf));
err = -EINVAL;
goto put;
#endif
--
2.34.1
