| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20251121-nbcon-v1-2-503d17b2b4af@debian.org>
Date: Fri, 21 Nov 2025 03:26:08 -0800
From: Breno Leitao <leitao@...ian.org>
To: Breno Leitao <leitao@...ian.org>, Jakub Kicinski <kuba@...nel.org>,
horms@...nel.org, efault@....de, john.ogness@...utronix.de,
pmladek@...e.com
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, calvin@...nvd.org, asml.silence@...il.com,
kernel-team@...a.com, gustavold@...il.com, asantostc@...il.com
Subject: [PATCH RFC net-next 2/2] netconsole: add CONFIG_NETCONSOLE_NBCON
for nbcon support
Add optional support for the nbcon infrastructure to netconsole via a new
CONFIG_NETCONSOLE_NBCON compile-time option.
The nbcon infrastructure provides a lock-free, priority-based console
system that supports atomic printing from any context including NMI,
with safe handover mechanisms between different priority levels. This
makes it particularly suitable for crash-safe kernel logging.
When disabled (default), netconsole uses the legacy console callbacks,
maintaining full backward compatibility.
PS: .write_atomic and .write_thread uses the same callback, given that
there is no safe .write_atomic, so .write_atomic is called as the last
resource. This is what CON_NBCON_ATOMIC_UNSAFE is telling nbcon.
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
drivers/net/Kconfig | 14 ++++++++++
drivers/net/netconsole.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 82 insertions(+)
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index ac12eaf11755..aa8771b5b723 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -369,6 +369,20 @@ config NETCONSOLE_PREPEND_RELEASE
message. See <file:Documentation/networking/netconsole.rst> for
details.
+config NETCONSOLE_NBCON
+ bool "Use nbcon infrastructure (EXPERIMENTAL)"
+ depends on NETCONSOLE
+ default n
+ help
+ Enable nbcon support for netconsole. This uses the new lock-free
+ console infrastructure which supports threaded and atomic printing.
+ Given that netconsole does not support atomic operations, the current
+ implementation focuses on threaded callbacks, unless the host is
+ crashing, then it uses an unsafe atomic callbacks. This feature is
+ available for both extended and non-extended consoles.
+
+ If unsure, say N to use the legacy console infrastructure.
+
config NETPOLL
def_bool NETCONSOLE
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index f4b1706fb081..2943f00b83f6 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -1724,6 +1724,57 @@ static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg,
extradata_len);
}
+#ifdef CONFIG_NETCONSOLE_NBCON
+static void netcon_write_nbcon(struct console *con,
+ struct nbcon_write_context *wctxt,
+ bool extended)
+{
+ struct netconsole_target *nt;
+
+ lockdep_assert_held(&target_list_lock);
+
+ list_for_each_entry(nt, &target_list, list) {
+ if (nt->extended != extended || !nt->enabled ||
+ !netif_running(nt->np.dev))
+ continue;
+
+ if (!nbcon_enter_unsafe(wctxt))
+ continue;
+
+ if (extended)
+ send_ext_msg_udp(nt, wctxt->outbuf, wctxt->len);
+ else
+ write_msg_target(nt, wctxt->outbuf, wctxt->len);
+
+ nbcon_exit_unsafe(wctxt);
+ }
+}
+
+static void netcon_write_nbcon_ext(struct console *con,
+ struct nbcon_write_context *wctxt)
+{
+ netcon_write_nbcon(con, wctxt, true);
+}
+
+static void netcon_write_nbcon_basic(struct console *con,
+ struct nbcon_write_context *wctxt)
+{
+ netcon_write_nbcon(con, wctxt, false);
+}
+
+static void netconsole_device_lock(struct console *con, unsigned long *flags)
+{
+ /* protects all the targets at the same time */
+ spin_lock_irqsave(&target_list_lock, *flags);
+}
+
+static void netconsole_device_unlock(struct console *con, unsigned long flags)
+{
+ spin_unlock_irqrestore(&target_list_lock, flags);
+}
+
+#else
+
static void write_ext_msg(struct console *con, const char *msg,
unsigned int len)
{
@@ -1765,6 +1816,7 @@ static void write_msg(struct console *con, const char *msg, unsigned int len)
}
spin_unlock_irqrestore(&target_list_lock, flags);
}
+#endif
static int netconsole_parser_cmdline(struct netpoll *np, char *opt)
{
@@ -1923,14 +1975,30 @@ static void free_param_target(struct netconsole_target *nt)
static struct console netconsole_ext = {
.name = "netcon_ext",
+#ifdef CONFIG_NETCONSOLE_NBCON
+ .flags = CON_ENABLED | CON_EXTENDED | CON_NBCON | CON_NBCON_ATOMIC_UNSAFE,
+ .write_thread = netcon_write_nbcon_ext,
+ .write_atomic = netcon_write_nbcon_ext,
+ .device_lock = netconsole_device_lock,
+ .device_unlock = netconsole_device_unlock,
+#else
.flags = CON_ENABLED | CON_EXTENDED,
.write = write_ext_msg,
+#endif
};
static struct console netconsole = {
.name = "netcon",
+#ifdef CONFIG_NETCONSOLE_NBCON
+ .flags = CON_ENABLED | CON_NBCON | CON_NBCON_ATOMIC_UNSAFE,
+ .write_thread = netcon_write_nbcon_basic,
+ .write_atomic = netcon_write_nbcon_basic,
+ .device_lock = netconsole_device_lock,
+ .device_unlock = netconsole_device_unlock,
+#else
.flags = CON_ENABLED,
.write = write_msg,
+#endif
};
static int __init init_netconsole(void)
--
2.47.3
Powered by blists - more mailing lists