ipconfig: Write NTP server IPs to /proc/net/ipconfig/ntp_servers

Updated 1997 by Martin Mares <mj@atrey.karlin.mff.cuni.cz>

Updated 2006 by Nico Schottelius <nico-kernel-nfsroot@schottelius.org>

Updated 2006 by Horms <horms@verge.net.au>

Updated 2018 by Chris Novakovic <chris@chrisn.me.uk>

ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:

   <dns0-ip>:<dns1-ip>

   <dns0-ip>:<dns1-ip>:<ntp0-ip>

  This parameter tells the kernel how to configure IP addresses of devices

  and also how to set up the IP routing table. It was originally called

  <dns1-ip>	IP address of secondary nameserver.

		See <dns0-ip>.

  After configuration (whether manual or automatic) is complete, a file is

  created at /proc/net/pnp in the following format; lines are omitted if

  their respective value is empty following configuration.

  <ntp0-ip>	IP address of a Network Time Protocol (NTP) server.

		Value is exported to /proc/net/ipconfig/ntp_servers, but is

		otherwise unused (see below).

		Default: None if not using autoconfiguration; determined

		automatically if using autoconfiguration.

  After configuration (whether manual or automatic) is complete, two files

  are created in the following format; lines are omitted if their respective

  value is empty following configuration:

  - /proc/net/pnp:

	#PROTO: <DHCP|BOOTP|RARP|MANUAL>	(depending on configuration method)

	domain <dns-domain>			(if autoconfigured, the DNS domain)

	nameserver <dns2-ip>			(tertiary name server IP)

	bootserver <server-ip>			(NFS server IP)

  <dns-domain> and <dns2-ip> are requested during autoconfiguration; they

  cannot be specified as part of the "ip=" kernel command line parameter.

  - /proc/net/ipconfig/ntp_servers:

	<ntp0-ip>				(NTP server IP)

	<ntp1-ip>				(NTP server IP)

	<ntp2-ip>				(NTP server IP)

  <dns-domain> and <dns2-ip> (in /proc/net/pnp) and <ntp1-ip> and <ntp2-ip>

  (in /proc/net/ipconfig/ntp_servers) are requested during autoconfiguration;

  they cannot be specified as part of the "ip=" kernel command line parameter.

  Because the "domain" and "nameserver" options are recognised by DNS

  resolvers, /etc/resolv.conf is often linked to /proc/net/pnp on systems

  that use an NFS root filesystem.

  Note that the kernel will not synchronise the system time with any NTP

  servers it discovers; this is the responsibility of a user space process

  (e.g. an initrd/initramfs script that passes the IP addresses listed in

  /proc/net/ipconfig/ntp_servers to an NTP client before mounting the real

  root filesystem if it is on NFS).

nfsrootdebug

 *

 *  Multiple Nameservers in /proc/net/pnp

 *              --  Josef Siemes <jsiemes@web.de>, Aug 2002

 *

 *  NTP servers in /proc/net/ipconfig/ntp_servers

 *              --  Chris Novakovic <chris@chrisn.me.uk>, April 2018

 */

#include <linux/types.h>

#define CONF_TIMEOUT_MAX	(HZ*30)	/* Maximum allowed timeout */

#define CONF_NAMESERVERS_MAX   3       /* Maximum number of nameservers

					   - '3' from resolv.h */

#define CONF_NTP_SERVERS_MAX   3	/* Maximum number of NTP servers */

#define NONE cpu_to_be32(INADDR_NONE)

#define ANY cpu_to_be32(INADDR_ANY)

#define ic_proto_used 0

#endif

static __be32 ic_nameservers[CONF_NAMESERVERS_MAX]; /* DNS Server IP addresses */

static __be32 ic_ntp_servers[CONF_NTP_SERVERS_MAX]; /* NTP server IP addresses */

static u8 ic_domain[64];		/* DNS (not NIS) domain name */

/*

		ic_nameservers[i] = NONE;

}

/* Predefine NTP servers */

static inline void __init ic_ntp_servers_predef(void)

{

	int i;

	for (i = 0; i < CONF_NTP_SERVERS_MAX; i++)

		ic_ntp_servers[i] = NONE;

}

/*

 *	DHCP/BOOTP support.

 */

			17,	/* Boot path */

			26,	/* MTU */

			40,	/* NIS domain name */

			42,	/* NTP servers */

		};

		*e++ = 55;	/* Parameter request list */

 */

static inline void __init ic_bootp_init(void)

{

	/* Re-initialise all name servers to NONE, in case any were set via the

	 * "ip=" or "nfsaddrs=" kernel command line parameters: any IP addresses

	 * specified there will already have been decoded but are no longer

	 * needed

	/* Re-initialise all name servers and NTP servers to NONE, in case any

	 * were set via the "ip=" or "nfsaddrs=" kernel command line parameters:

	 * any IP addresses specified there will already have been decoded but

	 * are no longer needed

	 */

	ic_nameservers_predef();

	ic_ntp_servers_predef();

	dev_add_pack(&bootp_packet_type);

}

		ic_bootp_string(utsname()->domainname, ext+1, *ext,

				__NEW_UTS_LEN);

		break;

	case 42:	/* NTP servers */

		servers = *ext / 4;

		if (servers > CONF_NTP_SERVERS_MAX)

			servers = CONF_NTP_SERVERS_MAX;

		for (i = 0; i < servers; i++) {

			if (ic_ntp_servers[i] == NONE)

				memcpy(&ic_ntp_servers[i], ext+1+4*i, 4);

		}

		break;

	}

}

#ifdef CONFIG_PROC_FS

/* Name servers: */

static int pnp_seq_show(struct seq_file *seq, void *v)

{

	int i;

};

/* Create the /proc/net/ipconfig directory */

static int ipconfig_proc_net_init(void)

static int __init ipconfig_proc_net_init(void)

{

	ipconfig_dir = proc_net_mkdir(&init_net, "ipconfig", init_net.proc_net);

	if (!ipconfig_dir)

	return 0;

}

/* Create a new file under /proc/net/ipconfig */

static int ipconfig_proc_net_create(const char *name,

				    const struct file_operations *fops)

{

	char *pname;

	struct proc_dir_entry *p;

	if (!ipconfig_dir)

		return -ENOMEM;

	pname = kasprintf(GFP_KERNEL, "%s%s", "ipconfig/", name);

	if (!pname)

		return -ENOMEM;

	p = proc_create(pname, 0444, init_net.proc_net, fops);

	kfree(pname);

	if (!p)

		return -ENOMEM;

	return 0;

}

/* Write NTP server IP addresses to /proc/net/ipconfig/ntp_servers */

static int ntp_servers_seq_show(struct seq_file *seq, void *v)

{

	int i;

	for (i = 0; i < CONF_NTP_SERVERS_MAX; i++) {

		if (ic_ntp_servers[i] != NONE)

			seq_printf(seq, "%pI4\n", &ic_ntp_servers[i]);

	}

	return 0;

}

static int ntp_servers_seq_open(struct inode *inode, struct file *file)

{

	return single_open(file, ntp_servers_seq_show, NULL);

}

static const struct file_operations ntp_servers_seq_fops = {

	.open		= ntp_servers_seq_open,

	.read		= seq_read,

	.llseek		= seq_lseek,

	.release	= single_release,

};

#endif /* CONFIG_PROC_FS */

/*

	int err;

	unsigned int i;

	/* Initialise all name servers to NONE (but only if the "ip=" or

	 * "nfsaddrs=" kernel command line parameters weren't decoded, otherwise

	 * we'll overwrite the IP addresses specified there)

	/* Initialise all name servers and NTP servers to NONE (but only if the

	 * "ip=" or "nfsaddrs=" kernel command line parameters weren't decoded,

	 * otherwise we'll overwrite the IP addresses specified there)

	 */

	if (ic_set_manually == 0)

	if (ic_set_manually == 0) {

		ic_nameservers_predef();

		ic_ntp_servers_predef();

	}

#ifdef CONFIG_PROC_FS

	proc_create("pnp", 0444, init_net.proc_net, &pnp_seq_fops);

	ipconfig_proc_net_init();

	if (ipconfig_proc_net_init() == 0)

		ipconfig_proc_net_create("ntp_servers", &ntp_servers_seq_fops);

#endif /* CONFIG_PROC_FS */

	if (!ic_enable)

		if (i + 1 == CONF_NAMESERVERS_MAX)

			pr_cont("\n");

	}

	/* NTP servers (if any): */

	for (i = 0; i < CONF_NTP_SERVERS_MAX; i++) {

		if (ic_ntp_servers[i] != NONE) {

			if (i == 0)

				pr_info("     ntpserver%u=%pI4",

					i, &ic_ntp_servers[i]);

			else

				pr_cont(", ntpserver%u=%pI4",

					i, &ic_ntp_servers[i]);

		}

		if (i + 1 == CONF_NTP_SERVERS_MAX)

			pr_cont("\n");

	}

#endif /* !SILENT */

	/*

		return 1;

	}

	/* Initialise all name servers to NONE */

	/* Initialise all name servers and NTP servers to NONE */

	ic_nameservers_predef();

	ic_ntp_servers_predef();

	/* Parse string for static IP assignment.  */

	ip = addrs;

						ic_nameservers[1] = NONE;

				}

				break;

			case 9:

				if (CONF_NTP_SERVERS_MAX >= 1) {

					ic_ntp_servers[0] = in_aton(ip);

					if (ic_ntp_servers[0] == ANY)

						ic_ntp_servers[0] = NONE;

				}

				break;

			}

		}

		ip = cp;