cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sysctl_net.c (4479B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/* -*- linux-c -*-
      3 * sysctl_net.c: sysctl interface to net subsystem.
      4 *
      5 * Begun April 1, 1996, Mike Shaver.
      6 * Added /proc/sys/net directories for each protocol family. [MS]
      7 *
      8 * Revision 1.2  1996/05/08  20:24:40  shaver
      9 * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
     10 * NET_IPV4_IP_FORWARD.
     11 *
     12 *
     13 */
     14
     15#include <linux/mm.h>
     16#include <linux/export.h>
     17#include <linux/sysctl.h>
     18#include <linux/nsproxy.h>
     19
     20#include <net/sock.h>
     21
     22#ifdef CONFIG_INET
     23#include <net/ip.h>
     24#endif
     25
     26#ifdef CONFIG_NET
     27#include <linux/if_ether.h>
     28#endif
     29
     30static struct ctl_table_set *
     31net_ctl_header_lookup(struct ctl_table_root *root)
     32{
     33	return &current->nsproxy->net_ns->sysctls;
     34}
     35
     36static int is_seen(struct ctl_table_set *set)
     37{
     38	return &current->nsproxy->net_ns->sysctls == set;
     39}
     40
     41/* Return standard mode bits for table entry. */
     42static int net_ctl_permissions(struct ctl_table_header *head,
     43			       struct ctl_table *table)
     44{
     45	struct net *net = container_of(head->set, struct net, sysctls);
     46
     47	/* Allow network administrator to have same access as root. */
     48	if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {
     49		int mode = (table->mode >> 6) & 7;
     50		return (mode << 6) | (mode << 3) | mode;
     51	}
     52
     53	return table->mode;
     54}
     55
     56static void net_ctl_set_ownership(struct ctl_table_header *head,
     57				  struct ctl_table *table,
     58				  kuid_t *uid, kgid_t *gid)
     59{
     60	struct net *net = container_of(head->set, struct net, sysctls);
     61	kuid_t ns_root_uid;
     62	kgid_t ns_root_gid;
     63
     64	ns_root_uid = make_kuid(net->user_ns, 0);
     65	if (uid_valid(ns_root_uid))
     66		*uid = ns_root_uid;
     67
     68	ns_root_gid = make_kgid(net->user_ns, 0);
     69	if (gid_valid(ns_root_gid))
     70		*gid = ns_root_gid;
     71}
     72
     73static struct ctl_table_root net_sysctl_root = {
     74	.lookup = net_ctl_header_lookup,
     75	.permissions = net_ctl_permissions,
     76	.set_ownership = net_ctl_set_ownership,
     77};
     78
     79static int __net_init sysctl_net_init(struct net *net)
     80{
     81	setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
     82	return 0;
     83}
     84
     85static void __net_exit sysctl_net_exit(struct net *net)
     86{
     87	retire_sysctl_set(&net->sysctls);
     88}
     89
     90static struct pernet_operations sysctl_pernet_ops = {
     91	.init = sysctl_net_init,
     92	.exit = sysctl_net_exit,
     93};
     94
     95static struct ctl_table_header *net_header;
     96__init int net_sysctl_init(void)
     97{
     98	static struct ctl_table empty[1];
     99	int ret = -ENOMEM;
    100	/* Avoid limitations in the sysctl implementation by
    101	 * registering "/proc/sys/net" as an empty directory not in a
    102	 * network namespace.
    103	 */
    104	net_header = register_sysctl("net", empty);
    105	if (!net_header)
    106		goto out;
    107	ret = register_pernet_subsys(&sysctl_pernet_ops);
    108	if (ret)
    109		goto out1;
    110out:
    111	return ret;
    112out1:
    113	unregister_sysctl_table(net_header);
    114	net_header = NULL;
    115	goto out;
    116}
    117
    118/* Verify that sysctls for non-init netns are safe by either:
    119 * 1) being read-only, or
    120 * 2) having a data pointer which points outside of the global kernel/module
    121 *    data segment, and rather into the heap where a per-net object was
    122 *    allocated.
    123 */
    124static void ensure_safe_net_sysctl(struct net *net, const char *path,
    125				   struct ctl_table *table)
    126{
    127	struct ctl_table *ent;
    128
    129	pr_debug("Registering net sysctl (net %p): %s\n", net, path);
    130	for (ent = table; ent->procname; ent++) {
    131		unsigned long addr;
    132		const char *where;
    133
    134		pr_debug("  procname=%s mode=%o proc_handler=%ps data=%p\n",
    135			 ent->procname, ent->mode, ent->proc_handler, ent->data);
    136
    137		/* If it's not writable inside the netns, then it can't hurt. */
    138		if ((ent->mode & 0222) == 0) {
    139			pr_debug("    Not writable by anyone\n");
    140			continue;
    141		}
    142
    143		/* Where does data point? */
    144		addr = (unsigned long)ent->data;
    145		if (is_module_address(addr))
    146			where = "module";
    147		else if (is_kernel_core_data(addr))
    148			where = "kernel";
    149		else
    150			continue;
    151
    152		/* If it is writable and points to kernel/module global
    153		 * data, then it's probably a netns leak.
    154		 */
    155		WARN(1, "sysctl %s/%s: data points to %s global data: %ps\n",
    156		     path, ent->procname, where, ent->data);
    157
    158		/* Make it "safe" by dropping writable perms */
    159		ent->mode &= ~0222;
    160	}
    161}
    162
    163struct ctl_table_header *register_net_sysctl(struct net *net,
    164	const char *path, struct ctl_table *table)
    165{
    166	if (!net_eq(net, &init_net))
    167		ensure_safe_net_sysctl(net, path, table);
    168
    169	return __register_sysctl_table(&net->sysctls, path, table);
    170}
    171EXPORT_SYMBOL_GPL(register_net_sysctl);
    172
    173void unregister_net_sysctl_table(struct ctl_table_header *header)
    174{
    175	unregister_sysctl_table(header);
    176}
    177EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);