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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180// SPDX-License-Identifier: GPL-2.0-only/* -*- linux-c -*- * sysctl_net.c: sysctl interface to net subsystem. * * Begun April 1, 1996, Mike Shaver. * Added /proc/sys/net directories for each protocol family. [MS] * * Revision 1.2 1996/05/08 20:24:40 shaver * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and * NET_IPV4_IP_FORWARD. * * */
#include <linux/mm.h>#include <linux/export.h>#include <linux/sysctl.h>#include <linux/nsproxy.h>
#include <net/sock.h>
#ifdef CONFIG_INET#include <net/ip.h>#endif
#ifdef CONFIG_NET#include <linux/if_ether.h>#endif
static struct ctl_table_set *net_ctl_header_lookup(struct ctl_table_root *root){ return ¤t->nsproxy->net_ns->sysctls;}
static int is_seen(struct ctl_table_set *set){ return ¤t->nsproxy->net_ns->sysctls == set;}
/* Return standard mode bits for table entry. */static int net_ctl_permissions(struct ctl_table_header *head, const struct ctl_table *table){ struct net *net = container_of(head->set, struct net, sysctls);
/* Allow network administrator to have same access as root. */ if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) { int mode = (table->mode >> 6) & 7; return (mode << 6) | (mode << 3) | mode; }
return table->mode;}
static void net_ctl_set_ownership(struct ctl_table_header *head, kuid_t *uid, kgid_t *gid){ struct net *net = container_of(head->set, struct net, sysctls); kuid_t ns_root_uid; kgid_t ns_root_gid;
ns_root_uid = make_kuid(net->user_ns, 0); if (uid_valid(ns_root_uid)) *uid = ns_root_uid;
ns_root_gid = make_kgid(net->user_ns, 0); if (gid_valid(ns_root_gid)) *gid = ns_root_gid;}
static struct ctl_table_root net_sysctl_root = { .lookup = net_ctl_header_lookup, .permissions = net_ctl_permissions, .set_ownership = net_ctl_set_ownership,};
static int __net_init sysctl_net_init(struct net *net){ setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen); return 0;}
static void __net_exit sysctl_net_exit(struct net *net){ retire_sysctl_set(&net->sysctls);}
static struct pernet_operations sysctl_pernet_ops = { .init = sysctl_net_init, .exit = sysctl_net_exit,};
static struct ctl_table_header *net_header;__init int net_sysctl_init(void){ static struct ctl_table empty[1]; int ret = -ENOMEM; /* Avoid limitations in the sysctl implementation by * registering "/proc/sys/net" as an empty directory not in a * network namespace. */ net_header = register_sysctl_sz("net", empty, 0); if (!net_header) goto out; ret = register_pernet_subsys(&sysctl_pernet_ops); if (ret) goto out1;out: return ret;out1: unregister_sysctl_table(net_header); net_header = NULL; goto out;}
/* Verify that sysctls for non-init netns are safe by either: * 1) being read-only, or * 2) having a data pointer which points outside of the global kernel/module * data segment, and rather into the heap where a per-net object was * allocated. */static void ensure_safe_net_sysctl(struct net *net, const char *path, struct ctl_table *table, size_t table_size){ struct ctl_table *ent;
pr_debug("Registering net sysctl (net %p): %s\n", net, path); ent = table; for (size_t i = 0; i < table_size; ent++, i++) { unsigned long addr; const char *where;
pr_debug(" procname=%s mode=%o proc_handler=%ps data=%p\n", ent->procname, ent->mode, ent->proc_handler, ent->data);
/* If it's not writable inside the netns, then it can't hurt. */ if ((ent->mode & 0222) == 0) { pr_debug(" Not writable by anyone\n"); continue; }
/* Where does data point? */ addr = (unsigned long)ent->data; if (is_module_address(addr)) where = "module"; else if (is_kernel_core_data(addr)) where = "kernel"; else continue;
/* If it is writable and points to kernel/module global * data, then it's probably a netns leak. */ WARN(1, "sysctl %s/%s: data points to %s global data: %ps\n", path, ent->procname, where, ent->data);
/* Make it "safe" by dropping writable perms */ ent->mode &= ~0222; }}
struct ctl_table_header *register_net_sysctl_sz(struct net *net, const char *path, struct ctl_table *table, size_t table_size){ if (!net_eq(net, &init_net)) ensure_safe_net_sysctl(net, path, table, table_size);
return __register_sysctl_table(&net->sysctls, path, table, table_size);}EXPORT_SYMBOL_GPL(register_net_sysctl_sz);
void unregister_net_sysctl_table(struct ctl_table_header *header){ unregister_sysctl_table(header);}EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);