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4ecb90090c
Extend the permission check for networking sysctl's to allow modification when current process has CAP_NET_ADMIN capability and is not root. This version uses the until now unused permissions hook to override the mode value for /proc/sys/net if accessed by a user with capabilities. Found while working with Quagga. It is impossible to turn forwarding on/off through the command interface because Quagga uses secure coding practice of dropping privledges during initialization and only raising via capabilities when necessary. Since the dameon has reset real/effective uid after initialization, all attempts to access /proc/sys/net variables will fail. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morgan <morgan@kernel.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
130 lines
3 KiB
C
130 lines
3 KiB
C
/* -*- linux-c -*-
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* sysctl_net.c: sysctl interface to net subsystem.
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*
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* Begun April 1, 1996, Mike Shaver.
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* Added /proc/sys/net directories for each protocol family. [MS]
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*
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* Revision 1.2 1996/05/08 20:24:40 shaver
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* Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
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* NET_IPV4_IP_FORWARD.
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*
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*
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*/
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#include <linux/mm.h>
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#include <linux/sysctl.h>
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#include <linux/nsproxy.h>
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#include <net/sock.h>
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#ifdef CONFIG_INET
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#include <net/ip.h>
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#endif
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#ifdef CONFIG_NET
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#include <linux/if_ether.h>
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#endif
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#ifdef CONFIG_TR
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#include <linux/if_tr.h>
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#endif
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static struct list_head *
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net_ctl_header_lookup(struct ctl_table_root *root, struct nsproxy *namespaces)
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{
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return &namespaces->net_ns->sysctl_table_headers;
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}
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/* Return standard mode bits for table entry. */
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static int net_ctl_permissions(struct ctl_table_root *root,
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struct nsproxy *nsproxy,
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struct ctl_table *table)
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{
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/* Allow network administrator to have same access as root. */
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if (capable(CAP_NET_ADMIN)) {
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int mode = (table->mode >> 6) & 7;
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return (mode << 6) | (mode << 3) | mode;
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}
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return table->mode;
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}
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static struct ctl_table_root net_sysctl_root = {
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.lookup = net_ctl_header_lookup,
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.permissions = net_ctl_permissions,
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};
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static LIST_HEAD(net_sysctl_ro_tables);
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static struct list_head *net_ctl_ro_header_lookup(struct ctl_table_root *root,
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struct nsproxy *namespaces)
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{
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return &net_sysctl_ro_tables;
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}
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static int net_ctl_ro_header_perms(struct ctl_table_root *root,
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struct nsproxy *namespaces, struct ctl_table *table)
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{
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if (namespaces->net_ns == &init_net)
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return table->mode;
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else
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return table->mode & ~0222;
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}
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static struct ctl_table_root net_sysctl_ro_root = {
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.lookup = net_ctl_ro_header_lookup,
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.permissions = net_ctl_ro_header_perms,
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};
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static int sysctl_net_init(struct net *net)
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{
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INIT_LIST_HEAD(&net->sysctl_table_headers);
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return 0;
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}
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static void sysctl_net_exit(struct net *net)
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{
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WARN_ON(!list_empty(&net->sysctl_table_headers));
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return;
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}
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static struct pernet_operations sysctl_pernet_ops = {
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.init = sysctl_net_init,
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.exit = sysctl_net_exit,
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};
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static __init int sysctl_init(void)
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{
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int ret;
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ret = register_pernet_subsys(&sysctl_pernet_ops);
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if (ret)
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goto out;
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register_sysctl_root(&net_sysctl_root);
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register_sysctl_root(&net_sysctl_ro_root);
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out:
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return ret;
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}
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subsys_initcall(sysctl_init);
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struct ctl_table_header *register_net_sysctl_table(struct net *net,
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const struct ctl_path *path, struct ctl_table *table)
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{
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struct nsproxy namespaces;
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namespaces = *current->nsproxy;
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namespaces.net_ns = net;
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return __register_sysctl_paths(&net_sysctl_root,
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&namespaces, path, table);
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}
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EXPORT_SYMBOL_GPL(register_net_sysctl_table);
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struct ctl_table_header *register_net_sysctl_rotable(const
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struct ctl_path *path, struct ctl_table *table)
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{
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return __register_sysctl_paths(&net_sysctl_ro_root,
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&init_nsproxy, path, table);
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}
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EXPORT_SYMBOL_GPL(register_net_sysctl_rotable);
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void unregister_net_sysctl_table(struct ctl_table_header *header)
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{
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unregister_sysctl_table(header);
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}
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EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);
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