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![Sean Tranchetti](/assets/img/avatar_default.png)
[ Upstream commit1e82a62fec
] A potential deadlock can occur during registering or unregistering a new generic netlink family between the main nl_table_lock and the cb_lock where each thread wants the lock held by the other, as demonstrated below. 1) Thread 1 is performing a netlink_bind() operation on a socket. As part of this call, it will call netlink_lock_table(), incrementing the nl_table_users count to 1. 2) Thread 2 is registering (or unregistering) a genl_family via the genl_(un)register_family() API. The cb_lock semaphore will be taken for writing. 3) Thread 1 will call genl_bind() as part of the bind operation to handle subscribing to GENL multicast groups at the request of the user. It will attempt to take the cb_lock semaphore for reading, but it will fail and be scheduled away, waiting for Thread 2 to finish the write. 4) Thread 2 will call netlink_table_grab() during the (un)registration call. However, as Thread 1 has incremented nl_table_users, it will not be able to proceed, and both threads will be stuck waiting for the other. genl_bind() is a noop, unless a genl_family implements the mcast_bind() function to handle setting up family-specific multicast operations. Since no one in-tree uses this functionality as Cong pointed out, simply removing the genl_bind() function will remove the possibility for deadlock, as there is no attempt by Thread 1 above to take the cb_lock semaphore. Fixes:c380d9a7af
("genetlink: pass multicast bind/unbind to families") Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Johannes Berg <johannes.berg@intel.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Sean Tranchetti <stranche@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1124 lines
26 KiB
C
1124 lines
26 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* NETLINK Generic Netlink Family
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*
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* Authors: Jamal Hadi Salim
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* Thomas Graf <tgraf@suug.ch>
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* Johannes Berg <johannes@sipsolutions.net>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/string.h>
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#include <linux/skbuff.h>
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#include <linux/mutex.h>
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#include <linux/bitmap.h>
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#include <linux/rwsem.h>
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#include <linux/idr.h>
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#include <net/sock.h>
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#include <net/genetlink.h>
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static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
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static DECLARE_RWSEM(cb_lock);
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atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
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DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
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void genl_lock(void)
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{
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mutex_lock(&genl_mutex);
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}
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EXPORT_SYMBOL(genl_lock);
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void genl_unlock(void)
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{
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mutex_unlock(&genl_mutex);
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}
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EXPORT_SYMBOL(genl_unlock);
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#ifdef CONFIG_LOCKDEP
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bool lockdep_genl_is_held(void)
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{
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return lockdep_is_held(&genl_mutex);
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}
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EXPORT_SYMBOL(lockdep_genl_is_held);
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#endif
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static void genl_lock_all(void)
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{
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down_write(&cb_lock);
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genl_lock();
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}
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static void genl_unlock_all(void)
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{
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genl_unlock();
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up_write(&cb_lock);
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}
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static DEFINE_IDR(genl_fam_idr);
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/*
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* Bitmap of multicast groups that are currently in use.
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*
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* To avoid an allocation at boot of just one unsigned long,
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* declare it global instead.
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* Bit 0 is marked as already used since group 0 is invalid.
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* Bit 1 is marked as already used since the drop-monitor code
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* abuses the API and thinks it can statically use group 1.
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* That group will typically conflict with other groups that
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* any proper users use.
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* Bit 16 is marked as used since it's used for generic netlink
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* and the code no longer marks pre-reserved IDs as used.
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* Bit 17 is marked as already used since the VFS quota code
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* also abused this API and relied on family == group ID, we
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* cater to that by giving it a static family and group ID.
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* Bit 18 is marked as already used since the PMCRAID driver
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* did the same thing as the VFS quota code (maybe copied?)
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*/
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static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
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BIT(GENL_ID_VFS_DQUOT) |
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BIT(GENL_ID_PMCRAID);
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static unsigned long *mc_groups = &mc_group_start;
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static unsigned long mc_groups_longs = 1;
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static int genl_ctrl_event(int event, const struct genl_family *family,
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const struct genl_multicast_group *grp,
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int grp_id);
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static const struct genl_family *genl_family_find_byid(unsigned int id)
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{
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return idr_find(&genl_fam_idr, id);
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}
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static const struct genl_family *genl_family_find_byname(char *name)
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{
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const struct genl_family *family;
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unsigned int id;
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idr_for_each_entry(&genl_fam_idr, family, id)
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if (strcmp(family->name, name) == 0)
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return family;
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return NULL;
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}
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static const struct genl_ops *genl_get_cmd(u8 cmd,
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const struct genl_family *family)
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{
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int i;
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for (i = 0; i < family->n_ops; i++)
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if (family->ops[i].cmd == cmd)
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return &family->ops[i];
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return NULL;
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}
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static int genl_allocate_reserve_groups(int n_groups, int *first_id)
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{
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unsigned long *new_groups;
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int start = 0;
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int i;
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int id;
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bool fits;
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do {
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if (start == 0)
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id = find_first_zero_bit(mc_groups,
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mc_groups_longs *
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BITS_PER_LONG);
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else
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id = find_next_zero_bit(mc_groups,
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mc_groups_longs * BITS_PER_LONG,
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start);
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fits = true;
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for (i = id;
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i < min_t(int, id + n_groups,
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mc_groups_longs * BITS_PER_LONG);
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i++) {
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if (test_bit(i, mc_groups)) {
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start = i;
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fits = false;
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break;
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}
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}
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if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
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unsigned long new_longs = mc_groups_longs +
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BITS_TO_LONGS(n_groups);
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size_t nlen = new_longs * sizeof(unsigned long);
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if (mc_groups == &mc_group_start) {
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new_groups = kzalloc(nlen, GFP_KERNEL);
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if (!new_groups)
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return -ENOMEM;
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mc_groups = new_groups;
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*mc_groups = mc_group_start;
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} else {
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new_groups = krealloc(mc_groups, nlen,
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GFP_KERNEL);
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if (!new_groups)
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return -ENOMEM;
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mc_groups = new_groups;
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for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
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mc_groups[mc_groups_longs + i] = 0;
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}
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mc_groups_longs = new_longs;
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}
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} while (!fits);
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for (i = id; i < id + n_groups; i++)
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set_bit(i, mc_groups);
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*first_id = id;
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return 0;
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}
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static struct genl_family genl_ctrl;
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static int genl_validate_assign_mc_groups(struct genl_family *family)
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{
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int first_id;
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int n_groups = family->n_mcgrps;
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int err = 0, i;
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bool groups_allocated = false;
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if (!n_groups)
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return 0;
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for (i = 0; i < n_groups; i++) {
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const struct genl_multicast_group *grp = &family->mcgrps[i];
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if (WARN_ON(grp->name[0] == '\0'))
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return -EINVAL;
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if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
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return -EINVAL;
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}
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/* special-case our own group and hacks */
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if (family == &genl_ctrl) {
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first_id = GENL_ID_CTRL;
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BUG_ON(n_groups != 1);
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} else if (strcmp(family->name, "NET_DM") == 0) {
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first_id = 1;
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BUG_ON(n_groups != 1);
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} else if (family->id == GENL_ID_VFS_DQUOT) {
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first_id = GENL_ID_VFS_DQUOT;
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BUG_ON(n_groups != 1);
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} else if (family->id == GENL_ID_PMCRAID) {
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first_id = GENL_ID_PMCRAID;
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BUG_ON(n_groups != 1);
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} else {
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groups_allocated = true;
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err = genl_allocate_reserve_groups(n_groups, &first_id);
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if (err)
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return err;
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}
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family->mcgrp_offset = first_id;
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/* if still initializing, can't and don't need to to realloc bitmaps */
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if (!init_net.genl_sock)
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return 0;
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if (family->netnsok) {
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struct net *net;
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netlink_table_grab();
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rcu_read_lock();
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for_each_net_rcu(net) {
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err = __netlink_change_ngroups(net->genl_sock,
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mc_groups_longs * BITS_PER_LONG);
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if (err) {
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/*
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* No need to roll back, can only fail if
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* memory allocation fails and then the
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* number of _possible_ groups has been
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* increased on some sockets which is ok.
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*/
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break;
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}
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}
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rcu_read_unlock();
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netlink_table_ungrab();
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} else {
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err = netlink_change_ngroups(init_net.genl_sock,
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mc_groups_longs * BITS_PER_LONG);
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}
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if (groups_allocated && err) {
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for (i = 0; i < family->n_mcgrps; i++)
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clear_bit(family->mcgrp_offset + i, mc_groups);
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}
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return err;
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}
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static void genl_unregister_mc_groups(const struct genl_family *family)
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{
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struct net *net;
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int i;
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netlink_table_grab();
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rcu_read_lock();
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for_each_net_rcu(net) {
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for (i = 0; i < family->n_mcgrps; i++)
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__netlink_clear_multicast_users(
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net->genl_sock, family->mcgrp_offset + i);
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}
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rcu_read_unlock();
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netlink_table_ungrab();
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for (i = 0; i < family->n_mcgrps; i++) {
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int grp_id = family->mcgrp_offset + i;
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if (grp_id != 1)
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clear_bit(grp_id, mc_groups);
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genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
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&family->mcgrps[i], grp_id);
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}
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}
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static int genl_validate_ops(const struct genl_family *family)
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{
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const struct genl_ops *ops = family->ops;
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unsigned int n_ops = family->n_ops;
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int i, j;
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if (WARN_ON(n_ops && !ops))
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return -EINVAL;
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if (!n_ops)
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return 0;
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for (i = 0; i < n_ops; i++) {
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if (ops[i].dumpit == NULL && ops[i].doit == NULL)
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return -EINVAL;
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for (j = i + 1; j < n_ops; j++)
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if (ops[i].cmd == ops[j].cmd)
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return -EINVAL;
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}
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return 0;
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}
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/**
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* genl_register_family - register a generic netlink family
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* @family: generic netlink family
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*
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* Registers the specified family after validating it first. Only one
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* family may be registered with the same family name or identifier.
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*
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* The family's ops, multicast groups and module pointer must already
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* be assigned.
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*
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* Return 0 on success or a negative error code.
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*/
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int genl_register_family(struct genl_family *family)
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{
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int err, i;
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int start = GENL_START_ALLOC, end = GENL_MAX_ID;
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err = genl_validate_ops(family);
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if (err)
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return err;
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genl_lock_all();
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if (genl_family_find_byname(family->name)) {
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err = -EEXIST;
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goto errout_locked;
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}
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/*
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* Sadly, a few cases need to be special-cased
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* due to them having previously abused the API
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* and having used their family ID also as their
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* multicast group ID, so we use reserved IDs
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* for both to be sure we can do that mapping.
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*/
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if (family == &genl_ctrl) {
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/* and this needs to be special for initial family lookups */
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start = end = GENL_ID_CTRL;
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} else if (strcmp(family->name, "pmcraid") == 0) {
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start = end = GENL_ID_PMCRAID;
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} else if (strcmp(family->name, "VFS_DQUOT") == 0) {
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start = end = GENL_ID_VFS_DQUOT;
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}
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if (family->maxattr && !family->parallel_ops) {
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family->attrbuf = kmalloc_array(family->maxattr + 1,
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sizeof(struct nlattr *),
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GFP_KERNEL);
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if (family->attrbuf == NULL) {
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err = -ENOMEM;
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goto errout_locked;
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}
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} else
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family->attrbuf = NULL;
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family->id = idr_alloc_cyclic(&genl_fam_idr, family,
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start, end + 1, GFP_KERNEL);
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if (family->id < 0) {
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err = family->id;
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goto errout_free;
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}
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err = genl_validate_assign_mc_groups(family);
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if (err)
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goto errout_remove;
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genl_unlock_all();
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/* send all events */
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genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
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for (i = 0; i < family->n_mcgrps; i++)
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genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
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&family->mcgrps[i], family->mcgrp_offset + i);
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return 0;
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errout_remove:
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idr_remove(&genl_fam_idr, family->id);
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errout_free:
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kfree(family->attrbuf);
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errout_locked:
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genl_unlock_all();
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return err;
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}
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EXPORT_SYMBOL(genl_register_family);
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/**
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* genl_unregister_family - unregister generic netlink family
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* @family: generic netlink family
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*
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* Unregisters the specified family.
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*
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* Returns 0 on success or a negative error code.
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*/
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int genl_unregister_family(const struct genl_family *family)
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{
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genl_lock_all();
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if (!genl_family_find_byid(family->id)) {
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genl_unlock_all();
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return -ENOENT;
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}
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genl_unregister_mc_groups(family);
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idr_remove(&genl_fam_idr, family->id);
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up_write(&cb_lock);
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wait_event(genl_sk_destructing_waitq,
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atomic_read(&genl_sk_destructing_cnt) == 0);
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genl_unlock();
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kfree(family->attrbuf);
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genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
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return 0;
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}
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EXPORT_SYMBOL(genl_unregister_family);
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/**
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* genlmsg_put - Add generic netlink header to netlink message
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* @skb: socket buffer holding the message
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* @portid: netlink portid the message is addressed to
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* @seq: sequence number (usually the one of the sender)
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* @family: generic netlink family
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* @flags: netlink message flags
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* @cmd: generic netlink command
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*
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* Returns pointer to user specific header
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*/
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void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
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const struct genl_family *family, int flags, u8 cmd)
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{
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struct nlmsghdr *nlh;
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struct genlmsghdr *hdr;
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nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
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family->hdrsize, flags);
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if (nlh == NULL)
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return NULL;
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hdr = nlmsg_data(nlh);
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hdr->cmd = cmd;
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hdr->version = family->version;
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hdr->reserved = 0;
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return (char *) hdr + GENL_HDRLEN;
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}
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EXPORT_SYMBOL(genlmsg_put);
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|
|
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static int genl_lock_start(struct netlink_callback *cb)
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{
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/* our ops are always const - netlink API doesn't propagate that */
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const struct genl_ops *ops = cb->data;
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int rc = 0;
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|
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if (ops->start) {
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genl_lock();
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rc = ops->start(cb);
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genl_unlock();
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}
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return rc;
|
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}
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|
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static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
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|
{
|
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/* our ops are always const - netlink API doesn't propagate that */
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const struct genl_ops *ops = cb->data;
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int rc;
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|
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genl_lock();
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rc = ops->dumpit(skb, cb);
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genl_unlock();
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return rc;
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}
|
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|
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static int genl_lock_done(struct netlink_callback *cb)
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|
{
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/* our ops are always const - netlink API doesn't propagate that */
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const struct genl_ops *ops = cb->data;
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int rc = 0;
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|
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if (ops->done) {
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genl_lock();
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rc = ops->done(cb);
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genl_unlock();
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|
}
|
|
return rc;
|
|
}
|
|
|
|
static int genl_family_rcv_msg(const struct genl_family *family,
|
|
struct sk_buff *skb,
|
|
struct nlmsghdr *nlh,
|
|
struct netlink_ext_ack *extack)
|
|
{
|
|
const struct genl_ops *ops;
|
|
struct net *net = sock_net(skb->sk);
|
|
struct genl_info info;
|
|
struct genlmsghdr *hdr = nlmsg_data(nlh);
|
|
struct nlattr **attrbuf;
|
|
int hdrlen, err;
|
|
|
|
/* this family doesn't exist in this netns */
|
|
if (!family->netnsok && !net_eq(net, &init_net))
|
|
return -ENOENT;
|
|
|
|
hdrlen = GENL_HDRLEN + family->hdrsize;
|
|
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
|
|
return -EINVAL;
|
|
|
|
ops = genl_get_cmd(hdr->cmd, family);
|
|
if (ops == NULL)
|
|
return -EOPNOTSUPP;
|
|
|
|
if ((ops->flags & GENL_ADMIN_PERM) &&
|
|
!netlink_capable(skb, CAP_NET_ADMIN))
|
|
return -EPERM;
|
|
|
|
if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
|
|
!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
|
|
return -EPERM;
|
|
|
|
if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
|
|
int rc;
|
|
|
|
if (ops->dumpit == NULL)
|
|
return -EOPNOTSUPP;
|
|
|
|
if (!(ops->validate & GENL_DONT_VALIDATE_DUMP)) {
|
|
int hdrlen = GENL_HDRLEN + family->hdrsize;
|
|
|
|
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
|
|
return -EINVAL;
|
|
|
|
if (family->maxattr) {
|
|
unsigned int validate = NL_VALIDATE_STRICT;
|
|
|
|
if (ops->validate &
|
|
GENL_DONT_VALIDATE_DUMP_STRICT)
|
|
validate = NL_VALIDATE_LIBERAL;
|
|
rc = __nla_validate(nlmsg_attrdata(nlh, hdrlen),
|
|
nlmsg_attrlen(nlh, hdrlen),
|
|
family->maxattr,
|
|
family->policy,
|
|
validate, extack);
|
|
if (rc)
|
|
return rc;
|
|
}
|
|
}
|
|
|
|
if (!family->parallel_ops) {
|
|
struct netlink_dump_control c = {
|
|
.module = family->module,
|
|
/* we have const, but the netlink API doesn't */
|
|
.data = (void *)ops,
|
|
.start = genl_lock_start,
|
|
.dump = genl_lock_dumpit,
|
|
.done = genl_lock_done,
|
|
};
|
|
|
|
genl_unlock();
|
|
rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
|
|
genl_lock();
|
|
|
|
} else {
|
|
struct netlink_dump_control c = {
|
|
.module = family->module,
|
|
.start = ops->start,
|
|
.dump = ops->dumpit,
|
|
.done = ops->done,
|
|
};
|
|
|
|
rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
if (ops->doit == NULL)
|
|
return -EOPNOTSUPP;
|
|
|
|
if (family->maxattr && family->parallel_ops) {
|
|
attrbuf = kmalloc_array(family->maxattr + 1,
|
|
sizeof(struct nlattr *),
|
|
GFP_KERNEL);
|
|
if (attrbuf == NULL)
|
|
return -ENOMEM;
|
|
} else
|
|
attrbuf = family->attrbuf;
|
|
|
|
if (attrbuf) {
|
|
enum netlink_validation validate = NL_VALIDATE_STRICT;
|
|
|
|
if (ops->validate & GENL_DONT_VALIDATE_STRICT)
|
|
validate = NL_VALIDATE_LIBERAL;
|
|
|
|
err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
|
|
family->policy, validate, extack);
|
|
if (err < 0)
|
|
goto out;
|
|
}
|
|
|
|
info.snd_seq = nlh->nlmsg_seq;
|
|
info.snd_portid = NETLINK_CB(skb).portid;
|
|
info.nlhdr = nlh;
|
|
info.genlhdr = nlmsg_data(nlh);
|
|
info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
|
|
info.attrs = attrbuf;
|
|
info.extack = extack;
|
|
genl_info_net_set(&info, net);
|
|
memset(&info.user_ptr, 0, sizeof(info.user_ptr));
|
|
|
|
if (family->pre_doit) {
|
|
err = family->pre_doit(ops, skb, &info);
|
|
if (err)
|
|
goto out;
|
|
}
|
|
|
|
err = ops->doit(skb, &info);
|
|
|
|
if (family->post_doit)
|
|
family->post_doit(ops, skb, &info);
|
|
|
|
out:
|
|
if (family->parallel_ops)
|
|
kfree(attrbuf);
|
|
|
|
return err;
|
|
}
|
|
|
|
static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
|
|
struct netlink_ext_ack *extack)
|
|
{
|
|
const struct genl_family *family;
|
|
int err;
|
|
|
|
family = genl_family_find_byid(nlh->nlmsg_type);
|
|
if (family == NULL)
|
|
return -ENOENT;
|
|
|
|
if (!family->parallel_ops)
|
|
genl_lock();
|
|
|
|
err = genl_family_rcv_msg(family, skb, nlh, extack);
|
|
|
|
if (!family->parallel_ops)
|
|
genl_unlock();
|
|
|
|
return err;
|
|
}
|
|
|
|
static void genl_rcv(struct sk_buff *skb)
|
|
{
|
|
down_read(&cb_lock);
|
|
netlink_rcv_skb(skb, &genl_rcv_msg);
|
|
up_read(&cb_lock);
|
|
}
|
|
|
|
/**************************************************************************
|
|
* Controller
|
|
**************************************************************************/
|
|
|
|
static struct genl_family genl_ctrl;
|
|
|
|
static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
|
|
u32 flags, struct sk_buff *skb, u8 cmd)
|
|
{
|
|
void *hdr;
|
|
|
|
hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
|
|
if (hdr == NULL)
|
|
return -1;
|
|
|
|
if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
|
|
nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
|
|
nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
|
|
nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
|
|
nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
|
|
goto nla_put_failure;
|
|
|
|
if (family->n_ops) {
|
|
struct nlattr *nla_ops;
|
|
int i;
|
|
|
|
nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS);
|
|
if (nla_ops == NULL)
|
|
goto nla_put_failure;
|
|
|
|
for (i = 0; i < family->n_ops; i++) {
|
|
struct nlattr *nest;
|
|
const struct genl_ops *ops = &family->ops[i];
|
|
u32 op_flags = ops->flags;
|
|
|
|
if (ops->dumpit)
|
|
op_flags |= GENL_CMD_CAP_DUMP;
|
|
if (ops->doit)
|
|
op_flags |= GENL_CMD_CAP_DO;
|
|
if (family->policy)
|
|
op_flags |= GENL_CMD_CAP_HASPOL;
|
|
|
|
nest = nla_nest_start_noflag(skb, i + 1);
|
|
if (nest == NULL)
|
|
goto nla_put_failure;
|
|
|
|
if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
|
|
nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
|
|
goto nla_put_failure;
|
|
|
|
nla_nest_end(skb, nest);
|
|
}
|
|
|
|
nla_nest_end(skb, nla_ops);
|
|
}
|
|
|
|
if (family->n_mcgrps) {
|
|
struct nlattr *nla_grps;
|
|
int i;
|
|
|
|
nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
|
|
if (nla_grps == NULL)
|
|
goto nla_put_failure;
|
|
|
|
for (i = 0; i < family->n_mcgrps; i++) {
|
|
struct nlattr *nest;
|
|
const struct genl_multicast_group *grp;
|
|
|
|
grp = &family->mcgrps[i];
|
|
|
|
nest = nla_nest_start_noflag(skb, i + 1);
|
|
if (nest == NULL)
|
|
goto nla_put_failure;
|
|
|
|
if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
|
|
family->mcgrp_offset + i) ||
|
|
nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
|
|
grp->name))
|
|
goto nla_put_failure;
|
|
|
|
nla_nest_end(skb, nest);
|
|
}
|
|
nla_nest_end(skb, nla_grps);
|
|
}
|
|
|
|
genlmsg_end(skb, hdr);
|
|
return 0;
|
|
|
|
nla_put_failure:
|
|
genlmsg_cancel(skb, hdr);
|
|
return -EMSGSIZE;
|
|
}
|
|
|
|
static int ctrl_fill_mcgrp_info(const struct genl_family *family,
|
|
const struct genl_multicast_group *grp,
|
|
int grp_id, u32 portid, u32 seq, u32 flags,
|
|
struct sk_buff *skb, u8 cmd)
|
|
{
|
|
void *hdr;
|
|
struct nlattr *nla_grps;
|
|
struct nlattr *nest;
|
|
|
|
hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
|
|
if (hdr == NULL)
|
|
return -1;
|
|
|
|
if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
|
|
nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
|
|
goto nla_put_failure;
|
|
|
|
nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
|
|
if (nla_grps == NULL)
|
|
goto nla_put_failure;
|
|
|
|
nest = nla_nest_start_noflag(skb, 1);
|
|
if (nest == NULL)
|
|
goto nla_put_failure;
|
|
|
|
if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
|
|
nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
|
|
grp->name))
|
|
goto nla_put_failure;
|
|
|
|
nla_nest_end(skb, nest);
|
|
nla_nest_end(skb, nla_grps);
|
|
|
|
genlmsg_end(skb, hdr);
|
|
return 0;
|
|
|
|
nla_put_failure:
|
|
genlmsg_cancel(skb, hdr);
|
|
return -EMSGSIZE;
|
|
}
|
|
|
|
static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
|
|
{
|
|
int n = 0;
|
|
struct genl_family *rt;
|
|
struct net *net = sock_net(skb->sk);
|
|
int fams_to_skip = cb->args[0];
|
|
unsigned int id;
|
|
|
|
idr_for_each_entry(&genl_fam_idr, rt, id) {
|
|
if (!rt->netnsok && !net_eq(net, &init_net))
|
|
continue;
|
|
|
|
if (n++ < fams_to_skip)
|
|
continue;
|
|
|
|
if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
|
|
cb->nlh->nlmsg_seq, NLM_F_MULTI,
|
|
skb, CTRL_CMD_NEWFAMILY) < 0) {
|
|
n--;
|
|
break;
|
|
}
|
|
}
|
|
|
|
cb->args[0] = n;
|
|
return skb->len;
|
|
}
|
|
|
|
static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
|
|
u32 portid, int seq, u8 cmd)
|
|
{
|
|
struct sk_buff *skb;
|
|
int err;
|
|
|
|
skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
|
|
if (skb == NULL)
|
|
return ERR_PTR(-ENOBUFS);
|
|
|
|
err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
|
|
if (err < 0) {
|
|
nlmsg_free(skb);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
return skb;
|
|
}
|
|
|
|
static struct sk_buff *
|
|
ctrl_build_mcgrp_msg(const struct genl_family *family,
|
|
const struct genl_multicast_group *grp,
|
|
int grp_id, u32 portid, int seq, u8 cmd)
|
|
{
|
|
struct sk_buff *skb;
|
|
int err;
|
|
|
|
skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
|
|
if (skb == NULL)
|
|
return ERR_PTR(-ENOBUFS);
|
|
|
|
err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
|
|
seq, 0, skb, cmd);
|
|
if (err < 0) {
|
|
nlmsg_free(skb);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
return skb;
|
|
}
|
|
|
|
static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
|
|
[CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
|
|
[CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
|
|
.len = GENL_NAMSIZ - 1 },
|
|
};
|
|
|
|
static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
|
|
{
|
|
struct sk_buff *msg;
|
|
const struct genl_family *res = NULL;
|
|
int err = -EINVAL;
|
|
|
|
if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
|
|
u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
|
|
res = genl_family_find_byid(id);
|
|
err = -ENOENT;
|
|
}
|
|
|
|
if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
|
|
char *name;
|
|
|
|
name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
|
|
res = genl_family_find_byname(name);
|
|
#ifdef CONFIG_MODULES
|
|
if (res == NULL) {
|
|
genl_unlock();
|
|
up_read(&cb_lock);
|
|
request_module("net-pf-%d-proto-%d-family-%s",
|
|
PF_NETLINK, NETLINK_GENERIC, name);
|
|
down_read(&cb_lock);
|
|
genl_lock();
|
|
res = genl_family_find_byname(name);
|
|
}
|
|
#endif
|
|
err = -ENOENT;
|
|
}
|
|
|
|
if (res == NULL)
|
|
return err;
|
|
|
|
if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
|
|
/* family doesn't exist here */
|
|
return -ENOENT;
|
|
}
|
|
|
|
msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
|
|
CTRL_CMD_NEWFAMILY);
|
|
if (IS_ERR(msg))
|
|
return PTR_ERR(msg);
|
|
|
|
return genlmsg_reply(msg, info);
|
|
}
|
|
|
|
static int genl_ctrl_event(int event, const struct genl_family *family,
|
|
const struct genl_multicast_group *grp,
|
|
int grp_id)
|
|
{
|
|
struct sk_buff *msg;
|
|
|
|
/* genl is still initialising */
|
|
if (!init_net.genl_sock)
|
|
return 0;
|
|
|
|
switch (event) {
|
|
case CTRL_CMD_NEWFAMILY:
|
|
case CTRL_CMD_DELFAMILY:
|
|
WARN_ON(grp);
|
|
msg = ctrl_build_family_msg(family, 0, 0, event);
|
|
break;
|
|
case CTRL_CMD_NEWMCAST_GRP:
|
|
case CTRL_CMD_DELMCAST_GRP:
|
|
BUG_ON(!grp);
|
|
msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (IS_ERR(msg))
|
|
return PTR_ERR(msg);
|
|
|
|
if (!family->netnsok) {
|
|
genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
|
|
0, GFP_KERNEL);
|
|
} else {
|
|
rcu_read_lock();
|
|
genlmsg_multicast_allns(&genl_ctrl, msg, 0,
|
|
0, GFP_ATOMIC);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct genl_ops genl_ctrl_ops[] = {
|
|
{
|
|
.cmd = CTRL_CMD_GETFAMILY,
|
|
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
|
|
.doit = ctrl_getfamily,
|
|
.dumpit = ctrl_dumpfamily,
|
|
},
|
|
};
|
|
|
|
static const struct genl_multicast_group genl_ctrl_groups[] = {
|
|
{ .name = "notify", },
|
|
};
|
|
|
|
static struct genl_family genl_ctrl __ro_after_init = {
|
|
.module = THIS_MODULE,
|
|
.ops = genl_ctrl_ops,
|
|
.n_ops = ARRAY_SIZE(genl_ctrl_ops),
|
|
.mcgrps = genl_ctrl_groups,
|
|
.n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
|
|
.id = GENL_ID_CTRL,
|
|
.name = "nlctrl",
|
|
.version = 0x2,
|
|
.maxattr = CTRL_ATTR_MAX,
|
|
.policy = ctrl_policy,
|
|
.netnsok = true,
|
|
};
|
|
|
|
static int __net_init genl_pernet_init(struct net *net)
|
|
{
|
|
struct netlink_kernel_cfg cfg = {
|
|
.input = genl_rcv,
|
|
.flags = NL_CFG_F_NONROOT_RECV,
|
|
};
|
|
|
|
/* we'll bump the group number right afterwards */
|
|
net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
|
|
|
|
if (!net->genl_sock && net_eq(net, &init_net))
|
|
panic("GENL: Cannot initialize generic netlink\n");
|
|
|
|
if (!net->genl_sock)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __net_exit genl_pernet_exit(struct net *net)
|
|
{
|
|
netlink_kernel_release(net->genl_sock);
|
|
net->genl_sock = NULL;
|
|
}
|
|
|
|
static struct pernet_operations genl_pernet_ops = {
|
|
.init = genl_pernet_init,
|
|
.exit = genl_pernet_exit,
|
|
};
|
|
|
|
static int __init genl_init(void)
|
|
{
|
|
int err;
|
|
|
|
err = genl_register_family(&genl_ctrl);
|
|
if (err < 0)
|
|
goto problem;
|
|
|
|
err = register_pernet_subsys(&genl_pernet_ops);
|
|
if (err)
|
|
goto problem;
|
|
|
|
return 0;
|
|
|
|
problem:
|
|
panic("GENL: Cannot register controller: %d\n", err);
|
|
}
|
|
|
|
subsys_initcall(genl_init);
|
|
|
|
/**
|
|
* genl_family_attrbuf - return family's attrbuf
|
|
* @family: the family
|
|
*
|
|
* Return the family's attrbuf, while validating that it's
|
|
* actually valid to access it.
|
|
*
|
|
* You cannot use this function with a family that has parallel_ops
|
|
* and you can only use it within (pre/post) doit/dumpit callbacks.
|
|
*/
|
|
struct nlattr **genl_family_attrbuf(const struct genl_family *family)
|
|
{
|
|
if (!WARN_ON(family->parallel_ops))
|
|
lockdep_assert_held(&genl_mutex);
|
|
|
|
return family->attrbuf;
|
|
}
|
|
EXPORT_SYMBOL(genl_family_attrbuf);
|
|
|
|
static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
|
|
gfp_t flags)
|
|
{
|
|
struct sk_buff *tmp;
|
|
struct net *net, *prev = NULL;
|
|
bool delivered = false;
|
|
int err;
|
|
|
|
for_each_net_rcu(net) {
|
|
if (prev) {
|
|
tmp = skb_clone(skb, flags);
|
|
if (!tmp) {
|
|
err = -ENOMEM;
|
|
goto error;
|
|
}
|
|
err = nlmsg_multicast(prev->genl_sock, tmp,
|
|
portid, group, flags);
|
|
if (!err)
|
|
delivered = true;
|
|
else if (err != -ESRCH)
|
|
goto error;
|
|
}
|
|
|
|
prev = net;
|
|
}
|
|
|
|
err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
|
|
if (!err)
|
|
delivered = true;
|
|
else if (err != -ESRCH)
|
|
return err;
|
|
return delivered ? 0 : -ESRCH;
|
|
error:
|
|
kfree_skb(skb);
|
|
return err;
|
|
}
|
|
|
|
int genlmsg_multicast_allns(const struct genl_family *family,
|
|
struct sk_buff *skb, u32 portid,
|
|
unsigned int group, gfp_t flags)
|
|
{
|
|
if (WARN_ON_ONCE(group >= family->n_mcgrps))
|
|
return -EINVAL;
|
|
group = family->mcgrp_offset + group;
|
|
return genlmsg_mcast(skb, portid, group, flags);
|
|
}
|
|
EXPORT_SYMBOL(genlmsg_multicast_allns);
|
|
|
|
void genl_notify(const struct genl_family *family, struct sk_buff *skb,
|
|
struct genl_info *info, u32 group, gfp_t flags)
|
|
{
|
|
struct net *net = genl_info_net(info);
|
|
struct sock *sk = net->genl_sock;
|
|
int report = 0;
|
|
|
|
if (info->nlhdr)
|
|
report = nlmsg_report(info->nlhdr);
|
|
|
|
if (WARN_ON_ONCE(group >= family->n_mcgrps))
|
|
return;
|
|
group = family->mcgrp_offset + group;
|
|
nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
|
|
}
|
|
EXPORT_SYMBOL(genl_notify);
|