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kernel/net/sctp/sysctl.c
Eric Dumazet 10206302af sctp: add mutual exclusion in proc_sctp_do_udp_port() 
We must serialize calls to sctp_udp_sock_stop() and sctp_udp_sock_start()
or risk a crash as syzbot reported:

Oops: general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 1 UID: 0 PID: 6551 Comm: syz.1.44 Not tainted 6.14.0-syzkaller-g7f2ff7b62617 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
 RIP: 0010:kernel_sock_shutdown+0x47/0x70 net/socket.c:3653
Call Trace:
 <TASK>
  udp_tunnel_sock_release+0x68/0x80 net/ipv4/udp_tunnel_core.c:181
  sctp_udp_sock_stop+0x71/0x160 net/sctp/protocol.c:930
  proc_sctp_do_udp_port+0x264/0x450 net/sctp/sysctl.c:553
  proc_sys_call_handler+0x3d0/0x5b0 fs/proc/proc_sysctl.c:601
  iter_file_splice_write+0x91c/0x1150 fs/splice.c:738
  do_splice_from fs/splice.c:935 [inline]
  direct_splice_actor+0x18f/0x6c0 fs/splice.c:1158
  splice_direct_to_actor+0x342/0xa30 fs/splice.c:1102
  do_splice_direct_actor fs/splice.c:1201 [inline]
  do_splice_direct+0x174/0x240 fs/splice.c:1227
  do_sendfile+0xafd/0xe50 fs/read_write.c:1368
  __do_sys_sendfile64 fs/read_write.c:1429 [inline]
  __se_sys_sendfile64 fs/read_write.c:1415 [inline]
  __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1415
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]

Fixes: 046c052b47 ("sctp: enable udp tunneling socks")
Reported-by: syzbot+fae49d997eb56fa7c74d@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/67ea5c01.050a0220.1547ec.012b.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20250331091532.224982-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-04-02 16:04:19 -07:00

648 lines
16 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
* (C) Copyright IBM Corp. 2002, 2004
* Copyright (c) 2002 Intel Corp.
*
* This file is part of the SCTP kernel implementation
*
* Sysctl related interfaces for SCTP.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <linux-sctp@vger.kernel.org>
*
* Written or modified by:
* Mingqin Liu <liuming@us.ibm.com>
* Jon Grimm <jgrimm@us.ibm.com>
* Ardelle Fan <ardelle.fan@intel.com>
* Ryan Layer <rmlayer@us.ibm.com>
* Sridhar Samudrala <sri@us.ibm.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <net/sctp/structs.h>
#include <net/sctp/sctp.h>
#include <linux/sysctl.h>
static int timer_max = 86400000; /* ms in one day */
static int sack_timer_min = 1;
static int sack_timer_max = 500;
static int addr_scope_max = SCTP_SCOPE_POLICY_MAX;
static int rwnd_scale_max = 16;
static int rto_alpha_min = 0;
static int rto_beta_min = 0;
static int rto_alpha_max = 1000;
static int rto_beta_max = 1000;
static int pf_expose_max = SCTP_PF_EXPOSE_MAX;
static int ps_retrans_max = SCTP_PS_RETRANS_MAX;
static int udp_port_max = 65535;
static unsigned long max_autoclose_min = 0;
static unsigned long max_autoclose_max =
(MAX_SCHEDULE_TIMEOUT / HZ > UINT_MAX)
? UINT_MAX : MAX_SCHEDULE_TIMEOUT / HZ;
static int proc_sctp_do_hmac_alg(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos);
static int proc_sctp_do_rto_min(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos);
static int proc_sctp_do_rto_max(const struct ctl_table *ctl, int write, void *buffer,
size_t *lenp, loff_t *ppos);
static int proc_sctp_do_udp_port(const struct ctl_table *ctl, int write, void *buffer,
size_t *lenp, loff_t *ppos);
static int proc_sctp_do_alpha_beta(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos);
static int proc_sctp_do_auth(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos);
static int proc_sctp_do_probe_interval(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos);
static struct ctl_table sctp_table[] = {
{
.procname = "sctp_mem",
.data = &sysctl_sctp_mem,
.maxlen = sizeof(sysctl_sctp_mem),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax
},
{
.procname = "sctp_rmem",
.data = &sysctl_sctp_rmem,
.maxlen = sizeof(sysctl_sctp_rmem),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "sctp_wmem",
.data = &sysctl_sctp_wmem,
.maxlen = sizeof(sysctl_sctp_wmem),
.mode = 0644,
.proc_handler = proc_dointvec,
},
};
/* The following index defines are used in sctp_sysctl_net_register().
* If you add new items to the sctp_net_table, please ensure that
* the index values of these defines hold the same meaning indicated by
* their macro names when they appear in sctp_net_table.
*/
#define SCTP_RTO_MIN_IDX 0
#define SCTP_RTO_MAX_IDX 1
#define SCTP_PF_RETRANS_IDX 2
#define SCTP_PS_RETRANS_IDX 3
static struct ctl_table sctp_net_table[] = {
[SCTP_RTO_MIN_IDX] = {
.procname = "rto_min",
.data = &init_net.sctp.rto_min,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_sctp_do_rto_min,
.extra1 = SYSCTL_ONE,
.extra2 = &init_net.sctp.rto_max
},
[SCTP_RTO_MAX_IDX] = {
.procname = "rto_max",
.data = &init_net.sctp.rto_max,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_sctp_do_rto_max,
.extra1 = &init_net.sctp.rto_min,
.extra2 = &timer_max
},
[SCTP_PF_RETRANS_IDX] = {
.procname = "pf_retrans",
.data = &init_net.sctp.pf_retrans,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = &init_net.sctp.ps_retrans,
},
[SCTP_PS_RETRANS_IDX] = {
.procname = "ps_retrans",
.data = &init_net.sctp.ps_retrans,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &init_net.sctp.pf_retrans,
.extra2 = &ps_retrans_max,
},
{
.procname = "rto_initial",
.data = &init_net.sctp.rto_initial,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = &timer_max
},
{
.procname = "rto_alpha_exp_divisor",
.data = &init_net.sctp.rto_alpha,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_sctp_do_alpha_beta,
.extra1 = &rto_alpha_min,
.extra2 = &rto_alpha_max,
},
{
.procname = "rto_beta_exp_divisor",
.data = &init_net.sctp.rto_beta,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_sctp_do_alpha_beta,
.extra1 = &rto_beta_min,
.extra2 = &rto_beta_max,
},
{
.procname = "max_burst",
.data = &init_net.sctp.max_burst,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_INT_MAX,
},
{
.procname = "cookie_preserve_enable",
.data = &init_net.sctp.cookie_preserve_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "cookie_hmac_alg",
.data = &init_net.sctp.sctp_hmac_alg,
.maxlen = 8,
.mode = 0644,
.proc_handler = proc_sctp_do_hmac_alg,
},
{
.procname = "valid_cookie_life",
.data = &init_net.sctp.valid_cookie_life,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = &timer_max
},
{
.procname = "sack_timeout",
.data = &init_net.sctp.sack_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &sack_timer_min,
.extra2 = &sack_timer_max,
},
{
.procname = "hb_interval",
.data = &init_net.sctp.hb_interval,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = &timer_max
},
{
.procname = "association_max_retrans",
.data = &init_net.sctp.max_retrans_association,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_INT_MAX,
},
{
.procname = "path_max_retrans",
.data = &init_net.sctp.max_retrans_path,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_INT_MAX,
},
{
.procname = "max_init_retransmits",
.data = &init_net.sctp.max_retrans_init,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_INT_MAX,
},
{
.procname = "sndbuf_policy",
.data = &init_net.sctp.sndbuf_policy,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "rcvbuf_policy",
.data = &init_net.sctp.rcvbuf_policy,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "default_auto_asconf",
.data = &init_net.sctp.default_auto_asconf,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "addip_enable",
.data = &init_net.sctp.addip_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "addip_noauth_enable",
.data = &init_net.sctp.addip_noauth,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "prsctp_enable",
.data = &init_net.sctp.prsctp_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "reconf_enable",
.data = &init_net.sctp.reconf_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "auth_enable",
.data = &init_net.sctp.auth_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_sctp_do_auth,
},
{
.procname = "intl_enable",
.data = &init_net.sctp.intl_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "ecn_enable",
.data = &init_net.sctp.ecn_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "plpmtud_probe_interval",
.data = &init_net.sctp.probe_interval,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_sctp_do_probe_interval,
},
{
.procname = "udp_port",
.data = &init_net.sctp.udp_port,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_sctp_do_udp_port,
.extra1 = SYSCTL_ZERO,
.extra2 = &udp_port_max,
},
{
.procname = "encap_port",
.data = &init_net.sctp.encap_port,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = &udp_port_max,
},
{
.procname = "addr_scope_policy",
.data = &init_net.sctp.scope_policy,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = &addr_scope_max,
},
{
.procname = "rwnd_update_shift",
.data = &init_net.sctp.rwnd_upd_shift,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = &rwnd_scale_max,
},
{
.procname = "max_autoclose",
.data = &init_net.sctp.max_autoclose,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
.extra1 = &max_autoclose_min,
.extra2 = &max_autoclose_max,
},
#ifdef CONFIG_NET_L3_MASTER_DEV
{
.procname = "l3mdev_accept",
.data = &init_net.sctp.l3mdev_accept,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
#endif
{
.procname = "pf_enable",
.data = &init_net.sctp.pf_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "pf_expose",
.data = &init_net.sctp.pf_expose,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = &pf_expose_max,
},
};
static int proc_sctp_do_hmac_alg(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = container_of(ctl->data, struct net,
sctp.sctp_hmac_alg);
struct ctl_table tbl;
bool changed = false;
char *none = "none";
char tmp[8] = {0};
int ret;
memset(&tbl, 0, sizeof(struct ctl_table));
if (write) {
tbl.data = tmp;
tbl.maxlen = sizeof(tmp);
} else {
tbl.data = net->sctp.sctp_hmac_alg ? : none;
tbl.maxlen = strlen(tbl.data);
}
ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
#ifdef CONFIG_CRYPTO_MD5
if (!strncmp(tmp, "md5", 3)) {
net->sctp.sctp_hmac_alg = "md5";
changed = true;
}
#endif
#ifdef CONFIG_CRYPTO_SHA1
if (!strncmp(tmp, "sha1", 4)) {
net->sctp.sctp_hmac_alg = "sha1";
changed = true;
}
#endif
if (!strncmp(tmp, "none", 4)) {
net->sctp.sctp_hmac_alg = NULL;
changed = true;
}
if (!changed)
ret = -EINVAL;
}
return ret;
}
static int proc_sctp_do_rto_min(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = container_of(ctl->data, struct net, sctp.rto_min);
unsigned int min = *(unsigned int *) ctl->extra1;
unsigned int max = *(unsigned int *) ctl->extra2;
struct ctl_table tbl;
int ret, new_value;
memset(&tbl, 0, sizeof(struct ctl_table));
tbl.maxlen = sizeof(unsigned int);
if (write)
tbl.data = &new_value;
else
tbl.data = &net->sctp.rto_min;
ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
if (new_value > max || new_value < min)
return -EINVAL;
net->sctp.rto_min = new_value;
}
return ret;
}
static int proc_sctp_do_rto_max(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = container_of(ctl->data, struct net, sctp.rto_max);
unsigned int min = *(unsigned int *) ctl->extra1;
unsigned int max = *(unsigned int *) ctl->extra2;
struct ctl_table tbl;
int ret, new_value;
memset(&tbl, 0, sizeof(struct ctl_table));
tbl.maxlen = sizeof(unsigned int);
if (write)
tbl.data = &new_value;
else
tbl.data = &net->sctp.rto_max;
ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
if (new_value > max || new_value < min)
return -EINVAL;
net->sctp.rto_max = new_value;
}
return ret;
}
static int proc_sctp_do_alpha_beta(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
if (write)
pr_warn_once("Changing rto_alpha or rto_beta may lead to "
"suboptimal rtt/srtt estimations!\n");
return proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
}
static int proc_sctp_do_auth(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = container_of(ctl->data, struct net, sctp.auth_enable);
struct ctl_table tbl;
int new_value, ret;
memset(&tbl, 0, sizeof(struct ctl_table));
tbl.maxlen = sizeof(unsigned int);
if (write)
tbl.data = &new_value;
else
tbl.data = &net->sctp.auth_enable;
ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
struct sock *sk = net->sctp.ctl_sock;
net->sctp.auth_enable = new_value;
/* Update the value in the control socket */
lock_sock(sk);
sctp_sk(sk)->ep->auth_enable = new_value;
release_sock(sk);
}
return ret;
}
static DEFINE_MUTEX(sctp_sysctl_mutex);
static int proc_sctp_do_udp_port(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = container_of(ctl->data, struct net, sctp.udp_port);
unsigned int min = *(unsigned int *)ctl->extra1;
unsigned int max = *(unsigned int *)ctl->extra2;
struct ctl_table tbl;
int ret, new_value;
memset(&tbl, 0, sizeof(struct ctl_table));
tbl.maxlen = sizeof(unsigned int);
if (write)
tbl.data = &new_value;
else
tbl.data = &net->sctp.udp_port;
ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
struct sock *sk = net->sctp.ctl_sock;
if (new_value > max || new_value < min)
return -EINVAL;
mutex_lock(&sctp_sysctl_mutex);
net->sctp.udp_port = new_value;
sctp_udp_sock_stop(net);
if (new_value) {
ret = sctp_udp_sock_start(net);
if (ret)
net->sctp.udp_port = 0;
}
/* Update the value in the control socket */
lock_sock(sk);
sctp_sk(sk)->udp_port = htons(net->sctp.udp_port);
release_sock(sk);
mutex_unlock(&sctp_sysctl_mutex);
}
return ret;
}
static int proc_sctp_do_probe_interval(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = container_of(ctl->data, struct net,
sctp.probe_interval);
struct ctl_table tbl;
int ret, new_value;
memset(&tbl, 0, sizeof(struct ctl_table));
tbl.maxlen = sizeof(unsigned int);
if (write)
tbl.data = &new_value;
else
tbl.data = &net->sctp.probe_interval;
ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
if (new_value && new_value < SCTP_PROBE_TIMER_MIN)
return -EINVAL;
net->sctp.probe_interval = new_value;
}
return ret;
}
int sctp_sysctl_net_register(struct net *net)
{
size_t table_size = ARRAY_SIZE(sctp_net_table);
struct ctl_table *table;
int i;
table = kmemdup(sctp_net_table, sizeof(sctp_net_table), GFP_KERNEL);
if (!table)
return -ENOMEM;
for (i = 0; i < table_size; i++)
table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;
table[SCTP_RTO_MIN_IDX].extra2 = &net->sctp.rto_max;
table[SCTP_RTO_MAX_IDX].extra1 = &net->sctp.rto_min;
table[SCTP_PF_RETRANS_IDX].extra2 = &net->sctp.ps_retrans;
table[SCTP_PS_RETRANS_IDX].extra1 = &net->sctp.pf_retrans;
net->sctp.sysctl_header = register_net_sysctl_sz(net, "net/sctp",
table, table_size);
if (net->sctp.sysctl_header == NULL) {
kfree(table);
return -ENOMEM;
}
return 0;
}
void sctp_sysctl_net_unregister(struct net *net)
{
const struct ctl_table *table;
table = net->sctp.sysctl_header->ctl_table_arg;
unregister_net_sysctl_table(net->sctp.sysctl_header);
kfree(table);
}
static struct ctl_table_header *sctp_sysctl_header;
/* Sysctl registration. */
void sctp_sysctl_register(void)
{
sctp_sysctl_header = register_net_sysctl(&init_net, "net/sctp", sctp_table);
}
/* Sysctl deregistration. */
void sctp_sysctl_unregister(void)
{
unregister_net_sysctl_table(sctp_sysctl_header);
}
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