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![Daniel Borkmann](/assets/img/avatar_default.png)
Michael and Sandipan report: Commitede95a63b5
introduced a bpf_jit_limit tuneable to limit BPF JIT allocations. At compile time it defaults to PAGE_SIZE * 40000, and is adjusted again at init time if MODULES_VADDR is defined. For ppc64 kernels, MODULES_VADDR isn't defined, so we're stuck with the compile-time default at boot-time, which is 0x9c400000 when using 64K page size. This overflows the signed 32-bit bpf_jit_limit value: root@ubuntu:/tmp# cat /proc/sys/net/core/bpf_jit_limit -1673527296 and can cause various unexpected failures throughout the network stack. In one case `strace dhclient eth0` reported: setsockopt(5, SOL_SOCKET, SO_ATTACH_FILTER, {len=11, filter=0x105dd27f8}, 16) = -1 ENOTSUPP (Unknown error 524) and similar failures can be seen with tools like tcpdump. This doesn't always reproduce however, and I'm not sure why. The more consistent failure I've seen is an Ubuntu 18.04 KVM guest booted on a POWER9 host would time out on systemd/netplan configuring a virtio-net NIC with no noticeable errors in the logs. Given this and also given that in near future some architectures like arm64 will have a custom area for BPF JIT image allocations we should get rid of the BPF_JIT_LIMIT_DEFAULT fallback / default entirely. For 4.21, we have an overridable bpf_jit_alloc_exec(), bpf_jit_free_exec() so therefore add another overridable bpf_jit_alloc_exec_limit() helper function which returns the possible size of the memory area for deriving the default heuristic in bpf_jit_charge_init(). Like bpf_jit_alloc_exec() and bpf_jit_free_exec(), the new bpf_jit_alloc_exec_limit() assumes that module_alloc() is the default JIT memory provider, and therefore in case archs implement their custom module_alloc() we use MODULES_{END,_VADDR} for limits and otherwise for vmalloc_exec() cases like on ppc64 we use VMALLOC_{END,_START}. Additionally, for archs supporting large page sizes, we should change the sysctl to be handled as long to not run into sysctl restrictions in future. Fixes:ede95a63b5
("bpf: add bpf_jit_limit knob to restrict unpriv allocations") Reported-by: Sandipan Das <sandipan@linux.ibm.com> Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
614 lines
14 KiB
C
614 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* -*- linux-c -*-
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* sysctl_net_core.c: sysctl interface to net core subsystem.
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*
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* Begun April 1, 1996, Mike Shaver.
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* Added /proc/sys/net/core directory entry (empty =) ). [MS]
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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/module.h>
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#include <linux/socket.h>
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#include <linux/netdevice.h>
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#include <linux/ratelimit.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <net/ip.h>
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#include <net/sock.h>
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#include <net/net_ratelimit.h>
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#include <net/busy_poll.h>
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#include <net/pkt_sched.h>
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static int zero = 0;
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static int one = 1;
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static int two __maybe_unused = 2;
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static int min_sndbuf = SOCK_MIN_SNDBUF;
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static int min_rcvbuf = SOCK_MIN_RCVBUF;
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static int max_skb_frags = MAX_SKB_FRAGS;
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static long long_one __maybe_unused = 1;
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static long long_max __maybe_unused = LONG_MAX;
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static int net_msg_warn; /* Unused, but still a sysctl */
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int sysctl_fb_tunnels_only_for_init_net __read_mostly = 0;
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EXPORT_SYMBOL(sysctl_fb_tunnels_only_for_init_net);
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#ifdef CONFIG_RPS
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static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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unsigned int orig_size, size;
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int ret, i;
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struct ctl_table tmp = {
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.data = &size,
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.maxlen = sizeof(size),
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.mode = table->mode
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};
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struct rps_sock_flow_table *orig_sock_table, *sock_table;
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static DEFINE_MUTEX(sock_flow_mutex);
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mutex_lock(&sock_flow_mutex);
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orig_sock_table = rcu_dereference_protected(rps_sock_flow_table,
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lockdep_is_held(&sock_flow_mutex));
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size = orig_size = orig_sock_table ? orig_sock_table->mask + 1 : 0;
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ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
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if (write) {
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if (size) {
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if (size > 1<<29) {
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/* Enforce limit to prevent overflow */
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mutex_unlock(&sock_flow_mutex);
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return -EINVAL;
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}
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size = roundup_pow_of_two(size);
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if (size != orig_size) {
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sock_table =
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vmalloc(RPS_SOCK_FLOW_TABLE_SIZE(size));
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if (!sock_table) {
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mutex_unlock(&sock_flow_mutex);
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return -ENOMEM;
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}
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rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1;
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sock_table->mask = size - 1;
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} else
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sock_table = orig_sock_table;
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for (i = 0; i < size; i++)
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sock_table->ents[i] = RPS_NO_CPU;
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} else
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sock_table = NULL;
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if (sock_table != orig_sock_table) {
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rcu_assign_pointer(rps_sock_flow_table, sock_table);
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if (sock_table) {
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static_key_slow_inc(&rps_needed);
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static_key_slow_inc(&rfs_needed);
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}
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if (orig_sock_table) {
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static_key_slow_dec(&rps_needed);
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static_key_slow_dec(&rfs_needed);
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synchronize_rcu();
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vfree(orig_sock_table);
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}
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}
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}
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mutex_unlock(&sock_flow_mutex);
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return ret;
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}
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#endif /* CONFIG_RPS */
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#ifdef CONFIG_NET_FLOW_LIMIT
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static DEFINE_MUTEX(flow_limit_update_mutex);
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static int flow_limit_cpu_sysctl(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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struct sd_flow_limit *cur;
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struct softnet_data *sd;
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cpumask_var_t mask;
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int i, len, ret = 0;
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if (!alloc_cpumask_var(&mask, GFP_KERNEL))
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return -ENOMEM;
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if (write) {
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ret = cpumask_parse_user(buffer, *lenp, mask);
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if (ret)
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goto done;
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mutex_lock(&flow_limit_update_mutex);
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len = sizeof(*cur) + netdev_flow_limit_table_len;
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for_each_possible_cpu(i) {
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sd = &per_cpu(softnet_data, i);
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cur = rcu_dereference_protected(sd->flow_limit,
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lockdep_is_held(&flow_limit_update_mutex));
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if (cur && !cpumask_test_cpu(i, mask)) {
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RCU_INIT_POINTER(sd->flow_limit, NULL);
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synchronize_rcu();
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kfree(cur);
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} else if (!cur && cpumask_test_cpu(i, mask)) {
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cur = kzalloc_node(len, GFP_KERNEL,
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cpu_to_node(i));
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if (!cur) {
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/* not unwinding previous changes */
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ret = -ENOMEM;
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goto write_unlock;
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}
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cur->num_buckets = netdev_flow_limit_table_len;
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rcu_assign_pointer(sd->flow_limit, cur);
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}
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}
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write_unlock:
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mutex_unlock(&flow_limit_update_mutex);
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} else {
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char kbuf[128];
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if (*ppos || !*lenp) {
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*lenp = 0;
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goto done;
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}
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cpumask_clear(mask);
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rcu_read_lock();
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for_each_possible_cpu(i) {
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sd = &per_cpu(softnet_data, i);
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if (rcu_dereference(sd->flow_limit))
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cpumask_set_cpu(i, mask);
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}
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rcu_read_unlock();
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len = min(sizeof(kbuf) - 1, *lenp);
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len = scnprintf(kbuf, len, "%*pb", cpumask_pr_args(mask));
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if (!len) {
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*lenp = 0;
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goto done;
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}
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if (len < *lenp)
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kbuf[len++] = '\n';
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if (copy_to_user(buffer, kbuf, len)) {
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ret = -EFAULT;
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goto done;
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}
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*lenp = len;
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*ppos += len;
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}
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done:
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free_cpumask_var(mask);
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return ret;
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}
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static int flow_limit_table_len_sysctl(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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unsigned int old, *ptr;
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int ret;
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mutex_lock(&flow_limit_update_mutex);
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ptr = table->data;
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old = *ptr;
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ret = proc_dointvec(table, write, buffer, lenp, ppos);
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if (!ret && write && !is_power_of_2(*ptr)) {
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*ptr = old;
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ret = -EINVAL;
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}
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mutex_unlock(&flow_limit_update_mutex);
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return ret;
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}
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#endif /* CONFIG_NET_FLOW_LIMIT */
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#ifdef CONFIG_NET_SCHED
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static int set_default_qdisc(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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char id[IFNAMSIZ];
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struct ctl_table tbl = {
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.data = id,
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.maxlen = IFNAMSIZ,
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};
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int ret;
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qdisc_get_default(id, IFNAMSIZ);
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ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
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if (write && ret == 0)
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ret = qdisc_set_default(id);
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return ret;
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}
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#endif
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static int proc_do_dev_weight(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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int ret;
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ret = proc_dointvec(table, write, buffer, lenp, ppos);
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if (ret != 0)
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return ret;
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dev_rx_weight = weight_p * dev_weight_rx_bias;
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dev_tx_weight = weight_p * dev_weight_tx_bias;
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return ret;
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}
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static int proc_do_rss_key(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table fake_table;
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char buf[NETDEV_RSS_KEY_LEN * 3];
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snprintf(buf, sizeof(buf), "%*phC", NETDEV_RSS_KEY_LEN, netdev_rss_key);
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fake_table.data = buf;
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fake_table.maxlen = sizeof(buf);
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return proc_dostring(&fake_table, write, buffer, lenp, ppos);
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}
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#ifdef CONFIG_BPF_JIT
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static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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int ret, jit_enable = *(int *)table->data;
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struct ctl_table tmp = *table;
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if (write && !capable(CAP_SYS_ADMIN))
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return -EPERM;
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tmp.data = &jit_enable;
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ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
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if (write && !ret) {
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if (jit_enable < 2 ||
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(jit_enable == 2 && bpf_dump_raw_ok())) {
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*(int *)table->data = jit_enable;
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if (jit_enable == 2)
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pr_warn("bpf_jit_enable = 2 was set! NEVER use this in production, only for JIT debugging!\n");
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} else {
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ret = -EPERM;
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}
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}
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return ret;
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}
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static int
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proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
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}
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static int
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proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
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}
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#endif
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static struct ctl_table net_core_table[] = {
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#ifdef CONFIG_NET
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{
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.procname = "wmem_max",
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.data = &sysctl_wmem_max,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = &min_sndbuf,
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},
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{
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.procname = "rmem_max",
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.data = &sysctl_rmem_max,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = &min_rcvbuf,
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},
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{
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.procname = "wmem_default",
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.data = &sysctl_wmem_default,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = &min_sndbuf,
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},
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{
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.procname = "rmem_default",
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.data = &sysctl_rmem_default,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = &min_rcvbuf,
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},
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{
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.procname = "dev_weight",
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.data = &weight_p,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_do_dev_weight,
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},
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{
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.procname = "dev_weight_rx_bias",
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.data = &dev_weight_rx_bias,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_do_dev_weight,
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},
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{
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.procname = "dev_weight_tx_bias",
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.data = &dev_weight_tx_bias,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_do_dev_weight,
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},
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{
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.procname = "netdev_max_backlog",
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.data = &netdev_max_backlog,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{
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.procname = "netdev_rss_key",
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.data = &netdev_rss_key,
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.maxlen = sizeof(int),
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.mode = 0444,
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.proc_handler = proc_do_rss_key,
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},
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#ifdef CONFIG_BPF_JIT
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{
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.procname = "bpf_jit_enable",
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.data = &bpf_jit_enable,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax_bpf_enable,
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# ifdef CONFIG_BPF_JIT_ALWAYS_ON
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.extra1 = &one,
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.extra2 = &one,
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# else
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.extra1 = &zero,
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.extra2 = &two,
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# endif
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},
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# ifdef CONFIG_HAVE_EBPF_JIT
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{
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.procname = "bpf_jit_harden",
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.data = &bpf_jit_harden,
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.maxlen = sizeof(int),
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.mode = 0600,
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.proc_handler = proc_dointvec_minmax_bpf_restricted,
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.extra1 = &zero,
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.extra2 = &two,
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},
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{
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.procname = "bpf_jit_kallsyms",
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.data = &bpf_jit_kallsyms,
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.maxlen = sizeof(int),
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.mode = 0600,
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.proc_handler = proc_dointvec_minmax_bpf_restricted,
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.extra1 = &zero,
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.extra2 = &one,
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},
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# endif
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{
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.procname = "bpf_jit_limit",
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.data = &bpf_jit_limit,
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.maxlen = sizeof(long),
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.mode = 0600,
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.proc_handler = proc_dolongvec_minmax_bpf_restricted,
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.extra1 = &long_one,
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.extra2 = &long_max,
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},
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#endif
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{
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.procname = "netdev_tstamp_prequeue",
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.data = &netdev_tstamp_prequeue,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{
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.procname = "message_cost",
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.data = &net_ratelimit_state.interval,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_jiffies,
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},
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{
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.procname = "message_burst",
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.data = &net_ratelimit_state.burst,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec,
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},
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{
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.procname = "optmem_max",
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.data = &sysctl_optmem_max,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{
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.procname = "tstamp_allow_data",
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.data = &sysctl_tstamp_allow_data,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &one
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},
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#ifdef CONFIG_RPS
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{
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.procname = "rps_sock_flow_entries",
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = rps_sock_flow_sysctl
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},
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#endif
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|
#ifdef CONFIG_NET_FLOW_LIMIT
|
|
{
|
|
.procname = "flow_limit_cpu_bitmap",
|
|
.mode = 0644,
|
|
.proc_handler = flow_limit_cpu_sysctl
|
|
},
|
|
{
|
|
.procname = "flow_limit_table_len",
|
|
.data = &netdev_flow_limit_table_len,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = flow_limit_table_len_sysctl
|
|
},
|
|
#endif /* CONFIG_NET_FLOW_LIMIT */
|
|
#ifdef CONFIG_NET_RX_BUSY_POLL
|
|
{
|
|
.procname = "busy_poll",
|
|
.data = &sysctl_net_busy_poll,
|
|
.maxlen = sizeof(unsigned int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &zero,
|
|
},
|
|
{
|
|
.procname = "busy_read",
|
|
.data = &sysctl_net_busy_read,
|
|
.maxlen = sizeof(unsigned int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &zero,
|
|
},
|
|
#endif
|
|
#ifdef CONFIG_NET_SCHED
|
|
{
|
|
.procname = "default_qdisc",
|
|
.mode = 0644,
|
|
.maxlen = IFNAMSIZ,
|
|
.proc_handler = set_default_qdisc
|
|
},
|
|
#endif
|
|
#endif /* CONFIG_NET */
|
|
{
|
|
.procname = "netdev_budget",
|
|
.data = &netdev_budget,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec
|
|
},
|
|
{
|
|
.procname = "warnings",
|
|
.data = &net_msg_warn,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec
|
|
},
|
|
{
|
|
.procname = "max_skb_frags",
|
|
.data = &sysctl_max_skb_frags,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &one,
|
|
.extra2 = &max_skb_frags,
|
|
},
|
|
{
|
|
.procname = "netdev_budget_usecs",
|
|
.data = &netdev_budget_usecs,
|
|
.maxlen = sizeof(unsigned int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &zero,
|
|
},
|
|
{
|
|
.procname = "fb_tunnels_only_for_init_net",
|
|
.data = &sysctl_fb_tunnels_only_for_init_net,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &zero,
|
|
.extra2 = &one,
|
|
},
|
|
{ }
|
|
};
|
|
|
|
static struct ctl_table netns_core_table[] = {
|
|
{
|
|
.procname = "somaxconn",
|
|
.data = &init_net.core.sysctl_somaxconn,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.extra1 = &zero,
|
|
.proc_handler = proc_dointvec_minmax
|
|
},
|
|
{ }
|
|
};
|
|
|
|
static __net_init int sysctl_core_net_init(struct net *net)
|
|
{
|
|
struct ctl_table *tbl;
|
|
|
|
tbl = netns_core_table;
|
|
if (!net_eq(net, &init_net)) {
|
|
tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
|
|
if (tbl == NULL)
|
|
goto err_dup;
|
|
|
|
tbl[0].data = &net->core.sysctl_somaxconn;
|
|
|
|
/* Don't export any sysctls to unprivileged users */
|
|
if (net->user_ns != &init_user_ns) {
|
|
tbl[0].procname = NULL;
|
|
}
|
|
}
|
|
|
|
net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
|
|
if (net->core.sysctl_hdr == NULL)
|
|
goto err_reg;
|
|
|
|
return 0;
|
|
|
|
err_reg:
|
|
if (tbl != netns_core_table)
|
|
kfree(tbl);
|
|
err_dup:
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static __net_exit void sysctl_core_net_exit(struct net *net)
|
|
{
|
|
struct ctl_table *tbl;
|
|
|
|
tbl = net->core.sysctl_hdr->ctl_table_arg;
|
|
unregister_net_sysctl_table(net->core.sysctl_hdr);
|
|
BUG_ON(tbl == netns_core_table);
|
|
kfree(tbl);
|
|
}
|
|
|
|
static __net_initdata struct pernet_operations sysctl_core_ops = {
|
|
.init = sysctl_core_net_init,
|
|
.exit = sysctl_core_net_exit,
|
|
};
|
|
|
|
static __init int sysctl_core_init(void)
|
|
{
|
|
register_net_sysctl(&init_net, "net/core", net_core_table);
|
|
return register_pernet_subsys(&sysctl_core_ops);
|
|
}
|
|
|
|
fs_initcall(sysctl_core_init);
|