01b3f52157
For large map->value_size the user space can trigger memory allocation warnings like:
WARNING: CPU: 2 PID: 11122 at mm/page_alloc.c:2989
__alloc_pages_nodemask+0x695/0x14e0()
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff82743b56>] dump_stack+0x68/0x92 lib/dump_stack.c:50
[<ffffffff81244ec9>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:460
[<ffffffff812450f9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:493
[< inline >] __alloc_pages_slowpath mm/page_alloc.c:2989
[<ffffffff81554e95>] __alloc_pages_nodemask+0x695/0x14e0 mm/page_alloc.c:3235
[<ffffffff816188fe>] alloc_pages_current+0xee/0x340 mm/mempolicy.c:2055
[< inline >] alloc_pages include/linux/gfp.h:451
[<ffffffff81550706>] alloc_kmem_pages+0x16/0xf0 mm/page_alloc.c:3414
[<ffffffff815a1c89>] kmalloc_order+0x19/0x60 mm/slab_common.c:1007
[<ffffffff815a1cef>] kmalloc_order_trace+0x1f/0xa0 mm/slab_common.c:1018
[< inline >] kmalloc_large include/linux/slab.h:390
[<ffffffff81627784>] __kmalloc+0x234/0x250 mm/slub.c:3525
[< inline >] kmalloc include/linux/slab.h:463
[< inline >] map_update_elem kernel/bpf/syscall.c:288
[< inline >] SYSC_bpf kernel/bpf/syscall.c:744
To avoid never succeeding kmalloc with order >= MAX_ORDER check that
elem->value_size and computed elem_size are within limits for both hash and
array type maps.
Also add __GFP_NOWARN to kmalloc(value_size | elem_size) to avoid OOM warnings.
Note kmalloc(key_size) is highly unlikely to trigger OOM, since key_size <= 512,
so keep those kmalloc-s as-is.
Large value_size can cause integer overflows in elem_size and map.pages
formulas, so check for that as well.
Fixes: aaac3ba95e
("bpf: charge user for creation of BPF maps and programs")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
348 lines
8.7 KiB
C
348 lines
8.7 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/bpf.h>
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#include <linux/err.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/filter.h>
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#include <linux/perf_event.h>
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/* Called from syscall */
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static struct bpf_map *array_map_alloc(union bpf_attr *attr)
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{
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struct bpf_array *array;
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u32 elem_size, array_size;
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/* check sanity of attributes */
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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attr->value_size == 0)
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return ERR_PTR(-EINVAL);
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if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
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/* if value_size is bigger, the user space won't be able to
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* access the elements.
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*/
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return ERR_PTR(-E2BIG);
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elem_size = round_up(attr->value_size, 8);
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/* check round_up into zero and u32 overflow */
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if (elem_size == 0 ||
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attr->max_entries > (U32_MAX - PAGE_SIZE - sizeof(*array)) / elem_size)
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return ERR_PTR(-ENOMEM);
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array_size = sizeof(*array) + attr->max_entries * elem_size;
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/* allocate all map elements and zero-initialize them */
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array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
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if (!array) {
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array = vzalloc(array_size);
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if (!array)
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return ERR_PTR(-ENOMEM);
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}
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/* copy mandatory map attributes */
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array->map.key_size = attr->key_size;
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array->map.value_size = attr->value_size;
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array->map.max_entries = attr->max_entries;
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array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
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array->elem_size = elem_size;
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return &array->map;
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}
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/* Called from syscall or from eBPF program */
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static void *array_map_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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if (index >= array->map.max_entries)
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return NULL;
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return array->value + array->elem_size * index;
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}
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/* Called from syscall */
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static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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u32 *next = (u32 *)next_key;
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if (index >= array->map.max_entries) {
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*next = 0;
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return 0;
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}
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if (index == array->map.max_entries - 1)
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return -ENOENT;
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*next = index + 1;
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return 0;
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}
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/* Called from syscall or from eBPF program */
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static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
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u64 map_flags)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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if (map_flags > BPF_EXIST)
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/* unknown flags */
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return -EINVAL;
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if (index >= array->map.max_entries)
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/* all elements were pre-allocated, cannot insert a new one */
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return -E2BIG;
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if (map_flags == BPF_NOEXIST)
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/* all elements already exist */
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return -EEXIST;
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memcpy(array->value + array->elem_size * index, value, map->value_size);
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return 0;
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}
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/* Called from syscall or from eBPF program */
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static int array_map_delete_elem(struct bpf_map *map, void *key)
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{
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return -EINVAL;
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}
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/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
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static void array_map_free(struct bpf_map *map)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
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* so the programs (can be more than one that used this map) were
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* disconnected from events. Wait for outstanding programs to complete
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* and free the array
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*/
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synchronize_rcu();
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kvfree(array);
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}
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static const struct bpf_map_ops array_ops = {
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.map_alloc = array_map_alloc,
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.map_free = array_map_free,
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.map_get_next_key = array_map_get_next_key,
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.map_lookup_elem = array_map_lookup_elem,
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.map_update_elem = array_map_update_elem,
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.map_delete_elem = array_map_delete_elem,
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};
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static struct bpf_map_type_list array_type __read_mostly = {
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.ops = &array_ops,
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.type = BPF_MAP_TYPE_ARRAY,
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};
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static int __init register_array_map(void)
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{
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bpf_register_map_type(&array_type);
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return 0;
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}
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late_initcall(register_array_map);
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static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
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{
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/* only file descriptors can be stored in this type of map */
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if (attr->value_size != sizeof(u32))
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return ERR_PTR(-EINVAL);
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return array_map_alloc(attr);
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}
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static void fd_array_map_free(struct bpf_map *map)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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int i;
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synchronize_rcu();
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/* make sure it's empty */
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for (i = 0; i < array->map.max_entries; i++)
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BUG_ON(array->ptrs[i] != NULL);
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kvfree(array);
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}
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static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
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{
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return NULL;
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}
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/* only called from syscall */
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static int fd_array_map_update_elem(struct bpf_map *map, void *key,
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void *value, u64 map_flags)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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void *new_ptr, *old_ptr;
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u32 index = *(u32 *)key, ufd;
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if (map_flags != BPF_ANY)
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return -EINVAL;
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if (index >= array->map.max_entries)
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return -E2BIG;
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ufd = *(u32 *)value;
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new_ptr = map->ops->map_fd_get_ptr(map, ufd);
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if (IS_ERR(new_ptr))
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return PTR_ERR(new_ptr);
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old_ptr = xchg(array->ptrs + index, new_ptr);
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if (old_ptr)
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map->ops->map_fd_put_ptr(old_ptr);
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return 0;
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}
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static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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void *old_ptr;
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u32 index = *(u32 *)key;
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if (index >= array->map.max_entries)
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return -E2BIG;
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old_ptr = xchg(array->ptrs + index, NULL);
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if (old_ptr) {
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map->ops->map_fd_put_ptr(old_ptr);
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return 0;
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} else {
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return -ENOENT;
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}
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}
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static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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struct bpf_prog *prog = bpf_prog_get(fd);
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if (IS_ERR(prog))
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return prog;
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if (!bpf_prog_array_compatible(array, prog)) {
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bpf_prog_put(prog);
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return ERR_PTR(-EINVAL);
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}
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return prog;
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}
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static void prog_fd_array_put_ptr(void *ptr)
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{
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struct bpf_prog *prog = ptr;
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bpf_prog_put_rcu(prog);
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}
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/* decrement refcnt of all bpf_progs that are stored in this map */
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void bpf_fd_array_map_clear(struct bpf_map *map)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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int i;
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for (i = 0; i < array->map.max_entries; i++)
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fd_array_map_delete_elem(map, &i);
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}
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static const struct bpf_map_ops prog_array_ops = {
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.map_alloc = fd_array_map_alloc,
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.map_free = fd_array_map_free,
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.map_get_next_key = array_map_get_next_key,
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.map_lookup_elem = fd_array_map_lookup_elem,
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.map_update_elem = fd_array_map_update_elem,
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.map_delete_elem = fd_array_map_delete_elem,
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.map_fd_get_ptr = prog_fd_array_get_ptr,
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.map_fd_put_ptr = prog_fd_array_put_ptr,
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};
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static struct bpf_map_type_list prog_array_type __read_mostly = {
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.ops = &prog_array_ops,
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.type = BPF_MAP_TYPE_PROG_ARRAY,
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};
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static int __init register_prog_array_map(void)
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{
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bpf_register_map_type(&prog_array_type);
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return 0;
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}
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late_initcall(register_prog_array_map);
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static void perf_event_array_map_free(struct bpf_map *map)
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{
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bpf_fd_array_map_clear(map);
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fd_array_map_free(map);
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}
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static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
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{
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struct perf_event *event;
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const struct perf_event_attr *attr;
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event = perf_event_get(fd);
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if (IS_ERR(event))
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return event;
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attr = perf_event_attrs(event);
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if (IS_ERR(attr))
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goto err;
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if (attr->inherit)
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goto err;
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if (attr->type == PERF_TYPE_RAW)
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return event;
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if (attr->type == PERF_TYPE_HARDWARE)
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return event;
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if (attr->type == PERF_TYPE_SOFTWARE &&
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attr->config == PERF_COUNT_SW_BPF_OUTPUT)
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return event;
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err:
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perf_event_release_kernel(event);
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return ERR_PTR(-EINVAL);
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}
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static void perf_event_fd_array_put_ptr(void *ptr)
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{
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struct perf_event *event = ptr;
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perf_event_release_kernel(event);
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}
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static const struct bpf_map_ops perf_event_array_ops = {
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.map_alloc = fd_array_map_alloc,
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.map_free = perf_event_array_map_free,
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.map_get_next_key = array_map_get_next_key,
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.map_lookup_elem = fd_array_map_lookup_elem,
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.map_update_elem = fd_array_map_update_elem,
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.map_delete_elem = fd_array_map_delete_elem,
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.map_fd_get_ptr = perf_event_fd_array_get_ptr,
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.map_fd_put_ptr = perf_event_fd_array_put_ptr,
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};
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static struct bpf_map_type_list perf_event_array_type __read_mostly = {
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.ops = &perf_event_array_ops,
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.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
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};
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static int __init register_perf_event_array_map(void)
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{
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bpf_register_map_type(&perf_event_array_type);
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return 0;
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}
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late_initcall(register_perf_event_array_map);
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