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bpf: Use kvmalloc for map values in syscall 

Use kvmalloc/kvfree for temporary value when manipulating a map via
syscall. kmalloc might not be sufficient for percpu maps where the value
is big (and further multiplied by hundreds of CPUs).

Can be reproduced with netcnt test on qemu with "-smp 255".

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818235216.1159202-1-sdf@google.com
This commit is contained in:
Stanislav Fomichev 2021-08-18 16:52:15 -07:00 committed by Daniel Borkmann
parent 3666b167ea
commit f0dce1d9b7
1 changed files with 11 additions and 17 deletions
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28
kernel/bpf/syscall.c
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@ -1076,7 +1076,7 @@ static int map_lookup_elem(union bpf_attr *attr)
value_size = bpf_map_value_size(map);
err = -ENOMEM;
value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
if (!value)
goto free_key;
@ -1091,7 +1091,7 @@ static int map_lookup_elem(union bpf_attr *attr)
err = 0;
free_value:
kfree(value);
kvfree(value);
free_key:
kfree(key);
err_put:
@ -1137,16 +1137,10 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
goto err_put;
}
if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY ||
map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
value_size = round_up(map->value_size, 8) * num_possible_cpus();
else
value_size = map->value_size;
value_size = bpf_map_value_size(map);
err = -ENOMEM;
value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
if (!value)
goto free_key;
@ -1157,7 +1151,7 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
err = bpf_map_update_value(map, f, key, value, attr->flags);
free_value:
kfree(value);
kvfree(value);
free_key:
kfree(key);
err_put:
@ -1367,7 +1361,7 @@ int generic_map_update_batch(struct bpf_map *map,
if (!key)
return -ENOMEM;
value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
if (!value) {
kfree(key);
return -ENOMEM;
@ -1390,7 +1384,7 @@ int generic_map_update_batch(struct bpf_map *map,
if (copy_to_user(&uattr->batch.count, &cp, sizeof(cp)))
err = -EFAULT;
kfree(value);
kvfree(value);
kfree(key);
return err;
}
@ -1429,7 +1423,7 @@ int generic_map_lookup_batch(struct bpf_map *map,
if (!buf_prevkey)
return -ENOMEM;
buf = kmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN);
buf = kvmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN);
if (!buf) {
kfree(buf_prevkey);
return -ENOMEM;
@ -1492,7 +1486,7 @@ int generic_map_lookup_batch(struct bpf_map *map,
free_buf:
kfree(buf_prevkey);
kfree(buf);
kvfree(buf);
return err;
}
@ -1547,7 +1541,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
value_size = bpf_map_value_size(map);
err = -ENOMEM;
value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
if (!value)
goto free_key;
@ -1579,7 +1573,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
err = 0;
free_value:
kfree(value);
kvfree(value);
free_key:
kfree(key);
err_put: