From: Alexei Starovoitov <ast@kernel.org>
Date: Wed, 14 Jul 2021 17:54:10 -0700
Subject: bpf: Add map side support for bpf timers.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.15-rc1
Git-commit: 68134668c17f31f51930478f75495b552a411550
References: jsc#PED-1377
Restrict bpf timers to array, hash (both preallocated and kmalloced), and
lru map types. The per-cpu maps with timers don't make sense, since 'struct
bpf_timer' is a part of map value. bpf timers in per-cpu maps would mean that
the number of timers depends on number of possible cpus and timers would not be
accessible from all cpus. lpm map support can be added in the future.
The timers in inner maps are supported.
The bpf_map_update/delete_elem() helpers and sys_bpf commands cancel and free
bpf_timer in a given map element.
Similar to 'struct bpf_spin_lock' BTF is required and it is used to validate
that map element indeed contains 'struct bpf_timer'.
Make check_and_init_map_value() init both bpf_spin_lock and bpf_timer when
map element data is reused in preallocated htab and lru maps.
Teach copy_map_value() to support both bpf_spin_lock and bpf_timer in a single
map element. There could be one of each, but not more than one. Due to 'one
bpf_timer in one element' restriction do not support timers in global data,
since global data is a map of single element, but from bpf program side it's
seen as many global variables and restriction of single global timer would be
odd. The sys_bpf map_freeze and sys_mmap syscalls are not allowed on maps with
timers, since user space could have corrupted mmap element and crashed the
kernel. The maps with timers cannot be readonly. Due to these restrictions
search for bpf_timer in datasec BTF in case it was placed in the global data to
report clear error.
The previous patch allowed 'struct bpf_timer' as a first field in a map
element only. Relax this restriction.
Refactor lru map to s/bpf_lru_push_free/htab_lru_push_free/ to cancel and free
the timer when lru map deletes an element as a part of it eviction algorithm.
Make sure that bpf program cannot access 'struct bpf_timer' via direct load/store.
The timer operation are done through helpers only.
This is similar to 'struct bpf_spin_lock'.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-5-alexei.starovoitov@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
include/linux/bpf.h | 44 ++++++++++++++----
include/linux/btf.h | 1
kernel/bpf/arraymap.c | 21 +++++++++
kernel/bpf/btf.c | 77 +++++++++++++++++++++++++++------
kernel/bpf/hashtab.c | 105 +++++++++++++++++++++++++++++++++++++++------
kernel/bpf/local_storage.c | 4 -
kernel/bpf/map_in_map.c | 2
kernel/bpf/syscall.c | 21 +++++++--
kernel/bpf/verifier.c | 30 +++++++++++-
9 files changed, 259 insertions(+), 46 deletions(-)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -198,24 +198,46 @@ static inline bool map_value_has_spin_lo
return map->spin_lock_off >= 0;
}
-static inline void check_and_init_map_lock(struct bpf_map *map, void *dst)
+static inline bool map_value_has_timer(const struct bpf_map *map)
{
- if (likely(!map_value_has_spin_lock(map)))
- return;
- *(struct bpf_spin_lock *)(dst + map->spin_lock_off) =
- (struct bpf_spin_lock){};
+ return map->timer_off >= 0;
}
-/* copy everything but bpf_spin_lock */
+static inline void check_and_init_map_value(struct bpf_map *map, void *dst)
+{
+ if (unlikely(map_value_has_spin_lock(map)))
+ *(struct bpf_spin_lock *)(dst + map->spin_lock_off) =
+ (struct bpf_spin_lock){};
+ if (unlikely(map_value_has_timer(map)))
+ *(struct bpf_timer *)(dst + map->timer_off) =
+ (struct bpf_timer){};
+}
+
+/* copy everything but bpf_spin_lock and bpf_timer. There could be one of each. */
static inline void copy_map_value(struct bpf_map *map, void *dst, void *src)
{
+ u32 s_off = 0, s_sz = 0, t_off = 0, t_sz = 0;
+
if (unlikely(map_value_has_spin_lock(map))) {
- u32 off = map->spin_lock_off;
+ s_off = map->spin_lock_off;
+ s_sz = sizeof(struct bpf_spin_lock);
+ } else if (unlikely(map_value_has_timer(map))) {
+ t_off = map->timer_off;
+ t_sz = sizeof(struct bpf_timer);
+ }
- memcpy(dst, src, off);
- memcpy(dst + off + sizeof(struct bpf_spin_lock),
- src + off + sizeof(struct bpf_spin_lock),
- map->value_size - off - sizeof(struct bpf_spin_lock));
+ if (unlikely(s_sz || t_sz)) {
+ if (s_off < t_off || !s_sz) {
+ swap(s_off, t_off);
+ swap(s_sz, t_sz);
+ }
+ memcpy(dst, src, t_off);
+ memcpy(dst + t_off + t_sz,
+ src + t_off + t_sz,
+ s_off - t_off - t_sz);
+ memcpy(dst + s_off + s_sz,
+ src + s_off + s_sz,
+ map->value_size - s_off - s_sz);
} else {
memcpy(dst, src, map->value_size);
}
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -99,6 +99,7 @@ bool btf_member_is_reg_int(const struct
const struct btf_member *m,
u32 expected_offset, u32 expected_size);
int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
+int btf_find_timer(const struct btf *btf, const struct btf_type *t);
bool btf_type_is_void(const struct btf_type *t);
s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -287,6 +287,12 @@ static int array_map_get_next_key(struct
return 0;
}
+static void check_and_free_timer_in_array(struct bpf_array *arr, void *val)
+{
+ if (unlikely(map_value_has_timer(&arr->map)))
+ bpf_timer_cancel_and_free(val + arr->map.timer_off);
+}
+
/* Called from syscall or from eBPF program */
static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
u64 map_flags)
@@ -321,6 +327,7 @@ static int array_map_update_elem(struct
copy_map_value_locked(map, val, value, false);
else
copy_map_value(map, val, value);
+ check_and_free_timer_in_array(array, val);
}
return 0;
}
@@ -374,6 +381,19 @@ static void *array_map_vmalloc_addr(stru
return (void *)round_down((unsigned long)array, PAGE_SIZE);
}
+static void array_map_free_timers(struct bpf_map *map)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ int i;
+
+ if (likely(!map_value_has_timer(map)))
+ return;
+
+ for (i = 0; i < array->map.max_entries; i++)
+ bpf_timer_cancel_and_free(array->value + array->elem_size * i +
+ map->timer_off);
+}
+
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void array_map_free(struct bpf_map *map)
{
@@ -668,6 +688,7 @@ const struct bpf_map_ops array_map_ops =
.map_alloc = array_map_alloc,
.map_free = array_map_free,
.map_get_next_key = array_map_get_next_key,
+ .map_release_uref = array_map_free_timers,
.map_lookup_elem = array_map_lookup_elem,
.map_update_elem = array_map_update_elem,
.map_delete_elem = array_map_delete_elem,
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3046,43 +3046,92 @@ static void btf_struct_log(struct btf_ve
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
-/* find 'struct bpf_spin_lock' in map value.
- * return >= 0 offset if found
- * and < 0 in case of error
- */
-int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
+static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t,
+ const char *name, int sz, int align)
{
const struct btf_member *member;
u32 i, off = -ENOENT;
- if (!__btf_type_is_struct(t))
- return -EINVAL;
-
for_each_member(i, t, member) {
const struct btf_type *member_type = btf_type_by_id(btf,
member->type);
if (!__btf_type_is_struct(member_type))
continue;
- if (member_type->size != sizeof(struct bpf_spin_lock))
+ if (member_type->size != sz)
continue;
- if (strcmp(__btf_name_by_offset(btf, member_type->name_off),
- "bpf_spin_lock"))
+ if (strcmp(__btf_name_by_offset(btf, member_type->name_off), name))
continue;
if (off != -ENOENT)
- /* only one 'struct bpf_spin_lock' is allowed */
+ /* only one such field is allowed */
return -E2BIG;
off = btf_member_bit_offset(t, member);
if (off % 8)
/* valid C code cannot generate such BTF */
return -EINVAL;
off /= 8;
- if (off % __alignof__(struct bpf_spin_lock))
- /* valid struct bpf_spin_lock will be 4 byte aligned */
+ if (off % align)
+ return -EINVAL;
+ }
+ return off;
+}
+
+static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
+ const char *name, int sz, int align)
+{
+ const struct btf_var_secinfo *vsi;
+ u32 i, off = -ENOENT;
+
+ for_each_vsi(i, t, vsi) {
+ const struct btf_type *var = btf_type_by_id(btf, vsi->type);
+ const struct btf_type *var_type = btf_type_by_id(btf, var->type);
+
+ if (!__btf_type_is_struct(var_type))
+ continue;
+ if (var_type->size != sz)
+ continue;
+ if (vsi->size != sz)
+ continue;
+ if (strcmp(__btf_name_by_offset(btf, var_type->name_off), name))
+ continue;
+ if (off != -ENOENT)
+ /* only one such field is allowed */
+ return -E2BIG;
+ off = vsi->offset;
+ if (off % align)
return -EINVAL;
}
return off;
}
+static int btf_find_field(const struct btf *btf, const struct btf_type *t,
+ const char *name, int sz, int align)
+{
+
+ if (__btf_type_is_struct(t))
+ return btf_find_struct_field(btf, t, name, sz, align);
+ else if (btf_type_is_datasec(t))
+ return btf_find_datasec_var(btf, t, name, sz, align);
+ return -EINVAL;
+}
+
+/* find 'struct bpf_spin_lock' in map value.
+ * return >= 0 offset if found
+ * and < 0 in case of error
+ */
+int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
+{
+ return btf_find_field(btf, t, "bpf_spin_lock",
+ sizeof(struct bpf_spin_lock),
+ __alignof__(struct bpf_spin_lock));
+}
+
+int btf_find_timer(const struct btf *btf, const struct btf_type *t)
+{
+ return btf_find_field(btf, t, "bpf_timer",
+ sizeof(struct bpf_timer),
+ __alignof__(struct bpf_timer));
+}
+
static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -228,6 +228,32 @@ static struct htab_elem *get_htab_elem(s
return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size);
}
+static bool htab_has_extra_elems(struct bpf_htab *htab)
+{
+ return !htab_is_percpu(htab) && !htab_is_lru(htab);
+}
+
+static void htab_free_prealloced_timers(struct bpf_htab *htab)
+{
+ u32 num_entries = htab->map.max_entries;
+ int i;
+
+ if (likely(!map_value_has_timer(&htab->map)))
+ return;
+ if (htab_has_extra_elems(htab))
+ num_entries += num_possible_cpus();
+
+ for (i = 0; i < num_entries; i++) {
+ struct htab_elem *elem;
+
+ elem = get_htab_elem(htab, i);
+ bpf_timer_cancel_and_free(elem->key +
+ round_up(htab->map.key_size, 8) +
+ htab->map.timer_off);
+ cond_resched();
+ }
+}
+
static void htab_free_elems(struct bpf_htab *htab)
{
int i;
@@ -265,8 +291,12 @@ static struct htab_elem *prealloc_lru_po
struct htab_elem *l;
if (node) {
+ u32 key_size = htab->map.key_size;
+
l = container_of(node, struct htab_elem, lru_node);
- memcpy(l->key, key, htab->map.key_size);
+ memcpy(l->key, key, key_size);
+ check_and_init_map_value(&htab->map,
+ l->key + round_up(key_size, 8));
return l;
}
@@ -278,7 +308,7 @@ static int prealloc_init(struct bpf_htab
u32 num_entries = htab->map.max_entries;
int err = -ENOMEM, i;
- if (!htab_is_percpu(htab) && !htab_is_lru(htab))
+ if (htab_has_extra_elems(htab))
num_entries += num_possible_cpus();
htab->elems = bpf_map_area_alloc((u64)htab->elem_size * num_entries,
@@ -695,6 +725,14 @@ static int htab_lru_map_gen_lookup(struc
return insn - insn_buf;
}
+static void check_and_free_timer(struct bpf_htab *htab, struct htab_elem *elem)
+{
+ if (unlikely(map_value_has_timer(&htab->map)))
+ bpf_timer_cancel_and_free(elem->key +
+ round_up(htab->map.key_size, 8) +
+ htab->map.timer_off);
+}
+
/* It is called from the bpf_lru_list when the LRU needs to delete
* older elements from the htab.
*/
@@ -719,6 +757,7 @@ static bool htab_lru_map_delete_node(voi
hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
if (l == tgt_l) {
hlist_nulls_del_rcu(&l->hash_node);
+ check_and_free_timer(htab, l);
break;
}
@@ -790,6 +829,7 @@ static void htab_elem_free(struct bpf_ht
{
if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
+ check_and_free_timer(htab, l);
kfree(l);
}
@@ -817,6 +857,7 @@ static void free_htab_elem(struct bpf_ht
htab_put_fd_value(htab, l);
if (htab_is_prealloc(htab)) {
+ check_and_free_timer(htab, l);
__pcpu_freelist_push(&htab->freelist, &l->fnode);
} else {
atomic_dec(&htab->count);
@@ -920,8 +961,8 @@ static struct htab_elem *alloc_htab_elem
l_new = ERR_PTR(-ENOMEM);
goto dec_count;
}
- check_and_init_map_lock(&htab->map,
- l_new->key + round_up(key_size, 8));
+ check_and_init_map_value(&htab->map,
+ l_new->key + round_up(key_size, 8));
}
memcpy(l_new->key, key, key_size);
@@ -1062,6 +1103,8 @@ static int htab_map_update_elem(struct b
hlist_nulls_del_rcu(&l_old->hash_node);
if (!htab_is_prealloc(htab))
free_htab_elem(htab, l_old);
+ else
+ check_and_free_timer(htab, l_old);
}
ret = 0;
err:
@@ -1069,6 +1112,12 @@ err:
return ret;
}
+static void htab_lru_push_free(struct bpf_htab *htab, struct htab_elem *elem)
+{
+ check_and_free_timer(htab, elem);
+ bpf_lru_push_free(&htab->lru, &elem->lru_node);
+}
+
static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
u64 map_flags)
{
@@ -1102,7 +1151,8 @@ static int htab_lru_map_update_elem(stru
l_new = prealloc_lru_pop(htab, key, hash);
if (!l_new)
return -ENOMEM;
- memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);
+ copy_map_value(&htab->map,
+ l_new->key + round_up(map->key_size, 8), value);
ret = htab_lock_bucket(htab, b, hash, &flags);
if (ret)
@@ -1128,9 +1178,9 @@ err:
htab_unlock_bucket(htab, b, hash, flags);
if (ret)
- bpf_lru_push_free(&htab->lru, &l_new->lru_node);
+ htab_lru_push_free(htab, l_new);
else if (l_old)
- bpf_lru_push_free(&htab->lru, &l_old->lru_node);
+ htab_lru_push_free(htab, l_old);
return ret;
}
@@ -1339,7 +1389,7 @@ static int htab_lru_map_delete_elem(stru
htab_unlock_bucket(htab, b, hash, flags);
if (l)
- bpf_lru_push_free(&htab->lru, &l->lru_node);
+ htab_lru_push_free(htab, l);
return ret;
}
@@ -1359,6 +1409,35 @@ static void delete_all_elements(struct b
}
}
+static void htab_free_malloced_timers(struct bpf_htab *htab)
+{
+ int i;
+
+ rcu_read_lock();
+ for (i = 0; i < htab->n_buckets; i++) {
+ struct hlist_nulls_head *head = select_bucket(htab, i);
+ struct hlist_nulls_node *n;
+ struct htab_elem *l;
+
+ hlist_nulls_for_each_entry(l, n, head, hash_node)
+ check_and_free_timer(htab, l);
+ cond_resched_rcu();
+ }
+ rcu_read_unlock();
+}
+
+static void htab_map_free_timers(struct bpf_map *map)
+{
+ struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+
+ if (likely(!map_value_has_timer(&htab->map)))
+ return;
+ if (!htab_is_prealloc(htab))
+ htab_free_malloced_timers(htab);
+ else
+ htab_free_prealloced_timers(htab);
+}
+
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void htab_map_free(struct bpf_map *map)
{
@@ -1456,7 +1535,7 @@ static int __htab_map_lookup_and_delete_
else
copy_map_value(map, value, l->key +
roundup_key_size);
- check_and_init_map_lock(map, value);
+ check_and_init_map_value(map, value);
}
hlist_nulls_del_rcu(&l->hash_node);
@@ -1467,7 +1546,7 @@ static int __htab_map_lookup_and_delete_
htab_unlock_bucket(htab, b, hash, bflags);
if (is_lru_map && l)
- bpf_lru_push_free(&htab->lru, &l->lru_node);
+ htab_lru_push_free(htab, l);
return ret;
}
@@ -1645,7 +1724,7 @@ again_nocopy:
true);
else
copy_map_value(map, dst_val, value);
- check_and_init_map_lock(map, dst_val);
+ check_and_init_map_value(map, dst_val);
}
if (do_delete) {
hlist_nulls_del_rcu(&l->hash_node);
@@ -1672,7 +1751,7 @@ again_nocopy:
while (node_to_free) {
l = node_to_free;
node_to_free = node_to_free->batch_flink;
- bpf_lru_push_free(&htab->lru, &l->lru_node);
+ htab_lru_push_free(htab, l);
}
next_batch:
@@ -2034,6 +2113,7 @@ const struct bpf_map_ops htab_map_ops =
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
+ .map_release_uref = htab_map_free_timers,
.map_lookup_elem = htab_map_lookup_elem,
.map_lookup_and_delete_elem = htab_map_lookup_and_delete_elem,
.map_update_elem = htab_map_update_elem,
@@ -2055,6 +2135,7 @@ const struct bpf_map_ops htab_lru_map_op
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
+ .map_release_uref = htab_map_free_timers,
.map_lookup_elem = htab_lru_map_lookup_elem,
.map_lookup_and_delete_elem = htab_lru_map_lookup_and_delete_elem,
.map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -173,7 +173,7 @@ static int cgroup_storage_update_elem(st
return -ENOMEM;
memcpy(&new->data[0], value, map->value_size);
- check_and_init_map_lock(map, new->data);
+ check_and_init_map_value(map, new->data);
new = xchg(&storage->buf, new);
kfree_rcu(new, rcu);
@@ -509,7 +509,7 @@ struct bpf_cgroup_storage *bpf_cgroup_st
map->numa_node);
if (!storage->buf)
goto enomem;
- check_and_init_map_lock(map, storage->buf->data);
+ check_and_init_map_value(map, storage->buf->data);
} else {
storage->percpu_buf = bpf_map_alloc_percpu(map, size, 8, gfp);
if (!storage->percpu_buf)
--- a/kernel/bpf/map_in_map.c
+++ b/kernel/bpf/map_in_map.c
@@ -50,6 +50,7 @@ struct bpf_map *bpf_map_meta_alloc(int i
inner_map_meta->map_flags = inner_map->map_flags;
inner_map_meta->max_entries = inner_map->max_entries;
inner_map_meta->spin_lock_off = inner_map->spin_lock_off;
+ inner_map_meta->timer_off = inner_map->timer_off;
/* Misc members not needed in bpf_map_meta_equal() check. */
inner_map_meta->ops = inner_map->ops;
@@ -75,6 +76,7 @@ bool bpf_map_meta_equal(const struct bpf
return meta0->map_type == meta1->map_type &&
meta0->key_size == meta1->key_size &&
meta0->value_size == meta1->value_size &&
+ meta0->timer_off == meta1->timer_off &&
meta0->map_flags == meta1->map_flags;
}
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -260,8 +260,8 @@ static int bpf_map_copy_value(struct bpf
copy_map_value_locked(map, value, ptr, true);
else
copy_map_value(map, value, ptr);
- /* mask lock, since value wasn't zero inited */
- check_and_init_map_lock(map, value);
+ /* mask lock and timer, since value wasn't zero inited */
+ check_and_init_map_value(map, value);
}
rcu_read_unlock();
}
@@ -623,7 +623,8 @@ static int bpf_map_mmap(struct file *fil
struct bpf_map *map = filp->private_data;
int err;
- if (!map->ops->map_mmap || map_value_has_spin_lock(map))
+ if (!map->ops->map_mmap || map_value_has_spin_lock(map) ||
+ map_value_has_timer(map))
return -ENOTSUPP;
if (!(vma->vm_flags & VM_SHARED))
@@ -793,6 +794,16 @@ static int map_check_btf(struct bpf_map
}
}
+ map->timer_off = btf_find_timer(btf, value_type);
+ if (map_value_has_timer(map)) {
+ if (map->map_flags & BPF_F_RDONLY_PROG)
+ return -EACCES;
+ if (map->map_type != BPF_MAP_TYPE_HASH &&
+ map->map_type != BPF_MAP_TYPE_LRU_HASH &&
+ map->map_type != BPF_MAP_TYPE_ARRAY)
+ return -EOPNOTSUPP;
+ }
+
if (map->ops->map_check_btf)
ret = map->ops->map_check_btf(map, btf, key_type, value_type);
@@ -844,6 +855,7 @@ static int map_create(union bpf_attr *at
mutex_init(&map->freeze_mutex);
map->spin_lock_off = -EINVAL;
+ map->timer_off = -EINVAL;
if (attr->btf_key_type_id || attr->btf_value_type_id ||
/* Even the map's value is a kernel's struct,
* the bpf_prog.o must have BTF to begin with
@@ -1591,7 +1603,8 @@ static int map_freeze(const union bpf_at
if (IS_ERR(map))
return PTR_ERR(map);
- if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
+ if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS ||
+ map_value_has_timer(map)) {
fdput(f);
return -ENOTSUPP;
}
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3217,6 +3217,15 @@ static int check_map_access(struct bpf_v
return -EACCES;
}
}
+ if (map_value_has_timer(map)) {
+ u32 t = map->timer_off;
+
+ if (reg->smin_value + off < t + sizeof(struct bpf_timer) &&
+ t < reg->umax_value + off + size) {
+ verbose(env, "bpf_timer cannot be accessed directly by load/store\n");
+ return -EACCES;
+ }
+ }
return err;
}
@@ -4653,9 +4662,24 @@ static int process_timer_func(struct bpf
map->name);
return -EINVAL;
}
- if (val) {
- /* This restriction will be removed in the next patch */
- verbose(env, "bpf_timer field can only be first in the map value element\n");
+ if (!map_value_has_timer(map)) {
+ if (map->timer_off == -E2BIG)
+ verbose(env,
+ "map '%s' has more than one 'struct bpf_timer'\n",
+ map->name);
+ else if (map->timer_off == -ENOENT)
+ verbose(env,
+ "map '%s' doesn't have 'struct bpf_timer'\n",
+ map->name);
+ else
+ verbose(env,
+ "map '%s' is not a struct type or bpf_timer is mangled\n",
+ map->name);
+ return -EINVAL;
+ }
+ if (map->timer_off != val + reg->off) {
+ verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n",
+ val + reg->off, map->timer_off);
return -EINVAL;
}
if (meta->map_ptr) {