summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--include/linux/bpf.h2
-rw-r--r--include/linux/bpf_verifier.h5
-rw-r--r--kernel/bpf/arraymap.c31
-rw-r--r--kernel/bpf/verifier.c42
4 files changed, 67 insertions, 13 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 97498be2ca2e..75ffd3b2149e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -43,6 +43,7 @@ struct bpf_map {
u32 max_entries;
u32 map_flags;
u32 pages;
+ bool unpriv_array;
struct user_struct *user;
const struct bpf_map_ops *ops;
struct work_struct work;
@@ -189,6 +190,7 @@ struct bpf_prog_aux {
struct bpf_array {
struct bpf_map map;
u32 elem_size;
+ u32 index_mask;
/* 'ownership' of prog_array is claimed by the first program that
* is going to use this map or by the first program which FD is stored
* in the map to make sure that all callers and callees have the same
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 4c4e9358c146..070fc49e39e2 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -67,7 +67,10 @@ struct bpf_verifier_state_list {
};
struct bpf_insn_aux_data {
- enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
+ union {
+ enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
+ struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */
+ };
bool seen; /* this insn was processed by the verifier */
};
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index f3721e150d94..bc57ead11b0f 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -46,9 +46,10 @@ static int bpf_array_alloc_percpu(struct bpf_array *array)
static struct bpf_map *array_map_alloc(union bpf_attr *attr)
{
bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
+ u32 elem_size, index_mask, max_entries;
+ bool unpriv = !capable(CAP_SYS_ADMIN);
struct bpf_array *array;
u64 array_size;
- u32 elem_size;
/* check sanity of attributes */
if (attr->max_entries == 0 || attr->key_size != 4 ||
@@ -63,11 +64,20 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
elem_size = round_up(attr->value_size, 8);
+ max_entries = attr->max_entries;
+ index_mask = roundup_pow_of_two(max_entries) - 1;
+
+ if (unpriv)
+ /* round up array size to nearest power of 2,
+ * since cpu will speculate within index_mask limits
+ */
+ max_entries = index_mask + 1;
+
array_size = sizeof(*array);
if (percpu)
- array_size += (u64) attr->max_entries * sizeof(void *);
+ array_size += (u64) max_entries * sizeof(void *);
else
- array_size += (u64) attr->max_entries * elem_size;
+ array_size += (u64) max_entries * elem_size;
/* make sure there is no u32 overflow later in round_up() */
if (array_size >= U32_MAX - PAGE_SIZE)
@@ -77,6 +87,8 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
array = bpf_map_area_alloc(array_size);
if (!array)
return ERR_PTR(-ENOMEM);
+ array->index_mask = index_mask;
+ array->map.unpriv_array = unpriv;
/* copy mandatory map attributes */
array->map.map_type = attr->map_type;
@@ -110,7 +122,7 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key)
if (unlikely(index >= array->map.max_entries))
return NULL;
- return array->value + array->elem_size * index;
+ return array->value + array->elem_size * (index & array->index_mask);
}
/* Called from eBPF program */
@@ -122,7 +134,7 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
if (unlikely(index >= array->map.max_entries))
return NULL;
- return this_cpu_ptr(array->pptrs[index]);
+ return this_cpu_ptr(array->pptrs[index & array->index_mask]);
}
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
@@ -142,7 +154,7 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
*/
size = round_up(map->value_size, 8);
rcu_read_lock();
- pptr = array->pptrs[index];
+ pptr = array->pptrs[index & array->index_mask];
for_each_possible_cpu(cpu) {
bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
off += size;
@@ -190,10 +202,11 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
return -EEXIST;
if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
- memcpy(this_cpu_ptr(array->pptrs[index]),
+ memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
value, map->value_size);
else
- memcpy(array->value + array->elem_size * index,
+ memcpy(array->value +
+ array->elem_size * (index & array->index_mask),
value, map->value_size);
return 0;
}
@@ -227,7 +240,7 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
*/
size = round_up(map->value_size, 8);
rcu_read_lock();
- pptr = array->pptrs[index];
+ pptr = array->pptrs[index & array->index_mask];
for_each_possible_cpu(cpu) {
bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
off += size;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 27370410c04d..19c44cf59bb2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1187,7 +1187,7 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
}
}
-static int check_call(struct bpf_verifier_env *env, int func_id)
+static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
{
struct bpf_verifier_state *state = &env->cur_state;
const struct bpf_func_proto *fn = NULL;
@@ -1238,6 +1238,13 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
if (err)
return err;
+ if (func_id == BPF_FUNC_tail_call) {
+ if (meta.map_ptr == NULL) {
+ verbose("verifier bug\n");
+ return -EINVAL;
+ }
+ env->insn_aux_data[insn_idx].map_ptr = meta.map_ptr;
+ }
err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
if (err)
return err;
@@ -3019,7 +3026,7 @@ static int do_check(struct bpf_verifier_env *env)
return -EINVAL;
}
- err = check_call(env, insn->imm);
+ err = check_call(env, insn->imm, insn_idx);
if (err)
return err;
@@ -3372,7 +3379,11 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
struct bpf_insn *insn = prog->insnsi;
const struct bpf_func_proto *fn;
const int insn_cnt = prog->len;
- int i;
+ struct bpf_insn insn_buf[16];
+ struct bpf_prog *new_prog;
+ struct bpf_map *map_ptr;
+ int i, cnt, delta = 0;
+
for (i = 0; i < insn_cnt; i++, insn++) {
if (insn->code != (BPF_JMP | BPF_CALL))
@@ -3390,6 +3401,31 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
*/
insn->imm = 0;
insn->code |= BPF_X;
+
+ /* instead of changing every JIT dealing with tail_call
+ * emit two extra insns:
+ * if (index >= max_entries) goto out;
+ * index &= array->index_mask;
+ * to avoid out-of-bounds cpu speculation
+ */
+ map_ptr = env->insn_aux_data[i + delta].map_ptr;
+ if (!map_ptr->unpriv_array)
+ continue;
+ insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
+ map_ptr->max_entries, 2);
+ insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
+ container_of(map_ptr,
+ struct bpf_array,
+ map)->index_mask);
+ insn_buf[2] = *insn;
+ cnt = 3;
+ new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
+ if (!new_prog)
+ return -ENOMEM;
+
+ delta += cnt - 1;
+ env->prog = prog = new_prog;
+ insn = new_prog->insnsi + i + delta;
continue;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-15 15:35:00 +0000