We need to extend the bpf_timer API, but the way forward relies on kfuncs. So make bpf_timer known for kfuncs from the verifier PoV
Signed-off-by: Benjamin Tissoires bentiss@kernel.org
---
new in v3 (split from v2 02/10) --- kernel/bpf/verifier.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f81c799b2c80..2b11687063ff 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5444,6 +5444,26 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno, return -EACCES; } break; + case BPF_TIMER: + /* FIXME: kptr does the above, should we use the same? */ + if (src != ACCESS_DIRECT) { + verbose(env, "bpf_timer cannot be accessed indirectly by helper\n"); + return -EACCES; + } + if (!tnum_is_const(reg->var_off)) { + verbose(env, "bpf_timer access cannot have variable offset\n"); + return -EACCES; + } + if (p != off + reg->var_off.value) { + verbose(env, "bpf_timer access misaligned expected=%u off=%llu\n", + p, off + reg->var_off.value); + return -EACCES; + } + if (size != bpf_size_to_bytes(BPF_DW)) { + verbose(env, "bpf_timer access size must be BPF_DW\n"); + return -EACCES; + } + break; default: verbose(env, "%s cannot be accessed directly by load/store\n", btf_field_type_name(field->type)); @@ -10789,6 +10809,7 @@ enum { KF_ARG_LIST_NODE_ID, KF_ARG_RB_ROOT_ID, KF_ARG_RB_NODE_ID, + KF_ARG_TIMER_ID, };
BTF_ID_LIST(kf_arg_btf_ids) @@ -10797,6 +10818,7 @@ BTF_ID(struct, bpf_list_head) BTF_ID(struct, bpf_list_node) BTF_ID(struct, bpf_rb_root) BTF_ID(struct, bpf_rb_node) +BTF_ID(struct, bpf_timer_kern)
static bool __is_kfunc_ptr_arg_type(const struct btf *btf, const struct btf_param *arg, int type) @@ -10840,6 +10862,12 @@ static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_par return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID); }
+static bool is_kfunc_arg_timer(const struct btf *btf, const struct btf_param *arg) +{ + bool ret = __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_TIMER_ID); + return ret; +} + static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf, const struct btf_param *arg) { @@ -10908,6 +10936,7 @@ enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_RB_NODE, KF_ARG_PTR_TO_NULL, KF_ARG_PTR_TO_CONST_STR, + KF_ARG_PTR_TO_TIMER, };
enum special_kfunc_type { @@ -11061,6 +11090,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, if (is_kfunc_arg_const_str(meta->btf, &args[argno])) return KF_ARG_PTR_TO_CONST_STR;
+ if (is_kfunc_arg_timer(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_TIMER; + if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { if (!btf_type_is_struct(ref_t)) { verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", @@ -11693,6 +11725,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ case KF_ARG_PTR_TO_CALLBACK: case KF_ARG_PTR_TO_REFCOUNTED_KPTR: case KF_ARG_PTR_TO_CONST_STR: + case KF_ARG_PTR_TO_TIMER: /* Trusted by default */ break; default: @@ -11973,6 +12006,9 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ if (ret) return ret; break; + case KF_ARG_PTR_TO_TIMER: + /* FIXME: should we do anything here? */ + break; } }