github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 17:47:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

bpf: Unify dynptr handling in the verifier

Browse Source 
Simplify dynptr checking for helper and kfunc by unifying it. Remember
the initialized dynptr (i.e.,g !(arg_type |= MEM_UNINIT)) pass to a
dynptr kfunc during process_dynptr_func() so that we can easily
retrieve the information for verification later. By saving it in
meta->dynptr, there is no need to call dynptr helpers such as
dynptr_id(), dynptr_ref_obj_id() and dynptr_type() in check_func_arg().

Remove and open code the helpers in process_dynptr_func() when
saving id, ref_obj_id, and type.

Besides, since dynptr ref_obj_id information is now pass around in
meta->bpf_dynptr_desc, drop the check in helper_multiple_ref_obj_use.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-3-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Amery Hung 2026-05-28 18:49:25 -07:00 committed by Alexei Starovoitov
parent bab08d1f70
commit b5c0a07eb2
2 changed files with 40 additions and 151 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/bpf_verifier.h
View File

@ -1438,6 +1438,13 @@ struct bpf_map_desc {
int uid;
};
/* The last initialized dynptr; Populated by process_dynptr_func() */
struct bpf_dynptr_desc {
enum bpf_dynptr_type type;
u32 id;
u32 ref_obj_id;
};
struct bpf_kfunc_call_arg_meta {
/* In parameters */
struct btf *btf;
@ -1478,16 +1485,12 @@ struct bpf_kfunc_call_arg_meta {
struct {
struct btf_field *field;
} arg_rbtree_root;
struct {
enum bpf_dynptr_type type;
u32 id;
u32 ref_obj_id;
} initialized_dynptr;
struct {
u8 spi;
u8 frameno;
} iter;
struct bpf_map_desc map;
struct bpf_dynptr_desc dynptr;
u64 mem_size;
};

178
kernel/bpf/verifier.c
View File

@ -233,6 +233,7 @@ static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
struct bpf_call_arg_meta {
struct bpf_map_desc map;
struct bpf_dynptr_desc dynptr;
bool raw_mode;
bool pkt_access;
u8 release_regno;
@ -241,7 +242,6 @@ struct bpf_call_arg_meta {
int mem_size;
u64 msize_max_value;
int ref_obj_id;
int dynptr_id;
int func_id;
struct btf *btf;
u32 btf_id;
@ -470,11 +470,6 @@ static bool is_ptr_cast_function(enum bpf_func_id func_id)
func_id == BPF_FUNC_skc_to_tcp_request_sock;
}
static bool is_dynptr_ref_function(enum bpf_func_id func_id)
{
return func_id == BPF_FUNC_dynptr_data;
}
static bool is_sync_callback_calling_kfunc(u32 btf_id);
static bool is_async_callback_calling_kfunc(u32 btf_id);
static bool is_callback_calling_kfunc(u32 btf_id);
@ -542,8 +537,6 @@ static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id,
ref_obj_uses++;
if (is_acquire_function(func_id, map))
ref_obj_uses++;
if (is_dynptr_ref_function(func_id))
ref_obj_uses++;
return ref_obj_uses > 1;
}
@ -7221,8 +7214,9 @@ static int process_kptr_func(struct bpf_verifier_env *env, int regno,
* use case. The second level is tracked using the upper bit of bpf_dynptr->size
* and checked dynamically during runtime.
*/
static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno, int insn_idx,
enum bpf_arg_type arg_type, int clone_ref_obj_id)
static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
argno_t argno, int insn_idx, enum bpf_arg_type arg_type,
int clone_ref_obj_id, struct bpf_dynptr_desc *dynptr)
{
int spi, err = 0;
@ -7287,6 +7281,8 @@ static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_stat
}
if (reg->type != CONST_PTR_TO_DYNPTR) {
struct bpf_func_state *state = bpf_func(env, reg);
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
@ -7296,6 +7292,14 @@ static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_stat
* in check_helper_call and mark_btf_func_reg_size in check_kfunc_call.
*/
mark_stack_slots_scratched(env, spi, BPF_DYNPTR_NR_SLOTS);
reg = &state->stack[spi].spilled_ptr;
}
if (dynptr) {
dynptr->type = reg->dynptr.type;
dynptr->id = reg->id;
dynptr->ref_obj_id = reg->ref_obj_id;
}
}
return err;
@ -8065,72 +8069,6 @@ static int check_func_arg_reg_off(struct bpf_verifier_env *env,
}
}
static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
const struct bpf_func_proto *fn,
struct bpf_reg_state *regs)
{
struct bpf_reg_state *state = NULL;
int i;
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
if (arg_type_is_dynptr(fn->arg_type[i])) {
if (state) {
verbose(env, "verifier internal error: multiple dynptr args\n");
return NULL;
}
state = &regs[BPF_REG_1 + i];
}
if (!state)
verbose(env, "verifier internal error: no dynptr arg found\n");
return state;
}
static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = bpf_func(env, reg);
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return reg->id;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
return state->stack[spi].spilled_ptr.id;
}
static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = bpf_func(env, reg);
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return reg->ref_obj_id;
spi = dynptr_get_spi(env, reg);
if (spi < 0)
return spi;
return state->stack[spi].spilled_ptr.ref_obj_id;
}
static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env,
struct bpf_reg_state *reg)
{
struct bpf_func_state *state = bpf_func(env, reg);
int spi;
if (reg->type == CONST_PTR_TO_DYNPTR)
return reg->dynptr.type;
spi = bpf_get_spi(reg->var_off.value);
if (spi < 0) {
verbose(env, "verifier internal error: invalid spi when querying dynptr type\n");
return BPF_DYNPTR_TYPE_INVALID;
}
return state->stack[spi].spilled_ptr.dynptr.type;
}
static int check_arg_const_str(struct bpf_verifier_env *env,
struct bpf_reg_state *reg, argno_t argno)
{
@ -8488,7 +8426,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
true, meta);
break;
case ARG_PTR_TO_DYNPTR:
err = process_dynptr_func(env, reg, argno_from_reg(regno), insn_idx, arg_type, 0);
err = process_dynptr_func(env, reg, argno_from_reg(regno), insn_idx, arg_type, 0,
&meta->dynptr);
if (err)
return err;
break;
@ -9170,7 +9109,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
if (ret)
return ret;
ret = process_dynptr_func(env, reg, argno, -1, arg->arg_type, 0);
ret = process_dynptr_func(env, reg, argno, -1, arg->arg_type, 0, NULL);
if (ret)
return ret;
} else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
@ -10278,52 +10217,10 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
}
}
break;
case BPF_FUNC_dynptr_data:
{
struct bpf_reg_state *reg;
int id, ref_obj_id;
reg = get_dynptr_arg_reg(env, fn, regs);
if (!reg)
return -EFAULT;
if (meta.dynptr_id) {
verifier_bug(env, "meta.dynptr_id already set");
return -EFAULT;
}
if (meta.ref_obj_id) {
verifier_bug(env, "meta.ref_obj_id already set");
return -EFAULT;
}
id = dynptr_id(env, reg);
if (id < 0) {
verifier_bug(env, "failed to obtain dynptr id");
return id;
}
ref_obj_id = dynptr_ref_obj_id(env, reg);
if (ref_obj_id < 0) {
verifier_bug(env, "failed to obtain dynptr ref_obj_id");
return ref_obj_id;
}
meta.dynptr_id = id;
meta.ref_obj_id = ref_obj_id;
break;
}
case BPF_FUNC_dynptr_write:
{
enum bpf_dynptr_type dynptr_type;
struct bpf_reg_state *reg;
enum bpf_dynptr_type dynptr_type = meta.dynptr.type;
reg = get_dynptr_arg_reg(env, fn, regs);
if (!reg)
return -EFAULT;
dynptr_type = dynptr_get_type(env, reg);
if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
return -EFAULT;
@ -10515,10 +10412,7 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
return -EFAULT;
}
if (is_dynptr_ref_function(func_id))
regs[BPF_REG_0].dynptr_id = meta.dynptr_id;
if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) {
if (is_ptr_cast_function(func_id)) {
/* For release_reference() */
regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
} else if (is_acquire_function(func_id, meta.map.ptr)) {
@ -10532,6 +10426,11 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
regs[BPF_REG_0].ref_obj_id = id;
}
if (func_id == BPF_FUNC_dynptr_data) {
regs[BPF_REG_0].dynptr_id = meta.dynptr.id;
regs[BPF_REG_0].ref_obj_id = meta.dynptr.ref_obj_id;
}
err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
if (err)
return err;
@ -12187,7 +12086,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
meta->release_regno = regno;
} else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] &&
(dynptr_arg_type & MEM_UNINIT)) {
enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type;
enum bpf_dynptr_type parent_type = meta->dynptr.type;
if (parent_type == BPF_DYNPTR_TYPE_INVALID) {
verifier_bug(env, "no dynptr type for parent of clone");
@ -12195,30 +12094,17 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
}
dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type);
clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id;
clone_ref_obj_id = meta->dynptr.ref_obj_id;
if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) {
verifier_bug(env, "missing ref obj id for parent of clone");
return -EFAULT;
}
}
ret = process_dynptr_func(env, reg, argno, insn_idx,
dynptr_arg_type, clone_ref_obj_id);
ret = process_dynptr_func(env, reg, argno, insn_idx, dynptr_arg_type,
clone_ref_obj_id, &meta->dynptr);
if (ret < 0)
return ret;
if (!(dynptr_arg_type & MEM_UNINIT)) {
int id = dynptr_id(env, reg);
if (id < 0) {
verifier_bug(env, "failed to obtain dynptr id");
return id;
}
meta->initialized_dynptr.id = id;
meta->initialized_dynptr.type = dynptr_get_type(env, reg);
meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg);
}
break;
}
case KF_ARG_PTR_TO_ITER:
@ -12849,7 +12735,7 @@ static int check_special_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_ca
}
} else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_slice] ||
meta->func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
enum bpf_type_flag type_flag = get_dynptr_type_flag(meta->initialized_dynptr.type);
enum bpf_type_flag type_flag = get_dynptr_type_flag(meta->dynptr.type);
mark_reg_known_zero(env, regs, BPF_REG_0);
@ -12873,11 +12759,11 @@ static int check_special_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_ca
}
}
if (!meta->initialized_dynptr.id) {
if (!meta->dynptr.id) {
verifier_bug(env, "no dynptr id");
return -EFAULT;
}
regs[BPF_REG_0].dynptr_id = meta->initialized_dynptr.id;
regs[BPF_REG_0].dynptr_id = meta->dynptr.id;
/* we don't need to set BPF_REG_0's ref obj id
* because packet slices are not refcounted (see
@ -13063,7 +12949,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (meta.release_regno) {
struct bpf_reg_state *reg = &regs[meta.release_regno];
if (meta.initialized_dynptr.ref_obj_id) {
if (meta.dynptr.ref_obj_id) {
err = unmark_stack_slots_dynptr(env, reg);
} else {
err = release_reference(env, reg->ref_obj_id);