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authorKumar Kartikeya Dwivedi <memxor@gmail.com>2022-09-04 22:41:28 +0200
committerAlexei Starovoitov <ast@kernel.org>2022-09-07 16:42:23 -0700
commitb239da34203f49c40b5d656220c39647c3ff0b3c (patch)
tree9c58217e8b690db2a69a88c7ed3ee13746986961 /kernel/bpf
parentcc48755808c646666436745b35629c3f0d05e165 (diff)
downloadlinux-b239da34203f49c40b5d656220c39647c3ff0b3c.tar.bz2
bpf: Add helper macro bpf_for_each_reg_in_vstate
For a lot of use cases in future patches, we will want to modify the state of registers part of some same 'group' (e.g. same ref_obj_id). It won't just be limited to releasing reference state, but setting a type flag dynamically based on certain actions, etc. Hence, we need a way to easily pass a callback to the function that iterates over all registers in current bpf_verifier_state in all frames upto (and including) the curframe. While in C++ we would be able to easily use a lambda to pass state and the callback together, sadly we aren't using C++ in the kernel. The next best thing to avoid defining a function for each case seems like statement expressions in GNU C. The kernel already uses them heavily, hence they can passed to the macro in the style of a lambda. The statement expression will then be substituted in the for loop bodies. Variables __state and __reg are set to current bpf_func_state and reg for each invocation of the expression inside the passed in verifier state. Then, convert mark_ptr_or_null_regs, clear_all_pkt_pointers, release_reference, find_good_pkt_pointers, find_equal_scalars to use bpf_for_each_reg_in_vstate. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20220904204145.3089-16-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c135
1 files changed, 28 insertions, 107 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f3344a86d88d..c0f175ac187a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6513,31 +6513,15 @@ static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
* are now invalid, so turn them into unknown SCALAR_VALUE.
*/
-static void __clear_all_pkt_pointers(struct bpf_verifier_env *env,
- struct bpf_func_state *state)
+static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
- struct bpf_reg_state *regs = state->regs, *reg;
- int i;
-
- for (i = 0; i < MAX_BPF_REG; i++)
- if (reg_is_pkt_pointer_any(&regs[i]))
- mark_reg_unknown(env, regs, i);
+ struct bpf_func_state *state;
+ struct bpf_reg_state *reg;
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
+ bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
if (reg_is_pkt_pointer_any(reg))
__mark_reg_unknown(env, reg);
- }
-}
-
-static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
-{
- struct bpf_verifier_state *vstate = env->cur_state;
- int i;
-
- for (i = 0; i <= vstate->curframe; i++)
- __clear_all_pkt_pointers(env, vstate->frame[i]);
+ }));
}
enum {
@@ -6566,41 +6550,24 @@ static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range
reg->range = AT_PKT_END;
}
-static void release_reg_references(struct bpf_verifier_env *env,
- struct bpf_func_state *state,
- int ref_obj_id)
-{
- struct bpf_reg_state *regs = state->regs, *reg;
- int i;
-
- for (i = 0; i < MAX_BPF_REG; i++)
- if (regs[i].ref_obj_id == ref_obj_id)
- mark_reg_unknown(env, regs, i);
-
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- if (reg->ref_obj_id == ref_obj_id)
- __mark_reg_unknown(env, reg);
- }
-}
-
/* The pointer with the specified id has released its reference to kernel
* resources. Identify all copies of the same pointer and clear the reference.
*/
static int release_reference(struct bpf_verifier_env *env,
int ref_obj_id)
{
- struct bpf_verifier_state *vstate = env->cur_state;
+ struct bpf_func_state *state;
+ struct bpf_reg_state *reg;
int err;
- int i;
err = release_reference_state(cur_func(env), ref_obj_id);
if (err)
return err;
- for (i = 0; i <= vstate->curframe; i++)
- release_reg_references(env, vstate->frame[i], ref_obj_id);
+ bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
+ if (reg->ref_obj_id == ref_obj_id)
+ __mark_reg_unknown(env, reg);
+ }));
return 0;
}
@@ -9335,34 +9302,14 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
return 0;
}
-static void __find_good_pkt_pointers(struct bpf_func_state *state,
- struct bpf_reg_state *dst_reg,
- enum bpf_reg_type type, int new_range)
-{
- struct bpf_reg_state *reg;
- int i;
-
- for (i = 0; i < MAX_BPF_REG; i++) {
- reg = &state->regs[i];
- if (reg->type == type && reg->id == dst_reg->id)
- /* keep the maximum range already checked */
- reg->range = max(reg->range, new_range);
- }
-
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- if (reg->type == type && reg->id == dst_reg->id)
- reg->range = max(reg->range, new_range);
- }
-}
-
static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
struct bpf_reg_state *dst_reg,
enum bpf_reg_type type,
bool range_right_open)
{
- int new_range, i;
+ struct bpf_func_state *state;
+ struct bpf_reg_state *reg;
+ int new_range;
if (dst_reg->off < 0 ||
(dst_reg->off == 0 && range_right_open))
@@ -9427,9 +9374,11 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
* the range won't allow anything.
* dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
*/
- for (i = 0; i <= vstate->curframe; i++)
- __find_good_pkt_pointers(vstate->frame[i], dst_reg, type,
- new_range);
+ bpf_for_each_reg_in_vstate(vstate, state, reg, ({
+ if (reg->type == type && reg->id == dst_reg->id)
+ /* keep the maximum range already checked */
+ reg->range = max(reg->range, new_range);
+ }));
}
static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode)
@@ -9918,7 +9867,7 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
if (!reg_may_point_to_spin_lock(reg)) {
/* For not-NULL ptr, reg->ref_obj_id will be reset
- * in release_reg_references().
+ * in release_reference().
*
* reg->id is still used by spin_lock ptr. Other
* than spin_lock ptr type, reg->id can be reset.
@@ -9928,22 +9877,6 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
}
}
-static void __mark_ptr_or_null_regs(struct bpf_func_state *state, u32 id,
- bool is_null)
-{
- struct bpf_reg_state *reg;
- int i;
-
- for (i = 0; i < MAX_BPF_REG; i++)
- mark_ptr_or_null_reg(state, &state->regs[i], id, is_null);
-
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- mark_ptr_or_null_reg(state, reg, id, is_null);
- }
-}
-
/* The logic is similar to find_good_pkt_pointers(), both could eventually
* be folded together at some point.
*/
@@ -9951,10 +9884,9 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
bool is_null)
{
struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_reg_state *regs = state->regs;
+ struct bpf_reg_state *regs = state->regs, *reg;
u32 ref_obj_id = regs[regno].ref_obj_id;
u32 id = regs[regno].id;
- int i;
if (ref_obj_id && ref_obj_id == id && is_null)
/* regs[regno] is in the " == NULL" branch.
@@ -9963,8 +9895,9 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
*/
WARN_ON_ONCE(release_reference_state(state, id));
- for (i = 0; i <= vstate->curframe; i++)
- __mark_ptr_or_null_regs(vstate->frame[i], id, is_null);
+ bpf_for_each_reg_in_vstate(vstate, state, reg, ({
+ mark_ptr_or_null_reg(state, reg, id, is_null);
+ }));
}
static bool try_match_pkt_pointers(const struct bpf_insn *insn,
@@ -10077,23 +10010,11 @@ static void find_equal_scalars(struct bpf_verifier_state *vstate,
{
struct bpf_func_state *state;
struct bpf_reg_state *reg;
- int i, j;
- for (i = 0; i <= vstate->curframe; i++) {
- state = vstate->frame[i];
- for (j = 0; j < MAX_BPF_REG; j++) {
- reg = &state->regs[j];
- if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
- *reg = *known_reg;
- }
-
- bpf_for_each_spilled_reg(j, state, reg) {
- if (!reg)
- continue;
- if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
- *reg = *known_reg;
- }
- }
+ bpf_for_each_reg_in_vstate(vstate, state, reg, ({
+ if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
+ *reg = *known_reg;
+ }));
}
static int check_cond_jmp_op(struct bpf_verifier_env *env,