From: Kumar Kartikeya Dwivedi memxor@gmail.com
[ Upstream commit b239da34203f49c40b5d656220c39647c3ff0b3c ]
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 Stable-dep-of: f1db20814af5 ("bpf: Fix wrong reg type conversion in release_reference()") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/bpf_verifier.h | 21 ++++++ kernel/bpf/verifier.c | 135 ++++++++--------------------------- 2 files changed, 49 insertions(+), 107 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 1fdddbf3546b..184b957e28ad 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -348,6 +348,27 @@ struct bpf_verifier_state { iter < frame->allocated_stack / BPF_REG_SIZE; \ iter++, reg = bpf_get_spilled_reg(iter, frame))
+/* Invoke __expr over regsiters in __vst, setting __state and __reg */ +#define bpf_for_each_reg_in_vstate(__vst, __state, __reg, __expr) \ + ({ \ + struct bpf_verifier_state *___vstate = __vst; \ + int ___i, ___j; \ + for (___i = 0; ___i <= ___vstate->curframe; ___i++) { \ + struct bpf_reg_state *___regs; \ + __state = ___vstate->frame[___i]; \ + ___regs = __state->regs; \ + for (___j = 0; ___j < MAX_BPF_REG; ___j++) { \ + __reg = &___regs[___j]; \ + (void)(__expr); \ + } \ + bpf_for_each_spilled_reg(___j, __state, __reg) { \ + if (!__reg) \ + continue; \ + (void)(__expr); \ + } \ + } \ + }) + /* linked list of verifier states used to prune search */ struct bpf_verifier_state_list { struct bpf_verifier_state state; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2d7ece2a87fa..7bfeb249214e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6500,31 +6500,15 @@ 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(®s[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 { @@ -6553,41 +6537,24 @@ 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; } @@ -9283,34 +9250,14 @@ 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)) @@ -9375,9 +9322,11 @@ 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) @@ -9866,7 +9815,7 @@ 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. @@ -9876,22 +9825,6 @@ 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. */ @@ -9899,10 +9832,9 @@ 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. @@ -9911,8 +9843,9 @@ 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, @@ -10025,23 +9958,11 @@ 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,