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Revert "bpf: decouple prune and jump points"

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This reverts commit 743f3548d3 which is
commit bffdeaa8a5af7200b0e74c9d5a41167f86626a36 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: If00d7f3353d6d173c93006a76d575194c7e4f517
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Greg Kroah-Hartman 2024-01-15 11:28:49 +00:00
parent eba57b3513
commit 190985b1db
2 changed files with 14 additions and 44 deletions
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1
include/linux/bpf_verifier.h
View File

@ -430,7 +430,6 @@ struct bpf_insn_aux_data {
/* below fields are initialized once */
unsigned int orig_idx; /* original instruction index */
bool prune_point;
bool jmp_point;
};
#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */

57
kernel/bpf/verifier.c
View File

@ -2512,16 +2512,6 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
return 0;
}
static void mark_jmp_point(struct bpf_verifier_env *env, int idx)
{
env->insn_aux_data[idx].jmp_point = true;
}
static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].jmp_point;
}
/* for any branch, call, exit record the history of jmps in the given state */
static int push_jmp_history(struct bpf_verifier_env *env,
struct bpf_verifier_state *cur)
@ -2530,9 +2520,6 @@ static int push_jmp_history(struct bpf_verifier_env *env,
struct bpf_idx_pair *p;
size_t alloc_size;
if (!is_jmp_point(env, env->insn_idx))
return 0;
cnt++;
alloc_size = kmalloc_size_roundup(size_mul(cnt, sizeof(*p)));
p = krealloc(cur->jmp_history, alloc_size, GFP_USER);
@ -11030,16 +11017,11 @@ static struct bpf_verifier_state_list **explored_state(
return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
}
static void mark_prune_point(struct bpf_verifier_env *env, int idx)
static void init_explored_state(struct bpf_verifier_env *env, int idx)
{
env->insn_aux_data[idx].prune_point = true;
}
static bool is_prune_point(struct bpf_verifier_env *env, int insn_idx)
{
return env->insn_aux_data[insn_idx].prune_point;
}
enum {
DONE_EXPLORING = 0,
KEEP_EXPLORING = 1,
@ -11068,11 +11050,9 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env,
return -EINVAL;
}
if (e == BRANCH) {
if (e == BRANCH)
/* mark branch target for state pruning */
mark_prune_point(env, w);
mark_jmp_point(env, w);
}
init_explored_state(env, w);
if (insn_state[w] == 0) {
/* tree-edge */
@ -11110,13 +11090,10 @@ static int visit_func_call_insn(int t, int insn_cnt,
if (ret)
return ret;
if (t + 1 < insn_cnt) {
mark_prune_point(env, t + 1);
mark_jmp_point(env, t + 1);
}
if (t + 1 < insn_cnt)
init_explored_state(env, t + 1);
if (visit_callee) {
mark_prune_point(env, t);
mark_jmp_point(env, t);
init_explored_state(env, t);
ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env,
/* It's ok to allow recursion from CFG point of
* view. __check_func_call() will do the actual
@ -11150,15 +11127,13 @@ static int visit_insn(int t, int insn_cnt, struct bpf_verifier_env *env)
return DONE_EXPLORING;
case BPF_CALL:
if (insns[t].imm == BPF_FUNC_timer_set_callback) {
if (insns[t].imm == BPF_FUNC_timer_set_callback)
/* Mark this call insn to trigger is_state_visited() check
* before call itself is processed by __check_func_call().
* Otherwise new async state will be pushed for further
* exploration.
*/
mark_prune_point(env, t);
mark_jmp_point(env, t);
}
init_explored_state(env, t);
return visit_func_call_insn(t, insn_cnt, insns, env,
insns[t].src_reg == BPF_PSEUDO_CALL);
@ -11176,22 +11151,18 @@ static int visit_insn(int t, int insn_cnt, struct bpf_verifier_env *env)
* but it's marked, since backtracking needs
* to record jmp history in is_state_visited().
*/
mark_prune_point(env, t + insns[t].off + 1);
mark_jmp_point(env, t + insns[t].off + 1);
init_explored_state(env, t + insns[t].off + 1);
/* tell verifier to check for equivalent states
* after every call and jump
*/
if (t + 1 < insn_cnt) {
mark_prune_point(env, t + 1);
mark_jmp_point(env, t + 1);
}
if (t + 1 < insn_cnt)
init_explored_state(env, t + 1);
return ret;
default:
/* conditional jump with two edges */
mark_prune_point(env, t);
mark_jmp_point(env, t);
init_explored_state(env, t);
ret = push_insn(t, t + 1, FALLTHROUGH, env, true);
if (ret)
return ret;
@ -12224,11 +12195,11 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
bool add_new_state = env->test_state_freq ? true : false;
cur->last_insn_idx = env->prev_insn_idx;
if (!is_prune_point(env, insn_idx))
if (!env->insn_aux_data[insn_idx].prune_point)
/* this 'insn_idx' instruction wasn't marked, so we will not
* be doing state search here
*/
return push_jmp_history(env, cur);
return 0;
/* bpf progs typically have pruning point every 4 instructions
* http://vger.kernel.org/bpfconf2019.html#session-1