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bpf: extract setup_func_entry() utility function

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Move code for simulated stack frame creation to a separate utility
function. This function would be used in the follow-up change for
callbacks handling.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman 2023-11-21 04:06:55 +02:00 committed by Alexei Starovoitov
parent 683b96f960
commit 58124a98cb
1 changed files with 48 additions and 36 deletions
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84
kernel/bpf/verifier.c
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@ -9370,11 +9370,10 @@ static int set_callee_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee, int insn_idx);
static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int *insn_idx, int subprog,
set_callee_state_fn set_callee_state_cb)
static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite,
set_callee_state_fn set_callee_state_cb,
struct bpf_verifier_state *state)
{
struct bpf_verifier_state *state = env->cur_state;
struct bpf_func_state *caller, *callee;
int err;
@ -9384,13 +9383,53 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn
return -E2BIG;
}
caller = state->frame[state->curframe];
if (state->frame[state->curframe + 1]) {
verbose(env, "verifier bug. Frame %d already allocated\n",
state->curframe + 1);
return -EFAULT;
}
caller = state->frame[state->curframe];
callee = kzalloc(sizeof(*callee), GFP_KERNEL);
if (!callee)
return -ENOMEM;
state->frame[state->curframe + 1] = callee;
/* callee cannot access r0, r6 - r9 for reading and has to write
* into its own stack before reading from it.
* callee can read/write into caller's stack
*/
init_func_state(env, callee,
/* remember the callsite, it will be used by bpf_exit */
callsite,
state->curframe + 1 /* frameno within this callchain */,
subprog /* subprog number within this prog */);
/* Transfer references to the callee */
err = copy_reference_state(callee, caller);
err = err ?: set_callee_state_cb(env, caller, callee, callsite);
if (err)
goto err_out;
/* only increment it after check_reg_arg() finished */
state->curframe++;
return 0;
err_out:
free_func_state(callee);
state->frame[state->curframe + 1] = NULL;
return err;
}
static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int *insn_idx, int subprog,
set_callee_state_fn set_callee_state_cb)
{
struct bpf_verifier_state *state = env->cur_state;
struct bpf_func_state *caller, *callee;
int err;
caller = state->frame[state->curframe];
err = btf_check_subprog_call(env, subprog, caller->regs);
if (err == -EFAULT)
return err;
@ -9460,35 +9499,12 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn
return 0;
}
callee = kzalloc(sizeof(*callee), GFP_KERNEL);
if (!callee)
return -ENOMEM;
state->frame[state->curframe + 1] = callee;
/* callee cannot access r0, r6 - r9 for reading and has to write
* into its own stack before reading from it.
* callee can read/write into caller's stack
*/
init_func_state(env, callee,
/* remember the callsite, it will be used by bpf_exit */
*insn_idx /* callsite */,
state->curframe + 1 /* frameno within this callchain */,
subprog /* subprog number within this prog */);
/* Transfer references to the callee */
err = copy_reference_state(callee, caller);
err = setup_func_entry(env, subprog, *insn_idx, set_callee_state_cb, state);
if (err)
goto err_out;
err = set_callee_state_cb(env, caller, callee, *insn_idx);
if (err)
goto err_out;
return err;
clear_caller_saved_regs(env, caller->regs);
/* only increment it after check_reg_arg() finished */
state->curframe++;
/* and go analyze first insn of the callee */
*insn_idx = env->subprog_info[subprog].start - 1;
@ -9496,14 +9512,10 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn
verbose(env, "caller:\n");
print_verifier_state(env, caller, true);
verbose(env, "callee:\n");
print_verifier_state(env, callee, true);
print_verifier_state(env, state->frame[state->curframe], true);
}
return 0;
err_out:
free_func_state(callee);
state->frame[state->curframe + 1] = NULL;
return err;
return 0;
}
int map_set_for_each_callback_args(struct bpf_verifier_env *env,