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|
// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
/*
* Programs may use MAX_BPF_STACK_JIT (2 KiB) of stack on JITs that support
* large stacks, combined over a call chain, with no separate limit on a
* single frame. Interpreted programs and other JITs keep 512 bytes.
*/
SEC("socket")
__description("single frame of 2048 bytes")
__load_if_large_stack()
__success __success_unpriv __retval(42)
__naked void single_frame_2048(void)
{
asm volatile (" \
r1 = r10; \
r1 += -2048; \
r0 = 42; \
*(u64*)(r1 + 0) = r0; \
r0 = *(u64*)(r1 + 0); \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("single frame of 2048 bytes without large stack support")
__load_if_no_large_stack()
__failure __msg("invalid write to stack R1 off=-2048 size=8")
__naked void single_frame_2048_no_large_stack(void)
{
asm volatile (" \
r1 = r10; \
r1 += -2048; \
r0 = 42; \
*(u64*)(r1 + 0) = r0; \
exit; \
" ::: __clobber_all);
}
__used __naked
static void frame_512_leaf(void)
{
asm volatile (" \
r1 = 1; \
*(u64 *)(r10 - 512) = r1; \
exit; \
" ::: __clobber_all);
}
__used __naked
static void frame_512_depth_2(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 512) = r1; \
call frame_512_leaf; \
exit; \
" ::: __clobber_all);
}
__used __naked
static void frame_512_depth_3(void)
{
asm volatile (" \
r1 = 3; \
*(u64 *)(r10 - 512) = r1; \
call frame_512_depth_2; \
exit; \
" ::: __clobber_all);
}
__used __naked
static void frame_512_depth_4(void)
{
asm volatile (" \
r1 = 4; \
*(u64 *)(r10 - 512) = r1; \
call frame_512_depth_3; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("four frames of 512 bytes fit the 2 KiB budget")
__load_if_large_stack()
__success __log_level(4) __msg("stack depth max 2048")
__naked void four_frames_of_512(void)
{
asm volatile (" \
call frame_512_depth_4; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("five frames of 512 bytes exceed the 2 KiB budget")
__load_if_large_stack()
__failure __msg("combined stack size of 5 calls is 2560. Too large")
__naked void five_frames_of_512(void)
{
asm volatile (" \
r1 = 5; \
*(u64 *)(r10 - 512) = r1; \
call frame_512_depth_4; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
__used __naked
static void frame_1536_leaf(void)
{
asm volatile (" \
r1 = 1; \
*(u64 *)(r10 - 1536) = r1; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("512-byte frame calling a 1536-byte frame")
__load_if_large_stack()
__success __log_level(4) __msg("stack depth max 2048")
__naked void uneven_frames_fit(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 512) = r1; \
call frame_1536_leaf; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("520-byte frame calling a 1536-byte frame")
__load_if_large_stack()
__failure __msg("combined stack size of 2 calls is 2064. Too large")
__naked void uneven_frames_exceed(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 520) = r1; \
call frame_1536_leaf; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
#ifdef __BPF_FEATURE_MAY_GOTO
/* may_goto adds its counter below the frame; a JIT does not hold that against the budget */
SEC("socket")
__description("frame of 2048 bytes with may_goto")
__load_if_large_stack()
__success __retval(42)
__naked void frame_2048_with_may_goto(void)
{
asm volatile (" \
r1 = r10; \
r1 += -2048; \
r0 = 42; \
*(u32*)(r1 + 0) = r0; \
may_goto l0_%=; \
r2 = 100; \
l0_%=: \
exit; \
" ::: __clobber_all);
}
#endif
SEC("socket")
__description("variable offset write reaching 2048 bytes deep")
__load_if_large_stack()
__success
__naked void var_off_write_to_2048(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 8; \
r2 = r10; \
r2 += -2048; \
r2 += r0; \
r1 = 0; \
*(u64*)(r2 + 0) = r1; \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__description("variable offset write reaching 2056 bytes deep")
__load_if_large_stack()
__failure __msg("invalid variable-offset write to stack R2")
__naked void var_off_write_to_2056(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 8; \
r2 = r10; \
r2 += -2056; \
r2 += r0; \
r1 = 0; \
*(u64*)(r2 + 0) = r1; \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* Each frame of a private stack gets the whole budget. */
__used __naked
static void priv_stack_frame_2048(void)
{
asm volatile (" \
r1 = 1; \
*(u64 *)(r10 - 2048) = r1; \
exit; \
" ::: __clobber_all);
}
SEC("kprobe")
__description("private stack: two frames of 2048 bytes")
__load_if_large_stack()
__arch_x86_64
__arch_arm64
__success __log_level(4)
__msg("stack depth max 2048")
__msg("subprog 0 (private_stack_two_frames) main {{.*}} stack 2048")
__msg("subprog 1 (priv_stack_frame_2048) static {{.*}} stack 2048")
__naked void private_stack_two_frames(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 2048) = r1; \
call priv_stack_frame_2048; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
struct {
__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
__uint(max_entries, 1);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(__u32));
} jmp_table SEC(".maps");
/*
* A tail call unwinds the frame of the program doing it, so a large main
* frame is fine; the 256-byte rule only concerns the frames of callers of a
* subprog that tail calls.
*/
SEC("tc")
__description("tail call from a 1 KiB frame")
__load_if_large_stack()
__success
__naked void tail_call_from_large_frame(void)
{
asm volatile (" \
r2 = 42; \
*(u64 *)(r10 - 1024) = r2; \
r2 = %[jmp_table] ll; \
r3 = 0; \
call %[bpf_tail_call]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_tail_call),
__imm_addr(jmp_table)
: __clobber_all);
}
/*
* bpf_clone_redirect() can run the program again on top of its own frame,
* ten frames deep, so a program calling it keeps the 512-byte budget. The
* redirect that happens after the program returns does not.
*/
SEC("tc")
__description("1 KiB frame with bpf_clone_redirect keeps the 512-byte budget")
__load_if_large_stack()
__failure __msg("invalid write to stack R1 off=-1024 size=8")
__naked void clone_redirect_keeps_512(void)
{
asm volatile (" \
r6 = r1; \
r1 = r10; \
r1 += -1024; \
r0 = 42; \
*(u64 *)(r1 + 0) = r0; \
r1 = r6; \
r2 = 1; \
r3 = 0; \
call %[bpf_clone_redirect]; \
r0 = 0; \
exit; \
" :
: __imm(bpf_clone_redirect)
: __clobber_all);
}
SEC("tc")
__description("1 KiB frame with bpf_redirect keeps the 2 KiB budget")
__load_if_large_stack()
__success
__naked void redirect_keeps_2048(void)
{
asm volatile (" \
r1 = r10; \
r1 += -1024; \
r0 = 42; \
*(u64 *)(r1 + 0) = r0; \
r1 = 1; \
r2 = 0; \
call %[bpf_redirect]; \
exit; \
" :
: __imm(bpf_redirect)
: __clobber_all);
}
/* Global subprogs are verified on their own but share the call chain budget. */
__used __naked int global_frame_1536(void)
{
asm volatile (" \
r1 = 1; \
*(u64 *)(r10 - 1536) = r1; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("512-byte frame calling a 1536-byte global subprog")
__load_if_large_stack()
__success __log_level(4) __msg("stack depth max 2048")
__naked void global_subprog_fits(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 512) = r1; \
call global_frame_1536; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("520-byte frame calling a 1536-byte global subprog")
__load_if_large_stack()
__failure __msg("combined stack size of 2 calls is 2064. Too large")
__naked void global_subprog_exceeds(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 520) = r1; \
call global_frame_1536; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
/* Callback frames are part of the chain of the helper that calls them. */
static __naked int loop_cb_1536(void)
{
asm volatile (" \
r1 = 1; \
*(u64 *)(r10 - 1536) = r1; \
r0 = 0; \
exit; \
" ::: __clobber_all);
}
SEC("socket")
__description("512-byte frame with a 1536-byte bpf_loop callback")
__load_if_large_stack()
__success __log_level(4) __msg("stack depth max 2048")
__naked void loop_callback_fits(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 512) = r1; \
r1 = 1; \
r2 = %[loop_cb_1536]; \
r3 = 0; \
r4 = 0; \
call %[bpf_loop]; \
r0 = 0; \
exit; \
" :
: __imm_ptr(loop_cb_1536),
__imm(bpf_loop)
: __clobber_common);
}
SEC("socket")
__description("520-byte frame with a 1536-byte bpf_loop callback")
__load_if_large_stack()
__failure __msg("combined stack size of 2 calls is 2064. Too large")
__naked void loop_callback_exceeds(void)
{
asm volatile (" \
r1 = 2; \
*(u64 *)(r10 - 520) = r1; \
r1 = 1; \
r2 = %[loop_cb_1536]; \
r3 = 0; \
r4 = 0; \
call %[bpf_loop]; \
r0 = 0; \
exit; \
" :
: __imm_ptr(loop_cb_1536),
__imm(bpf_loop)
: __clobber_common);
}
char _license[] SEC("license") = "GPL";
|
