mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-08-05 16:54:27 +00:00
aced132599
Add range tracking for instruction BPF_NEG. Without this logic, a trivial
program like the following will fail
volatile bool found_value_b;
SEC("lsm.s/socket_connect")
int BPF_PROG(test_socket_connect)
{
if (!found_value_b)
return -1;
return 0;
}
with verifier log:
"At program exit the register R0 has smin=0 smax=4294967295 should have
been in [-4095, 0]".
This is because range information is lost in BPF_NEG:
0: R1=ctx() R10=fp0
; if (!found_value_b) @ xxxx.c:24
0: (18) r1 = 0xffa00000011e7048 ; R1_w=map_value(...)
2: (71) r0 = *(u8 *)(r1 +0) ; R0_w=scalar(smin32=0,smax=255)
3: (a4) w0 ^= 1 ; R0_w=scalar(smin32=0,smax=255)
4: (84) w0 = -w0 ; R0_w=scalar(range info lost)
Note that, the log above is manually modified to highlight relevant bits.
Fix this by maintaining proper range information with BPF_NEG, so that
the verifier will know:
4: (84) w0 = -w0 ; R0_w=scalar(smin32=-255,smax=0)
Also updated selftests based on the expected behavior.
Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250625164025.3310203-2-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
174 lines
4.4 KiB
C
174 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Converted from tools/testing/selftests/bpf/verifier/bounds_deduction.c */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_misc.h"
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SEC("socket")
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__description("check deducing bounds from const, 1")
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__failure __msg("R0 tried to subtract pointer from scalar")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__naked void deducing_bounds_from_const_1(void)
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{
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asm volatile (" \
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r0 = 1; \
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if r0 s>= 1 goto l0_%=; \
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l0_%=: r0 -= r1; \
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exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 2")
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__success __failure_unpriv
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__retval(1)
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__naked void deducing_bounds_from_const_2(void)
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{
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asm volatile (" \
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r0 = 1; \
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if r0 s>= 1 goto l0_%=; \
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exit; \
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l0_%=: if r0 s<= 1 goto l1_%=; \
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exit; \
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l1_%=: r1 -= r0; \
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exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 3")
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__failure __msg("R0 tried to subtract pointer from scalar")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__naked void deducing_bounds_from_const_3(void)
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{
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asm volatile (" \
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r0 = 0; \
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if r0 s<= 0 goto l0_%=; \
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l0_%=: r0 -= r1; \
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exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 4")
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__success __failure_unpriv
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__msg_unpriv("R6 has pointer with unsupported alu operation")
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__retval(0)
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__naked void deducing_bounds_from_const_4(void)
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{
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asm volatile (" \
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r6 = r1; \
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r0 = 0; \
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if r0 s<= 0 goto l0_%=; \
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exit; \
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l0_%=: if r0 s>= 0 goto l1_%=; \
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exit; \
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l1_%=: r6 -= r0; \
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exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 5")
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__failure __msg("R0 tried to subtract pointer from scalar")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__naked void deducing_bounds_from_const_5(void)
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{
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asm volatile (" \
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r0 = 0; \
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if r0 s>= 1 goto l0_%=; \
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r0 -= r1; \
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l0_%=: exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 6")
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__failure __msg("R0 tried to subtract pointer from scalar")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__naked void deducing_bounds_from_const_6(void)
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{
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asm volatile (" \
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r0 = 0; \
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if r0 s>= 0 goto l0_%=; \
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exit; \
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l0_%=: r0 -= r1; \
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exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 7")
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__failure __msg("dereference of modified ctx ptr")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__flag(BPF_F_ANY_ALIGNMENT)
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__naked void deducing_bounds_from_const_7(void)
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{
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asm volatile (" \
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r0 = %[__imm_0]; \
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if r0 s>= 0 goto l0_%=; \
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l0_%=: r1 -= r0; \
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r0 = *(u32*)(r1 + %[__sk_buff_mark]); \
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exit; \
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" :
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: __imm_const(__imm_0, ~0),
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__imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark))
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: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 8")
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__failure __msg("negative offset ctx ptr R1 off=-1 disallowed")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__flag(BPF_F_ANY_ALIGNMENT)
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__naked void deducing_bounds_from_const_8(void)
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{
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asm volatile (" \
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r0 = %[__imm_0]; \
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if r0 s>= 0 goto l0_%=; \
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r1 += r0; \
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l0_%=: r0 = *(u32*)(r1 + %[__sk_buff_mark]); \
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exit; \
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" :
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: __imm_const(__imm_0, ~0),
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__imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark))
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: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 9")
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__failure __msg("R0 tried to subtract pointer from scalar")
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__msg_unpriv("R1 has pointer with unsupported alu operation")
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__naked void deducing_bounds_from_const_9(void)
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{
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asm volatile (" \
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r0 = 0; \
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if r0 s>= 0 goto l0_%=; \
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l0_%=: r0 -= r1; \
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exit; \
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" ::: __clobber_all);
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}
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SEC("socket")
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__description("check deducing bounds from const, 10")
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__failure
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__msg("math between ctx pointer and register with unbounded min value is not allowed")
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__failure_unpriv
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__naked void deducing_bounds_from_const_10(void)
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{
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asm volatile (" \
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r6 = r1; \
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r0 = 0; \
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if r0 s<= 0 goto l0_%=; \
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l0_%=: /* Marks r0 as unknown. */ \
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call %[bpf_get_prandom_u32]; \
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r0 -= r6; \
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exit; \
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" :
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: __imm(bpf_get_prandom_u32)
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: __clobber_all);
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}
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char _license[] SEC("license") = "GPL";
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