8a021e7fa1
This patch simplifies the verification of size arguments associated to pointer arguments to helpers and kfuncs. Many helpers take a pointer argument followed by the size of the memory access performed to be performed through that pointer. Before this patch, the handling of the size argument in check_mem_size_reg() was confusing and wasteful: if the size register's lower bound was 0, then the verification was done twice: once considering the size of the access to be the lower-bound of the respective argument, and once considering the upper bound (even if the two are the same). The upper bound checking is a super-set of the lower-bound checking(*), except: the only point of the lower-bound check is to handle the case where zero-sized-accesses are explicitly not allowed and the lower-bound is zero. This static condition is now checked explicitly, replacing a much more complex, expensive and confusing verification call to check_helper_mem_access(). Error messages change in this patch. Before, messages about illegal zero-size accesses depended on the type of the pointer and on other conditions, and sometimes the message was plain wrong: in some tests that changed you'll see that the old message was something like "R1 min value is outside of the allowed memory range", where R1 is the pointer register; the error was wrongly claiming that the pointer was bad instead of the size being bad. Other times the information that the size came for a register with a possible range of values was wrong, and the error presented the size as a fixed zero. Now the errors refer to the right register. However, the old error messages did contain useful information about the pointer register which is now lost; recovering this information was deemed not important enough. (*) Besides standing to reason that the checks for a bigger size access are a super-set of the checks for a smaller size access, I have also mechanically verified this by reading the code for all types of pointers. I could convince myself that it's true for all but PTR_TO_BTF_ID (check_ptr_to_btf_access). There, simply looking line-by-line does not immediately prove what we want. If anyone has any qualms, let me know. Signed-off-by: Andrei Matei <andreimatei1@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com
372 lines
8.4 KiB
C
372 lines
8.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Converted from tools/testing/selftests/bpf/verifier/raw_stack.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("raw_stack: no skb_load_bytes")
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__success
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__failure_unpriv __msg_unpriv("invalid read from stack R6 off=-8 size=8")
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__naked void stack_no_skb_load_bytes(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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r3 = r6; \
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r4 = 8; \
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/* Call to skb_load_bytes() omitted. */ \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" ::: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, negative len")
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__failure __msg("R4 min value is negative")
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__naked void skb_load_bytes_negative_len(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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r3 = r6; \
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r4 = -8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, negative len 2")
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__failure __msg("R4 min value is negative")
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__naked void load_bytes_negative_len_2(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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r3 = r6; \
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r4 = %[__imm_0]; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes),
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__imm_const(__imm_0, ~0)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, zero len")
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__failure __msg("R4 invalid zero-sized read: u64=[0,0]")
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__naked void skb_load_bytes_zero_len(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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r3 = r6; \
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r4 = 0; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, no init")
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__success __retval(0)
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__naked void skb_load_bytes_no_init(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, init")
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__success __retval(0)
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__naked void stack_skb_load_bytes_init(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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r3 = 0xcafe; \
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*(u64*)(r6 + 0) = r3; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, spilled regs around bounds")
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__success __retval(0)
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__naked void bytes_spilled_regs_around_bounds(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -16; \
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*(u64*)(r6 - 8) = r1; \
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*(u64*)(r6 + 8) = r1; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 - 8); \
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r2 = *(u64*)(r6 + 8); \
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r0 = *(u32*)(r0 + %[__sk_buff_mark]); \
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r2 = *(u32*)(r2 + %[__sk_buff_priority]); \
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r0 += r2; \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes),
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__imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark)),
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__imm_const(__sk_buff_priority, offsetof(struct __sk_buff, priority))
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, spilled regs corruption")
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__failure __msg("R0 invalid mem access 'scalar'")
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__flag(BPF_F_ANY_ALIGNMENT)
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__naked void load_bytes_spilled_regs_corruption(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -8; \
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*(u64*)(r6 + 0) = r1; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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r0 = *(u32*)(r0 + %[__sk_buff_mark]); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes),
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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("tc")
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__description("raw_stack: skb_load_bytes, spilled regs corruption 2")
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__failure __msg("R3 invalid mem access 'scalar'")
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__flag(BPF_F_ANY_ALIGNMENT)
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__naked void bytes_spilled_regs_corruption_2(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -16; \
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*(u64*)(r6 - 8) = r1; \
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*(u64*)(r6 + 0) = r1; \
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*(u64*)(r6 + 8) = r1; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 - 8); \
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r2 = *(u64*)(r6 + 8); \
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r3 = *(u64*)(r6 + 0); \
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r0 = *(u32*)(r0 + %[__sk_buff_mark]); \
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r2 = *(u32*)(r2 + %[__sk_buff_priority]); \
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r0 += r2; \
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r3 = *(u32*)(r3 + %[__sk_buff_pkt_type]); \
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r0 += r3; \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes),
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__imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark)),
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__imm_const(__sk_buff_pkt_type, offsetof(struct __sk_buff, pkt_type)),
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__imm_const(__sk_buff_priority, offsetof(struct __sk_buff, priority))
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, spilled regs + data")
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__success __retval(0)
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__naked void load_bytes_spilled_regs_data(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -16; \
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*(u64*)(r6 - 8) = r1; \
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*(u64*)(r6 + 0) = r1; \
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*(u64*)(r6 + 8) = r1; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 - 8); \
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r2 = *(u64*)(r6 + 8); \
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r3 = *(u64*)(r6 + 0); \
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r0 = *(u32*)(r0 + %[__sk_buff_mark]); \
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r2 = *(u32*)(r2 + %[__sk_buff_priority]); \
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r0 += r2; \
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r0 += r3; \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes),
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__imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark)),
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__imm_const(__sk_buff_priority, offsetof(struct __sk_buff, priority))
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, invalid access 1")
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__failure __msg("invalid indirect access to stack R3 off=-513 size=8")
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__naked void load_bytes_invalid_access_1(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -513; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, invalid access 2")
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__failure __msg("invalid indirect access to stack R3 off=-1 size=8")
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__naked void load_bytes_invalid_access_2(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -1; \
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r3 = r6; \
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r4 = 8; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, invalid access 3")
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__failure __msg("R4 min value is negative")
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__naked void load_bytes_invalid_access_3(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += 0xffffffff; \
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r3 = r6; \
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r4 = 0xffffffff; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, invalid access 4")
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__failure
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__msg("R4 unbounded memory access, use 'var &= const' or 'if (var < const)'")
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__naked void load_bytes_invalid_access_4(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -1; \
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r3 = r6; \
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r4 = 0x7fffffff; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, invalid access 5")
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__failure
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__msg("R4 unbounded memory access, use 'var &= const' or 'if (var < const)'")
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__naked void load_bytes_invalid_access_5(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -512; \
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r3 = r6; \
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r4 = 0x7fffffff; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, invalid access 6")
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__failure __msg("invalid zero-sized read")
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__naked void load_bytes_invalid_access_6(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -512; \
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r3 = r6; \
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r4 = 0; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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SEC("tc")
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__description("raw_stack: skb_load_bytes, large access")
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__success __retval(0)
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__naked void skb_load_bytes_large_access(void)
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{
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asm volatile (" \
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r2 = 4; \
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r6 = r10; \
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r6 += -512; \
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r3 = r6; \
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r4 = 512; \
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call %[bpf_skb_load_bytes]; \
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r0 = *(u64*)(r6 + 0); \
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exit; \
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" :
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: __imm(bpf_skb_load_bytes)
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: __clobber_all);
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}
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char _license[] SEC("license") = "GPL";
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