Add a small test to write a (verification-time) fixed vs unknown but bounded-sized buffer into .rodata BPF map and assert that both get rejected. # ./vmtest.sh -- ./test_progs -t verifier_const [...] ./test_progs -t verifier_const [ 1.418717] tsc: Refined TSC clocksource calibration: 3407.994 MHz [ 1.419113] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fcde90a1, max_idle_ns: 440795222066 ns [ 1.419972] clocksource: Switched to clocksource tsc [ 1.449596] bpf_testmod: loading out-of-tree module taints kernel. [ 1.449958] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #475/1 verifier_const/rodata/strtol: write rejected:OK #475/2 verifier_const/bss/strtol: write accepted:OK #475/3 verifier_const/data/strtol: write accepted:OK #475/4 verifier_const/rodata/mtu: write rejected:OK #475/5 verifier_const/bss/mtu: write accepted:OK #475/6 verifier_const/data/mtu: write accepted:OK #475/7 verifier_const/rodata/mark: write with unknown reg rejected:OK #475/8 verifier_const/rodata/mark: write with unknown reg rejected:OK #475 verifier_const:OK #476/1 verifier_const_or/constant register |= constant should keep constant type:OK #476/2 verifier_const_or/constant register |= constant should not bypass stack boundary checks:OK #476/3 verifier_const_or/constant register |= constant register should keep constant type:OK #476/4 verifier_const_or/constant register |= constant register should not bypass stack boundary checks:OK #476 verifier_const_or:OK Summary: 2/12 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> --- .../selftests/bpf/progs/verifier_const.c | 31 ++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/progs/verifier_const.c b/tools/testing/selftests/bpf/progs/verifier_const.c index 2e533d7eec2f..e118dbb768bf 100644 --- a/tools/testing/selftests/bpf/progs/verifier_const.c +++ b/tools/testing/selftests/bpf/progs/verifier_const.c @@ -1,8 +1,9 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2024 Isovalent */ -#include <linux/bpf.h> +#include "vmlinux.h" #include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> #include "bpf_misc.h" const volatile long foo = 42; @@ -66,4 +67,32 @@ int tcx6(struct __sk_buff *skb) return TCX_PASS; } +static inline void write_fixed(volatile void *p, __u32 val) +{ + *(volatile __u32 *)p = val; +} + +static inline void write_dyn(void *p, void *val, int len) +{ + bpf_copy_from_user(p, len, val); +} + +SEC("tc/ingress") +__description("rodata/mark: write with unknown reg rejected") +__failure __msg("write into map forbidden") +int tcx7(struct __sk_buff *skb) +{ + write_fixed((void *)&foo, skb->mark); + return TCX_PASS; +} + +SEC("lsm.s/bprm_committed_creds") +__description("rodata/mark: write with unknown reg rejected") +__failure __msg("write into map forbidden") +int BPF_PROG(bprm, struct linux_binprm *bprm) +{ + write_dyn((void *)&foo, &bart, bpf_get_prandom_u32() & 3); + return 0; +} + char LICENSE[] SEC("license") = "GPL"; -- 2.43.0