diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/verifier_var_off.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_var_off.c | 91 |
1 files changed, 80 insertions, 11 deletions
diff --git a/tools/testing/selftests/bpf/progs/verifier_var_off.c b/tools/testing/selftests/bpf/progs/verifier_var_off.c index 83a90afba785..c810f4f6f479 100644 --- a/tools/testing/selftests/bpf/progs/verifier_var_off.c +++ b/tools/testing/selftests/bpf/progs/verifier_var_off.c @@ -59,9 +59,10 @@ __naked void stack_read_priv_vs_unpriv(void) " ::: __clobber_all); } -SEC("lwt_in") +SEC("cgroup/skb") __description("variable-offset stack read, uninitialized") -__failure __msg("invalid variable-offset read from stack R2") +__success +__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root") __naked void variable_offset_stack_read_uninitialized(void) { asm volatile (" \ @@ -83,13 +84,56 @@ __naked void variable_offset_stack_read_uninitialized(void) SEC("socket") __description("variable-offset stack write, priv vs unpriv") -__success __failure_unpriv +__success +/* Check that the maximum stack depth is correctly maintained according to the + * maximum possible variable offset. + */ +__log_level(4) __msg("stack depth 16") +__failure_unpriv /* Variable stack access is rejected for unprivileged. */ __msg_unpriv("R2 variable stack access prohibited for !root") __retval(0) __naked void stack_write_priv_vs_unpriv(void) { + asm volatile (" \ + /* Get an unknown value */ \ + r2 = *(u32*)(r1 + 0); \ + /* Make it small and 8-byte aligned */ \ + r2 &= 8; \ + r2 -= 16; \ + /* Add it to fp. We now have either fp-8 or \ + * fp-16, but we don't know which \ + */ \ + r2 += r10; \ + /* Dereference it for a stack write */ \ + r0 = 0; \ + *(u64*)(r2 + 0) = r0; \ + exit; \ +" ::: __clobber_all); +} + +/* Similar to the previous test, but this time also perform a read from the + * address written to with a variable offset. The read is allowed, showing that, + * after a variable-offset write, a priviledged program can read the slots that + * were in the range of that write (even if the verifier doesn't actually know if + * the slot being read was really written to or not. + * + * Despite this test being mostly a superset, the previous test is also kept for + * the sake of it checking the stack depth in the case where there is no read. + */ +SEC("socket") +__description("variable-offset stack write followed by read") +__success +/* Check that the maximum stack depth is correctly maintained according to the + * maximum possible variable offset. + */ +__log_level(4) __msg("stack depth 16") +__failure_unpriv +__msg_unpriv("R2 variable stack access prohibited for !root") +__retval(0) +__naked void stack_write_followed_by_read(void) +{ asm volatile (" \ /* Get an unknown value */ \ r2 = *(u32*)(r1 + 0); \ @@ -103,12 +147,7 @@ __naked void stack_write_priv_vs_unpriv(void) /* Dereference it for a stack write */ \ r0 = 0; \ *(u64*)(r2 + 0) = r0; \ - /* Now read from the address we just wrote. This shows\ - * that, after a variable-offset write, a priviledged\ - * program can read the slots that were in the range of\ - * that write (even if the verifier doesn't actually know\ - * if the slot being read was really written to or not.\ - */ \ + /* Now read from the address we just wrote. */ \ r3 = *(u64*)(r2 + 0); \ r0 = 0; \ exit; \ @@ -224,6 +263,35 @@ __naked void access_max_out_of_bound(void) : __clobber_all); } +/* Similar to the test above, but this time check the special case of a + * zero-sized stack access. We used to have a bug causing crashes for zero-sized + * out-of-bounds accesses. + */ +SEC("socket") +__description("indirect variable-offset stack access, zero-sized, max out of bound") +__failure __msg("invalid variable-offset indirect access to stack R1") +__naked void zero_sized_access_max_out_of_bound(void) +{ + asm volatile (" \ + r0 = 0; \ + /* Fill some stack */ \ + *(u64*)(r10 - 16) = r0; \ + *(u64*)(r10 - 8) = r0; \ + /* Get an unknown value */ \ + r1 = *(u32*)(r1 + 0); \ + r1 &= 63; \ + r1 += -16; \ + /* r1 is now anywhere in [-16,48) */ \ + r1 += r10; \ + r2 = 0; \ + r3 = 0; \ + call %[bpf_probe_read_kernel]; \ + exit; \ +" : + : __imm(bpf_probe_read_kernel) + : __clobber_all); +} + SEC("lwt_in") __description("indirect variable-offset stack access, min out of bound") __failure __msg("invalid variable-offset indirect access to stack R2") @@ -253,9 +321,10 @@ __naked void access_min_out_of_bound(void) : __clobber_all); } -SEC("lwt_in") +SEC("cgroup/skb") __description("indirect variable-offset stack access, min_off < min_initialized") -__failure __msg("invalid indirect read from stack R2 var_off") +__success +__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root") __naked void access_min_off_min_initialized(void) { asm volatile (" \ |