59fe41b525
This patch adds a test exercising logic that was fixed / improved in
the previous patch in the series, as well as general sanity checking for
jit's PROBE_MEM logic which should've been unaffected by the previous
patch.
The added verifier test does the following:
* Acquire a referenced kptr to struct prog_test_ref_kfunc using
existing net/bpf/test_run.c kfunc
* Helper returns ptr to a specific prog_test_ref_kfunc whose first
two fields - both ints - have been prepopulated w/ vals 42 and
108, respectively
* kptr_xchg the acquired ptr into an arraymap
* Do a direct map_value load of the just-added ptr
* Goal of all this setup is to get an unreferenced kptr pointing to
struct with ints of known value, which is the result of this step
* Using unreferenced kptr obtained in previous step, do loads of
prog_test_ref_kfunc.a (offset 0) and .b (offset 4)
* Then incr the kptr by 8 and load prog_test_ref_kfunc.a again (this
time at offset -8)
* Add all the loaded ints together and return
Before the PROBE_MEM fixes in previous patch, the loads at offset 0 and
4 would succeed, while the load at offset -8 would incorrectly fail
runtime check emitted by the JIT and 0 out dst reg as a result. This
confirmed by retval of 150 for this test before previous patch - since
second .a read is 0'd out - and a retval of 192 with the fixed logic.
The test exercises the two optimizations to fixed logic added in last
patch as well:
* First load, with insn "r8 = *(u32 *)(r9 + 0)" exercises "insn->off
is 0, no need to add / sub from src_reg" optimization
* Third load, with insn "r9 = *(u32 *)(r9 - 8)" exercises "src_reg ==
dst_reg, no need to restore src_reg after load" optimization
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221216214319.3408356-2-davemarchevsky@fb.com
61 lines
1.2 KiB
C
61 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
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#include <vmlinux.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_helpers.h>
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static struct prog_test_ref_kfunc __kptr_ref *v;
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long total_sum = -1;
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extern struct prog_test_ref_kfunc *bpf_kfunc_call_test_acquire(unsigned long *sp) __ksym;
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extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;
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SEC("tc")
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int test_jit_probe_mem(struct __sk_buff *ctx)
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{
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struct prog_test_ref_kfunc *p;
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unsigned long zero = 0, sum;
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p = bpf_kfunc_call_test_acquire(&zero);
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if (!p)
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return 1;
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p = bpf_kptr_xchg(&v, p);
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if (p)
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goto release_out;
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/* Direct map value access of kptr, should be PTR_UNTRUSTED */
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p = v;
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if (!p)
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return 1;
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asm volatile (
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"r9 = %[p];"
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"%[sum] = 0;"
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/* r8 = p->a */
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"r8 = *(u32 *)(r9 + 0);"
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"%[sum] += r8;"
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/* r8 = p->b */
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"r8 = *(u32 *)(r9 + 4);"
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"%[sum] += r8;"
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"r9 += 8;"
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/* r9 = p->a */
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"r9 = *(u32 *)(r9 - 8);"
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"%[sum] += r9;"
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: [sum] "=r"(sum)
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: [p] "r"(p)
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: "r8", "r9"
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);
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total_sum = sum;
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return 0;
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release_out:
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bpf_kfunc_call_test_release(p);
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return 1;
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}
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char _license[] SEC("license") = "GPL";
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