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authorAlexei Starovoitov <ast@kernel.org>2021-12-15 12:35:34 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2021-12-16 21:41:13 +0100
commit7edc3fcbf9a2b2e3df53c9656a9f85bf807affac (patch)
treee67f6302d7d49c1c331031619e4f66ab13164907
parent588a25e92458c6efeb7a261d5ca5726f5de89184 (diff)
selftest/bpf: Add a test that reads various addresses.
Add a function to bpf_testmod that returns invalid kernel and user addresses. Then attach an fexit program to that function that tries to read memory through these addresses. This logic checks that bpf_probe_read_kernel and BPF_PROBE_MEM logic is sane. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
-rw-r--r--tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c20
-rw-r--r--tools/testing/selftests/bpf/progs/test_module_attach.c12
2 files changed, 32 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 5d52ea2768df..df3b292a8ffe 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -33,6 +33,22 @@ noinline int bpf_testmod_loop_test(int n)
return sum;
}
+__weak noinline struct file *bpf_testmod_return_ptr(int arg)
+{
+ static struct file f = {};
+
+ switch (arg) {
+ case 1: return (void *)EINVAL; /* user addr */
+ case 2: return (void *)0xcafe4a11; /* user addr */
+ case 3: return (void *)-EINVAL; /* canonical, but invalid */
+ case 4: return (void *)(1ull << 60); /* non-canonical and invalid */
+ case 5: return (void *)~(1ull << 30); /* trigger extable */
+ case 6: return &f; /* valid addr */
+ case 7: return (void *)((long)&f | 1); /* kernel tricks */
+ default: return NULL;
+ }
+}
+
noinline ssize_t
bpf_testmod_test_read(struct file *file, struct kobject *kobj,
struct bin_attribute *bin_attr,
@@ -43,6 +59,10 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj,
.off = off,
.len = len,
};
+ int i = 1;
+
+ while (bpf_testmod_return_ptr(i))
+ i++;
/* This is always true. Use the check to make sure the compiler
* doesn't remove bpf_testmod_loop_test.
diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c
index b36857093f71..50ce16d02da7 100644
--- a/tools/testing/selftests/bpf/progs/test_module_attach.c
+++ b/tools/testing/selftests/bpf/progs/test_module_attach.c
@@ -87,6 +87,18 @@ int BPF_PROG(handle_fexit,
return 0;
}
+SEC("fexit/bpf_testmod_return_ptr")
+int BPF_PROG(handle_fexit_ret, int arg, struct file *ret)
+{
+ long buf = 0;
+
+ bpf_probe_read_kernel(&buf, 8, ret);
+ bpf_probe_read_kernel(&buf, 8, (char *)ret + 256);
+ *(volatile long long *)ret;
+ *(volatile int *)&ret->f_mode;
+ return 0;
+}
+
__u32 fmod_ret_read_sz = 0;
SEC("fmod_ret/bpf_testmod_test_read")