| Message ID | 20201019194225.1051596-1-kafai@fb.com |
|---|---|
| State | New |
| Headers | show |
| Series | bpf: Enforce NULL check on new _OR_NULL return types | expand |
Thanks Martin for catching and fixing this! On Mon, Oct 19, 2020 at 12:43 PM Martin KaFai Lau <kafai@fb.com> wrote: > > This patch tests all pointers returned by bpf_per_cpu_ptr() must be > tested for NULL first before it can be accessed. > > This patch adds a subtest "null_check", so it moves the ".data..percpu" > existence check to the very beginning and before doing any subtest. > > Signed-off-by: Martin KaFai Lau <kafai@fb.com> > --- > .../selftests/bpf/prog_tests/ksyms_btf.c | 57 +++++++++++++------ > .../bpf/progs/test_ksyms_btf_null_check.c | 31 ++++++++++ > 2 files changed, 70 insertions(+), 18 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c > index 28e26bd3e0ca..b58b775d19f3 100644 > --- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c > +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c > @@ -5,18 +5,17 @@ > #include <bpf/libbpf.h> > #include <bpf/btf.h> > #include "test_ksyms_btf.skel.h" > +#include "test_ksyms_btf_null_check.skel.h" > > static int duration; > > -void test_ksyms_btf(void) > +static void test_basic(void) > { > __u64 runqueues_addr, bpf_prog_active_addr; > __u32 this_rq_cpu; > int this_bpf_prog_active; > struct test_ksyms_btf *skel = NULL; > struct test_ksyms_btf__data *data; > - struct btf *btf; > - int percpu_datasec; > int err; > > err = kallsyms_find("runqueues", &runqueues_addr); > @@ -31,20 +30,6 @@ void test_ksyms_btf(void) > if (CHECK(err == -ENOENT, "ksym_find", "symbol 'bpf_prog_active' not found\n")) > return; > > - btf = libbpf_find_kernel_btf(); > - if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n", > - PTR_ERR(btf))) > - return; > - > - percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu", > - BTF_KIND_DATASEC); > - if (percpu_datasec < 0) { > - printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n", > - __func__); > - test__skip(); > - goto cleanup; > - } > - > skel = test_ksyms_btf__open_and_load(); > if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n")) > goto cleanup; > @@ -83,6 +68,42 @@ void test_ksyms_btf(void) > data->out__bpf_prog_active); > > cleanup: > - btf__free(btf); > test_ksyms_btf__destroy(skel); > } > + > +static void test_null_check(void) > +{ > + struct test_ksyms_btf_null_check *skel; > + > + skel = test_ksyms_btf_null_check__open_and_load(); > + CHECK(skel, "skel_open", "unexpected load of a prog missing null check\n"); > + > + test_ksyms_btf_null_check__destroy(skel); > +} > + > +void test_ksyms_btf(void) > +{ > + int percpu_datasec; > + struct btf *btf; > + > + btf = libbpf_find_kernel_btf(); > + if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n", > + PTR_ERR(btf))) > + return; > + > + percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu", > + BTF_KIND_DATASEC); > + btf__free(btf); > + if (percpu_datasec < 0) { > + printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n", > + __func__); > + test__skip(); > + return; > + } > + > + if (test__start_subtest("basic")) > + test_basic(); > + > + if (test__start_subtest("null_check")) > + test_null_check(); > +} > diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c > new file mode 100644 > index 000000000000..8bc8f7c637bc > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c > @@ -0,0 +1,31 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2020 Facebook */ > + > +#include "vmlinux.h" > + > +#include <bpf/bpf_helpers.h> > + > +extern const struct rq runqueues __ksym; /* struct type global var. */ > +extern const int bpf_prog_active __ksym; /* int type global var. */ > + > +SEC("raw_tp/sys_enter") > +int handler(const void *ctx) > +{ > + struct rq *rq; > + int *active; > + __u32 cpu; > + > + cpu = bpf_get_smp_processor_id(); > + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu); > + active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu); > + if (active) { > + /* READ_ONCE */ > + *(volatile int *)active; > + /* !rq has not been tested, so verifier should reject. */ > + *(volatile int *)(&rq->cpu); > + } > + > + return 0; > +} > + > +char _license[] SEC("license") = "GPL"; > -- > 2.24.1 >
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c index 28e26bd3e0ca..b58b775d19f3 100644 --- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c @@ -5,18 +5,17 @@ #include <bpf/libbpf.h> #include <bpf/btf.h> #include "test_ksyms_btf.skel.h" +#include "test_ksyms_btf_null_check.skel.h" static int duration; -void test_ksyms_btf(void) +static void test_basic(void) { __u64 runqueues_addr, bpf_prog_active_addr; __u32 this_rq_cpu; int this_bpf_prog_active; struct test_ksyms_btf *skel = NULL; struct test_ksyms_btf__data *data; - struct btf *btf; - int percpu_datasec; int err; err = kallsyms_find("runqueues", &runqueues_addr); @@ -31,20 +30,6 @@ void test_ksyms_btf(void) if (CHECK(err == -ENOENT, "ksym_find", "symbol 'bpf_prog_active' not found\n")) return; - btf = libbpf_find_kernel_btf(); - if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n", - PTR_ERR(btf))) - return; - - percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu", - BTF_KIND_DATASEC); - if (percpu_datasec < 0) { - printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n", - __func__); - test__skip(); - goto cleanup; - } - skel = test_ksyms_btf__open_and_load(); if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n")) goto cleanup; @@ -83,6 +68,42 @@ void test_ksyms_btf(void) data->out__bpf_prog_active); cleanup: - btf__free(btf); test_ksyms_btf__destroy(skel); } + +static void test_null_check(void) +{ + struct test_ksyms_btf_null_check *skel; + + skel = test_ksyms_btf_null_check__open_and_load(); + CHECK(skel, "skel_open", "unexpected load of a prog missing null check\n"); + + test_ksyms_btf_null_check__destroy(skel); +} + +void test_ksyms_btf(void) +{ + int percpu_datasec; + struct btf *btf; + + btf = libbpf_find_kernel_btf(); + if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n", + PTR_ERR(btf))) + return; + + percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu", + BTF_KIND_DATASEC); + btf__free(btf); + if (percpu_datasec < 0) { + printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n", + __func__); + test__skip(); + return; + } + + if (test__start_subtest("basic")) + test_basic(); + + if (test__start_subtest("null_check")) + test_null_check(); +} diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c new file mode 100644 index 000000000000..8bc8f7c637bc --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Facebook */ + +#include "vmlinux.h" + +#include <bpf/bpf_helpers.h> + +extern const struct rq runqueues __ksym; /* struct type global var. */ +extern const int bpf_prog_active __ksym; /* int type global var. */ + +SEC("raw_tp/sys_enter") +int handler(const void *ctx) +{ + struct rq *rq; + int *active; + __u32 cpu; + + cpu = bpf_get_smp_processor_id(); + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu); + active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu); + if (active) { + /* READ_ONCE */ + *(volatile int *)active; + /* !rq has not been tested, so verifier should reject. */ + *(volatile int *)(&rq->cpu); + } + + return 0; +} + +char _license[] SEC("license") = "GPL";
This patch tests all pointers returned by bpf_per_cpu_ptr() must be tested for NULL first before it can be accessed. This patch adds a subtest "null_check", so it moves the ".data..percpu" existence check to the very beginning and before doing any subtest. Signed-off-by: Martin KaFai Lau <kafai@fb.com> --- .../selftests/bpf/prog_tests/ksyms_btf.c | 57 +++++++++++++------ .../bpf/progs/test_ksyms_btf_null_check.c | 31 ++++++++++ 2 files changed, 70 insertions(+), 18 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c