| Message ID | 20230427023019.73576-3-zhoufeng.zf@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce a new kfunc of bpf_task_under_cgroup | expand |
On 4/26/23 7:30 PM, Feng zhou wrote: > From: Feng Zhou <zhoufeng.zf@bytedance.com> > > test_progs: > Tests new kfunc bpf_task_under_cgroup(). > > The bpf program saves the pid which call the getpgid syscall within a > given cgroup to the remote_pid, which is convenient for the user-mode > program to verify the test correctness. > > The user-mode program creates its own mount namespace, and mounts the > cgroupsv2 hierarchy in there, call the getpgid syscall, then check if > remote_pid and local_pid are equal. > > Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com> > --- > tools/testing/selftests/bpf/DENYLIST.s390x | 1 + > .../bpf/prog_tests/task_under_cgroup.c | 47 +++++++++++++++++++ > .../selftests/bpf/progs/cgrp_kfunc_common.h | 1 + > .../bpf/progs/test_task_under_cgroup.c | 37 +++++++++++++++ > 4 files changed, 86 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c > create mode 100644 tools/testing/selftests/bpf/progs/test_task_under_cgroup.c > > diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x > index c7463f3ec3c0..5061d9e24c16 100644 > --- a/tools/testing/selftests/bpf/DENYLIST.s390x > +++ b/tools/testing/selftests/bpf/DENYLIST.s390x > @@ -26,3 +26,4 @@ user_ringbuf # failed to find kernel BTF type ID of > verif_stats # trace_vprintk__open_and_load unexpected error: -9 (?) > xdp_bonding # failed to auto-attach program 'trace_on_entry': -524 (trampoline) > xdp_metadata # JIT does not support calling kernel function (kfunc) > +test_task_under_cgroup # JIT does not support calling kernel function (kfunc) > diff --git a/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c > new file mode 100644 > index 000000000000..6d5709a8203d > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c > @@ -0,0 +1,47 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2023 Bytedance */ > + > +#include <sys/syscall.h> > +#include <test_progs.h> > +#include <cgroup_helpers.h> > +#include "test_task_under_cgroup.skel.h" > + > +#define FOO "/foo" > + > +void test_task_under_cgroup(void) > +{ > + struct test_task_under_cgroup *skel; > + int ret, foo = -1; > + > + foo = test__join_cgroup(FOO); > + if (!ASSERT_OK(foo < 0, "cgroup_join_foo")) > + return; > + > + skel = test_task_under_cgroup__open(); > + if (!ASSERT_OK_PTR(skel, "test_task_under_cgroup__open")) > + goto cleanup; > + > + skel->rodata->local_pid = getpid(); > + skel->rodata->cgid = get_cgroup_id(FOO); > + > + ret = test_task_under_cgroup__load(skel); > + if (!ASSERT_OK(ret, "test_task_under_cgroup__load")) > + goto cleanup; > + > + ret = test_task_under_cgroup__attach(skel); > + if (!ASSERT_OK(ret, "test_task_under_cgroup__attach")) > + goto cleanup; > + > + syscall(SYS_getpgid); > + > + test_task_under_cgroup__detach(skel); > + > + ASSERT_EQ(skel->bss->remote_pid, skel->rodata->local_pid, > + "test task_under_cgroup"); > + > +cleanup: > + if (foo >= 0) > + close(foo); > + > + test_task_under_cgroup__destroy(skel); > +} > diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h > index 22914a70db54..001c416b42bc 100644 > --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h > +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h > @@ -26,6 +26,7 @@ struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym; > struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym; > void bpf_rcu_read_lock(void) __ksym; > void bpf_rcu_read_unlock(void) __ksym; > +int bpf_task_under_cgroup(struct task_struct *task, struct cgroup *ancestor) __ksym; return type 'long'? > > static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp) > { > diff --git a/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c > new file mode 100644 > index 000000000000..8f23a2933fde > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c > @@ -0,0 +1,37 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2023 Bytedance */ > + > +#include <vmlinux.h> > +#include <bpf/bpf_tracing.h> > +#include <bpf/bpf_helpers.h> > + > +#include "bpf_misc.h" > +#include "cgrp_kfunc_common.h" > + > +const volatile int local_pid; > +const volatile long cgid; > +int remote_pid; > + > +SEC("fentry/" SYS_PREFIX "sys_getpgid") > +int sys_getpgid(void *ctx) > +{ > + struct cgroup *cgrp; > + > + if (local_pid != (bpf_get_current_pid_tgid() >> 32)) > + return 0; > + > + cgrp = bpf_cgroup_from_id(cgid); > + if (!cgrp) > + return 0; > + > + if (!bpf_task_under_cgroup(bpf_get_current_task_btf(), cgrp)) > + goto out; The whole point of using bpf_task_under_cgroup() is to test a non-current task is under a particular cgroup. Tracing kernel function enqueue_task_fair() is an option, but it may be inlined with certain compilers as enqueue_task_fair() is a static function. Also, the 'task' argument in enqueue_task_fair() is not trusted, could be null ptr and not rcu safe as well. We could promote 'task' in enqueue_task_fair() by: - checking NULL ptr, if not - increase reference count by 1 if current reference count is not 0 (using bpf_task_acquire kfunc) - if reference count can be increased, it becomes trusted, and then bpf_task_under_cgroup() can be used. Could you try this approach or even better if there is another non-static function also having a task (not the current task)? > + > + remote_pid = local_pid; > + > +out: > + bpf_cgroup_release(cgrp); > + return 0; > +} > + > +char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index c7463f3ec3c0..5061d9e24c16 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -26,3 +26,4 @@ user_ringbuf # failed to find kernel BTF type ID of verif_stats # trace_vprintk__open_and_load unexpected error: -9 (?) xdp_bonding # failed to auto-attach program 'trace_on_entry': -524 (trampoline) xdp_metadata # JIT does not support calling kernel function (kfunc) +test_task_under_cgroup # JIT does not support calling kernel function (kfunc) diff --git a/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c new file mode 100644 index 000000000000..6d5709a8203d --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Bytedance */ + +#include <sys/syscall.h> +#include <test_progs.h> +#include <cgroup_helpers.h> +#include "test_task_under_cgroup.skel.h" + +#define FOO "/foo" + +void test_task_under_cgroup(void) +{ + struct test_task_under_cgroup *skel; + int ret, foo = -1; + + foo = test__join_cgroup(FOO); + if (!ASSERT_OK(foo < 0, "cgroup_join_foo")) + return; + + skel = test_task_under_cgroup__open(); + if (!ASSERT_OK_PTR(skel, "test_task_under_cgroup__open")) + goto cleanup; + + skel->rodata->local_pid = getpid(); + skel->rodata->cgid = get_cgroup_id(FOO); + + ret = test_task_under_cgroup__load(skel); + if (!ASSERT_OK(ret, "test_task_under_cgroup__load")) + goto cleanup; + + ret = test_task_under_cgroup__attach(skel); + if (!ASSERT_OK(ret, "test_task_under_cgroup__attach")) + goto cleanup; + + syscall(SYS_getpgid); + + test_task_under_cgroup__detach(skel); + + ASSERT_EQ(skel->bss->remote_pid, skel->rodata->local_pid, + "test task_under_cgroup"); + +cleanup: + if (foo >= 0) + close(foo); + + test_task_under_cgroup__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h index 22914a70db54..001c416b42bc 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h @@ -26,6 +26,7 @@ struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym; struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym; void bpf_rcu_read_lock(void) __ksym; void bpf_rcu_read_unlock(void) __ksym; +int bpf_task_under_cgroup(struct task_struct *task, struct cgroup *ancestor) __ksym; static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp) { diff --git a/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c new file mode 100644 index 000000000000..8f23a2933fde --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Bytedance */ + +#include <vmlinux.h> +#include <bpf/bpf_tracing.h> +#include <bpf/bpf_helpers.h> + +#include "bpf_misc.h" +#include "cgrp_kfunc_common.h" + +const volatile int local_pid; +const volatile long cgid; +int remote_pid; + +SEC("fentry/" SYS_PREFIX "sys_getpgid") +int sys_getpgid(void *ctx) +{ + struct cgroup *cgrp; + + if (local_pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + cgrp = bpf_cgroup_from_id(cgid); + if (!cgrp) + return 0; + + if (!bpf_task_under_cgroup(bpf_get_current_task_btf(), cgrp)) + goto out; + + remote_pid = local_pid; + +out: + bpf_cgroup_release(cgrp); + return 0; +} + +char _license[] SEC("license") = "GPL";