From 663af70aabb7c9b6bd5e1c1cdeb44e7025a4f855 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 16 Mar 2022 10:38:23 -0700 Subject: [PATCH 1/3] bpf: selftests: Add helpers to directly use the capget and capset syscall After upgrading to the newer libcap (>= 2.60), the libcap commit aca076443591 ("Make cap_t operations thread safe.") added a "__u8 mutex;" to the "struct _cap_struct". It caused a few byte shift that breaks the assumption made in the "struct libcap" definition in test_verifier.c. The bpf selftest usage only needs to enable and disable the effective caps of the running task. It is easier to directly syscall the capget and capset instead. It can also remove the libcap library dependency. The cap_helpers.{c,h} is added. One __u64 is used for all CAP_* bits instead of two __u32. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20220316173823.2036955-1-kafai@fb.com --- tools/testing/selftests/bpf/cap_helpers.c | 67 +++++++++++++++++++++++ tools/testing/selftests/bpf/cap_helpers.h | 19 +++++++ 2 files changed, 86 insertions(+) create mode 100644 tools/testing/selftests/bpf/cap_helpers.c create mode 100644 tools/testing/selftests/bpf/cap_helpers.h diff --git a/tools/testing/selftests/bpf/cap_helpers.c b/tools/testing/selftests/bpf/cap_helpers.c new file mode 100644 index 000000000000..d5ac507401d7 --- /dev/null +++ b/tools/testing/selftests/bpf/cap_helpers.c @@ -0,0 +1,67 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "cap_helpers.h" + +/* Avoid including from the libcap-devel package, + * so directly declare them here and use them from glibc. + */ +int capget(cap_user_header_t header, cap_user_data_t data); +int capset(cap_user_header_t header, const cap_user_data_t data); + +int cap_enable_effective(__u64 caps, __u64 *old_caps) +{ + struct __user_cap_data_struct data[_LINUX_CAPABILITY_U32S_3]; + struct __user_cap_header_struct hdr = { + .version = _LINUX_CAPABILITY_VERSION_3, + }; + __u32 cap0 = caps; + __u32 cap1 = caps >> 32; + int err; + + err = capget(&hdr, data); + if (err) + return err; + + if (old_caps) + *old_caps = (__u64)(data[1].effective) << 32 | data[0].effective; + + if ((data[0].effective & cap0) == cap0 && + (data[1].effective & cap1) == cap1) + return 0; + + data[0].effective |= cap0; + data[1].effective |= cap1; + err = capset(&hdr, data); + if (err) + return err; + + return 0; +} + +int cap_disable_effective(__u64 caps, __u64 *old_caps) +{ + struct __user_cap_data_struct data[_LINUX_CAPABILITY_U32S_3]; + struct __user_cap_header_struct hdr = { + .version = _LINUX_CAPABILITY_VERSION_3, + }; + __u32 cap0 = caps; + __u32 cap1 = caps >> 32; + int err; + + err = capget(&hdr, data); + if (err) + return err; + + if (old_caps) + *old_caps = (__u64)(data[1].effective) << 32 | data[0].effective; + + if (!(data[0].effective & cap0) && !(data[1].effective & cap1)) + return 0; + + data[0].effective &= ~cap0; + data[1].effective &= ~cap1; + err = capset(&hdr, data); + if (err) + return err; + + return 0; +} diff --git a/tools/testing/selftests/bpf/cap_helpers.h b/tools/testing/selftests/bpf/cap_helpers.h new file mode 100644 index 000000000000..6d163530cb0f --- /dev/null +++ b/tools/testing/selftests/bpf/cap_helpers.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __CAP_HELPERS_H +#define __CAP_HELPERS_H + +#include +#include + +#ifndef CAP_PERFMON +#define CAP_PERFMON 38 +#endif + +#ifndef CAP_BPF +#define CAP_BPF 39 +#endif + +int cap_enable_effective(__u64 caps, __u64 *old_caps); +int cap_disable_effective(__u64 caps, __u64 *old_caps); + +#endif From b1c2768a82b9cd149f54e335de38ea1212f47b07 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 16 Mar 2022 10:38:29 -0700 Subject: [PATCH 2/3] bpf: selftests: Remove libcap usage from test_verifier This patch removes the libcap usage from test_verifier. The cap_*_effective() helpers added in the earlier patch are used instead. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20220316173829.2038682-1-kafai@fb.com --- tools/testing/selftests/bpf/Makefile | 3 +- tools/testing/selftests/bpf/test_verifier.c | 84 ++++++--------------- 2 files changed, 25 insertions(+), 62 deletions(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index fe12b4f5fe20..1c6e55740019 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -195,6 +195,7 @@ $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(BPFOBJ) CGROUP_HELPERS := $(OUTPUT)/cgroup_helpers.o TESTING_HELPERS := $(OUTPUT)/testing_helpers.o TRACE_HELPERS := $(OUTPUT)/trace_helpers.o +CAP_HELPERS := $(OUTPUT)/cap_helpers.o $(OUTPUT)/test_dev_cgroup: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_skb_cgroup_id_user: $(CGROUP_HELPERS) $(TESTING_HELPERS) @@ -211,7 +212,7 @@ $(OUTPUT)/test_lirc_mode2_user: $(TESTING_HELPERS) $(OUTPUT)/xdping: $(TESTING_HELPERS) $(OUTPUT)/flow_dissector_load: $(TESTING_HELPERS) $(OUTPUT)/test_maps: $(TESTING_HELPERS) -$(OUTPUT)/test_verifier: $(TESTING_HELPERS) +$(OUTPUT)/test_verifier: $(TESTING_HELPERS) $(CAP_HELPERS) BPFTOOL ?= $(DEFAULT_BPFTOOL) $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \ diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 92e3465fbae8..a2cd236c32eb 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -22,8 +22,6 @@ #include #include -#include - #include #include #include @@ -42,6 +40,7 @@ # define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS 1 # endif #endif +#include "cap_helpers.h" #include "bpf_rand.h" #include "bpf_util.h" #include "test_btf.h" @@ -62,6 +61,10 @@ #define F_NEEDS_EFFICIENT_UNALIGNED_ACCESS (1 << 0) #define F_LOAD_WITH_STRICT_ALIGNMENT (1 << 1) +/* need CAP_BPF, CAP_NET_ADMIN, CAP_PERFMON to load progs */ +#define ADMIN_CAPS (1ULL << CAP_NET_ADMIN | \ + 1ULL << CAP_PERFMON | \ + 1ULL << CAP_BPF) #define UNPRIV_SYSCTL "kernel/unprivileged_bpf_disabled" static bool unpriv_disabled = false; static int skips; @@ -973,47 +976,19 @@ struct libcap { static int set_admin(bool admin) { - cap_t caps; - /* need CAP_BPF, CAP_NET_ADMIN, CAP_PERFMON to load progs */ - const cap_value_t cap_net_admin = CAP_NET_ADMIN; - const cap_value_t cap_sys_admin = CAP_SYS_ADMIN; - struct libcap *cap; - int ret = -1; + int err; - caps = cap_get_proc(); - if (!caps) { - perror("cap_get_proc"); - return -1; - } - cap = (struct libcap *)caps; - if (cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap_sys_admin, CAP_CLEAR)) { - perror("cap_set_flag clear admin"); - goto out; - } - if (cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap_net_admin, - admin ? CAP_SET : CAP_CLEAR)) { - perror("cap_set_flag set_or_clear net"); - goto out; - } - /* libcap is likely old and simply ignores CAP_BPF and CAP_PERFMON, - * so update effective bits manually - */ if (admin) { - cap->data[1].effective |= 1 << (38 /* CAP_PERFMON */ - 32); - cap->data[1].effective |= 1 << (39 /* CAP_BPF */ - 32); + err = cap_enable_effective(ADMIN_CAPS, NULL); + if (err) + perror("cap_enable_effective(ADMIN_CAPS)"); } else { - cap->data[1].effective &= ~(1 << (38 - 32)); - cap->data[1].effective &= ~(1 << (39 - 32)); + err = cap_disable_effective(ADMIN_CAPS, NULL); + if (err) + perror("cap_disable_effective(ADMIN_CAPS)"); } - if (cap_set_proc(caps)) { - perror("cap_set_proc"); - goto out; - } - ret = 0; -out: - if (cap_free(caps)) - perror("cap_free"); - return ret; + + return err; } static int do_prog_test_run(int fd_prog, bool unpriv, uint32_t expected_val, @@ -1291,31 +1266,18 @@ fail_log: static bool is_admin(void) { - cap_flag_value_t net_priv = CAP_CLEAR; - bool perfmon_priv = false; - bool bpf_priv = false; - struct libcap *cap; - cap_t caps; + __u64 caps; -#ifdef CAP_IS_SUPPORTED - if (!CAP_IS_SUPPORTED(CAP_SETFCAP)) { - perror("cap_get_flag"); + /* The test checks for finer cap as CAP_NET_ADMIN, + * CAP_PERFMON, and CAP_BPF instead of CAP_SYS_ADMIN. + * Thus, disable CAP_SYS_ADMIN at the beginning. + */ + if (cap_disable_effective(1ULL << CAP_SYS_ADMIN, &caps)) { + perror("cap_disable_effective(CAP_SYS_ADMIN)"); return false; } -#endif - caps = cap_get_proc(); - if (!caps) { - perror("cap_get_proc"); - return false; - } - cap = (struct libcap *)caps; - bpf_priv = cap->data[1].effective & (1 << (39/* CAP_BPF */ - 32)); - perfmon_priv = cap->data[1].effective & (1 << (38/* CAP_PERFMON */ - 32)); - if (cap_get_flag(caps, CAP_NET_ADMIN, CAP_EFFECTIVE, &net_priv)) - perror("cap_get_flag NET"); - if (cap_free(caps)) - perror("cap_free"); - return bpf_priv && perfmon_priv && net_priv == CAP_SET; + + return (caps & ADMIN_CAPS) == ADMIN_CAPS; } static void get_unpriv_disabled() From 82cb2b30773e3ccbbd2ed4427d52a91862d4db6d Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 16 Mar 2022 10:38:35 -0700 Subject: [PATCH 3/3] bpf: selftests: Remove libcap usage from test_progs This patch removes the libcap usage from test_progs. bind_perm.c is the only user. cap_*_effective() helpers added in the earlier patch are directly used instead. No other selftest binary is using libcap, so '-lcap' is also removed from the Makefile. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Reviewed-by: Stanislav Fomichev Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20220316173835.2039334-1-kafai@fb.com --- tools/testing/selftests/bpf/Makefile | 5 ++- .../selftests/bpf/prog_tests/bind_perm.c | 44 ++++--------------- 2 files changed, 11 insertions(+), 38 deletions(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 1c6e55740019..11f5883636c3 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -25,7 +25,7 @@ CFLAGS += -g -O0 -rdynamic -Wall -Werror $(GENFLAGS) $(SAN_CFLAGS) \ -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) \ -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT) LDFLAGS += $(SAN_CFLAGS) -LDLIBS += -lcap -lelf -lz -lrt -lpthread +LDLIBS += -lelf -lz -lrt -lpthread # Silence some warnings when compiled with clang ifneq ($(LLVM),) @@ -480,7 +480,8 @@ TRUNNER_TESTS_DIR := prog_tests TRUNNER_BPF_PROGS_DIR := progs TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \ network_helpers.c testing_helpers.c \ - btf_helpers.c flow_dissector_load.h + btf_helpers.c flow_dissector_load.h \ + cap_helpers.c TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \ ima_setup.sh \ $(wildcard progs/btf_dump_test_case_*.c) diff --git a/tools/testing/selftests/bpf/prog_tests/bind_perm.c b/tools/testing/selftests/bpf/prog_tests/bind_perm.c index eac71fbb24ce..a1766a298bb7 100644 --- a/tools/testing/selftests/bpf/prog_tests/bind_perm.c +++ b/tools/testing/selftests/bpf/prog_tests/bind_perm.c @@ -4,9 +4,9 @@ #include #include #include -#include #include "test_progs.h" +#include "cap_helpers.h" #include "bind_perm.skel.h" static int duration; @@ -49,41 +49,11 @@ close_socket: close(fd); } -bool cap_net_bind_service(cap_flag_value_t flag) -{ - const cap_value_t cap_net_bind_service = CAP_NET_BIND_SERVICE; - cap_flag_value_t original_value; - bool was_effective = false; - cap_t caps; - - caps = cap_get_proc(); - if (CHECK(!caps, "cap_get_proc", "errno %d", errno)) - goto free_caps; - - if (CHECK(cap_get_flag(caps, CAP_NET_BIND_SERVICE, CAP_EFFECTIVE, - &original_value), - "cap_get_flag", "errno %d", errno)) - goto free_caps; - - was_effective = (original_value == CAP_SET); - - if (CHECK(cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap_net_bind_service, - flag), - "cap_set_flag", "errno %d", errno)) - goto free_caps; - - if (CHECK(cap_set_proc(caps), "cap_set_proc", "errno %d", errno)) - goto free_caps; - -free_caps: - CHECK(cap_free(caps), "cap_free", "errno %d", errno); - return was_effective; -} - void test_bind_perm(void) { - bool cap_was_effective; + const __u64 net_bind_svc_cap = 1ULL << CAP_NET_BIND_SERVICE; struct bind_perm *skel; + __u64 old_caps = 0; int cgroup_fd; if (create_netns()) @@ -105,7 +75,8 @@ void test_bind_perm(void) if (!ASSERT_OK_PTR(skel, "bind_v6_prog")) goto close_skeleton; - cap_was_effective = cap_net_bind_service(CAP_CLEAR); + ASSERT_OK(cap_disable_effective(net_bind_svc_cap, &old_caps), + "cap_disable_effective"); try_bind(AF_INET, 110, EACCES); try_bind(AF_INET6, 110, EACCES); @@ -113,8 +84,9 @@ void test_bind_perm(void) try_bind(AF_INET, 111, 0); try_bind(AF_INET6, 111, 0); - if (cap_was_effective) - cap_net_bind_service(CAP_SET); + if (old_caps & net_bind_svc_cap) + ASSERT_OK(cap_enable_effective(net_bind_svc_cap, NULL), + "cap_enable_effective"); close_skeleton: bind_perm__destroy(skel);