From 197afc631413d96dc60acfc7970bdd4125d38cd3 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 6 Nov 2020 16:02:51 -0800 Subject: libbpf: Don't attempt to load unused subprog as an entry-point BPF program If BPF code contains unused BPF subprogram and there are no other subprogram calls (which can realistically happen in real-world applications given sufficiently smart Clang code optimizations), libbpf will erroneously assume that subprograms are entry-point programs and will attempt to load them with UNSPEC program type. Fix by not relying on subcall instructions and rather detect it based on the structure of BPF object's sections. Fixes: 9a94f277c4fb ("tools: libbpf: restore the ability to load programs from .text section") Reported-by: Dmitrii Banshchikov Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20201107000251.256821-1-andrii@kernel.org --- tools/lib/bpf/libbpf.c | 23 ++++++++++++---------- tools/testing/selftests/bpf/prog_tests/subprogs.c | 6 ++++++ .../selftests/bpf/progs/test_subprogs_unused.c | 21 ++++++++++++++++++++ 3 files changed, 40 insertions(+), 10 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/test_subprogs_unused.c (limited to 'tools') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 313034117070..28baee7ba1ca 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -560,8 +560,6 @@ bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog, const char *name, size_t sec_idx, const char *sec_name, size_t sec_off, void *insn_data, size_t insn_data_sz) { - int i; - if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) { pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n", sec_name, name, sec_off, insn_data_sz); @@ -600,13 +598,6 @@ bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog, goto errout; memcpy(prog->insns, insn_data, insn_data_sz); - for (i = 0; i < prog->insns_cnt; i++) { - if (insn_is_subprog_call(&prog->insns[i])) { - obj->has_subcalls = true; - break; - } - } - return 0; errout: pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name); @@ -3280,7 +3271,19 @@ bpf_object__find_program_by_title(const struct bpf_object *obj, static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog) { - return prog->sec_idx == obj->efile.text_shndx && obj->has_subcalls; + /* For legacy reasons, libbpf supports an entry-point BPF programs + * without SEC() attribute, i.e., those in the .text section. But if + * there are 2 or more such programs in the .text section, they all + * must be subprograms called from entry-point BPF programs in + * designated SEC()'tions, otherwise there is no way to distinguish + * which of those programs should be loaded vs which are a subprogram. + * Similarly, if there is a function/program in .text and at least one + * other BPF program with custom SEC() attribute, then we just assume + * .text programs are subprograms (even if they are not called from + * other programs), because libbpf never explicitly supported mixing + * SEC()-designated BPF programs and .text entry-point BPF programs. + */ + return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1; } struct bpf_program * diff --git a/tools/testing/selftests/bpf/prog_tests/subprogs.c b/tools/testing/selftests/bpf/prog_tests/subprogs.c index a00abf58c037..3f3d2ac4dd57 100644 --- a/tools/testing/selftests/bpf/prog_tests/subprogs.c +++ b/tools/testing/selftests/bpf/prog_tests/subprogs.c @@ -3,12 +3,14 @@ #include #include #include "test_subprogs.skel.h" +#include "test_subprogs_unused.skel.h" static int duration; void test_subprogs(void) { struct test_subprogs *skel; + struct test_subprogs_unused *skel2; int err; skel = test_subprogs__open_and_load(); @@ -26,6 +28,10 @@ void test_subprogs(void) CHECK(skel->bss->res3 != 19, "res3", "got %d, exp %d\n", skel->bss->res3, 19); CHECK(skel->bss->res4 != 36, "res4", "got %d, exp %d\n", skel->bss->res4, 36); + skel2 = test_subprogs_unused__open_and_load(); + ASSERT_OK_PTR(skel2, "unused_progs_skel"); + test_subprogs_unused__destroy(skel2); + cleanup: test_subprogs__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/test_subprogs_unused.c b/tools/testing/selftests/bpf/progs/test_subprogs_unused.c new file mode 100644 index 000000000000..75d975f8cf90 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_subprogs_unused.c @@ -0,0 +1,21 @@ +#include "vmlinux.h" +#include +#include + +const char LICENSE[] SEC("license") = "GPL"; + +__attribute__((maybe_unused)) __noinline int unused1(int x) +{ + return x + 1; +} + +static __attribute__((maybe_unused)) __noinline int unused2(int x) +{ + return x + 2; +} + +SEC("raw_tp/sys_enter") +int main_prog(void *ctx) +{ + return 0; +} -- cgit v1.2.3 From fd63729cc0a6872bdabd393ee933a969642e4076 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 11 Nov 2020 15:12:15 -0800 Subject: selftests/bpf: Fix unused attribute usage in subprogs_unused test Correct attribute name is "unused". maybe_unused is a C++17 addition. This patch fixes compilation warning during selftests compilation. Fixes: 197afc631413 ("libbpf: Don't attempt to load unused subprog as an entry-point BPF program") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201111231215.1779147-1-andrii@kernel.org --- tools/testing/selftests/bpf/progs/test_subprogs_unused.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/progs/test_subprogs_unused.c b/tools/testing/selftests/bpf/progs/test_subprogs_unused.c index 75d975f8cf90..bc49e050d342 100644 --- a/tools/testing/selftests/bpf/progs/test_subprogs_unused.c +++ b/tools/testing/selftests/bpf/progs/test_subprogs_unused.c @@ -4,12 +4,12 @@ const char LICENSE[] SEC("license") = "GPL"; -__attribute__((maybe_unused)) __noinline int unused1(int x) +__attribute__((unused)) __noinline int unused1(int x) { return x + 1; } -static __attribute__((maybe_unused)) __noinline int unused2(int x) +static __attribute__((unused)) __noinline int unused2(int x) { return x + 2; } -- cgit v1.2.3 From 50431b45685b600fc2851a3f2b53e24643efe6d3 Mon Sep 17 00:00:00 2001 From: Wang Hai Date: Fri, 13 Nov 2020 19:51:52 +0800 Subject: tools, bpftool: Add missing close before bpftool net attach exit progfd is created by prog_parse_fd() in do_attach() and before the latter returns in case of success, the file descriptor should be closed. Fixes: 04949ccc273e ("tools: bpftool: add net attach command to attach XDP on interface") Signed-off-by: Wang Hai Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20201113115152.53178-1-wanghai38@huawei.com --- tools/bpf/bpftool/net.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'tools') diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c index 910e7bac6e9e..3fae61ef6339 100644 --- a/tools/bpf/bpftool/net.c +++ b/tools/bpf/bpftool/net.c @@ -578,8 +578,8 @@ static int do_attach(int argc, char **argv) ifindex = net_parse_dev(&argc, &argv); if (ifindex < 1) { - close(progfd); - return -EINVAL; + err = -EINVAL; + goto cleanup; } if (argc) { @@ -587,8 +587,8 @@ static int do_attach(int argc, char **argv) overwrite = true; } else { p_err("expected 'overwrite', got: '%s'?", *argv); - close(progfd); - return -EINVAL; + err = -EINVAL; + goto cleanup; } } @@ -596,17 +596,17 @@ static int do_attach(int argc, char **argv) if (is_prefix("xdp", attach_type_strings[attach_type])) err = do_attach_detach_xdp(progfd, attach_type, ifindex, overwrite); - - if (err < 0) { + if (err) { p_err("interface %s attach failed: %s", attach_type_strings[attach_type], strerror(-err)); - return err; + goto cleanup; } if (json_output) jsonw_null(json_wtr); - - return 0; +cleanup: + close(progfd); + return err; } static int do_detach(int argc, char **argv) -- cgit v1.2.3 From f782e2c300a717233b64697affda3ea7aac00b2b Mon Sep 17 00:00:00 2001 From: Dmitrii Banshchikov Date: Fri, 13 Nov 2020 17:17:56 +0000 Subject: bpf: Relax return code check for subprograms Currently verifier enforces return code checks for subprograms in the same manner as it does for program entry points. This prevents returning arbitrary scalar values from subprograms. Scalar type of returned values is checked by btf_prepare_func_args() and hence it should be safe to allow only scalars for now. Relax return code checks for subprograms and allow any correct scalar values. Fixes: 51c39bb1d5d10 (bpf: Introduce function-by-function verification) Signed-off-by: Dmitrii Banshchikov Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20201113171756.90594-1-me@ubique.spb.ru --- kernel/bpf/verifier.c | 15 +++++++++++++-- .../selftests/bpf/prog_tests/test_global_funcs.c | 1 + tools/testing/selftests/bpf/progs/test_global_func8.c | 19 +++++++++++++++++++ 3 files changed, 33 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/test_global_func8.c (limited to 'tools') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6204ec705d80..1388bf733071 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7786,9 +7786,11 @@ static int check_return_code(struct bpf_verifier_env *env) struct tnum range = tnum_range(0, 1); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; + const bool is_subprog = env->cur_state->frame[0]->subprogno; /* LSM and struct_ops func-ptr's return type could be "void" */ - if ((prog_type == BPF_PROG_TYPE_STRUCT_OPS || + if (!is_subprog && + (prog_type == BPF_PROG_TYPE_STRUCT_OPS || prog_type == BPF_PROG_TYPE_LSM) && !prog->aux->attach_func_proto->type) return 0; @@ -7808,6 +7810,16 @@ static int check_return_code(struct bpf_verifier_env *env) return -EACCES; } + reg = cur_regs(env) + BPF_REG_0; + if (is_subprog) { + if (reg->type != SCALAR_VALUE) { + verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n", + reg_type_str[reg->type]); + return -EINVAL; + } + return 0; + } + switch (prog_type) { case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG || @@ -7861,7 +7873,6 @@ static int check_return_code(struct bpf_verifier_env *env) return 0; } - reg = cur_regs(env) + BPF_REG_0; if (reg->type != SCALAR_VALUE) { verbose(env, "At program exit the register R0 is not a known value (%s)\n", reg_type_str[reg->type]); diff --git a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c index 193002b14d7f..32e4348b714b 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c +++ b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c @@ -60,6 +60,7 @@ void test_test_global_funcs(void) { "test_global_func5.o" , "expected pointer to ctx, but got PTR" }, { "test_global_func6.o" , "modified ctx ptr R2" }, { "test_global_func7.o" , "foo() doesn't return scalar" }, + { "test_global_func8.o" }, }; libbpf_print_fn_t old_print_fn = NULL; int err, i, duration = 0; diff --git a/tools/testing/selftests/bpf/progs/test_global_func8.c b/tools/testing/selftests/bpf/progs/test_global_func8.c new file mode 100644 index 000000000000..d55a6544b1ab --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_global_func8.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2020 Facebook */ +#include +#include +#include + +__noinline int foo(struct __sk_buff *skb) +{ + return bpf_get_prandom_u32(); +} + +SEC("cgroup_skb/ingress") +int test_cls(struct __sk_buff *skb) +{ + if (!foo(skb)) + return 0; + + return 1; +} -- cgit v1.2.3 From 2acc3c1bc8e98bc66b1badec42e9ea205b4fcdaa Mon Sep 17 00:00:00 2001 From: Wang Hai Date: Mon, 16 Nov 2020 18:16:33 +0800 Subject: selftests/bpf: Fix error return code in run_getsockopt_test() Fix to return a negative error code from the error handling case instead of 0, as done elsewhere in this function. Fixes: 65b4414a05eb ("selftests/bpf: add sockopt test that exercises BPF_F_ALLOW_MULTI") Reported-by: Hulk Robot Signed-off-by: Wang Hai Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20201116101633.64627-1-wanghai38@huawei.com --- tools/testing/selftests/bpf/prog_tests/sockopt_multi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_multi.c b/tools/testing/selftests/bpf/prog_tests/sockopt_multi.c index 29188d6f5c8d..51fac975b316 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockopt_multi.c +++ b/tools/testing/selftests/bpf/prog_tests/sockopt_multi.c @@ -138,7 +138,8 @@ static int run_getsockopt_test(struct bpf_object *obj, int cg_parent, */ buf = 0x40; - if (setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1) < 0) { + err = setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1); + if (err < 0) { log_err("Failed to call setsockopt(IP_TOS)"); goto detach; } -- cgit v1.2.3 From 1fd6cee127e2ddff36d648573d7566aafb0d0b77 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 18 Nov 2020 22:13:50 +0100 Subject: libbpf: Fix VERSIONED_SYM_COUNT number parsing We remove "other info" from "readelf -s --wide" output when parsing GLOBAL_SYM_COUNT variable, which was added in [1]. But we don't do that for VERSIONED_SYM_COUNT and it's failing the check_abi target on powerpc Fedora 33. The extra "other info" wasn't problem for VERSIONED_SYM_COUNT parsing until commit [2] added awk in the pipe, which assumes that the last column is symbol, but it can be "other info". Adding "other info" removal for VERSIONED_SYM_COUNT the same way as we did for GLOBAL_SYM_COUNT parsing. [1] aa915931ac3e ("libbpf: Fix readelf output parsing for Fedora") [2] 746f534a4809 ("tools/libbpf: Avoid counting local symbols in ABI check") Fixes: 746f534a4809 ("tools/libbpf: Avoid counting local symbols in ABI check") Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20201118211350.1493421-1-jolsa@kernel.org --- tools/lib/bpf/Makefile | 2 ++ 1 file changed, 2 insertions(+) (limited to 'tools') diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile index 5f9abed3e226..55bd78b3496f 100644 --- a/tools/lib/bpf/Makefile +++ b/tools/lib/bpf/Makefile @@ -146,6 +146,7 @@ GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \ awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \ sort -u | wc -l) VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \ + sed 's/\[.*\]//' | \ awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \ grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l) @@ -214,6 +215,7 @@ check_abi: $(OUTPUT)libbpf.so awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \ sort -u > $(OUTPUT)libbpf_global_syms.tmp; \ readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \ + sed 's/\[.*\]//' | \ awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \ grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | \ sort -u > $(OUTPUT)libbpf_versioned_syms.tmp; \ -- cgit v1.2.3 From c8a36aedf3e24768e94d87fdcdd37684bd241c44 Mon Sep 17 00:00:00 2001 From: Daniel Xu Date: Tue, 17 Nov 2020 12:05:46 -0800 Subject: selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes after NUL Previously, bpf_probe_read_user_str() could potentially overcopy the trailing bytes after the NUL due to how do_strncpy_from_user() does the copy in long-sized strides. The issue has been fixed in the previous commit. This commit adds a selftest that ensures we don't regress bpf_probe_read_user_str() again. Signed-off-by: Daniel Xu Signed-off-by: Alexei Starovoitov Acked-by: Song Liu Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/4d977508fab4ec5b7b574b85bdf8b398868b6ee9.1605642949.git.dxu@dxuuu.xyz --- .../selftests/bpf/prog_tests/probe_read_user_str.c | 71 ++++++++++++++++++++++ .../selftests/bpf/progs/test_probe_read_user_str.c | 25 ++++++++ 2 files changed, 96 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c create mode 100644 tools/testing/selftests/bpf/progs/test_probe_read_user_str.c (limited to 'tools') diff --git a/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c b/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c new file mode 100644 index 000000000000..e419298132b5 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include "test_probe_read_user_str.skel.h" + +static const char str1[] = "mestring"; +static const char str2[] = "mestringalittlebigger"; +static const char str3[] = "mestringblubblubblubblubblub"; + +static int test_one_str(struct test_probe_read_user_str *skel, const char *str, + size_t len) +{ + int err, duration = 0; + char buf[256]; + + /* Ensure bytes after string are ones */ + memset(buf, 1, sizeof(buf)); + memcpy(buf, str, len); + + /* Give prog our userspace pointer */ + skel->bss->user_ptr = buf; + + /* Trigger tracepoint */ + usleep(1); + + /* Did helper fail? */ + if (CHECK(skel->bss->ret < 0, "prog_ret", "prog returned: %ld\n", + skel->bss->ret)) + return 1; + + /* Check that string was copied correctly */ + err = memcmp(skel->bss->buf, str, len); + if (CHECK(err, "memcmp", "prog copied wrong string")) + return 1; + + /* Now check that no extra trailing bytes were copied */ + memset(buf, 0, sizeof(buf)); + err = memcmp(skel->bss->buf + len, buf, sizeof(buf) - len); + if (CHECK(err, "memcmp", "trailing bytes were not stripped")) + return 1; + + return 0; +} + +void test_probe_read_user_str(void) +{ + struct test_probe_read_user_str *skel; + int err, duration = 0; + + skel = test_probe_read_user_str__open_and_load(); + if (CHECK(!skel, "test_probe_read_user_str__open_and_load", + "skeleton open and load failed\n")) + return; + + /* Give pid to bpf prog so it doesn't read from anyone else */ + skel->bss->pid = getpid(); + + err = test_probe_read_user_str__attach(skel); + if (CHECK(err, "test_probe_read_user_str__attach", + "skeleton attach failed: %d\n", err)) + goto out; + + if (test_one_str(skel, str1, sizeof(str1))) + goto out; + if (test_one_str(skel, str2, sizeof(str2))) + goto out; + if (test_one_str(skel, str3, sizeof(str3))) + goto out; + +out: + test_probe_read_user_str__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c new file mode 100644 index 000000000000..3ae398b75dcd --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include + +#include + +pid_t pid = 0; +long ret = 0; +void *user_ptr = 0; +char buf[256] = {}; + +SEC("tracepoint/syscalls/sys_enter_nanosleep") +int on_write(void *ctx) +{ + if (pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + ret = bpf_probe_read_user_str(buf, sizeof(buf), user_ptr); + + return 0; +} + +char _license[] SEC("license") = "GPL"; -- cgit v1.2.3