From 283ca526a9bd75aed7350220d7b1f8027d99c3fd Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 12 Dec 2017 02:25:30 +0100 Subject: [PATCH 1/3] bpf: fix corruption on concurrent perf_event_output calls When tracing and networking programs are both attached in the system and both use event-output helpers that eventually call into perf_event_output(), then we could end up in a situation where the tracing attached program runs in user context while a cls_bpf program is triggered on that same CPU out of softirq context. Since both rely on the same per-cpu perf_sample_data, we could potentially corrupt it. This can only ever happen in a combination of the two types; all tracing programs use a bpf_prog_active counter to bail out in case a program is already running on that CPU out of a different context. XDP and cls_bpf programs by themselves don't have this issue as they run in the same context only. Therefore, split both perf_sample_data so they cannot be accessed from each other. Fixes: 20b9d7ac4852 ("bpf: avoid excessive stack usage for perf_sample_data") Reported-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Tested-by: Song Liu Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov --- kernel/trace/bpf_trace.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 0ce99c379c30..40207c2a4113 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -343,14 +343,13 @@ static const struct bpf_func_proto bpf_perf_event_read_value_proto = { .arg4_type = ARG_CONST_SIZE, }; -static DEFINE_PER_CPU(struct perf_sample_data, bpf_sd); +static DEFINE_PER_CPU(struct perf_sample_data, bpf_trace_sd); static __always_inline u64 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, - u64 flags, struct perf_raw_record *raw) + u64 flags, struct perf_sample_data *sd) { struct bpf_array *array = container_of(map, struct bpf_array, map); - struct perf_sample_data *sd = this_cpu_ptr(&bpf_sd); unsigned int cpu = smp_processor_id(); u64 index = flags & BPF_F_INDEX_MASK; struct bpf_event_entry *ee; @@ -373,8 +372,6 @@ __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, if (unlikely(event->oncpu != cpu)) return -EOPNOTSUPP; - perf_sample_data_init(sd, 0, 0); - sd->raw = raw; perf_event_output(event, sd, regs); return 0; } @@ -382,6 +379,7 @@ __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, u64, flags, void *, data, u64, size) { + struct perf_sample_data *sd = this_cpu_ptr(&bpf_trace_sd); struct perf_raw_record raw = { .frag = { .size = size, @@ -392,7 +390,10 @@ BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, if (unlikely(flags & ~(BPF_F_INDEX_MASK))) return -EINVAL; - return __bpf_perf_event_output(regs, map, flags, &raw); + perf_sample_data_init(sd, 0, 0); + sd->raw = &raw; + + return __bpf_perf_event_output(regs, map, flags, sd); } static const struct bpf_func_proto bpf_perf_event_output_proto = { @@ -407,10 +408,12 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = { }; static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs); +static DEFINE_PER_CPU(struct perf_sample_data, bpf_misc_sd); u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy) { + struct perf_sample_data *sd = this_cpu_ptr(&bpf_misc_sd); struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs); struct perf_raw_frag frag = { .copy = ctx_copy, @@ -428,8 +431,10 @@ u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, }; perf_fetch_caller_regs(regs); + perf_sample_data_init(sd, 0, 0); + sd->raw = &raw; - return __bpf_perf_event_output(regs, map, flags, &raw); + return __bpf_perf_event_output(regs, map, flags, sd); } BPF_CALL_0(bpf_get_current_task) From a23f06f06dbe54696e8d4f156b317e8c9961c345 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 12 Dec 2017 02:25:31 +0100 Subject: [PATCH 2/3] bpf: fix build issues on um due to mising bpf_perf_event.h Since c895f6f703ad ("bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type") um (uml) won't build on i386 or x86_64: [...] CC init/main.o In file included from ../include/linux/perf_event.h:18:0, from ../include/linux/trace_events.h:10, from ../include/trace/syscall.h:7, from ../include/linux/syscalls.h:82, from ../init/main.c:20: ../include/uapi/linux/bpf_perf_event.h:11:32: fatal error: asm/bpf_perf_event.h: No such file or directory #include [...] Lets add missing bpf_perf_event.h also to um arch. This seems to be the only one still missing. Fixes: c895f6f703ad ("bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type") Reported-by: Randy Dunlap Suggested-by: Richard Weinberger Signed-off-by: Daniel Borkmann Tested-by: Randy Dunlap Cc: Hendrik Brueckner Cc: Richard Weinberger Acked-by: Alexei Starovoitov Acked-by: Richard Weinberger Signed-off-by: Alexei Starovoitov --- arch/um/include/asm/Kbuild | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild index 50a32c33d729..73c57f614c9e 100644 --- a/arch/um/include/asm/Kbuild +++ b/arch/um/include/asm/Kbuild @@ -1,4 +1,5 @@ generic-y += barrier.h +generic-y += bpf_perf_event.h generic-y += bug.h generic-y += clkdev.h generic-y += current.h From 720f228e8d3128b7ab1d39f51fdd8da07a7640c9 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 12 Dec 2017 02:25:32 +0100 Subject: [PATCH 3/3] bpf: fix broken BPF selftest build At least on x86_64, the kernel's BPF selftests seemed to have stopped to build due to 618e165b2a8e ("selftests/bpf: sync kernel headers and introduce arch support in Makefile"): [...] In file included from test_verifier.c:29:0: ../../../include/uapi/linux/bpf_perf_event.h:11:32: fatal error: asm/bpf_perf_event.h: No such file or directory #include ^ compilation terminated. [...] While pulling in tools/arch/*/include/uapi/asm/bpf_perf_event.h seems to work fine, there's no automated fall-back logic right now that would do the same out of tools/include/uapi/asm-generic/bpf_perf_event.h. The usual convention today is to add a include/[uapi/]asm/ equivalent that would pull in the correct arch header or generic one as fall-back, all ifdef'ed based on compiler target definition. It's similarly done also in other cases such as tools/include/asm/barrier.h, thus adapt the same here. Fixes: 618e165b2a8e ("selftests/bpf: sync kernel headers and introduce arch support in Makefile") Signed-off-by: Daniel Borkmann Cc: Hendrik Brueckner Cc: Arnaldo Carvalho de Melo Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov --- tools/include/uapi/asm/bpf_perf_event.h | 7 +++++++ tools/testing/selftests/bpf/Makefile | 13 +------------ 2 files changed, 8 insertions(+), 12 deletions(-) create mode 100644 tools/include/uapi/asm/bpf_perf_event.h diff --git a/tools/include/uapi/asm/bpf_perf_event.h b/tools/include/uapi/asm/bpf_perf_event.h new file mode 100644 index 000000000000..13a58531e6fa --- /dev/null +++ b/tools/include/uapi/asm/bpf_perf_event.h @@ -0,0 +1,7 @@ +#if defined(__aarch64__) +#include "../../arch/arm64/include/uapi/asm/bpf_perf_event.h" +#elif defined(__s390__) +#include "../../arch/s390/include/uapi/asm/bpf_perf_event.h" +#else +#include +#endif diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 21a2d76b67dc..792af7c3b74f 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -1,19 +1,8 @@ # SPDX-License-Identifier: GPL-2.0 -ifeq ($(srctree),) -srctree := $(patsubst %/,%,$(dir $(CURDIR))) -srctree := $(patsubst %/,%,$(dir $(srctree))) -srctree := $(patsubst %/,%,$(dir $(srctree))) -srctree := $(patsubst %/,%,$(dir $(srctree))) -endif -include $(srctree)/tools/scripts/Makefile.arch - -$(call detected_var,SRCARCH) - LIBDIR := ../../../lib BPFDIR := $(LIBDIR)/bpf APIDIR := ../../../include/uapi -ASMDIR:= ../../../arch/$(ARCH)/include/uapi GENDIR := ../../../../include/generated GENHDR := $(GENDIR)/autoconf.h @@ -21,7 +10,7 @@ ifneq ($(wildcard $(GENHDR)),) GENFLAGS := -DHAVE_GENHDR endif -CFLAGS += -Wall -O2 -I$(APIDIR) -I$(ASMDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include +CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include LDLIBS += -lcap -lelf TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \