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passt/Makefile
Stefano Brivio a48c5c2abf treewide: Disable gcc strict aliasing rules as needed, drop workarounds 
Recently, commit 4ddbcb9c0c ("tcp: Disable optimisations
for tcp_hash()") worked around yet another issue we hit with gcc 12
and '-flto -O2': some stores affecting the input data to siphash_20b()
were omitted altogether, and tcp_hash() wouldn't get the correct hash
for incoming connections.

Digging further into this revealed that, at least according to gcc's
interpretation of C99 aliasing rules, passing pointers to functions
with different types compared to the effective type of the object
(for example, a uint8_t pointer to an anonymous struct, as it happens
in tcp_hash()), doesn't guarantee that stores are not reordered
across the function call.

This means that, in general, our checksum and hash functions might
not see parts of input data that was intended to be provided by
callers.

Not even switching from uint8_t to character types, which should be
appropriate here, according to C99 (ISO/IEC 9899, TC3, draft N1256),
section 6.5, "Expressions", paragraph 7:

  An object shall have its stored value accessed only by an lvalue
  expression that has one of the following types:

  [...]

  — a character type.

does the trick. I guess this is also subject to interpretation:
casting passed pointers to character types, and then using those as
different types, might still violate (dubious) aliasing rules.

Disable gcc strict aliasing rules for potentially affected functions,
which, in turn, disables gcc's Type-Based Alias Analysis (TBAA)
optimisations based on those function arguments.

Drop the existing workarounds. Also the (seemingly?) bogus
'maybe-uninitialized' warning on the tcp_tap_handler() > tcp_hash() >
siphash_20b() path goes away with -fno-strict-aliasing on
siphash_20b().

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
2023-02-27 18:54:13 +01:00

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Makefile
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# SPDX-License-Identifier: AGPL-3.0-or-later
#
# PASST - Plug A Simple Socket Transport
# for qemu/UNIX domain socket mode
#
# PASTA - Pack A Subtle Tap Abstraction
# for network namespace/tap device mode
#
# Copyright (c) 2021 Red Hat GmbH
# Author: Stefano Brivio <sbrivio@redhat.com>
VERSION ?= $(shell git describe --tags HEAD 2>/dev/null || echo "unknown\ version")
# Does the target platform allow IPv4 connections to be handled via
# the IPv6 socket API? (Linux does)
DUAL_STACK_SOCKETS := 1
RLIMIT_STACK_VAL := $(shell /bin/sh -c 'ulimit -s')
ifeq ($(RLIMIT_STACK_VAL),unlimited)
RLIMIT_STACK_VAL := 1024
endif
TARGET := $(shell $(CC) -dumpmachine)
# Get 'uname -m'-like architecture description for target
TARGET_ARCH := $(shell echo $(TARGET) | cut -f1 -d- | tr [A-Z] [a-z])
TARGET_ARCH := $(shell echo $(TARGET_ARCH) | sed 's/powerpc/ppc/')
AUDIT_ARCH := $(shell echo $(TARGET_ARCH) | tr [a-z] [A-Z] | sed 's/^ARM.*/ARM/')
AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/I[456]86/I386/')
AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/PPC64/PPC/')
AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/PPCLE/PPC64LE/')
AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/MIPS64EL/MIPSEL64/')
AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/HPPA/PARISC/')
FLAGS := -Wall -Wextra -pedantic -std=c99 -D_XOPEN_SOURCE=700 -D_GNU_SOURCE
FLAGS += -D_FORTIFY_SOURCE=2 -O2 -pie -fPIE
FLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
FLAGS += -DNETNS_RUN_DIR=\"/run/netns\"
FLAGS += -DPASST_AUDIT_ARCH=AUDIT_ARCH_$(AUDIT_ARCH)
FLAGS += -DRLIMIT_STACK_VAL=$(RLIMIT_STACK_VAL)
FLAGS += -DARCH=\"$(TARGET_ARCH)\"
FLAGS += -DVERSION=\"$(VERSION)\"
FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c icmp.c igmp.c \
isolation.c lineread.c log.c mld.c ndp.c netlink.c packet.c passt.c \
pasta.c pcap.c siphash.c tap.c tcp.c tcp_splice.c udp.c util.c
QRAP_SRCS = qrap.c
SRCS = $(PASST_SRCS) $(QRAP_SRCS)
MANPAGES = passt.1 pasta.1 qrap.1
PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h icmp.h \
inany.h isolation.h lineread.h log.h ndp.h netlink.h packet.h passt.h \
pasta.h pcap.h port_fwd.h siphash.h tap.h tcp.h tcp_conn.h \
tcp_splice.h udp.h util.h
HEADERS = $(PASST_HEADERS) seccomp.h
C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_snd_wnd = 0 };
ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
FLAGS += -DHAS_SND_WND
endif
C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_bytes_acked = 0 };
ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
FLAGS += -DHAS_BYTES_ACKED
endif
C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_min_rtt = 0 };
ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
FLAGS += -DHAS_MIN_RTT
endif
C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
FLAGS += -DHAS_GETRANDOM
endif
ifeq ($(shell :|$(CC) -fstack-protector-strong -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
FLAGS += -fstack-protector-strong
endif
C := \#define _GNU_SOURCE\n\#include <fcntl.h>\nint x = FALLOC_FL_COLLAPSE_RANGE;
ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
EXTRA_SYSCALLS += fallocate
endif
prefix ?= /usr/local
exec_prefix ?= $(prefix)
bindir ?= $(exec_prefix)/bin
datarootdir ?= $(prefix)/share
docdir ?= $(datarootdir)/doc/passt
mandir ?= $(datarootdir)/man
man1dir ?= $(mandir)/man1
ifeq ($(TARGET_ARCH),x86_64)
BIN := passt passt.avx2 pasta pasta.avx2 qrap
else
BIN := passt pasta qrap
endif
all: $(BIN) $(MANPAGES) docs
static: FLAGS += -static -DGLIBC_NO_STATIC_NSS
static: clean all
seccomp.h: seccomp.sh $(PASST_SRCS) $(PASST_HEADERS)
@ EXTRA_SYSCALLS="$(EXTRA_SYSCALLS)" ./seccomp.sh $(PASST_SRCS) $(PASST_HEADERS)
passt: $(PASST_SRCS) $(HEADERS)
$(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) $(PASST_SRCS) -o passt $(LDFLAGS)
passt.avx2: FLAGS += -Ofast -mavx2 -ftree-vectorize -funroll-loops
passt.avx2: $(PASST_SRCS) $(HEADERS)
$(CC) $(filter-out -O2,$(FLAGS)) $(CFLAGS) $(CPPFLAGS) \
$(PASST_SRCS) -o passt.avx2 $(LDFLAGS)
passt.avx2: passt
pasta.avx2 pasta.1 pasta: pasta%: passt%
ln -sf $< $@
qrap: $(QRAP_SRCS) passt.h
$(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) $(QRAP_SRCS) -o qrap $(LDFLAGS)
valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction \
getpid gettid kill clock_gettime mmap \
munmap open unlink gettimeofday futex
valgrind: FLAGS:=-g -O0 $(filter-out -O%,$(FLAGS))
valgrind: all
.PHONY: clean
clean:
$(RM) $(BIN) *~ *.o seccomp.h pasta.1 \
passt.tar passt.tar.gz *.deb *.rpm \
passt.pid README.plain.md
install: $(BIN) $(MANPAGES) docs
mkdir -p $(DESTDIR)$(bindir) $(DESTDIR)$(man1dir)
cp -d $(BIN) $(DESTDIR)$(bindir)
cp -d $(MANPAGES) $(DESTDIR)$(man1dir)
mkdir -p $(DESTDIR)$(docdir)
cp -d README.plain.md $(DESTDIR)$(docdir)/README.md
cp -d doc/demo.sh $(DESTDIR)$(docdir)
uninstall:
$(RM) $(BIN:%=$(DESTDIR)$(prefix)/bin/%)
$(RM) $(MANPAGES:%=$(DESTDIR)$(man1dir)/%)
$(RM) $(DESTDIR)$(docdir)/README.md
$(RM) $(DESTDIR)$(docdir)/demo.sh
-rmdir $(DESTDIR)$(docdir)
pkgs: static
tar cf passt.tar -P --xform 's//\/usr\/bin\//' $(BIN)
tar rf passt.tar -P --xform 's//\/usr\/share\/man\/man1\//' \
$(MANPAGES)
gzip passt.tar
EMAIL="sbrivio@redhat.com" fakeroot alien --to-deb \
--description="User-mode networking for VMs and namespaces" \
-k --version=$(shell git rev-parse --short HEAD) \
passt.tar.gz
fakeroot alien --to-rpm --target=$(shell uname -m) \
--description="User-mode networking for VMs and namespaces" \
-k --version=g$(shell git rev-parse --short HEAD) passt.tar.gz
# TODO: This hack makes a "plain" Markdown version of README.md that can be
# reasonably shipped as documentation file, while the current README.md is
# definitely intended for web browser consumption. It should probably work the
# other way around: the web version should be obtained by adding HTML and
# JavaScript portions to a plain Markdown, instead. However, cgit needs to use
# a file in the git tree. Find a better way around this.
docs: README.md
@( \
skip=0; \
while read l; do \
case $$l in \
"## Demo") exit 0 ;; \
"<!"*) ;; \
"</"*) skip=1 ;; \
"<"*) skip=2 ;; \
esac; \
\
[ $$skip -eq 0 ] && echo "$$l"; \
[ $$skip -eq 1 ] && skip=0; \
done < README.md; \
) > README.plain.md
# Checkers currently disabled for clang-tidy:
# - llvmlibc-restrict-system-libc-headers
# TODO: this is Linux-only for the moment, nice to fix eventually
#
# - bugprone-macro-parentheses
# - google-readability-braces-around-statements
# - hicpp-braces-around-statements
# - readability-braces-around-statements
# Debatable whether that improves readability, right now it would look
# like a mess
#
# - readability-magic-numbers
# - cppcoreguidelines-avoid-magic-numbers
# TODO: in most cases they are justified, but probably not everywhere
#
# - clang-analyzer-valist.Uninitialized
# TODO: enable once https://bugs.llvm.org/show_bug.cgi?id=41311 is fixed
#
# - clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling
# Probably not doable to impement this without plain memcpy(), memset()
#
# - cppcoreguidelines-init-variables
# Dubious value, would kill readability
#
# - hicpp-signed-bitwise
# Those are needed for syscalls, epoll_wait flags, etc.
#
# - llvm-include-order
# TODO: not really important, but nice to fix eventually
#
# - readability-isolate-declaration
# Dubious value, would kill readability
#
# - bugprone-narrowing-conversions
# - cppcoreguidelines-narrowing-conversions
# TODO: nice to fix eventually
#
# - cppcoreguidelines-avoid-non-const-global-variables
# TODO: check, fix, and more in general constify wherever possible
#
# - altera-unroll-loops
# - altera-id-dependent-backward-branch
# TODO: check paths where it might make sense to improve performance
#
# - bugprone-easily-swappable-parameters
# Not much can be done about them other than being careful
#
# - readability-function-cognitive-complexity
# TODO: split reported functions
#
# - altera-struct-pack-align
# "Poor" alignment needed for structs reflecting message formats/headers
#
# - concurrency-mt-unsafe
# TODO: check again if multithreading is implemented
#
# - readability-identifier-length
# Complains about any identifier <3 characters, reasonable for
# globals, pointlessly verbose for locals and parameters.
#
# - bugprone-assignment-in-if-condition
# Dubious value over the compiler's built-in warning. Would
# increase verbosity.
clang-tidy: $(SRCS) $(HEADERS)
clang-tidy -checks=*,-modernize-*,\
-clang-analyzer-valist.Uninitialized,\
-cppcoreguidelines-init-variables,\
-bugprone-assignment-in-if-condition,\
-bugprone-macro-parentheses,\
-google-readability-braces-around-statements,\
-hicpp-braces-around-statements,\
-readability-braces-around-statements,\
-readability-magic-numbers,\
-llvmlibc-restrict-system-libc-headers,\
-hicpp-signed-bitwise,\
-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,\
-llvm-include-order,\
-cppcoreguidelines-avoid-magic-numbers,\
-readability-isolate-declaration,\
-bugprone-narrowing-conversions,\
-cppcoreguidelines-narrowing-conversions,\
-cppcoreguidelines-avoid-non-const-global-variables,\
-altera-unroll-loops,-altera-id-dependent-backward-branch,\
-bugprone-easily-swappable-parameters,\
-readability-function-cognitive-complexity,\
-altera-struct-pack-align,\
-concurrency-mt-unsafe,\
-readability-identifier-length \
-config='{CheckOptions: [{key: bugprone-suspicious-string-compare.WarnOnImplicitComparison, value: "false"}]}' \
--warnings-as-errors=* $(SRCS) -- $(filter-out -pie,$(FLAGS) $(CFLAGS) $(CPPFLAGS))
SYSTEM_INCLUDES := /usr/include $(wildcard /usr/include/$(TARGET))
ifeq ($(shell $(CC) -v 2>&1 | grep -c "gcc version"),1)
VER := $(shell $(CC) -dumpversion)
SYSTEM_INCLUDES += /usr/lib/gcc/$(TARGET)/$(VER)/include
endif
cppcheck: $(SRCS) $(HEADERS)
cppcheck --std=c99 --error-exitcode=1 --enable=all --force \
--inconclusive --library=posix --quiet \
$(SYSTEM_INCLUDES:%=-I%) \
$(SYSTEM_INCLUDES:%=--config-exclude=%) \
$(SYSTEM_INCLUDES:%=--suppress=*:%/*) \
$(SYSTEM_INCLUDES:%=--suppress=unmatchedSuppression:%/*) \
--inline-suppr \
--suppress=unusedStructMember \
$(filter -D%,$(FLAGS) $(CFLAGS) $(CPPFLAGS)) \
.
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