This is useful when using nolibc for security-critical tools. Using nolibc has the advantage that the code is easily auditable and sandboxable with seccomp as no unexpected syscalls are used. Using compiler-assistent stack protection provides another security mechanism. For this to work the compiler and libc have to collaborate. This patch adds the following parts to nolibc that are required by the compiler: * __stack_chk_guard: random sentinel value * __stack_chk_fail: handler for detected stack smashes In addition an initialization function is added that randomizes the sentinel value. Only support for global guards is implemented. Register guards are useful in multi-threaded context which nolibc does not provide support for. Link: https://lwn.net/Articles/584225/ Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> --- Changes in v2: - Code and comments style fixes - Only use raw syscalls in stackprotector functions - Remove need for dedicated entrypoint and exec() during tests - Add more rationale - Shuffle some code around between commits - Provide compatibility with the -fno-stack-protector patch - Remove RFC status - Link to v1: https://lore.kernel.org/r/20230223-nolibc-stackprotector-v1-0-3e74d81b3f21@xxxxxxxxxxxxxx This series is based on the current rcu/dev branch of Pauls rcu tree. --- Thomas Weißschuh (8): tools/nolibc: add definitions for standard fds tools/nolibc: add helpers for wait() signal exits tools/nolibc: tests: constify test_names tools/nolibc: add support for stack protector tools/nolibc: tests: fold in no-stack-protector cflags tools/nolibc: tests: add test for -fstack-protector tools/nolibc: i386: add stackprotector support tools/nolibc: x86_64: add stackprotector support tools/include/nolibc/Makefile | 4 +- tools/include/nolibc/arch-i386.h | 7 ++- tools/include/nolibc/arch-x86_64.h | 5 +++ tools/include/nolibc/nolibc.h | 1 + tools/include/nolibc/stackprotector.h | 53 +++++++++++++++++++++++ tools/include/nolibc/types.h | 2 + tools/include/nolibc/unistd.h | 5 +++ tools/testing/selftests/nolibc/Makefile | 11 ++++- tools/testing/selftests/nolibc/nolibc-test.c | 64 ++++++++++++++++++++++++++-- 9 files changed, 144 insertions(+), 8 deletions(-) --- base-commit: a9b8406e51603238941dbc6fa1437f8915254ebb change-id: 20230223-nolibc-stackprotector-d4d5f48ff771 Best regards, -- Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
