• Masahiro Yamada's avatar
    kbuild: re-implement detection of CONFIG options leaked to user-space · c7c0eecf
    Masahiro Yamada authored
    scripts/headers_check.pl can detect references to CONFIG options in
    exported headers, but it has been disabled for more than a decade.
    
    Reverting commit 7e3fa561 ("kbuild: drop check for CONFIG_ in
    headers_check") would emit the following warnings for headers_check
    on x86:
    
    usr/include/mtd/ubi-user.h:283: leaks CONFIG_MTD_UBI_BEB_LIMIT to userspace where it is not valid
    usr/include/linux/cm4000_cs.h:26: leaks CONFIG_COMPAT to userspace where it is not valid
    usr/include/linux/pkt_cls.h:301: leaks CONFIG_NET_CLS_ACT to userspace where it is not valid
    usr/include/linux/videodev2.h:2465: leaks CONFIG_VIDEO_ADV_DEBUG to userspace where it is not valid
    usr/include/linux/bpf.h:249: leaks CONFIG_EFFICIENT_UNALIGNED_ACCESS to userspace where it is not valid
    usr/include/linux/bpf.h:819: leaks CONFIG_CGROUP_NET_CLASSID to userspace where it is not valid
    usr/include/linux/bpf.h:1011: leaks CONFIG_IP_ROUTE_CLASSID to userspace where it is not valid
    usr/include/linux/bpf.h:1742: leaks CONFIG_BPF_KPROBE_OVERRIDE to userspace where it is not valid
    usr/include/linux/bpf.h:1747: leaks CONFIG_FUNCTION_ERROR_INJECTION to userspace where it is not valid
    usr/include/linux/bpf.h:1936: leaks CONFIG_XFRM to userspace where it is not valid
    usr/include/linux/bpf.h:2184: leaks CONFIG_BPF_LIRC_MODE2 to userspace where it is not valid
    usr/include/linux/bpf.h:2210: leaks CONFIG_BPF_LIRC_MODE2 to userspace where it is not valid
    usr/include/linux/bpf.h:2227: leaks CONFIG_SOCK_CGROUP_DATA to userspace where it is not valid
    usr/include/linux/bpf.h:2311: leaks CONFIG_NET to userspace where it is not valid
    usr/include/linux/bpf.h:2348: leaks CONFIG_NET to userspace where it is not valid
    usr/include/linux/bpf.h:2422: leaks CONFIG_BPF_LIRC_MODE2 to userspace where it is not valid
    usr/include/linux/bpf.h:2528: leaks CONFIG_NET to userspace where it is not valid
    usr/include/linux/pktcdvd.h:37: leaks CONFIG_CDROM_PKTCDVD_WCACHE to userspace where it is not valid
    usr/include/linux/hw_breakpoint.h:27: leaks CONFIG_HAVE_MIXED_BREAKPOINTS_REGS to userspace where it is not valid
    usr/include/linux/raw.h:17: leaks CONFIG_MAX_RAW_DEVS to userspace where it is not valid
    usr/include/linux/elfcore.h:62: leaks CONFIG_BINFMT_ELF_FDPIC to userspace where it is not valid
    usr/include/linux/eventpoll.h:82: leaks CONFIG_PM_SLEEP to userspace where it is not valid
    usr/include/linux/atmdev.h:104: leaks CONFIG_COMPAT to userspace where it is not valid
    usr/include/asm-generic/unistd.h:651: leaks CONFIG_MMU to userspace where it is not valid
    usr/include/asm-generic/bitsperlong.h:9: leaks CONFIG_64BIT to userspace where it is not valid
    usr/include/asm-generic/fcntl.h:119: leaks CONFIG_64BIT to userspace where it is not valid
    usr/include/asm/auxvec.h:14: leaks CONFIG_IA32_EMULATION to userspace where it is not valid
    usr/include/asm/e820.h:14: leaks CONFIG_NODES_SHIFT to userspace where it is not valid
    usr/include/asm/e820.h:39: leaks CONFIG_X86_PMEM_LEGACY to userspace where it is not valid
    usr/include/asm/e820.h:49: leaks CONFIG_INTEL_TXT to userspace where it is not valid
    usr/include/asm/mman.h:7: leaks CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS to userspace where it is not valid
    
    Most of these are false positives because scripts/headers_check.pl
    parses comment lines.
    
    It is also false negative. arch/x86/include/uapi/asm/auxvec.h contains
    CONFIG_IA32_EMULATION and CONFIG_X86_64, but the only former is reported.
    
    It would be possible to fix scripts/headers_check.pl, of course.
    However, we already have some duplicated checks between headers_check
    and CONFIG_UAPI_HEADER_TEST. At this moment of time, there are still
    dozens of headers excluded from the header test (usr/include/Makefile),
    but we might be able to remove headers_check eventually.
    
    I re-implemented it in scripts/headers_install.sh by using sed because
    the most of code in scripts/headers_install.sh is written in sed.
    
    This patch works like this:
    
    [1] Run scripts/unifdef first because we need to drop the code
        surrounded by #ifdef __KERNEL__ ... #endif
    
    [2] Remove all C style comments. The sed code is somewhat complicated
        since we need to deal with both single and multi line comments.
    
        Precisely speaking, a comment block is replaced with a space just
        in case.
    
          CONFIG_FOO/* this is a comment */CONFIG_BAR
    
        should be converted into:
    
          CONFIG_FOO CONFIG_BAR
    
        instead of:
    
          CONFIG_FOOCONFIG_BAR
    
    [3] Match CONFIG_... pattern. It correctly matches to all CONFIG
        options that appear in a single line.
    
    After this commit, this would detect the following warnings, all of
    which are real ones.
    
    warning: include/uapi/linux/pktcdvd.h: leak CONFIG_CDROM_PKTCDVD_WCACHE to user-space
    warning: include/uapi/linux/hw_breakpoint.h: leak CONFIG_HAVE_MIXED_BREAKPOINTS_REGS to user-space
    warning: include/uapi/linux/raw.h: leak CONFIG_MAX_RAW_DEVS to user-space
    warning: include/uapi/linux/elfcore.h: leak CONFIG_BINFMT_ELF_FDPIC to user-space
    warning: include/uapi/linux/eventpoll.h: leak CONFIG_PM_SLEEP to user-space
    warning: include/uapi/linux/atmdev.h: leak CONFIG_COMPAT to user-space
    warning: include/uapi/asm-generic/fcntl.h: leak CONFIG_64BIT to user-space
    warning: arch/x86/include/uapi/asm/auxvec.h: leak CONFIG_IA32_EMULATION to user-space
    warning: arch/x86/include/uapi/asm/auxvec.h: leak CONFIG_X86_64 to user-space
    warning: arch/x86/include/uapi/asm/mman.h: leak CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS to user-space
    
    However, it is not nice to show them right now. I created a list of
    existing leakages. They are not warned, but a new leakage will be
    blocked by the 0-day bot.
    Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
    Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
    c7c0eecf
headers_install.sh 3.56 KB