On Fri, Oct 09, 2020 at 12:14:33PM -0500, YiFei Zhu wrote: > From: YiFei Zhu <yifei...@illinois.edu> > > Currently the kernel does not provide an infrastructure to translate > architecture numbers to a human-readable name. Translating syscall > numbers to syscall names is possible through FTRACE_SYSCALL > infrastructure but it does not provide support for compat syscalls. > > This will create a file for each PID as /proc/pid/seccomp_cache. > The file will be empty when no seccomp filters are loaded, or be > in the format of: > <arch name> <decimal syscall number> <ALLOW | FILTER> > where ALLOW means the cache is guaranteed to allow the syscall, > and filter means the cache will pass the syscall to the BPF filter. > > For the docker default profile on x86_64 it looks like: > x86_64 0 ALLOW > x86_64 1 ALLOW > x86_64 2 ALLOW > x86_64 3 ALLOW > [...] > x86_64 132 ALLOW > x86_64 133 ALLOW > x86_64 134 FILTER > x86_64 135 FILTER > x86_64 136 FILTER > x86_64 137 ALLOW > x86_64 138 ALLOW > x86_64 139 FILTER > x86_64 140 ALLOW > x86_64 141 ALLOW > [...] > > This file is guarded by CONFIG_SECCOMP_CACHE_DEBUG with a default > of N because I think certain users of seccomp might not want the > application to know which syscalls are definitely usable. For > the same reason, it is also guarded by CAP_SYS_ADMIN. > > Suggested-by: Jann Horn <ja...@google.com> > Link: > https://lore.kernel.org/lkml/CAG48ez3Ofqp4crXGksLmZY6=fgrf_twyucg7pbkaetvbbop...@mail.gmail.com/ > Signed-off-by: YiFei Zhu <yifei...@illinois.edu> > --- > arch/Kconfig | 24 ++++++++++++++ > arch/x86/Kconfig | 1 + > arch/x86/include/asm/seccomp.h | 3 ++ > fs/proc/base.c | 6 ++++ > include/linux/seccomp.h | 5 +++ > kernel/seccomp.c | 59 ++++++++++++++++++++++++++++++++++ > 6 files changed, 98 insertions(+) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 21a3675a7a3a..85239a974f04 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -471,6 +471,15 @@ config HAVE_ARCH_SECCOMP_FILTER > results in the system call being skipped immediately. > - seccomp syscall wired up > > +config HAVE_ARCH_SECCOMP_CACHE > + bool > + help > + An arch should select this symbol if it provides all of these things: > + - all the requirements for HAVE_ARCH_SECCOMP_FILTER > + - SECCOMP_ARCH_NATIVE > + - SECCOMP_ARCH_NATIVE_NR > + - SECCOMP_ARCH_NATIVE_NAME > + > [...] > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 1ab22869a765..1a807f89ac77 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -150,6 +150,7 @@ config X86 > select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT > select HAVE_ARCH_PREL32_RELOCATIONS > select HAVE_ARCH_SECCOMP_FILTER > + select HAVE_ARCH_SECCOMP_CACHE > select HAVE_ARCH_THREAD_STRUCT_WHITELIST > select HAVE_ARCH_STACKLEAK > select HAVE_ARCH_TRACEHOOK
HAVE_ARCH_SECCOMP_CACHE isn't used any more. I think this was left over from before. -- Kees Cook
