linux-kernel - [PATCH v2 0/7] Two-phase seccomp and x86 tracing changes

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Message-Id: <cover.1405717901.git.luto@amacapital.net>
Date:	Fri, 18 Jul 2014 14:18:08 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
	Will Drewry <wad@...omium.org>
Cc:	Oleg Nesterov <oleg@...hat.com>, x86@...nel.org,
	linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org,
	linux-arch@...r.kernel.org, linux-security-module@...r.kernel.org,
	Alexei Starovoitov <ast@...mgrid.com>, hpa@...or.com,
	Andy Lutomirski <luto@...capital.net>
Subject: [PATCH v2 0/7] Two-phase seccomp and x86 tracing changes

This is both a cleanup and a speedup.  It reduces overhead due to
installing a trivial seccomp filter by 87%.  The speedup comes from
avoiding the full syscall tracing mechanism for filters that don't
return SECCOMP_RET_TRACE.

This series works by splitting the seccomp hooks into two phases.
The first phase evaluates the filter; it can skip syscalls, allow
them, kill the calling task, or pass a u32 to the second phase.  The
second phase requires a full tracing context, and it sends ptrace
events if necessary.

Once this is done, I implemented a similar split for the x86 syscall
entry work.  The C callback is invoked in two phases: the first has
only a partial frame, and it can request phase 2 processing with a
full frame.

Finally, I switch the 64-bit system_call code to use the new split
entry work.  This is a net deletion of assembly code: it replaces
all of the audit entry muck.

In the process, I fixed some bugs.

If this is acceptable, someone can do the same tweak for the
ia32entry and entry_32 code.

This passes all seccomp tests that I know of.  Now that it's properly
rebased, even the previously expected failures are gone.

Kees, if you like this version, can you create a branch with patches
1-3?  I think that the rest should go into tip/x86 once everyone's happy
with it.

Changes from v1:
 - Rebased on top of Kees' shiny new seccomp tree (no effect on the x86
   part).
 - Improved patch 6 vs patch 7 split (thanks Alexei!)
 - Fixed bogus -ENOSYS in patch 5 (thanks Kees!)
 - Improved changelog message in patch 6.

Changes from RFC version:
 - The first three patches are more or less the same
 - The rest is more or less a rewrite

Andy Lutomirski (7):
  seccomp,x86,arm,mips,s390: Remove nr parameter from secure_computing
  seccomp: Refactor the filter callback and the API
  seccomp: Allow arch code to provide seccomp_data
  x86,x32,audit: Fix x32's AUDIT_ARCH wrt audit
  x86: Split syscall_trace_enter into two phases
  x86_64,entry: Treat regs->ax the same in fastpath and slowpath
    syscalls
  x86_64,entry: Use split-phase syscall_trace_enter for 64-bit syscalls

 arch/arm/kernel/ptrace.c       |   7 +-
 arch/mips/kernel/ptrace.c      |   2 +-
 arch/s390/kernel/ptrace.c      |   2 +-
 arch/x86/include/asm/calling.h |   6 +-
 arch/x86/include/asm/ptrace.h  |   5 +
 arch/x86/kernel/entry_64.S     |  51 ++++-----
 arch/x86/kernel/ptrace.c       | 146 +++++++++++++++++++-----
 arch/x86/kernel/vsyscall_64.c  |   2 +-
 include/linux/seccomp.h        |  25 ++--
 kernel/seccomp.c               | 252 ++++++++++++++++++++++++++++-------------
 10 files changed, 344 insertions(+), 154 deletions(-)

-- 
1.9.3

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