1. 05 Sep, 2005 2 commits
    • Laurent Vivier's avatar
      [PATCH] UML Support - Ptrace: adds the host SYSEMU support, for UML and general usage · ed75e8d5
      Laurent Vivier authored
            Jeff Dike <jdike@addtoit.com>,
            Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>,
            Bodo Stroesser <bstroesser@fujitsu-siemens.com>
      Adds a new ptrace(2) mode, called PTRACE_SYSEMU, resembling PTRACE_SYSCALL
      except that the kernel does not execute the requested syscall; this is useful
      to improve performance for virtual environments, like UML, which want to run
      the syscall on their own.
      In fact, using PTRACE_SYSCALL means stopping child execution twice, on entry
      and on exit, and each time you also have two context switches; with SYSEMU you
      avoid the 2nd stop and so save two context switches per syscall.
      Also, some architectures don't have support in the host for changing the
      syscall number via ptrace(), which is currently needed to skip syscall
      execution (UML turns any syscall into getpid() to avoid it being executed on
      the host).  Fixing that is hard, while SYSEMU is easier to implement.
      * This version of the patch includes some suggestions of Jeff Dike to avoid
        adding any instructions to the syscall fast path, plus some other little
        changes, by myself, to make it work even when the syscall is executed with
        SYSENTER (but I'm unsure about them). It has been widely tested for quite a
        lot of time.
      * Various fixed were included to handle the various switches between
        various states, i.e. when for instance a syscall entry is traced with one of
        PT_SYSCALL / _SYSEMU / _SINGLESTEP and another one is used on exit.
        Basically, this is done by remembering which one of them was used even after
        the call to ptrace_notify().
        to make do_syscall_trace() notice that the current syscall was started with
        SYSEMU on entry, so that no notification ought to be done in the exit path;
        this is a bit of a hack, so this problem is solved in another way in next
      * Also, the effects of the patch:
      "Ptrace - i386: fix Syscall Audit interaction with singlestep"
      are cancelled; they are restored back in the last patch of this series.
      Detailed descriptions of the patches doing this kind of processing follow (but
      I've already summed everything up).
      * Fix behaviour when changing interception kind #1.
        In do_syscall_trace(), we check the status of the TIF_SYSCALL_EMU flag
        only after doing the debugger notification; but the debugger might have
        changed the status of this flag because he continued execution with
        PTRACE_SYSCALL, so this is wrong.  This patch fixes it by saving the flag
        status before calling ptrace_notify().
      * Fix behaviour when changing interception kind #2:
        avoid intercepting syscall on return when using SYSCALL again.
        A guest process switching from using PTRACE_SYSEMU to PTRACE_SYSCALL
        The problem is in arch/i386/kernel/entry.S.  The current SYSEMU patch
        inhibits the syscall-handler to be called, but does not prevent
        do_syscall_trace() to be called after this for syscall completion
        The appended patch fixes this.  It reuses the flag TIF_SYSCALL_EMU to
        remember "we come from PTRACE_SYSEMU and now are in PTRACE_SYSCALL", since
        the flag is unused in the depicted situation.
      * Fix behaviour when changing interception kind #3:
        avoid intercepting syscall on return when using SINGLESTEP.
        When testing 2.6.9 and the skas3.v6 patch, with my latest patch and had
        problems with singlestepping on UML in SKAS with SYSEMU.  It looped
        receiving SIGTRAPs without moving forward.  EIP of the traced process was
        the same for all SIGTRAPs.
      What's missing is to handle switching from PTRACE_SYSCALL_EMU to
      PTRACE_SINGLESTEP in a way very similar to what is done for the change from
      I.e., after calling ptrace(PTRACE_SYSEMU), on the return path, the debugger is
      notified and then wake ups the process; the syscall is executed (or skipped,
      when do_syscall_trace() returns 0, i.e.  when using PTRACE_SYSEMU), and
      do_syscall_trace() is called again.  Since we are on the return path of a
      SYSEMU'd syscall, if the wake up is performed through ptrace(PTRACE_SYSCALL),
      we must still avoid notifying the parent of the syscall exit.  Now, this
      behaviour is extended even to resuming with PTRACE_SINGLESTEP.
      Signed-off-by: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Cc: Jeff Dike <jdike@addtoit.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    • Bodo Stroesser's avatar
      [PATCH] Ptrace/i386: fix "syscall audit" interaction with singlestep · 94c80b25
      Bodo Stroesser authored
            Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Avoid giving two traps for singlestep instead of one, when syscall auditing is
      In fact no singlestep trap is sent on syscall entry, only on syscall exit, as
      can be seen in entry.S:
      # Note that in this mask _TIF_SINGLESTEP is not tested !!! <<<<<<<<<<<<<<
              testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),TI_flags(%ebp)
              jnz syscall_trace_entry
      	call do_syscall_trace
      But auditing a SINGLESTEP'ed process causes do_syscall_trace to be called, so
      the tracer will get one more trap on the syscall entry path, which it
      Signed-off-by: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      CC: Roland McGrath <roland@redhat.com>
      Cc: Jeff Dike <jdike@addtoit.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
  2. 23 Jun, 2005 1 commit
  3. 01 May, 2005 1 commit
  4. 29 Apr, 2005 1 commit
    • 's avatar
      [AUDIT] Don't allow ptrace to fool auditing, log arch of audited syscalls. · 2fd6f58b
      We were calling ptrace_notify() after auditing the syscall and arguments,
      but the debugger could have _changed_ them before the syscall was actually
      invoked. Reorder the calls to fix that.
      While we're touching ever call to audit_syscall_entry(), we also make it
      take an extra argument: the architecture of the syscall which was made,
      because some architectures allow more than one type of syscall.
      Also add an explicit success/failure flag to audit_syscall_exit(), for
      the benefit of architectures which return that in a condition register
      rather than only returning a single register.
      Change type of syscall return value to 'long' not 'int'.
      Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
  5. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      Let it rip!