1. 27 Apr, 2007 1 commit
  2. 05 Feb, 2007 1 commit
    • Gerald Schaefer's avatar
      [S390] noexec protection · c1821c2e
      Gerald Schaefer authored
      This provides a noexec protection on s390 hardware. Our hardware does
      not have any bits left in the pte for a hw noexec bit, so this is a
      different approach using shadow page tables and a special addressing
      mode that allows separate address spaces for code and data.
      
      As a special feature of our "secondary-space" addressing mode, separate
      page tables can be specified for the translation of data addresses
      (storage operands) and instruction addresses. The shadow page table is
      used for the instruction addresses and the standard page table for the
      data addresses.
      The shadow page table is linked to the standard page table by a pointer
      in page->lru.next of the struct page corresponding to the page that
      contains the standard page table (since page->private is not really
      private with the pte_lock and the page table pages are not in the LRU
      list).
      Depending on the software bits of a pte, it is either inserted into
      both page tables or just into the standard (data) page table. Pages of
      a vma that does not have the VM_EXEC bit set get mapped only in the
      data address space. Any try to execute code on such a page will cause a
      page translation exception. The standard reaction to this is a SIGSEGV
      with two exceptions: the two system call opcodes 0x0a77 (sys_sigreturn)
      and 0x0aad (sys_rt_sigreturn) are allowed. They are stored by the
      kernel to the signal stack frame. Unfortunately, the signal return
      mechanism cannot be modified to use an SA_RESTORER because the
      exception unwinding code depends on the system call opcode stored
      behind the signal stack frame.
      
      This feature requires that user space is executed in secondary-space
      mode and the kernel in home-space mode, which means that the addressing
      modes need to be switched and that the noexec protection only works
      for user space.
      After switching the addressing modes, we cannot use the mvcp/mvcs
      instructions anymore to copy between kernel and user space. A new
      mvcos instruction has been added to the z9 EC/BC hardware which allows
      to copy between arbitrary address spaces, but on older hardware the
      page tables need to be walked manually.
      Signed-off-by: default avatarGerald Schaefer <geraldsc@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      c1821c2e
  3. 27 Oct, 2006 1 commit
  4. 04 Oct, 2006 1 commit
  5. 20 Sep, 2006 2 commits
  6. 30 Jun, 2006 1 commit
  7. 02 May, 2006 1 commit
  8. 01 Feb, 2006 1 commit
  9. 06 Jan, 2006 2 commits
  10. 29 Sep, 2005 1 commit
  11. 29 Aug, 2005 1 commit
    • Steven Rostedt's avatar
      [PATCH] convert signal handling of NODEFER to act like other Unix boxes. · 69be8f18
      Steven Rostedt authored
      It has been reported that the way Linux handles NODEFER for signals is
      not consistent with the way other Unix boxes handle it.  I've written a
      program to test the behavior of how this flag affects signals and had
      several reports from people who ran this on various Unix boxes,
      confirming that Linux seems to be unique on the way this is handled.
      
      The way NODEFER affects signals on other Unix boxes is as follows:
      
      1) If NODEFER is set, other signals in sa_mask are still blocked.
      
      2) If NODEFER is set and the signal is in sa_mask, then the signal is
      still blocked. (Note: this is the behavior of all tested but Linux _and_
      NetBSD 2.0 *).
      
      The way NODEFER affects signals on Linux:
      
      1) If NODEFER is set, other signals are _not_ blocked regardless of
      sa_mask (Even NetBSD doesn't do this).
      
      2) If NODEFER is set and the signal is in sa_mask, then the signal being
      handled is not blocked.
      
      The patch converts signal handling in all current Linux architectures to
      the way most Unix boxes work.
      
      Unix boxes that were tested:  DU4, AIX 5.2, Irix 6.5, NetBSD 2.0, SFU
      3.5 on WinXP, AIX 5.3, Mac OSX, and of course Linux 2.6.13-rcX.
      
      * NetBSD was the only other Unix to behave like Linux on point #2. The
      main concern was brought up by point #1 which even NetBSD isn't like
      Linux.  So with this patch, we leave NetBSD as the lonely one that
      behaves differently here with #2.
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      69be8f18
  12. 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!
      1da177e4