skas3(-v3) for 2.4.27 with exec-shield
Hi all,
as I've no realy idea about the internal work of the skas patches, I'll have to bother you.
I'd like to run a 2.4.27 kernel with exec-shield patch and skas3, if possible the -v3 version from BlaisorBlade, except that it does not apply :-(
There are three conflicts in mm/mprotect.c but i suspect there are more not working sections.
The patch seams to mainly change current->mm to mm, after defining
struct mm_struct * mm = vma->vm_mm;
unfortunately i've no idea how current-> mm and vma->vm_mm (aka mm) relate. Are they the same?
Sorry, but obviosely I've no idea about the vm subsystem ... and not more about the rest of the kernel :-(
Signature · 15 lines
/"\ Goetz Bock at blacknet dot de -- secure mobile Linux everNETting \ / (c) 2004 Creative Commons, Attribution-ShareAlike 2.0 de X [ 1. Use descriptive subjects - 2. Edit a reply for brevity - ] / \ [ 3. Reply to the list - 4. Read the archive *before* you post ] ------------------------------------------------------- This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170 Project Admins to receive an Apple iPod Mini FREE for your judgement on who ports your project to Linux PPC the best. Sponsored by IBM. Deadline: Sept. 24. Go here: http://sf.net/ppc_contest.php _______________________________________________ User-mode-linux-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
Quoted 12 lines · Goetz Bock
Hi all,
as I've no realy idea about the internal work of the skas patches, I'll have to bother you.
I'd like to run a 2.4.27 kernel with exec-shield patch and skas3, if possible the -v3 version from BlaisorBlade, except that it does not apply :-(
There are three conflicts in
mm/mprotect.cbut i suspect there are more not working sections.
Quoted 6 lines
The patch seams to mainly change
current->mmto mm, after definingstruct mm_struct * mm = vma->vm_mm;unfortunately i've no idea how current-> mm and
vma->vm_mm(aka mm) relate. Are they the same?
Not at all; they must be different.
If you look below, you see that in the old code, sys_mprotect says: "I'm acting on current->mm"; the patch wants to be able to pass it any mm_struct (and this is done within mm/proc_mm.c), so I had to replace every reference to current->mm with a reference to the mm.
Quoted 2 lines
Sorry, but obviosely I've no idea about the vm subsystem ... and not more about the rest of the kernel :-(
Don't worry.
Signature · 13 lines
Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 ------------------------------------------------------- This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170 Project Admins to receive an Apple iPod Mini FREE for your judgement on who ports your project to Linux PPC the best. Sponsored by IBM. Deadline: Sept. 24. Go here: http://sf.net/ppc_contest.php _______________________________________________ User-mode-linux-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
Quoted 5 lines · BlaisorBlade
Quoted 4 lines · Goetz Bock
Hi all,
as I've no realy idea about the internal work of the skas patches, I'll have to bother you.
Don't worry.
Quoted 14 lines
Quoted 7 lines
I'd like to run a 2.4.27 kernel with exec-shield patch and skas3, if possible the -v3 version from BlaisorBlade, except that it does not apply :-(
There are three conflicts in
mm/mprotect.cbut i suspect there are more not working sections.Quoted 6 lines
The patch seams to mainly change
current->mmto mm, after definingstruct mm_struct * mm = vma->vm_mm;unfortunately i've no idea how current-> mm and
vma->vm_mm(aka mm) relate. Are they the same?
Quoted 6 lines
Not at all; they must be different.
If you look below, you see that in the old code,
sys_mprotectsays: "I'm acting oncurrent->mm"; the patch wants to be able to pass it anymm_struct(and this is done withinmm/proc_mm.c), so I had to replace every reference tocurrent->mmwith a reference to the mm.
Sorry, I did not finish the message.
Actually, the idea is to make that substitution in everything inside mm/mprotect.c (but also for all calls invoked by mm/proc_mm.c - write_proc_mm(), i.e. mmap and munmap); however, this also means adding one more parameter to each of those calls, so I implemented it in a different way, the one you see.
I investigated a bit and discovered that if, inside the mm_struct* mm0, I pick one vm_area_struct (vma1), then vma1->vm_mm is always equal to mm0. So the implementation is the one above.
Also, some general VM info:
- one mm_struct contains all the memory mappings of one process; if you have more threads (which share the same memory), they share the mm_struct.
- inside a mm_struct, there are lots of vm_area_struct; when you call mmap() in userspace, one new vm_area_struct is created, containing the data to represent the created mapping. There are also some other situations in which a vm_area_struct is created, however this is enough. Also, a vm_area_struct (a VMA) is never shared between two mm_struct.
Also, when you do cat /proc/<aPid>/maps, what you see is a dump of the VMAs of that process (the one with <aPid>); each line contains the data of one VMA.
Finally, what the patch does:
- it allows one UML thread (the kernel thread) to do something like mmap()/munmap()/mprotect(), except that these calls have effect on the userspace thread (the one running the various process); also, it allows this process to have various mm_struct; the kernel thread, with PTRACE_SWITCH_MM, can make the userspace thread switch from one mm_struct to another (and this is done when a different guest process must run).
Bye
Signature · 13 lines
Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 ------------------------------------------------------- This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170 Project Admins to receive an Apple iPod Mini FREE for your judgement on who ports your project to Linux PPC the best. Sponsored by IBM. Deadline: Sept. 24. Go here: http://sf.net/ppc_contest.php _______________________________________________ User-mode-linux-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel