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authorEric Paris <eparis@redhat.com>2007-06-28 15:55:21 -0400
committerJames Morris <jmorris@namei.org>2007-07-11 22:52:29 -0400
commited0321895182ffb6ecf210e066d87911b270d587 (patch)
tree832bb54666f73b06e55322df40f915c5e9ef64d7 /mm/mremap.c
parent13bddc2e9d591e31bf20020dc19ea6ca85de420e (diff)
security: Protection for exploiting null dereference using mmap
Add a new security check on mmap operations to see if the user is attempting to mmap to low area of the address space. The amount of space protected is indicated by the new proc tunable /proc/sys/vm/mmap_min_addr and defaults to 0, preserving existing behavior. This patch uses a new SELinux security class "memprotect." Policy already contains a number of allow rules like a_t self:process * (unconfined_t being one of them) which mean that putting this check in the process class (its best current fit) would make it useless as all user processes, which we also want to protect against, would be allowed. By taking the memprotect name of the new class it will also make it possible for us to move some of the other memory protect permissions out of 'process' and into the new class next time we bump the policy version number (which I also think is a good future idea) Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'mm/mremap.c')
-rw-r--r--mm/mremap.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index 5d4bd4f95b8..bc7c52efc71 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -291,6 +291,10 @@ unsigned long do_mremap(unsigned long addr,
291 if ((addr <= new_addr) && (addr+old_len) > new_addr) 291 if ((addr <= new_addr) && (addr+old_len) > new_addr)
292 goto out; 292 goto out;
293 293
294 ret = security_file_mmap(0, 0, 0, 0, new_addr, 1);
295 if (ret)
296 goto out;
297
294 ret = do_munmap(mm, new_addr, new_len); 298 ret = do_munmap(mm, new_addr, new_len);
295 if (ret) 299 if (ret)
296 goto out; 300 goto out;
@@ -390,8 +394,13 @@ unsigned long do_mremap(unsigned long addr,
390 394
391 new_addr = get_unmapped_area(vma->vm_file, 0, new_len, 395 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
392 vma->vm_pgoff, map_flags); 396 vma->vm_pgoff, map_flags);
393 ret = new_addr; 397 if (new_addr & ~PAGE_MASK) {
394 if (new_addr & ~PAGE_MASK) 398 ret = new_addr;
399 goto out;
400 }
401
402 ret = security_file_mmap(0, 0, 0, 0, new_addr, 1);
403 if (ret)
395 goto out; 404 goto out;
396 } 405 }
397 ret = move_vma(vma, addr, old_len, new_len, new_addr); 406 ret = move_vma(vma, addr, old_len, new_len, new_addr);