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authorPiotr Kwapulinski <kwapulinski.piotr@gmail.com>2016-03-22 14:27:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-22 15:36:02 -0700
commitf138556daf62665f19178732ec4daf86c4ca13f4 (patch)
tree6e873ed98d9cae5c202e75847224d66147f110dd
parenta5f4db877177d2a3d7ae62a7bac3a5a27e083d7f (diff)
mm/mprotect.c: don't imply PROT_EXEC on non-exec fs
The mprotect(PROT_READ) fails when called by the READ_IMPLIES_EXEC binary on a memory mapped file located on non-exec fs. The mprotect does not check whether fs is _executable_ or not. The PROT_EXEC flag is set automatically even if a memory mapped file is located on non-exec fs. Fix it by checking whether a memory mapped file is located on a non-exec fs. If so the PROT_EXEC is not implied by the PROT_READ. The implementation uses the VM_MAYEXEC flag set properly in mmap. Now it is consistent with mmap. I did the isolated tests (PT_GNU_STACK X/NX, multiple VMAs, X/NX fs). I also patched the official 3.19.0-47-generic Ubuntu 14.04 kernel and it seems to work. Signed-off-by: Piotr Kwapulinski <kwapulinski.piotr@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mprotect.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index fa37c4cd973a..b650c5412f58 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -359,6 +359,9 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
struct vm_area_struct *vma, *prev;
int error = -EINVAL;
const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
+ const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
+ (prot & PROT_READ);
+
prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
return -EINVAL;
@@ -375,11 +378,6 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
return -EINVAL;
reqprot = prot;
- /*
- * Does the application expect PROT_READ to imply PROT_EXEC:
- */
- if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
- prot |= PROT_EXEC;
down_write(&current->mm->mmap_sem);
@@ -414,6 +412,10 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
+ /* Does the application expect PROT_READ to imply PROT_EXEC */
+ if (rier && (vma->vm_flags & VM_MAYEXEC))
+ prot |= PROT_EXEC;
+
newflags = calc_vm_prot_bits(prot, pkey);
newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
@@ -445,6 +447,7 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
error = -ENOMEM;
goto out;
}
+ prot = reqprot;
}
out:
up_write(&current->mm->mmap_sem);