On Fri, Feb 26, 2016 at 12:20:32PM -0800, Andrew Morton wrote: > On Wed, 27 Jan 2016 17:29:37 +0100 Piotr Kwapulinski <kwapulinski.piotr@xxxxxxxxx> wrote: > > > 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. > > sys_mprotect() just took a mangling in linux-next due to > > commit 62b5f7d013fc455b8db26cf01e421f4c0d264b92 > Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > AuthorDate: Fri Feb 12 13:02:40 2016 -0800 > Commit: Ingo Molnar <mingo@xxxxxxxxxx> > CommitDate: Thu Feb 18 19:46:33 2016 +0100 > > mm/core, x86/mm/pkeys: Add execute-only protection keys support > > > Here is my rework of your "mm/mprotect.c: don't imply PROT_EXEC on > non-exec fs" to handle this. Please check very carefully. > > > From: Piotr Kwapulinski <kwapulinski.piotr@xxxxxxxxx> > Subject: 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@xxxxxxxxx> > Cc: Mel Gorman <mgorman@xxxxxxx> > Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > mm/mprotect.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff -puN mm/mprotect.c~mm-mprotectc-dont-imply-prot_exec-on-non-exec-fs mm/mprotect.c > --- a/mm/mprotect.c~mm-mprotectc-dont-imply-prot_exec-on-non-exec-fs > +++ a/mm/mprotect.c > @@ -359,6 +359,9 @@ SYSCALL_DEFINE3(mprotect, unsigned long, > 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, > 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(¤t->mm->mmap_sem); > > @@ -414,6 +412,10 @@ SYSCALL_DEFINE3(mprotect, unsigned long, > > /* 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, > error = -ENOMEM; > goto out; > } > + prot = reqprot; > } > out: > up_write(¤t->mm->mmap_sem); > _ > It looks good. I also did some tests (non-MPK CPU) - passed. Thank you. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>