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| author | Piotr Kwapulinski <kwapulinski.piotr@gmail.com> | 2016-03-22 14:27:51 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-22 15:36:02 -0700 |
| commit | f138556daf62665f19178732ec4daf86c4ca13f4 (patch) | |
| tree | 6e873ed98d9cae5c202e75847224d66147f110dd /mm/mprotect.c | |
| parent | a5f4db877177d2a3d7ae62a7bac3a5a27e083d7f (diff) | |
| download | lwn-f138556daf62665f19178732ec4daf86c4ca13f4.tar.gz lwn-f138556daf62665f19178732ec4daf86c4ca13f4.zip | |
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>
Diffstat (limited to 'mm/mprotect.c')
| -rw-r--r-- | mm/mprotect.c | 13 |
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(¤t->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(¤t->mm->mmap_sem); |