From: Jeff Xu jeffxu@google.com
This patch enables PKEY_ENFORCE_API for the munmap syscall.
Signed-off-by: Jeff Xujeffxu@google.com --- include/linux/mm.h | 8 +++++++- mm/mmap.c | 31 +++++++++++++++++++++++-------- mm/mremap.c | 6 ++++-- 3 files changed, 34 insertions(+), 11 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 27ce77080c79..795cdeee2ea7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -429,6 +429,12 @@ extern unsigned int kobjsize(const void *objp); #endif #define VM_FLAGS_CLEAR (ARCH_VM_PKEY_FLAGS | VM_ARCH_CLEAR)
+/* The current call stack is originated from user space or kernel */ +enum caller_origin { + ON_BEHALF_OF_KERNEL = 0, + ON_BEHALF_OF_USERSPACE, +}; + /* * mapping from the currently active vm_flags protection bits (the * low four bits) to a page protection mask.. @@ -3136,7 +3142,7 @@ extern unsigned long do_mmap(struct file *file, unsigned long addr, unsigned long pgoff, unsigned long *populate, struct list_head *uf); extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf, - bool downgrade); + bool downgrade, enum caller_origin called); extern int do_munmap(struct mm_struct *, unsigned long, size_t, struct list_head *uf); extern int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior); diff --git a/mm/mmap.c b/mm/mmap.c index 13678edaa22c..3de95a6a4397 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2498,6 +2498,7 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, * @uf: The userfaultfd list_head * @downgrade: set to true if the user wants to attempt to write_downgrade the * mmap_lock + * @called: originated from user space or kernel * * This function takes a @mas that is either pointing to the previous VMA or set * to MA_START and sets it up to remove the mapping(s). The @len will be @@ -2507,7 +2508,7 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, */ int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf, - bool downgrade) + bool downgrade, enum caller_origin called) { unsigned long end; struct vm_area_struct *vma; @@ -2519,6 +2520,15 @@ int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm, if (end == start) return -EINVAL;
+ /* + * When called by syscall from userspace, check if the calling + * thread has the PKEY permission to modify the memory mapping. + */ + if (called == ON_BEHALF_OF_USERSPACE && + arch_check_pkey_enforce_api(mm, start, end) < 0) { + return -EACCES; + } + /* arch_unmap() might do unmaps itself. */ arch_unmap(mm, start, end);
@@ -2541,7 +2551,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, { VMA_ITERATOR(vmi, mm, start);
- return do_vmi_munmap(&vmi, mm, start, len, uf, false); + return do_vmi_munmap(&vmi, mm, start, len, uf, false, ON_BEHALF_OF_KERNEL); }
unsigned long mmap_region(struct file *file, unsigned long addr, @@ -2575,7 +2585,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, }
/* Unmap any existing mapping in the area */ - if (do_vmi_munmap(&vmi, mm, addr, len, uf, false)) + if (do_vmi_munmap(&vmi, mm, addr, len, uf, false, + ON_BEHALF_OF_KERNEL)) return -ENOMEM;
/* @@ -2792,7 +2803,11 @@ unsigned long mmap_region(struct file *file, unsigned long addr, return error; }
-static int __vm_munmap(unsigned long start, size_t len, bool downgrade) +/* + * @called: originated from user space or kernel + */ +static int __vm_munmap(unsigned long start, size_t len, bool downgrade, + enum caller_origin called) { int ret; struct mm_struct *mm = current->mm; @@ -2802,7 +2817,7 @@ static int __vm_munmap(unsigned long start, size_t len, bool downgrade) if (mmap_write_lock_killable(mm)) return -EINTR;
- ret = do_vmi_munmap(&vmi, mm, start, len, &uf, downgrade); + ret = do_vmi_munmap(&vmi, mm, start, len, &uf, downgrade, called); /* * Returning 1 indicates mmap_lock is downgraded. * But 1 is not legal return value of vm_munmap() and munmap(), reset @@ -2820,14 +2835,14 @@ static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
int vm_munmap(unsigned long start, size_t len) { - return __vm_munmap(start, len, false); + return __vm_munmap(start, len, false, ON_BEHALF_OF_KERNEL); } EXPORT_SYMBOL(vm_munmap);
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) { addr = untagged_addr(addr); - return __vm_munmap(addr, len, true); + return __vm_munmap(addr, len, true, ON_BEHALF_OF_USERSPACE); }
@@ -3055,7 +3070,7 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) if (ret) goto limits_failed;
- ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0); + ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0, ON_BEHALF_OF_KERNEL); if (ret) goto munmap_failed;
diff --git a/mm/mremap.c b/mm/mremap.c index b11ce6c92099..a3f576effbb1 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -703,7 +703,8 @@ static unsigned long move_vma(struct vm_area_struct *vma, }
vma_iter_init(&vmi, mm, old_addr); - if (do_vmi_munmap(&vmi, mm, old_addr, old_len, uf_unmap, false) < 0) { + if (do_vmi_munmap(&vmi, mm, old_addr, old_len, uf_unmap, false, + ON_BEHALF_OF_KERNEL) < 0) { /* OOM: unable to split vma, just get accounts right */ if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP)) vm_acct_memory(old_len >> PAGE_SHIFT); @@ -993,7 +994,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, VMA_ITERATOR(vmi, mm, addr + new_len);
retval = do_vmi_munmap(&vmi, mm, addr + new_len, - old_len - new_len, &uf_unmap, true); + old_len - new_len, &uf_unmap, true, + ON_BEHALF_OF_KERNEL); /* Returning 1 indicates mmap_lock is downgraded to read. */ if (retval == 1) { downgraded = true;