[PATCH] c/r: tighten checks on supported vma to checkpoint or restart

[Oren Laadan <orenl@xxxxxxxxxxx>]

From: Oren Laadan <orenl@xxxxxxxxxxx>

Move test of vma flags against CKPT_VMA_NOT_SUPPORTED to one place:
{checkpoint,restore}_vma(). Also tighten sanity tests on restore.

Signed-off-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
---
 checkpoint/memory.c |   24 +++++++++---------------
 1 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/checkpoint/memory.c b/checkpoint/memory.c
index 7754074..0da948f 100644
--- a/checkpoint/memory.c
+++ b/checkpoint/memory.c
@@ -554,12 +554,6 @@ int generic_vma_checkpoint(struct ckpt_ctx *ctx, struct vm_area_struct *vma,
 	ckpt_debug("vma %#lx-%#lx flags %#lx type %d\n",
 		 vma->vm_start, vma->vm_end, vma->vm_flags, type);
 
-	if (vma->vm_flags & CKPT_VMA_NOT_SUPPORTED) {
-		ckpt_write_err(ctx, "TE", "vma: bad flags (%#lx)\n",
-			       -ENOSYS, vma->vm_flags);
-		return -ENOSYS;
-	}
-
 	h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_VMA);
 	if (!h)
 		return -ENOMEM;
@@ -644,12 +638,7 @@ static int anonymous_checkpoint(struct ckpt_ctx *ctx,
 				struct vm_area_struct *vma)
 {
 	/* should be private anonymous ... verify that this is the case */
-	if (vma->vm_flags & CKPT_VMA_NOT_SUPPORTED) {
-		ckpt_write_err(ctx, "TE", "vma: bad flags (%#lx)\n",
-			       -ENOSYS, vma->vm_flags);
-		return -ENOSYS;
-	}
-
+	BUG_ON(vma->vm_flags & VM_MAYSHARE);
 	BUG_ON(vma->vm_file);
 
 	return private_vma_checkpoint(ctx, vma, CKPT_VMA_ANON, 0);
@@ -707,6 +696,11 @@ static int do_checkpoint_mm(struct ckpt_ctx *ctx, struct mm_struct *mm)
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 		ckpt_debug("vma %#lx-%#lx flags %#lx\n",
 			 vma->vm_start, vma->vm_end, vma->vm_flags);
+		if (vma->vm_flags & CKPT_VMA_NOT_SUPPORTED) {
+			ckpt_write_err(ctx, "TE", "vma: bad flags (%#lx)\n",
+				       -ENOSYS, vma->vm_flags);
+			return -ENOSYS;
+		}
 		if (!vma->vm_ops)
 			ret = anonymous_checkpoint(ctx, vma);
 		else if (vma->vm_ops->checkpoint)
@@ -1033,8 +1027,6 @@ unsigned long generic_vma_restore(struct mm_struct *mm,
 		return -EINVAL;
 	if (h->vma_objref < 0)
 		return -EINVAL;
-	if (h->vm_flags & CKPT_VMA_NOT_SUPPORTED)
-		return -ENOSYS;
 
 	vm_start = h->vm_start;
 	vm_pgoff = h->vm_pgoff;
@@ -1064,7 +1056,7 @@ int private_vma_restore(struct ckpt_ctx *ctx, struct mm_struct *mm,
 {
 	unsigned long addr;
 
-	if (h->vm_flags & VM_SHARED)
+	if (h->vm_flags & (VM_SHARED | VM_MAYSHARE))
 		return -EINVAL;
 
 	addr = generic_vma_restore(mm, file, h);
@@ -1195,6 +1187,8 @@ static int restore_vma(struct ckpt_ctx *ctx, struct mm_struct *mm)
 		goto out;
 	if (h->vma_type >= CKPT_VMA_MAX)
 		goto out;
+	if (h->vm_flags & CKPT_VMA_NOT_SUPPORTED)
+		return -ENOSYS;
 
 	ops = &restore_vma_ops[h->vma_type];
 
-- 
1.6.0.4

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