[RFC PATCH v1 6/8] mseal mremap

[jeffxu]

From: Jeff Xu <jef...@google.com>

check seal for mremap(2)

Signed-off-by: Jeff Xu <jef...@google.com>
---
 mm/mremap.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/mm/mremap.c b/mm/mremap.c
index e43f9ceaa29d..2288f9d0b126 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -836,7 +836,15 @@ static unsigned long mremap_to(unsigned long addr, 
unsigned long old_len,
        if ((mm->map_count + 2) >= sysctl_max_map_count - 3)
                return -ENOMEM;
 
+       if (!can_modify_mm(mm, addr, addr + old_len, MM_ACTION_MREMAP,
+                          ON_BEHALF_OF_USERSPACE))
+               return -EACCES;
+
        if (flags & MREMAP_FIXED) {
+               if (!can_modify_mm(mm, new_addr, new_addr + new_len,
+                                  MM_ACTION_MREMAP, ON_BEHALF_OF_USERSPACE))
+                       return -EACCES;
+
                ret = do_munmap(mm, new_addr, new_len, uf_unmap_early);
                if (ret)
                        goto out;
@@ -995,6 +1003,12 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned 
long, old_len,
                goto out;
        }
 
+       if (!can_modify_mm(mm, addr, addr + old_len, MM_ACTION_MREMAP,
+                          ON_BEHALF_OF_USERSPACE)) {
+               ret = -EACCES;
+               goto out;
+       }
+
        /*
         * Always allow a shrinking remap: that just unmaps
         * the unnecessary pages..
-- 
2.42.0.609.gbb76f46606-goog