pagemap: do not leak physical addresses to non-privileged userspace

[pandora-kernel.git] / fs / proc / task_mmu.c

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e418c5a..d1bd6a9 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -409,6 +409,9 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
        } else {
                spin_unlock(&walk->mm->page_table_lock);
        }
+
+       if (pmd_trans_unstable(pmd))
+               return 0;
        /*
         * The mmap_sem held all the way back in m_start() is what
         * keeps khugepaged out of here and from collapsing things
@@ -507,6 +510,8 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
        struct page *page;
 
        split_huge_page_pmd(walk->mm, pmd);
+       if (pmd_trans_unstable(pmd))
+               return 0;
 
        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
        for (; addr != end; pte++, addr += PAGE_SIZE) {
@@ -518,6 +523,9 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
                if (!page)
                        continue;
 
+               if (PageReserved(page))
+                       continue;
+
                /* Clear accessed and referenced bits. */
                ptep_test_and_clear_young(vma, addr, pte);
                ClearPageReferenced(page);
@@ -596,7 +604,7 @@ const struct file_operations proc_clear_refs_operations = {
 };
 
 struct pagemapread {
-       int pos, len;
+       int pos, len;           /* units: PM_ENTRY_BYTES, not bytes */
        u64 *buffer;
 };
 
@@ -667,6 +675,8 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
        int err = 0;
 
        split_huge_page_pmd(walk->mm, pmd);
+       if (pmd_trans_unstable(pmd))
+               return 0;
 
        /* find the first VMA at or above 'addr' */
        vma = find_vma(walk->mm, addr);
@@ -782,8 +792,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
        if (!count)
                goto out_task;
 
-       pm.len = PM_ENTRY_BYTES * (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
-       pm.buffer = kmalloc(pm.len, GFP_TEMPORARY);
+       pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
+       pm.buffer = kmalloc(pm.len * PM_ENTRY_BYTES, GFP_TEMPORARY);
        ret = -ENOMEM;
        if (!pm.buffer)
                goto out_task;
@@ -854,9 +864,19 @@ out:
        return ret;
 }
 
+static int pagemap_open(struct inode *inode, struct file *file)
+{
+       /* do not disclose physical addresses to unprivileged
+          userspace (closes a rowhammer attack vector) */
+       if (!capable(CAP_SYS_ADMIN))
+               return -EPERM;
+       return 0;
+}
+
 const struct file_operations proc_pagemap_operations = {
        .llseek         = mem_lseek, /* borrow this */
        .read           = pagemap_read,
+       .open           = pagemap_open,
 };
 #endif /* CONFIG_PROC_PAGE_MONITOR */
 
@@ -958,6 +978,8 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
                spin_unlock(&walk->mm->page_table_lock);
        }
 
+       if (pmd_trans_unstable(pmd))
+               return 0;
        orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
        do {
                struct page *page = can_gather_numa_stats(*pte, md->vma, addr);