lkml.org 
[lkml]   [2012]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH] eCryptfs: Fix kernel bug for writing mmaped non-eCryptfs file
    Date
    eCryptfs did not handle the writing for mmaped non-eCryptfs file.
    Instead, it put BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED))
    on ecryptfs_writepage call path. This patch enables eCryptfs to
    deal with such case, to fully support non-eCryptfs operations as it
    claims.

    ---

    To make the bug present

    cd cipher // enter eCryptfs cipher text folder
    echo "123" > foo // make non-eCryptfs file
    cd ..
    mount -t ecryptfs cipher plain -o ecryptfs_passthrough // allow for non-eCryptfs files to be read and written from within an eCryptfs mount
    cd plain
    run the following program

    int main()
    {
    int fd = open("foo", O_RDWR);
    char * addr;
    addr = (char *)mmap(NULL, 256, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    add[0] = '3';
    munmap(addr, 256);
    close(fd);
    return 0;
    }

    Signed-off-by: Li Wang <liwang@nudt.edu.cn>
    Signed-off-by: Yunchuan Wen <wenyunchuan@kylinos.com.cn>
    ---
    fs/ecryptfs/mmap.c | 26 ++++++++++++++++++++++++++
    1 files changed, 26 insertions(+), 0 deletions(-)

    diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
    index 10ec695..a4be0e9 100644
    --- a/fs/ecryptfs/mmap.c
    +++ b/fs/ecryptfs/mmap.c
    @@ -65,6 +65,32 @@ struct page *ecryptfs_get_locked_page(struct inode *inode, loff_t index)
    static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
    {
    int rc;
    + struct inode *inode;
    + struct ecryptfs_crypt_stat *crypt_stat;
    +
    + inode = page->mapping->host;
    + crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
    + if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
    + size_t size;
    + loff_t file_size = i_size_read(inode);
    + pgoff_t end_page_index = file_size >> PAGE_CACHE_SHIFT;
    +
    + if (end_page_index < page->index)
    + size = 0;
    + else if (end_page_index == page->index)
    + size = file_size & ~PAGE_CACHE_MASK;
    + else
    + size = PAGE_CACHE_SIZE;
    +
    + rc = ecryptfs_write_lower_page_segment(inode, page, 0, size);
    + if (unlikely(rc)) {
    + ecryptfs_printk(KERN_WARNING, "Error write "
    + "page (upper index [0x%.16lx])\n", page->index);
    + ClearPageUptodate(page);
    + } else
    + SetPageUptodate(page);
    + goto out;
    + }

    /*
    * Refuse to write the page out if we are called from reclaim context
    --
    1.7.6.5


    \
     
     \ /
      Last update: 2012-03-13 04:47    [W:0.024 / U:29.568 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site