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    SubjectDriver-Core: devtmpfs - reset inode permissions before unlinking
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    From: Kay Sievers <kay.sievers@vrfy.org>
    Subject: Driver-Core: devtmpfs - reset inode permissions before unlinking

    Before unlinking the inode, reset the current permissions of possible
    references like hardlinks, so granted permissions can not be retained
    across the device lifetime by creating hardlinks, in the unusual case
    that there is a user-writable directory on the same filesystem.

    Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
    ---
    drivers/base/devtmpfs.c | 13 +++++++++++++
    1 file changed, 13 insertions(+)

    --- a/drivers/base/devtmpfs.c
    +++ b/drivers/base/devtmpfs.c
    @@ -301,6 +301,19 @@ int devtmpfs_delete_node(struct device *
    if (dentry->d_inode) {
    err = vfs_getattr(nd.path.mnt, dentry, &stat);
    if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
    + struct iattr newattrs;
    + /*
    + * before unlinking this node, reset permissions
    + * of possible references like hardlinks
    + */
    + newattrs.ia_uid = 0;
    + newattrs.ia_gid = 0;
    + newattrs.ia_mode = stat.mode & ~0777;
    + newattrs.ia_valid =
    + ATTR_UID|ATTR_GID|ATTR_MODE;
    + mutex_lock(&dentry->d_inode->i_mutex);
    + notify_change(dentry, &newattrs);
    + mutex_unlock(&dentry->d_inode->i_mutex);
    err = vfs_unlink(nd.path.dentry->d_inode,
    dentry);
    if (!err || err == -ENOENT)



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