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Groups > linux.kernel > #1385298

[PATCH v3 12/21] fs: Refuse uid/gid changes which don't map into s_user_ns

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Add checks to inode_change_ok to verify that uid and gid changes
will map into the superblock's user namespace. If they do not
fail with -EOVERFLOW. This cannot be overriden with ATTR_FORCE.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
---
 fs/attr.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/attr.c b/fs/attr.c
index 25b24d0f6c88..3cfaaac4a18e 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -42,6 +42,17 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr)
 			return error;
 	}
 
+	/*
+	 * Verify that uid/gid changes are valid in the target namespace
+	 * of the superblock. This cannot be overriden using ATTR_FORCE.
+	 */
+	if (ia_valid & ATTR_UID &&
+	    from_kuid(inode->i_sb->s_user_ns, attr->ia_uid) == (uid_t)-1)
+		return -EOVERFLOW;
+	if (ia_valid & ATTR_GID &&
+	    from_kgid(inode->i_sb->s_user_ns, attr->ia_gid) == (gid_t)-1)
+		return -EOVERFLOW;
+
 	/* If force is set do it anyway. */
 	if (ia_valid & ATTR_FORCE)
 		return 0;
-- 
1.9.1

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[PATCH v3 00/21] Support fuse mounts in user namespaces Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:40 +0200
  [PATCH v3 17/21] capabilities: Allow privileged user in s_user_ns to set security.* xattrs Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:40 +0200
  [PATCH v3 01/21] fs: fix a posible leak of allocated superblock Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:40 +0200
  [PATCH v3 15/21] fs: Don't remove suid for CAP_FSETID in s_user_ns Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:40 +0200
  [PATCH v3 16/21] fs: Allow superblock owner to access do_remount_sb() Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 05/21] block_dev: Check permissions towards block device inode when mounting Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 04/21] block_dev: Support checking inode permissions in lookup_bdev() Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 12/21] fs: Refuse uid/gid changes which don't map into s_user_ns Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 14/21] fs: Allow superblock owner to change ownership of inodes with unmappable ids Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
    Re: [PATCH v3 14/21] fs: Allow superblock owner to change ownership  of inodes with unmappable ids "Serge E. Hallyn" <serge@hallyn.com> - 2016-04-25 22:40 +0200
      Re: [PATCH v3 14/21] fs: Allow superblock owner to change ownership  of inodes with unmappable ids Seth Forshee <seth.forshee@canonical.com> - 2016-04-26 21:50 +0200
  [PATCH v3 11/21] cred: Reject inodes with invalid ids in set_create_file_as() Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 19/21] fuse: Support fuse filesystems outside of init_user_ns Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 21/21] fuse: Allow user namespace mounts Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 20/21] fuse: Restrict allow_other to the superblock's namespace or a descendant Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 10/21] fs: Check for invalid i_uid in may_follow_link() Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 09/21] Smack: Handle labels consistently in untrusted mounts Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 18/21] fuse: Add support for pid namespaces Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 08/21] userns: Replace in_userns with current_in_userns Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 17:50 +0200
  [PATCH v3 06/21] fs: Treat foreign mounts as nosuid Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 18:00 +0200
  [PATCH v3 07/21] selinux: Add support for unprivileged mounts from user namespaces Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 18:00 +0200
  [PATCH v3 03/21] fs: Allow sysfs and cgroupfs to share super blocks between user namespaces Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 18:00 +0200
    Re: [PATCH v3 03/21] fs: Allow sysfs and cgroupfs to share super  blocks between user namespaces "Serge E. Hallyn" <serge@hallyn.com> - 2016-04-25 21:10 +0200
  [PATCH v3 02/21] fs: Remove check of s_user_ns for existing mounts in fs_fully_visible() Seth Forshee <seth.forshee@canonical.com> - 2016-04-22 18:00 +0200

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