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userns: Changing any namespace id mappings should require privileges 

Changing uid/gid/projid mappings doesn't change your id within the
namespace; it reconfigures the namespace.  Unprivileged programs should
*not* be able to write these files.  (We're also checking the privileges
on the wrong task.)

Given the write-once nature of these files and the other security
checks, this is likely impossible to usefully exploit.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
This commit is contained in:
Andy Lutomirski 2013-04-14 11:44:04 -07:00
parent e3211c120a
commit 41c21e351e
1 changed files with 3 additions and 3 deletions
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6
kernel/user_namespace.c
View File

@ -613,10 +613,10 @@ static ssize_t map_write(struct file *file, const char __user *buf,
if (map->nr_extents != 0)
goto out;
/* Require the appropriate privilege CAP_SETUID or CAP_SETGID
* over the user namespace in order to set the id mapping.
/*
* Adjusting namespace settings requires capabilities on the target.
*/
if (cap_valid(cap_setid) && !ns_capable(ns, cap_setid))
if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
goto out;
/* Get a buffer */