[PATCH 2/2] user namespaces: require cap_set{ug}id for CLONE_NEWUSER

Serge E. Hallyn
2008-12-03T19:17:51Z

While ideally CLONE_NEWUSER will eventually require no
privilege, the required permission checks are currently
not there. As a result, CLONE_NEWUSER has the same effect
as a setuid(0)+setgroups(1,"0"). While we already require
CAP_SYS_ADMIN, requiring CAP_SETUID and CAP_SETGID seems
appropriate.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
---
kernel/fork.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 1dd8945..e3a85b3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1344,7 +1344,8 @@ long do_fork(unsigned long clone_flags,
/* hopefully this check will go away when userns support is
* complete
*/
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
+ !capable(CAP_SETGID))
return -EPERM;
}

--
1.5.4.3