Messages in this thread | | | Date | Sun, 27 Jan 2013 18:23:34 +0000 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH review 6/6] userns: Allow the userns root to mount tmpfs. |
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Quoting Eric W. Biederman (ebiederm@xmission.com): > > There is no backing store to tmpfs and file creation rules are the > same as for any other filesystem so it is semantically safe to allow > unprivileged users to mount it. ramfs is safe for the same reasons so > allow either flavor of tmpfs to be mounted by a user namespace root > user. > > The memory control group successfully limits how much memory tmpfs can > consume on any system that cares about a user namespace root using > tmpfs to exhaust memory the memory control group can be deployed. > > Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
> --- > mm/shmem.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 5c90d84..197ca5e 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -2766,6 +2766,7 @@ static struct file_system_type shmem_fs_type = { > .name = "tmpfs", > .mount = shmem_mount, > .kill_sb = kill_litter_super, > + .fs_flags = FS_USERNS_MOUNT, > }; > > int __init shmem_init(void) > @@ -2823,6 +2824,7 @@ static struct file_system_type shmem_fs_type = { > .name = "tmpfs", > .mount = ramfs_mount, > .kill_sb = kill_litter_super, > + .fs_flags = FS_USERNS_MOUNT, > }; > > int __init shmem_init(void) > -- > 1.7.5.4
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