Hi David, On Wed, Aug 10, 2016 at 2:36 PM, Dmitry Torokhov <dmitry.torok...@gmail.com> wrote: > If net namespace is attached to a user namespace let's make container's > root owner of sysctls affecting said network namespace instead of global > root. > > This also allows us to clean up net_ctl_permissions() because we do not > need to fudge permissions anymore for the container's owner since it now > owns the objects in question. > > Acked-by: "Eric W. Biederman" <ebied...@xmission.com> > Signed-off-by: Dmitry Torokhov <dmitry.torok...@gmail.com>
I was looking at linux-next today, and I noticed that, when you merged my patch, you basically reverted the following commit: commit d6e0d306449bcb5fa3c80e7a3edf11d45abf9ae9 Author: Tyler Hicks <tyhi...@canonical.com> Date: Thu Jun 2 23:43:22 2016 -0500 net: Use ns_capable_noaudit() when determining net sysctl permissions The capability check should not be audited since it is only being used to determine the inode permissions. A failed check does not indicate a violation of security policy but, when an LSM is enabled, a denial audit message was being generated. The denial audit message caused confusion for some application authors because root-running Go applications always triggered the denial. To prevent this confusion, the capability check in net_ctl_permissions() is switched to the noaudit variant. BugLink: https://launchpad.net/bugs/1465724 Signed-off-by: Tyler Hicks <tyhi...@canonical.com> Acked-by: Serge E. Hallyn <serge.hal...@ubuntu.com> Signed-off-by: James Morris <james.l.mor...@oracle.com> Thanks! > --- > fs/proc/proc_sysctl.c | 5 +++++ > include/linux/sysctl.h | 4 ++++ > net/sysctl_net.c | 29 ++++++++++++++++++++--------- > 3 files changed, 29 insertions(+), 9 deletions(-) > > diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c > index 5e57c3e..28f9085 100644 > --- a/fs/proc/proc_sysctl.c > +++ b/fs/proc/proc_sysctl.c > @@ -430,6 +430,7 @@ static int sysctl_perm(struct ctl_table_header *head, > struct ctl_table *table, i > static struct inode *proc_sys_make_inode(struct super_block *sb, > struct ctl_table_header *head, struct ctl_table *table) > { > + struct ctl_table_root *root = head->root; > struct inode *inode; > struct proc_inode *ei; > > @@ -457,6 +458,10 @@ static struct inode *proc_sys_make_inode(struct > super_block *sb, > if (is_empty_dir(head)) > make_empty_dir_inode(inode); > } > + > + if (root->set_ownership) > + root->set_ownership(head, table, &inode->i_uid, > &inode->i_gid); > + > out: > return inode; > } > diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h > index fa7bc29..55bec2f 100644 > --- a/include/linux/sysctl.h > +++ b/include/linux/sysctl.h > @@ -25,6 +25,7 @@ > #include <linux/rcupdate.h> > #include <linux/wait.h> > #include <linux/rbtree.h> > +#include <linux/uidgid.h> > #include <uapi/linux/sysctl.h> > > /* For the /proc/sys support */ > @@ -156,6 +157,9 @@ struct ctl_table_root { > struct ctl_table_set default_set; > struct ctl_table_set *(*lookup)(struct ctl_table_root *root, > struct nsproxy *namespaces); > + void (*set_ownership)(struct ctl_table_header *head, > + struct ctl_table *table, > + kuid_t *uid, kgid_t *gid); > int (*permissions)(struct ctl_table_header *head, struct ctl_table > *table); > }; > > diff --git a/net/sysctl_net.c b/net/sysctl_net.c > index ed98c1f..5bc1a3d 100644 > --- a/net/sysctl_net.c > +++ b/net/sysctl_net.c > @@ -42,26 +42,37 @@ static int net_ctl_permissions(struct ctl_table_header > *head, > struct ctl_table *table) > { > struct net *net = container_of(head->set, struct net, sysctls); > - kuid_t root_uid = make_kuid(net->user_ns, 0); > - kgid_t root_gid = make_kgid(net->user_ns, 0); > > /* Allow network administrator to have same access as root. */ > - if (ns_capable(net->user_ns, CAP_NET_ADMIN) || > - uid_eq(root_uid, current_euid())) { > + if (ns_capable(net->user_ns, CAP_NET_ADMIN)) { > int mode = (table->mode >> 6) & 7; > return (mode << 6) | (mode << 3) | mode; > } > - /* Allow netns root group to have the same access as the root group */ > - if (in_egroup_p(root_gid)) { > - int mode = (table->mode >> 3) & 7; > - return (mode << 3) | mode; > - } > + > return table->mode; > } > > +static void net_ctl_set_ownership(struct ctl_table_header *head, > + struct ctl_table *table, > + kuid_t *uid, kgid_t *gid) > +{ > + struct net *net = container_of(head->set, struct net, sysctls); > + kuid_t ns_root_uid; > + kgid_t ns_root_gid; > + > + ns_root_uid = make_kuid(net->user_ns, 0); > + if (uid_valid(ns_root_uid)) > + *uid = ns_root_uid; > + > + ns_root_gid = make_kgid(net->user_ns, 0); > + if (gid_valid(ns_root_gid)) > + *gid = ns_root_gid; > +} > + > static struct ctl_table_root net_sysctl_root = { > .lookup = net_ctl_header_lookup, > .permissions = net_ctl_permissions, > + .set_ownership = net_ctl_set_ownership, > }; > > static int __net_init sysctl_net_init(struct net *net) > -- > 2.8.0.rc3.226.g39d4020 > -- Dmitry