Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull (again) user namespace infrastructure changes from Eric Biederman:
"Those bugs, those darn embarrasing bugs just want don't want to get
fixed.
Linus I just updated my mirror of your kernel.org tree and it appears
you successfully pulled everything except the last 4 commits that fix
those embarrasing bugs.
When you get a chance can you please repull my branch"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
userns: Fix typo in description of the limitation of userns_install
userns: Add a more complete capability subset test to commit_creds
userns: Require CAP_SYS_ADMIN for most uses of setns.
Fix cap_capable to only allow owners in the parent user namespace to have caps.
diff --git a/fs/namespace.c b/fs/namespace.c
index c1bbe86..398a50f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2781,7 +2781,8 @@
struct path root;
if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
- !nsown_capable(CAP_SYS_CHROOT))
+ !nsown_capable(CAP_SYS_CHROOT) ||
+ !nsown_capable(CAP_SYS_ADMIN))
return -EPERM;
if (fs->users != 1)
diff --git a/ipc/namespace.c b/ipc/namespace.c
index cf3386a..7c1fa45 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -170,7 +170,8 @@
static int ipcns_install(struct nsproxy *nsproxy, void *new)
{
struct ipc_namespace *ns = new;
- if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_ADMIN))
return -EPERM;
/* Ditch state from the old ipc namespace */
diff --git a/kernel/cred.c b/kernel/cred.c
index 8888afb..e0573a4 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -372,6 +372,31 @@
return ret;
}
+static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
+{
+ const struct user_namespace *set_ns = set->user_ns;
+ const struct user_namespace *subset_ns = subset->user_ns;
+
+ /* If the two credentials are in the same user namespace see if
+ * the capabilities of subset are a subset of set.
+ */
+ if (set_ns == subset_ns)
+ return cap_issubset(subset->cap_permitted, set->cap_permitted);
+
+ /* The credentials are in a different user namespaces
+ * therefore one is a subset of the other only if a set is an
+ * ancestor of subset and set->euid is owner of subset or one
+ * of subsets ancestors.
+ */
+ for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
+ if ((set_ns == subset_ns->parent) &&
+ uid_eq(subset_ns->owner, set->euid))
+ return true;
+ }
+
+ return false;
+}
+
/**
* commit_creds - Install new credentials upon the current task
* @new: The credentials to be assigned
@@ -410,7 +435,7 @@
!gid_eq(old->egid, new->egid) ||
!uid_eq(old->fsuid, new->fsuid) ||
!gid_eq(old->fsgid, new->fsgid) ||
- !cap_issubset(new->cap_permitted, old->cap_permitted)) {
+ !cred_cap_issubset(old, new)) {
if (task->mm)
set_dumpable(task->mm, suid_dumpable);
task->pdeath_signal = 0;
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 560da0d..fdbd0cd 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -325,7 +325,8 @@
struct pid_namespace *active = task_active_pid_ns(current);
struct pid_namespace *ancestor, *new = ns;
- if (!ns_capable(new->user_ns, CAP_SYS_ADMIN))
+ if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_ADMIN))
return -EPERM;
/*
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index f5975cc..2b042c4 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -799,7 +799,7 @@
if (user_ns == current_user_ns())
return -EINVAL;
- /* Threaded many not enter a different user namespace */
+ /* Threaded processes may not enter a different user namespace */
if (atomic_read(¤t->mm->mm_users) > 1)
return -EINVAL;
diff --git a/kernel/utsname.c b/kernel/utsname.c
index f6336d5..08b197e 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -113,7 +113,8 @@
{
struct uts_namespace *ns = new;
- if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_ADMIN))
return -EPERM;
get_uts_ns(ns);
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 2e9a313..8acce01 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -649,7 +649,8 @@
{
struct net *net = ns;
- if (!ns_capable(net->user_ns, CAP_SYS_ADMIN))
+ if (!ns_capable(net->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_ADMIN))
return -EPERM;
put_net(nsproxy->net_ns);
diff --git a/security/commoncap.c b/security/commoncap.c
index 6dbae46..7ee08c7 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -76,24 +76,33 @@
int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
int cap, int audit)
{
- for (;;) {
- /* The owner of the user namespace has all caps. */
- if (targ_ns != &init_user_ns && uid_eq(targ_ns->owner, cred->euid))
- return 0;
+ struct user_namespace *ns = targ_ns;
+ /* See if cred has the capability in the target user namespace
+ * by examining the target user namespace and all of the target
+ * user namespace's parents.
+ */
+ for (;;) {
/* Do we have the necessary capabilities? */
- if (targ_ns == cred->user_ns)
+ if (ns == cred->user_ns)
return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
/* Have we tried all of the parent namespaces? */
- if (targ_ns == &init_user_ns)
+ if (ns == &init_user_ns)
return -EPERM;
+ /*
+ * The owner of the user namespace in the parent of the
+ * user namespace has all caps.
+ */
+ if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
+ return 0;
+
/*
- *If you have a capability in a parent user ns, then you have
+ * If you have a capability in a parent user ns, then you have
* it over all children user namespaces as well.
*/
- targ_ns = targ_ns->parent;
+ ns = ns->parent;
}
/* We never get here */