userns: user namespaces: convert several capable() calls

CAP_IPC_OWNER and CAP_IPC_LOCK can be checked against current_user_ns(),
because the resource comes from current's own ipc namespace.

setuid/setgid are to uids in own namespace, so again checks can be against
current_user_ns().

Changelog:
	Jan 11: Use task_ns_capable() in place of sched_capable().
	Jan 11: Use nsown_capable() as suggested by Bastian Blank.
	Jan 11: Clarify (hopefully) some logic in futex and sched.c
	Feb 15: use ns_capable for ipc, not nsown_capable
	Feb 23: let copy_ipcs handle setting ipc_ns->user_ns
	Feb 23: pass ns down rather than taking it from current

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 29 insertions, 13 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index bda415715382..6570c459f31c 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2418,10 +2418,19 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
                         goto err_unlock;
                 ret = -EPERM;
                 pcred = __task_cred(p);
+                /* If victim is in different user_ns, then uids are not
+                   comparable, so we must have CAP_SYS_PTRACE */
+                if (cred->user->user_ns != pcred->user->user_ns) {
+                        if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
+                                goto err_unlock;
+                        goto ok;
+                }
+                /* If victim is in same user_ns, then uids are comparable */
                 if (cred->euid != pcred->euid &&
                     cred->euid != pcred->uid &&
-                    !capable(CAP_SYS_PTRACE))
+                    !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
                         goto err_unlock;
+ok:
                 head = p->robust_list;
                 rcu_read_unlock();
         }
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index a7934ac75e5b..5f9e689dc8f0 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -153,10 +153,19 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
                         goto err_unlock;
                 ret = -EPERM;
                 pcred = __task_cred(p);
+                /* If victim is in different user_ns, then uids are not
+                   comparable, so we must have CAP_SYS_PTRACE */
+                if (cred->user->user_ns != pcred->user->user_ns) {
+                        if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
+                                goto err_unlock;
+                        goto ok;
+                }
+                /* If victim is in same user_ns, then uids are comparable */
                 if (cred->euid != pcred->euid &&
                     cred->euid != pcred->uid &&
-                    !capable(CAP_SYS_PTRACE))
+                    !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
                         goto err_unlock;
+ok:
                 head = p->compat_robust_list;
                 rcu_read_unlock();
         }
diff --git a/kernel/groups.c b/kernel/groups.c
index 253dc0f35cf4..1cc476d52dd3 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -233,7 +233,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
         struct group_info *group_info;
         int retval;
 
-        if (!capable(CAP_SETGID))
+        if (!nsown_capable(CAP_SETGID))
                 return -EPERM;
         if ((unsigned)gidsetsize > NGROUPS_MAX)
                 return -EINVAL;
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index ac8a56e90bf8..a05d191ffdd9 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -75,16 +75,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
                 goto out_uts;
         }
 
-        new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
+        new_nsp->ipc_ns = copy_ipcs(flags, tsk);
         if (IS_ERR(new_nsp->ipc_ns)) {
                 err = PTR_ERR(new_nsp->ipc_ns);
                 goto out_ipc;
         }
-        if (new_nsp->ipc_ns != tsk->nsproxy->ipc_ns) {
-                put_user_ns(new_nsp->ipc_ns->user_ns);
-                new_nsp->ipc_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
-                get_user_ns(new_nsp->ipc_ns->user_ns);
-        }
 
         new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
         if (IS_ERR(new_nsp->pid_ns)) {
diff --git a/kernel/sched.c b/kernel/sched.c
index a172494a9a63..480adeb63f8f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4892,8 +4892,11 @@ static bool check_same_owner(struct task_struct *p)
 
         rcu_read_lock();
         pcred = __task_cred(p);
-        match = (cred->euid == pcred->euid ||
-                 cred->euid == pcred->uid);
+        if (cred->user->user_ns == pcred->user->user_ns)
+                match = (cred->euid == pcred->euid ||
+                         cred->euid == pcred->uid);
+        else
+                match = false;
         rcu_read_unlock();
         return match;
 }
@@ -5221,7 +5224,7 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
                 goto out_free_cpus_allowed;
         }
         retval = -EPERM;
-        if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
+        if (!check_same_owner(p) && !task_ns_capable(p, CAP_SYS_NICE))
                 goto out_unlock;
 
         retval = security_task_setscheduler(p);
diff --git a/kernel/uid16.c b/kernel/uid16.c
index 419209893d87..51c6e89e8619 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -189,7 +189,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t __user *, grouplist)
         struct group_info *group_info;
         int retval;
 
-        if (!capable(CAP_SETGID))
+        if (!nsown_capable(CAP_SETGID))
                 return -EPERM;
         if ((unsigned)gidsetsize > NGROUPS_MAX)
                 return -EINVAL;