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>

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index d3c32dc..a6d1655 100644 (file)
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -5,6 +5,7 @@
 #include <linux/idr.h>
 #include <linux/rwsem.h>
 #include <linux/notifier.h>
+#include <linux/nsproxy.h>
 
 /*
  * ipc namespace events
@@ -93,7 +94,7 @@ static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }
 
 #if defined(CONFIG_IPC_NS)
 extern struct ipc_namespace *copy_ipcs(unsigned long flags,
-                                      struct ipc_namespace *ns);
+                                      struct task_struct *tsk);
 static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 {
        if (ns)
@@ -104,12 +105,12 @@ static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 extern void put_ipc_ns(struct ipc_namespace *ns);
 #else
 static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
-               struct ipc_namespace *ns)
+                                             struct task_struct *tsk)
 {
        if (flags & CLONE_NEWIPC)
                return ERR_PTR(-EINVAL);
 
-       return ns;
+       return tsk->nsproxy->ipc_ns;
 }
 
 static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)

diff --git a/ipc/msg.c b/ipc/msg.c
index 747b655..0e732e9 100644 (file)
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -421,7 +421,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
                        return -EFAULT;
        }
 
-       ipcp = ipcctl_pre_down(&msg_ids(ns), msqid, cmd,
+       ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd,
                               &msqid64.msg_perm, msqid64.msg_qbytes);
        if (IS_ERR(ipcp))
                return PTR_ERR(ipcp);
@@ -539,7 +539,7 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
                        success_return = 0;
                }
                err = -EACCES;
-               if (ipcperms(&msq->q_perm, S_IRUGO))
+               if (ipcperms(ns, &msq->q_perm, S_IRUGO))
                        goto out_unlock;
 
                err = security_msg_queue_msgctl(msq, cmd);
@@ -664,7 +664,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
                struct msg_sender s;
 
                err = -EACCES;
-               if (ipcperms(&msq->q_perm, S_IWUGO))
+               if (ipcperms(ns, &msq->q_perm, S_IWUGO))
                        goto out_unlock_free;
 
                err = security_msg_queue_msgsnd(msq, msg, msgflg);
@@ -774,7 +774,7 @@ long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
                struct list_head *tmp;
 
                msg = ERR_PTR(-EACCES);
-               if (ipcperms(&msq->q_perm, S_IRUGO))
+               if (ipcperms(ns, &msq->q_perm, S_IRUGO))
                        goto out_unlock;
 
                msg = ERR_PTR(-EAGAIN);

diff --git a/ipc/namespace.c b/ipc/namespace.c
index aa18899..3c3e522 100644 (file)
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -15,7 +15,8 @@
 
 #include "util.h"
 
-static struct ipc_namespace *create_ipc_ns(struct ipc_namespace *old_ns)
+static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
+                                          struct ipc_namespace *old_ns)
 {
        struct ipc_namespace *ns;
        int err;
@@ -44,17 +45,19 @@ static struct ipc_namespace *create_ipc_ns(struct ipc_namespace *old_ns)
        ipcns_notify(IPCNS_CREATED);
        register_ipcns_notifier(ns);
 
-       ns->user_ns = old_ns->user_ns;
-       get_user_ns(ns->user_ns);
+       ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
 
        return ns;
 }
 
-struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
+struct ipc_namespace *copy_ipcs(unsigned long flags,
+                               struct task_struct *tsk)
 {
+       struct ipc_namespace *ns = tsk->nsproxy->ipc_ns;
+
        if (!(flags & CLONE_NEWIPC))
                return get_ipc_ns(ns);
-       return create_ipc_ns(ns);
+       return create_ipc_ns(tsk, ns);
 }
 
 /*

diff --git a/ipc/sem.c b/ipc/sem.c
index 0e0d49b..ae040a0 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -817,7 +817,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
                }
 
                err = -EACCES;
-               if (ipcperms (&sma->sem_perm, S_IRUGO))
+               if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
                        goto out_unlock;
 
                err = security_sem_semctl(sma, cmd);
@@ -862,7 +862,8 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
        nsems = sma->sem_nsems;
 
        err = -EACCES;
-       if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO))
+       if (ipcperms(ns, &sma->sem_perm,
+                       (cmd == SETVAL || cmd == SETALL) ? S_IWUGO : S_IRUGO))
                goto out_unlock;
 
        err = security_sem_semctl(sma, cmd);
@@ -1047,7 +1048,8 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
                        return -EFAULT;
        }
 
-       ipcp = ipcctl_pre_down(&sem_ids(ns), semid, cmd, &semid64.sem_perm, 0);
+       ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid, cmd,
+                              &semid64.sem_perm, 0);
        if (IS_ERR(ipcp))
                return PTR_ERR(ipcp);
 
@@ -1386,7 +1388,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
                goto out_unlock_free;
 
        error = -EACCES;
-       if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
+       if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
                goto out_unlock_free;
 
        error = security_sem_semop(sma, sops, nsops, alter);

diff --git a/ipc/shm.c b/ipc/shm.c
index 7d3bb22..8644452 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -623,7 +623,8 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
                        return -EFAULT;
        }
 
-       ipcp = ipcctl_pre_down(&shm_ids(ns), shmid, cmd, &shmid64.shm_perm, 0);
+       ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
+                              &shmid64.shm_perm, 0);
        if (IS_ERR(ipcp))
                return PTR_ERR(ipcp);
 
@@ -737,7 +738,7 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
                        result = 0;
                }
                err = -EACCES;
-               if (ipcperms (&shp->shm_perm, S_IRUGO))
+               if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
                        goto out_unlock;
                err = security_shm_shmctl(shp, cmd);
                if (err)
@@ -773,7 +774,7 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 
                audit_ipc_obj(&(shp->shm_perm));
 
-               if (!capable(CAP_IPC_LOCK)) {
+               if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
                        uid_t euid = current_euid();
                        err = -EPERM;
                        if (euid != shp->shm_perm.uid &&
@@ -888,7 +889,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
        }
 
        err = -EACCES;
-       if (ipcperms(&shp->shm_perm, acc_mode))
+       if (ipcperms(ns, &shp->shm_perm, acc_mode))
                goto out_unlock;
 
        err = security_shm_shmat(shp, shmaddr, shmflg);

diff --git a/ipc/util.c b/ipc/util.c
index 69a0cc1..8fd1b89 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -329,12 +329,14 @@ retry:
  *
  *     It is called with ipc_ids.rw_mutex and ipcp->lock held.
  */
-static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
-                       struct ipc_params *params)
+static int ipc_check_perms(struct ipc_namespace *ns,
+                          struct kern_ipc_perm *ipcp,
+                          struct ipc_ops *ops,
+                          struct ipc_params *params)
 {
        int err;
 
-       if (ipcperms(ipcp, params->flg))
+       if (ipcperms(ns, ipcp, params->flg))
                err = -EACCES;
        else {
                err = ops->associate(ipcp, params->flg);
@@ -396,7 +398,7 @@ retry:
                                 * ipc_check_perms returns the IPC id on
                                 * success
                                 */
-                               err = ipc_check_perms(ipcp, ops, params);
+                               err = ipc_check_perms(ns, ipcp, ops, params);
                }
                ipc_unlock(ipcp);
        }
@@ -610,10 +612,12 @@ void ipc_rcu_putref(void *ptr)
  *
  *     Check user, group, other permissions for access
  *     to ipc resources. return 0 if allowed
+ *
+ *     @flag will most probably be 0 or S_...UGO from <linux/stat.h>
  */
  
-int ipcperms (struct kern_ipc_perm *ipcp, short flag)
-{      /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
+int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
+{
        uid_t euid = current_euid();
        int requested_mode, granted_mode;
 
@@ -627,7 +631,7 @@ int ipcperms (struct kern_ipc_perm *ipcp, short flag)
                granted_mode >>= 3;
        /* is there some bit set in requested_mode but not in granted_mode? */
        if ((requested_mode & ~granted_mode & 0007) && 
-           !capable(CAP_IPC_OWNER))
+           !ns_capable(ns->user_ns, CAP_IPC_OWNER))
                return -1;
 
        return security_ipc_permission(ipcp, flag);
@@ -765,6 +769,7 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 
 /**
  * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
+ * @ids:  the ipc namespace
  * @ids:  the table of ids where to look for the ipc
  * @id:   the id of the ipc to retrieve
  * @cmd:  the cmd to check
@@ -779,7 +784,8 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
  *  - returns the ipc with both ipc and rw_mutex locks held in case of success
  *    or an err-code without any lock held otherwise.
  */
-struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
+struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
+                                     struct ipc_ids *ids, int id, int cmd,
                                      struct ipc64_perm *perm, int extra_perm)
 {
        struct kern_ipc_perm *ipcp;
@@ -799,8 +805,8 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
                                         perm->gid, perm->mode);
 
        euid = current_euid();
-       if (euid == ipcp->cuid ||
-           euid == ipcp->uid  || capable(CAP_SYS_ADMIN))
+       if (euid == ipcp->cuid || euid == ipcp->uid  ||
+           ns_capable(ns->user_ns, CAP_SYS_ADMIN))
                return ipcp;
 
        err = -EPERM;

diff --git a/ipc/util.h b/ipc/util.h
index 764b51a..6f5c20b 100644 (file)
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -103,7 +103,7 @@ int ipc_get_maxid(struct ipc_ids *);
 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 
 /* must be called with ipcp locked */
-int ipcperms(struct kern_ipc_perm *ipcp, short flg);
+int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 
 /* for rare, potentially huge allocations.
  * both function can sleep
@@ -126,7 +126,8 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
-struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
+struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
+                                     struct ipc_ids *ids, int id, int cmd,
                                      struct ipc64_perm *perm, int extra_perm);
 
 #ifndef __ARCH_WANT_IPC_PARSE_VERSION

diff --git a/kernel/futex.c b/kernel/futex.c
index bda4157..6570c45 100644 (file)
--- 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 a7934ac..5f9e689 100644 (file)
--- 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 253dc0f..1cc476d 100644 (file)
--- 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 ac8a56e..a05d191 100644 (file)
--- 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 a172494..480adeb 100644 (file)
--- 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 4192098..51c6e89 100644 (file)
--- 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;