userns: Convert ipc to use kuid and kgid where appropriate

- Store the ipc owner and creator with a kuid
- Store the ipc group and the crators group with a kgid.
- Add error handling to ipc_update_perms, allowing it to
  fail if the uids and gids can not be converted to kuids
  or kgids.
- Modify the proc files to display the ipc creator and
  owner in the user namespace of the opener of the proc file.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

5 files changed, 50 insertions, 33 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 7385de25788a..a71af5a65abf 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -443,9 +443,12 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
                         goto out_unlock;
                 }
 
+                err = ipc_update_perm(&msqid64.msg_perm, ipcp);
+                if (err)
+                        goto out_unlock;
+
                 msq->q_qbytes = msqid64.msg_qbytes;
 
-                ipc_update_perm(&msqid64.msg_perm, ipcp);
                 msq->q_ctime = get_seconds();
                 /* sleeping receivers might be excluded by
                  * stricter permissions.
@@ -922,6 +925,7 @@ out:
 #ifdef CONFIG_PROC_FS
 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
 {
+        struct user_namespace *user_ns = seq_user_ns(s);
         struct msg_queue *msq = it;
 
         return seq_printf(s,
@@ -933,10 +937,10 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
                         msq->q_qnum,
                         msq->q_lspid,
                         msq->q_lrpid,
-                        msq->q_perm.uid,
-                        msq->q_perm.gid,
-                        msq->q_perm.cuid,
-                        msq->q_perm.cgid,
+                        from_kuid_munged(user_ns, msq->q_perm.uid),
+                        from_kgid_munged(user_ns, msq->q_perm.gid),
+                        from_kuid_munged(user_ns, msq->q_perm.cuid),
+                        from_kgid_munged(user_ns, msq->q_perm.cgid),
                         msq->q_stime,
                         msq->q_rtime,
                         msq->q_ctime);
diff --git a/ipc/sem.c b/ipc/sem.c
index 5215a81420df..58d31f1c1eb5 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1104,7 +1104,9 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
                 freeary(ns, ipcp);
                 goto out_up;
         case IPC_SET:
-                ipc_update_perm(&semid64.sem_perm, ipcp);
+                err = ipc_update_perm(&semid64.sem_perm, ipcp);
+                if (err)
+                        goto out_unlock;
                 sma->sem_ctime = get_seconds();
                 break;
         default:
@@ -1677,6 +1679,7 @@ void exit_sem(struct task_struct *tsk)
 #ifdef CONFIG_PROC_FS
 static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
 {
+        struct user_namespace *user_ns = seq_user_ns(s);
         struct sem_array *sma = it;
 
         return seq_printf(s,
@@ -1685,10 +1688,10 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
                           sma->sem_perm.id,
                           sma->sem_perm.mode,
                           sma->sem_nsems,
-                          sma->sem_perm.uid,
-                          sma->sem_perm.gid,
-                          sma->sem_perm.cuid,
-                          sma->sem_perm.cgid,
+                          from_kuid_munged(user_ns, sma->sem_perm.uid),
+                          from_kgid_munged(user_ns, sma->sem_perm.gid),
+                          from_kuid_munged(user_ns, sma->sem_perm.cuid),
+                          from_kgid_munged(user_ns, sma->sem_perm.cgid),
                           sma->sem_otime,
                           sma->sem_ctime);
 }
diff --git a/ipc/shm.c b/ipc/shm.c
index 00faa05cf72a..dff40c9f73c9 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -758,7 +758,9 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
                 do_shm_rmid(ns, ipcp);
                 goto out_up;
         case IPC_SET:
-                ipc_update_perm(&shmid64.shm_perm, ipcp);
+                err = ipc_update_perm(&shmid64.shm_perm, ipcp);
+                if (err)
+                        goto out_unlock;
                 shp->shm_ctim = get_seconds();
                 break;
         default:
@@ -893,10 +895,10 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
                 audit_ipc_obj(&(shp->shm_perm));
 
                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
-                        uid_t euid = current_euid();
+                        kuid_t euid = current_euid();
                         err = -EPERM;
-                        if (euid != shp->shm_perm.uid &&
-                            euid != shp->shm_perm.cuid)
+                        if (!uid_eq(euid, shp->shm_perm.uid) &&
+                            !uid_eq(euid, shp->shm_perm.cuid))
                                 goto out_unlock;
                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
                                 goto out_unlock;
@@ -1220,6 +1222,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
 #ifdef CONFIG_PROC_FS
 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
 {
+        struct user_namespace *user_ns = seq_user_ns(s);
         struct shmid_kernel *shp = it;
         unsigned long rss = 0, swp = 0;
 
@@ -1242,10 +1245,10 @@ static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
                           shp->shm_cprid,
                           shp->shm_lprid,
                           shp->shm_nattch,
-                          shp->shm_perm.uid,
-                          shp->shm_perm.gid,
-                          shp->shm_perm.cuid,
-                          shp->shm_perm.cgid,
+                          from_kuid_munged(user_ns, shp->shm_perm.uid),
+                          from_kgid_munged(user_ns, shp->shm_perm.gid),
+                          from_kuid_munged(user_ns, shp->shm_perm.cuid),
+                          from_kgid_munged(user_ns, shp->shm_perm.cgid),
                           shp->shm_atim,
                           shp->shm_dtim,
                           shp->shm_ctim,
diff --git a/ipc/util.c b/ipc/util.c
index eb07fd356f27..72fd0785ac94 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -249,8 +249,8 @@ int ipc_get_maxid(struct ipc_ids *ids)
  
 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 {
-        uid_t euid;
-        gid_t egid;
+        kuid_t euid;
+        kgid_t egid;
         int id, err;
 
         if (size > IPCMNI)
@@ -606,14 +606,14 @@ void ipc_rcu_putref(void *ptr)
  
 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 {
-        uid_t euid = current_euid();
+        kuid_t euid = current_euid();
         int requested_mode, granted_mode;
 
         audit_ipc_obj(ipcp);
         requested_mode = (flag >> 6) | (flag >> 3) | flag;
         granted_mode = ipcp->mode;
-        if (euid == ipcp->cuid ||
-            euid == ipcp->uid)
+        if (uid_eq(euid, ipcp->cuid) ||
+            uid_eq(euid, ipcp->uid))
                 granted_mode >>= 6;
         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
                 granted_mode >>= 3;
@@ -643,10 +643,10 @@ int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
 {
         out->key        = in->key;
-        out->uid        = in->uid;
-        out->gid        = in->gid;
-        out->cuid       = in->cuid;
-        out->cgid       = in->cgid;
+        out->uid        = from_kuid_munged(current_user_ns(), in->uid);
+        out->gid        = from_kgid_munged(current_user_ns(), in->gid);
+        out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
+        out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
         out->mode       = in->mode;
         out->seq        = in->seq;
 }
@@ -747,12 +747,19 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
  * @in:  the permission given as input.
  * @out: the permission of the ipc to set.
  */
-void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
+int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 {
-        out->uid = in->uid;
-        out->gid = in->gid;
+        kuid_t uid = make_kuid(current_user_ns(), in->uid);
+        kgid_t gid = make_kgid(current_user_ns(), in->gid);
+        if (!uid_valid(uid) || !gid_valid(gid))
+                return -EINVAL;
+
+        out->uid = uid;
+        out->gid = gid;
         out->mode = (out->mode & ~S_IRWXUGO)
                 | (in->mode & S_IRWXUGO);
+
+        return 0;
 }
 
 /**
@@ -777,7 +784,7 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
                                       struct ipc64_perm *perm, int extra_perm)
 {
         struct kern_ipc_perm *ipcp;
-        uid_t euid;
+        kuid_t euid;
         int err;
 
         down_write(&ids->rw_mutex);
@@ -793,7 +800,7 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
                                          perm->gid, perm->mode);
 
         euid = current_euid();
-        if (euid == ipcp->cuid || euid == ipcp->uid  ||
+        if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
                 return ipcp;
 
diff --git a/ipc/util.h b/ipc/util.h
index 850ef3e962cb..c8fe2f7631e9 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -125,7 +125,7 @@ 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);
+int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 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);