pid namespaces: helpers to obtain pid numbers

When showing pid to user or getting the pid numerical id for in-kernel use the value of this id may differ depending on the namespace. This set of helpers is used to get the global pid nr, the virtual (i.e. seen by task in its namespace) nr and the nr as it is seen from the specified namespace. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

pid namespaces: helpers to obtain pid numbers
When showing pid to user or getting the pid numerical id for in-kernel use the value of this id may differ depending on the namespace. This set of helpers is used to get the global pid nr, the virtual (i.e. seen by task in its namespace) nr and the nr as it is seen from the specified namespace. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Cc: Paul Menage <menage@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pavel Emelyanov · Linus Torvalds
1 parent 8ef047aaae
Showing 3 changed files with 134 additions and 11 deletions Side-by-side Diff
include/linux/pid.h
include/linux/sched.h
kernel/pid.c
@@ -114,11 +114,33 @@
 extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
  
+/*
+ * the helpers to get the pid's id seen from different namespaces
+ *
+ * pid_nr()    : global id, i.e. the id seen from the init namespace;
+ * pid_vnr()   : virtual id, i.e. the id seen from the namespace this pid
+ *               belongs to. this only makes sence when called in the
+ *               context of the task that belongs to the same namespace;
+ * pid_nr_ns() : id seen from the ns specified.
+ *
+ * see also task_xid_nr() etc in include/linux/sched.h
+ */
+
 static inline pid_t pid_nr(struct pid *pid)
 {
 	pid_t nr = 0;
 	if (pid)
-		nr = pid->nr;
+		nr = pid->numbers[0].nr;
+	return nr;
+}
+
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns);
+
+static inline pid_t pid_vnr(struct pid *pid)
+{
+	pid_t nr = 0;
+	if (pid)
+		nr = pid->numbers[pid->level].nr;
 	return nr;
 }
  
@@ -1188,16 +1188,6 @@
 	return rt_prio(p->prio);
 }
  
-static inline pid_t task_pgrp_nr(struct task_struct *tsk)
-{
-	return tsk->signal->pgrp;
-}
-
-static inline pid_t task_session_nr(struct task_struct *tsk)
-{
-	return tsk->signal->__session;
-}
-
 static inline void set_task_session(struct task_struct *tsk, pid_t session)
 {
 	tsk->signal->__session = session;
@@ -1221,6 +1211,104 @@
 static inline struct pid *task_session(struct task_struct *task)
 {
 	return task->group_leader->pids[PIDTYPE_SID].pid;
+}
+
+struct pid_namespace;
+
+/*
+ * the helpers to get the task's different pids as they are seen
+ * from various namespaces
+ *
+ * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
+ * task_xid_vnr()    : virtual id, i.e. the id seen from the namespace the task
+ *                     belongs to. this only makes sence when called in the
+ *                     context of the task that belongs to the same namespace;
+ * task_xid_nr_ns()  : id seen from the ns specified;
+ *
+ * set_task_vxid()   : assigns a virtual id to a task;
+ *
+ * task_ppid_nr_ns() : the parent's id as seen from the namespace specified.
+ *                     the result depends on the namespace and whether the
+ *                     task in question is the namespace's init. e.g. for the
+ *                     namespace's init this will return 0 when called from
+ *                     the namespace of this init, or appropriate id otherwise.
+ *
+ *
+ * see also pid_nr() etc in include/linux/pid.h
+ */
+
+static inline pid_t task_pid_nr(struct task_struct *tsk)
+{
+	return tsk->pid;
+}
+
+static inline pid_t task_pid_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_pid(tsk), ns);
+}
+
+static inline pid_t task_pid_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_pid(tsk));
+}
+
+
+static inline pid_t task_tgid_nr(struct task_struct *tsk)
+{
+	return tsk->tgid;
+}
+
+static inline pid_t task_tgid_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_tgid(tsk), ns);
+}
+
+static inline pid_t task_tgid_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_tgid(tsk));
+}
+
+
+static inline pid_t task_pgrp_nr(struct task_struct *tsk)
+{
+	return tsk->signal->pgrp;
+}
+
+static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_pgrp(tsk), ns);
+}
+
+static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_pgrp(tsk));
+}
+
+
+static inline pid_t task_session_nr(struct task_struct *tsk)
+{
+	return tsk->signal->__session;
+}
+
+static inline pid_t task_session_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_session(tsk), ns);
+}
+
+static inline pid_t task_session_vnr(struct task_struct *tsk)
+{
+	return pid_vnr(task_session(tsk));
+}
+
+
+static inline pid_t task_ppid_nr_ns(struct task_struct *tsk,
+		struct pid_namespace *ns)
+{
+	return pid_nr_ns(task_pid(rcu_dereference(tsk->real_parent)), ns);
 }
  
 /**
@@ -376,6 +376,19 @@
 	return pid;
 }
  
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
+{
+	struct upid *upid;
+	pid_t nr = 0;
+
+	if (pid && ns->level <= pid->level) {
+		upid = &pid->numbers[ns->level];
+		if (upid->ns == ns)
+			nr = upid->nr;
+	}
+	return nr;
+}
+
 /*
  * Used by proc to find the first pid that is greater then or equal to nr.
  *
...	...	@@ -114,11 +114,33 @@
114	114	extern struct pid alloc_pid(struct pid_namespace ns);
115	115	extern void FASTCALL(free_pid(struct pid *pid));
116	116
	117	+/*
	118	+ * the helpers to get the pid's id seen from different namespaces
	119	+ *
	120	+ * pid_nr() : global id, i.e. the id seen from the init namespace;
	121	+ * pid_vnr() : virtual id, i.e. the id seen from the namespace this pid
	122	+ * belongs to. this only makes sence when called in the
	123	+ * context of the task that belongs to the same namespace;
	124	+ * pid_nr_ns() : id seen from the ns specified.
	125	+ *
	126	+ * see also task_xid_nr() etc in include/linux/sched.h
	127	+ */
	128	+
117	129	static inline pid_t pid_nr(struct pid *pid)
118	130	{
119	131	pid_t nr = 0;
120	132	if (pid)
121		- nr = pid->nr;
	133	+ nr = pid->numbers[0].nr;
	134	+ return nr;
	135	+}
	136	+
	137	+pid_t pid_nr_ns(struct pid pid, struct pid_namespace ns);
	138	+
	139	+static inline pid_t pid_vnr(struct pid *pid)
	140	+{
	141	+ pid_t nr = 0;
	142	+ if (pid)
	143	+ nr = pid->numbers[pid->level].nr;
122	144	return nr;
123	145	}
124	146
...	...	@@ -1188,16 +1188,6 @@
1188	1188	return rt_prio(p->prio);
1189	1189	}
1190	1190
1191		-static inline pid_t task_pgrp_nr(struct task_struct *tsk)
1192		-{
1193		- return tsk->signal->pgrp;
1194		-}
1195		-
1196		-static inline pid_t task_session_nr(struct task_struct *tsk)
1197		-{
1198		- return tsk->signal->__session;
1199		-}
1200		-
1201	1191	static inline void set_task_session(struct task_struct *tsk, pid_t session)
1202	1192	{
1203	1193	tsk->signal->__session = session;
...	...	@@ -1221,6 +1211,104 @@
1221	1211	static inline struct pid task_session(struct task_struct task)
1222	1212	{
1223	1213	return task->group_leader->pids[PIDTYPE_SID].pid;
	1214	+}
	1215	+
	1216	+struct pid_namespace;
	1217	+
	1218	+/*
	1219	+ * the helpers to get the task's different pids as they are seen
	1220	+ * from various namespaces
	1221	+ *
	1222	+ * task_xid_nr() : global id, i.e. the id seen from the init namespace;
	1223	+ * task_xid_vnr() : virtual id, i.e. the id seen from the namespace the task
	1224	+ * belongs to. this only makes sence when called in the
	1225	+ * context of the task that belongs to the same namespace;
	1226	+ * task_xid_nr_ns() : id seen from the ns specified;
	1227	+ *
	1228	+ * set_task_vxid() : assigns a virtual id to a task;
	1229	+ *
	1230	+ * task_ppid_nr_ns() : the parent's id as seen from the namespace specified.
	1231	+ * the result depends on the namespace and whether the
	1232	+ * task in question is the namespace's init. e.g. for the
	1233	+ * namespace's init this will return 0 when called from
	1234	+ * the namespace of this init, or appropriate id otherwise.
	1235	+ *
	1236	+ *
	1237	+ * see also pid_nr() etc in include/linux/pid.h
	1238	+ */
	1239	+
	1240	+static inline pid_t task_pid_nr(struct task_struct *tsk)
	1241	+{
	1242	+ return tsk->pid;
	1243	+}
	1244	+
	1245	+static inline pid_t task_pid_nr_ns(struct task_struct *tsk,
	1246	+ struct pid_namespace *ns)
	1247	+{
	1248	+ return pid_nr_ns(task_pid(tsk), ns);
	1249	+}
	1250	+
	1251	+static inline pid_t task_pid_vnr(struct task_struct *tsk)
	1252	+{
	1253	+ return pid_vnr(task_pid(tsk));
	1254	+}
	1255	+
	1256	+
	1257	+static inline pid_t task_tgid_nr(struct task_struct *tsk)
	1258	+{
	1259	+ return tsk->tgid;
	1260	+}
	1261	+
	1262	+static inline pid_t task_tgid_nr_ns(struct task_struct *tsk,
	1263	+ struct pid_namespace *ns)
	1264	+{
	1265	+ return pid_nr_ns(task_tgid(tsk), ns);
	1266	+}
	1267	+
	1268	+static inline pid_t task_tgid_vnr(struct task_struct *tsk)
	1269	+{
	1270	+ return pid_vnr(task_tgid(tsk));
	1271	+}
	1272	+
	1273	+
	1274	+static inline pid_t task_pgrp_nr(struct task_struct *tsk)
	1275	+{
	1276	+ return tsk->signal->pgrp;
	1277	+}
	1278	+
	1279	+static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
	1280	+ struct pid_namespace *ns)
	1281	+{
	1282	+ return pid_nr_ns(task_pgrp(tsk), ns);
	1283	+}
	1284	+
	1285	+static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
	1286	+{
	1287	+ return pid_vnr(task_pgrp(tsk));
	1288	+}
	1289	+
	1290	+
	1291	+static inline pid_t task_session_nr(struct task_struct *tsk)
	1292	+{
	1293	+ return tsk->signal->__session;
	1294	+}
	1295	+
	1296	+static inline pid_t task_session_nr_ns(struct task_struct *tsk,
	1297	+ struct pid_namespace *ns)
	1298	+{
	1299	+ return pid_nr_ns(task_session(tsk), ns);
	1300	+}
	1301	+
	1302	+static inline pid_t task_session_vnr(struct task_struct *tsk)
	1303	+{
	1304	+ return pid_vnr(task_session(tsk));
	1305	+}
	1306	+
	1307	+
	1308	+static inline pid_t task_ppid_nr_ns(struct task_struct *tsk,
	1309	+ struct pid_namespace *ns)
	1310	+{
	1311	+ return pid_nr_ns(task_pid(rcu_dereference(tsk->real_parent)), ns);
1224	1312	}
1225	1313
1226	1314	/**
...	...	@@ -376,6 +376,19 @@
376	376	return pid;
377	377	}
378	378
	379	+pid_t pid_nr_ns(struct pid pid, struct pid_namespace ns)
	380	+{
	381	+ struct upid *upid;
	382	+ pid_t nr = 0;
	383	+
	384	+ if (pid && ns->level <= pid->level) {
	385	+ upid = &pid->numbers[ns->level];
	386	+ if (upid->ns == ns)
	387	+ nr = upid->nr;
	388	+ }
	389	+ return nr;
	390	+}
	391	+
379	392	/*
380	393	* Used by proc to find the first pid that is greater then or equal to nr.
381	394	*