From: Pierre Peiffer <[EMAIL PROTECTED]>
This patch provides three new API to change the ID of an existing
System V IPCs.
These APIs are:
long msg_chid(struct ipc_namespace *ns, int id, int newid);
long sem_chid(struct ipc_namespace *ns, int id, int newid);
long shm_chid(struct ipc_namespace *ns, int id, int newid);
They return 0 or an error code in case of failure.
They may be useful for setting a specific ID for an IPC when preparing
a restart operation.
To be successful, the following rules must be respected:
- the IPC exists (of course...)
- the new ID must satisfy the ID computation rule.
- the entry in the idr corresponding to the new ID must be free.
Signed-off-by: Pierre Peiffer <[EMAIL PROTECTED]>
Acked-by: Serge Hallyn <[EMAIL PROTECTED]>
---
include/linux/msg.h | 2 ++
include/linux/sem.h | 2 ++
include/linux/shm.h | 3 +++
ipc/msg.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
ipc/sem.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
ipc/shm.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
ipc/util.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
ipc/util.h | 1 +
8 files changed, 197 insertions(+)
Index: b/include/linux/msg.h
===================================================================
--- a/include/linux/msg.h
+++ b/include/linux/msg.h
@@ -63,6 +63,7 @@ struct msginfo {
#ifdef __KERNEL__
#include <linux/list.h>
+#include <linux/ipc_namespace.h>
/* one msg_msg structure for each message */
struct msg_msg {
@@ -96,6 +97,7 @@ extern long do_msgsnd(int msqid, long mt
size_t msgsz, int msgflg);
extern long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
size_t msgsz, long msgtyp, int msgflg);
+long msg_chid(struct ipc_namespace *ns, int id, int newid);
#endif /* __KERNEL__ */
Index: b/include/linux/sem.h
===================================================================
--- a/include/linux/sem.h
+++ b/include/linux/sem.h
@@ -138,9 +138,11 @@ struct sysv_sem {
};
#ifdef CONFIG_SYSVIPC
+#include <linux/ipc_namespace.h>
extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);
extern void exit_sem(struct task_struct *tsk);
+long sem_chid(struct ipc_namespace *ns, int id, int newid);
#else
static inline int copy_semundo(unsigned long clone_flags, struct task_struct
*tsk)
Index: b/include/linux/shm.h
===================================================================
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -104,8 +104,11 @@ struct shmid_kernel /* private to the ke
#define SHM_NORESERVE 010000 /* don't check for reservations */
#ifdef CONFIG_SYSVIPC
+#include <linux/ipc_namespace.h>
+
long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long
*addr);
extern int is_file_shm_hugepages(struct file *file);
+long shm_chid(struct ipc_namespace *ns, int id, int newid);
#else
static inline long do_shmat(int shmid, char __user *shmaddr,
int shmflg, unsigned long *addr)
Index: b/ipc/msg.c
===================================================================
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -291,6 +291,51 @@ asmlinkage long sys_msgget(key_t key, in
return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
}
+/* must be called with mutex and msq locks held */
+static long msg_chid_nolock(struct ipc_namespace *ns, struct msg_queue *msq,
+ int newid)
+{
+ long err;
+
+ err = ipc_chid(&msg_ids(ns), msq->q_perm.id, newid);
+ if (!err)
+ msq->q_ctime = get_seconds();
+
+ return err;
+}
+
+/* API to use for changing an id from kernel space, not from the syscall, as
+ there is no permission check done here */
+long msg_chid(struct ipc_namespace *ns, int id, int newid)
+{
+ long err;
+ struct msg_queue *msq;
+
+retry:
+ err = idr_pre_get(&msg_ids(ns).ipcs_idr, GFP_KERNEL);
+ if (!err)
+ return -ENOMEM;
+
+ down_write(&msg_ids(ns).rw_mutex);
+ msq = msg_lock_check(ns, id);
+
+ if (IS_ERR(msq)) {
+ up_write(&msg_ids(ns).rw_mutex);
+ return PTR_ERR(msq);
+ }
+
+ err = msg_chid_nolock(ns, msq, newid);
+
+ msg_unlock(msq);
+ up_write(&msg_ids(ns).rw_mutex);
+
+ /* ipc_chid may return -EAGAIN in case of memory requirement */
+ if (err == -EAGAIN)
+ goto retry;
+
+ return err;
+}
+
static inline unsigned long
copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
{
Index: b/ipc/sem.c
===================================================================
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -564,6 +564,57 @@ static void freeary(struct ipc_namespace
ipc_rcu_putref(sma);
}
+/* must be called with rw_mutex and sma locks held */
+static long sem_chid_nolock(struct ipc_namespace *ns, struct sem_array *sma,
+ int newid)
+{
+ long err;
+
+ err = ipc_chid(&sem_ids(ns), sma->sem_perm.id, newid);
+
+ if (!err) {
+ struct sem_undo *un;
+ for (un = sma->undo; un; un = un->id_next)
+ un->semid = newid;
+
+ sma->sem_ctime = get_seconds();
+ }
+
+ return err;
+}
+
+/* API to use for changing an id from kernel space, not from the syscall, as
+ there is no permission check done here */
+long sem_chid(struct ipc_namespace *ns, int id, int newid)
+{
+ long err;
+ struct sem_array *sma;
+
+retry:
+ err = idr_pre_get(&sem_ids(ns).ipcs_idr, GFP_KERNEL);
+ if (!err)
+ return -ENOMEM;
+
+ down_write(&sem_ids(ns).rw_mutex);
+ sma = sem_lock_check(ns, id);
+
+ if (IS_ERR(sma)) {
+ up_write(&sem_ids(ns).rw_mutex);
+ return PTR_ERR(sma);
+ }
+
+ err = sem_chid_nolock(ns, sma, newid);
+
+ sem_unlock(sma);
+ up_write(&sem_ids(ns).rw_mutex);
+
+ /* ipc_chid may return -EAGAIN in case of memory requirement */
+ if (err == -EAGAIN)
+ goto retry;
+
+ return err;
+}
+
static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds
*in, int version)
{
switch(version) {
Index: b/ipc/shm.c
===================================================================
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -162,7 +162,52 @@ static inline int shm_addid(struct ipc_n
return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
}
+/* must be called with mutex and shp locks held */
+static long shm_chid_nolock(struct ipc_namespace *ns, struct shmid_kernel *shp,
+ int newid)
+{
+ long err;
+
+ err = ipc_chid(&shm_ids(ns), shp->shm_perm.id, newid);
+ if (!err) {
+ shp->shm_file->f_dentry->d_inode->i_ino = newid;
+ shp->shm_ctim = get_seconds();
+ }
+
+ return err;
+}
+
+/* API to use for changing an id from kernel space, not from the syscall, as
+ there is no permission check done here */
+long shm_chid(struct ipc_namespace *ns, int id, int newid)
+{
+ long err;
+ struct shmid_kernel *shp;
+
+retry:
+ err = idr_pre_get(&shm_ids(ns).ipcs_idr, GFP_KERNEL);
+ if (!err)
+ return -ENOMEM;
+
+ down_write(&shm_ids(ns).rw_mutex);
+ shp = shm_lock_check(ns, id);
+
+ if (IS_ERR(shp)) {
+ up_write(&shm_ids(ns).rw_mutex);
+ return PTR_ERR(shp);
+ }
+
+ err = shm_chid_nolock(ns, shp, newid);
+ shm_unlock(shp);
+ up_write(&shm_ids(ns).rw_mutex);
+
+ /* ipc_chid may return -EAGAIN in case of memory requirement */
+ if (err == -EAGAIN)
+ goto retry;
+
+ return err;
+}
/* This is called by fork, once for every shm attach. */
static void shm_open(struct vm_area_struct *vma)
Index: b/ipc/util.c
===================================================================
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -363,6 +363,54 @@ retry:
/**
+ * ipc_chid - change an IPC identifier
+ * @ids: IPC identifier set
+ * @oldid: ID of the IPC permission set to move
+ * @newid: new ID of the IPC permission set to move
+ *
+ * Move an entry in the IPC idr from the 'oldid' place to the
+ * 'newid' place. The seq number of the entry is updated to match the
+ * 'newid' value.
+ *
+ * Called with the ipc lock and ipc_ids.rw_mutex held.
+ */
+int ipc_chid(struct ipc_ids *ids, int oldid, int newid)
+{
+ struct kern_ipc_perm *p;
+ int old_lid = oldid % SEQ_MULTIPLIER;
+ int new_lid = newid % SEQ_MULTIPLIER;
+
+ if (newid != (new_lid + (newid/SEQ_MULTIPLIER)*SEQ_MULTIPLIER))
+ return -EINVAL;
+
+ p = idr_find(&ids->ipcs_idr, old_lid);
+
+ if (!p)
+ return -EINVAL;
+
+ /* The idx in the idr may be the same but not the seq number. */
+ if (new_lid != old_lid) {
+ int id, err;
+
+ err = idr_get_new_above(&ids->ipcs_idr, p, new_lid, &id);
+ if (err)
+ return err;
+
+ /* do we get our wished id ? */
+ if (id == new_lid) {
+ idr_remove(&ids->ipcs_idr, old_lid);
+ } else {
+ idr_remove(&ids->ipcs_idr, id);
+ return -EBUSY;
+ }
+ }
+
+ p->id = newid;
+ p->seq = newid/SEQ_MULTIPLIER;
+ return 0;
+}
+
+/**
* ipc_rmid - remove an IPC identifier
* @ids: IPC identifier set
* @ipcp: ipc perm structure containing the identifier to remove
Index: b/ipc/util.h
===================================================================
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -85,6 +85,7 @@ int ipc_get_maxid(struct ipc_ids *);
void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
/* must be called with ipcp locked */
+int ipc_chid(struct ipc_ids *ids, int oldid, int newid);
int ipcperms(struct kern_ipc_perm *ipcp, short flg);
/* for rare, potentially huge allocations.
--
Pierre Peiffer
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