[PATCH v18 50/80] c/r (ipc): allow allocation of a desired ipc identifier

Oren Laadan
2009-09-24T00:42:22Z

During restart, we need to allocate ipc objects that with the same
identifiers as recorded during checkpoint. Modify the allocation
code allow an in-kernel caller to request a specific ipc identifier.
The system call interface remains unchanged.

Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
---
ipc/msg.c | 17 ++++++++++++-----
ipc/sem.c | 17 ++++++++++++-----
ipc/shm.c | 19 +++++++++++++------
ipc/util.c | 42 +++++++++++++++++++++++++++++-------------
ipc/util.h | 9 +++++----
5 files changed, 71 insertions(+), 33 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index 2ceab7f..1db7c45 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -73,7 +73,7 @@ struct msg_sender {
#define msg_unlock(msq) ipc_unlock(&(msq)->q_perm)

static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
-static int newque(struct ipc_namespace *, struct ipc_params *);
+static int newque(struct ipc_namespace *, struct ipc_params *, int);
#ifdef CONFIG_PROC_FS
static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
#endif
@@ -174,10 +174,12 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
* newque - Create a new msg queue
* @ns: namespace
* @params: ptr to the structure that contains the key and msgflg
+ * @req_id: request desired id if available (-1 if don't care)
*
* Called with msg_ids.rw_mutex held (writer)
*/
-static int newque(struct ipc_namespace *ns, struct ipc_params *params)
+static int
+newque(struct ipc_namespace *ns, struct ipc_params *params, int req_id)
{
struct msg_queue *msq;
int id, retval;
@@ -201,7 +203,7 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
/*
* ipc_addid() locks msq
*/
- id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
+ id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni, req_id);
if (id < 0) {
security_msg_queue_free(msq);
ipc_rcu_putref(msq);
@@ -309,7 +311,7 @@ static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
return security_msg_queue_associate(msq, msgflg);
}

-SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
+int do_msgget(key_t key, int msgflg, int req_id)
{
struct ipc_namespace *ns;
struct ipc_ops msg_ops;
@@ -324,7 +326,12 @@ SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
msg_params.key = key;
msg_params.flg = msgflg;

- return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
+ return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params, req_id);
+}
+
+SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
+{
+ return do_msgget(key, msgflg, -1);
}

static inline unsigned long
diff --git a/ipc/sem.c b/ipc/sem.c
index 87c2b64..a2b2135 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -92,7 +92,7 @@
#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid)

-static int newary(struct ipc_namespace *, struct ipc_params *);
+static int newary(struct ipc_namespace *, struct ipc_params *, int);
static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
#ifdef CONFIG_PROC_FS
static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
@@ -227,11 +227,13 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
* newary - Create a new semaphore set
* @ns: namespace
* @params: ptr to the structure that contains key, semflg and nsems
+ * @req_id: request desired id if available (-1 if don't care)
*
* Called with sem_ids.rw_mutex held (as a writer)
*/

-static int newary(struct ipc_namespace *ns, struct ipc_params *params)
+static int
+newary(struct ipc_namespace *ns, struct ipc_params *params, int req_id)
{
int id;
int retval;
@@ -263,7 +265,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
return retval;
}

- id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
+ id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni, req_id);
if (id < 0) {
security_sem_free(sma);
ipc_rcu_putref(sma);
@@ -308,7 +310,7 @@ static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
return 0;
}

-SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
+int do_semget(key_t key, int nsems, int semflg, int req_id)
{
struct ipc_namespace *ns;
struct ipc_ops sem_ops;
@@ -327,7 +329,12 @@ SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
sem_params.flg = semflg;
sem_params.u.nsems = nsems;

- return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
+ return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params, req_id);
+}
+
+SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
+{
+ return do_semget(key, nsems, semflg, -1);
}

/*
diff --git a/ipc/shm.c b/ipc/shm.c
index 1bc4701..749dd57 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -62,7 +62,7 @@ static struct vm_operations_struct shm_vm_ops;
#define shm_unlock(shp) \
ipc_unlock(&(shp)->shm_perm)

-static int newseg(struct ipc_namespace *, struct ipc_params *);
+static int newseg(struct ipc_namespace *, struct ipc_params *, int);
static void shm_open(struct vm_area_struct *vma);
static void shm_close(struct vm_area_struct *vma);
static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
@@ -83,7 +83,7 @@ void shm_init_ns(struct ipc_namespace *ns)
* Called with shm_ids.rw_mutex (writer) and the shp structure locked.
* Only shm_ids.rw_mutex remains locked on exit.
*/
-static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
+void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
{
struct shmid_kernel *shp;
shp = container_of(ipcp, struct shmid_kernel, shm_perm);
@@ -326,11 +326,13 @@ static struct vm_operations_struct shm_vm_ops = {
* newseg - Create a new shared memory segment
* @ns: namespace
* @params: ptr to the structure that contains key, size and shmflg
+ * @req_id: request desired id if available (-1 if don't care)
*
* Called with shm_ids.rw_mutex held as a writer.
*/

-static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
+static int
+newseg(struct ipc_namespace *ns, struct ipc_params *params, int req_id)
{
key_t key = params->key;
int shmflg = params->flg;
@@ -385,7 +387,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
if (IS_ERR(file))
goto no_file;

- id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
+ id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni, req_id);
if (id < 0) {
error = id;
goto no_id;
@@ -445,7 +447,7 @@ static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
return 0;
}

-SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
+int do_shmget(key_t key, size_t size, int shmflg, int req_id)
{
struct ipc_namespace *ns;
struct ipc_ops shm_ops;
@@ -461,7 +463,12 @@ SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
shm_params.flg = shmflg;
shm_params.u.size = size;

- return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
+ return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params, req_id);
+}
+
+SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
+{
+ return do_shmget(key, size, shmflg, -1);
}

static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
diff --git a/ipc/util.c b/ipc/util.c
index b8e4ba9..ca248ec 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -247,10 +247,12 @@ int ipc_get_maxid(struct ipc_ids *ids)
* Called with ipc_ids.rw_mutex held as a writer.
*/

-int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
+int
+ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size, int req_id)
{
uid_t euid;
gid_t egid;
+ int lid = 0;
int id, err;

if (size > IPCMNI)
@@ -259,28 +261,41 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
if (ids->in_use >= size)
return -ENOSPC;

+ if (req_id >= 0)
+ lid = ipcid_to_idx(req_id);
+
spin_lock_init(&new->lock);
new->deleted = 0;
rcu_read_lock();
spin_lock(&new->lock);

- err = idr_get_new(&ids->ipcs_idr, new, &id);
+ err = idr_get_new_above(&ids->ipcs_idr, new, lid, &id);
if (err) {
spin_unlock(&new->lock);
rcu_read_unlock();
return err;
}

+ if (req_id >= 0) {
+ if (id != lid) {
+ idr_remove(&ids->ipcs_idr, id);
+ spin_unlock(&new->lock);
+ rcu_read_unlock();
+ return -EBUSY;
+ }
+ new->seq = req_id / SEQ_MULTIPLIER;
+ } else {
+ new->seq = ids->seq++;
+ if (ids->seq > ids->seq_max)
+ ids->seq = 0;
+ }
+
ids->in_use++;

current_euid_egid(&euid, &egid);
new->cuid = new->uid = euid;
new->gid = new->cgid = egid;

- new->seq = ids->seq++;
- if(ids->seq > ids->seq_max)
- ids->seq = 0;
-
new->id = ipc_buildid(id, new->seq);
return id;
}
@@ -296,7 +311,7 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
* when the key is IPC_PRIVATE.
*/
static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
- struct ipc_ops *ops, struct ipc_params *params)
+ struct ipc_ops *ops, struct ipc_params *params, int req_id)
{
int err;
retry:
@@ -306,7 +321,7 @@ retry:
return -ENOMEM;

down_write(&ids->rw_mutex);
- err = ops->getnew(ns, params);
+ err = ops->getnew(ns, params, req_id);
up_write(&ids->rw_mutex);

if (err == -EAGAIN)
@@ -351,6 +366,7 @@ static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
* @ids: IPC identifer set
* @ops: the actual creation routine to call
* @params: its parameters
+ * @req_id: request desired id if available (-1 if don't care)
*
* This routine is called by sys_msgget, sys_semget() and sys_shmget()
* when the key is not IPC_PRIVATE.
@@ -360,7 +376,7 @@ static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
* On success, the ipc id is returned.
*/
static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
- struct ipc_ops *ops, struct ipc_params *params)
+ struct ipc_ops *ops, struct ipc_params *params, int req_id)
{
struct kern_ipc_perm *ipcp;
int flg = params->flg;
@@ -381,7 +397,7 @@ retry:
else if (!err)
err = -ENOMEM;
else
- err = ops->getnew(ns, params);
+ err = ops->getnew(ns, params, req_id);
} else {
/* ipc object has been locked by ipc_findkey() */

@@ -742,12 +758,12 @@ struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
* Common routine called by sys_msgget(), sys_semget() and sys_shmget().
*/
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
- struct ipc_ops *ops, struct ipc_params *params)
+ struct ipc_ops *ops, struct ipc_params *params, int req_id)
{
if (params->key == IPC_PRIVATE)
- return ipcget_new(ns, ids, ops, params);
+ return ipcget_new(ns, ids, ops, params, req_id);
else
- return ipcget_public(ns, ids, ops, params);
+ return ipcget_public(ns, ids, ops, params, req_id);
}

/**
diff --git a/ipc/util.h b/ipc/util.h
index 764b51a..159a73c 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -71,7 +71,7 @@ struct ipc_params {
* . routine to call for an extra check if needed
*/
struct ipc_ops {
- int (*getnew) (struct ipc_namespace *, struct ipc_params *);
+ int (*getnew) (struct ipc_namespace *, struct ipc_params *, int);
int (*associate) (struct kern_ipc_perm *, int);
int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
};
@@ -94,7 +94,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)

/* must be called with ids->rw_mutex acquired for writing */
-int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
+int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int, int);

/* must be called with ids->rw_mutex acquired for reading */
int ipc_get_maxid(struct ipc_ids *);
@@ -171,7 +171,8 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)

struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
- struct ipc_ops *ops, struct ipc_params *params);
+ struct ipc_ops *ops, struct ipc_params *params, int req_id);
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
- void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
+ void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
+
#endif
--
1.6.0.4