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Subject[RFC][PATCH 4/6] Integrating ipc_checkid() into ipc_lock()
[PATCH 04/06]


This patch introduces a new ipc_lock_check() routine interface:
. each time ipc_checkid() is called, this is done after calling ipc_lock().
ipc_checkid() is now called from inside ipc_lock_check().


Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>

---
ipc/msg.c | 62 ++++++++++++++++++++----------------------
ipc/sem.c | 70 ++++++++++++++++++++++-------------------------
ipc/shm.c | 90 ++++++++++++++++++++++++++++++++-----------------------------
ipc/util.c | 23 +--------------
ipc/util.h | 40 ++++++++++++++++++++++++---
5 files changed, 149 insertions(+), 136 deletions(-)
Index: linux-2.6.23-rc2/ipc/util.h
===================================================================
--- linux-2.6.23-rc2.orig/ipc/util.h 2007-08-31 11:59:11.000000000 +0200
+++ linux-2.6.23-rc2/ipc/util.h 2007-08-31 12:26:31.000000000 +0200
@@ -103,11 +103,8 @@ void* ipc_rcu_alloc(int size);
void ipc_rcu_getref(void *ptr);
void ipc_rcu_putref(void *ptr);

-struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id);
-void ipc_lock_by_ptr(struct kern_ipc_perm *ipcp);
-void ipc_unlock(struct kern_ipc_perm* perm);
+struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
int ipc_buildid(struct ipc_ids* ids, int id, int seq);
-int ipc_checkid(struct ipc_ids* ids, struct kern_ipc_perm* ipcp, int uid);

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);
@@ -127,6 +124,41 @@ extern int ipcget_new(struct ipc_namespa
extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
struct ipc_ops *, struct ipc_params *);

+static inline int ipc_checkid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp,
+ int uid)
+{
+ if (uid / SEQ_MULTIPLIER != ipcp->seq)
+ return 1;
+ return 0;
+}
+
+static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
+{
+ spin_lock(&perm->lock);
+}
+
+static inline void ipc_unlock(struct kern_ipc_perm *perm)
+{
+ spin_unlock(&perm->lock);
+}
+
+static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
+ int id)
+{
+ struct kern_ipc_perm *out;
+
+ out = ipc_lock(ids, id);
+ if (IS_ERR(out))
+ return out;
+
+ if (ipc_checkid(ids, out, id)) {
+ spin_unlock(&out->lock);
+ return ERR_PTR(-EIDRM);
+ }
+
+ return out;
+}
+
static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
struct ipc_ops *ops, struct ipc_params *params)
{
Index: linux-2.6.23-rc2/ipc/util.c
===================================================================
--- linux-2.6.23-rc2.orig/ipc/util.c 2007-08-31 11:59:46.000000000 +0200
+++ linux-2.6.23-rc2/ipc/util.c 2007-08-31 12:29:32.000000000 +0200
@@ -678,7 +678,7 @@ struct kern_ipc_perm *ipc_lock(struct ip
out = idr_find(&ids->ipcs_idr, lid);
if (out == NULL) {
rcu_read_unlock();
- return NULL;
+ return ERR_PTR(-EINVAL);
}

spin_lock(&out->lock);
@@ -689,36 +689,17 @@ struct kern_ipc_perm *ipc_lock(struct ip
if (out->deleted) {
spin_unlock(&out->lock);
rcu_read_unlock();
- return NULL;
+ return ERR_PTR(-EINVAL);
}

return out;
}

-void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
-{
- rcu_read_lock();
- spin_lock(&perm->lock);
-}
-
-void ipc_unlock(struct kern_ipc_perm* perm)
-{
- spin_unlock(&perm->lock);
- rcu_read_unlock();
-}
-
int ipc_buildid(struct ipc_ids* ids, int id, int seq)
{
return SEQ_MULTIPLIER*seq + id;
}

-int ipc_checkid(struct ipc_ids* ids, struct kern_ipc_perm* ipcp, int uid)
-{
- if(uid/SEQ_MULTIPLIER != ipcp->seq)
- return 1;
- return 0;
-}
-
#ifdef __ARCH_WANT_IPC_PARSE_VERSION


Index: linux-2.6.23-rc2/ipc/msg.c
===================================================================
--- linux-2.6.23-rc2.orig/ipc/msg.c 2007-08-31 11:42:10.000000000 +0200
+++ linux-2.6.23-rc2/ipc/msg.c 2007-08-31 12:33:38.000000000 +0200
@@ -73,10 +73,7 @@ static struct ipc_ids init_msg_ids;

#define msg_ids(ns) (*((ns)->ids[IPC_MSG_IDS]))

-#define msg_lock(ns, id) ((struct msg_queue*)ipc_lock(&msg_ids(ns), id))
#define msg_unlock(msq) ipc_unlock(&(msq)->q_perm)
-#define msg_checkid(ns, msq, msgid) \
- ipc_checkid(&msg_ids(ns), &msq->q_perm, msgid)
#define msg_buildid(ns, id, seq) \
ipc_buildid(&msg_ids(ns), id, seq)

@@ -139,6 +136,17 @@ void __init msg_init(void)
IPC_MSG_IDS, sysvipc_msg_proc_show);
}

+static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
+{
+ return (struct msg_queue *) ipc_lock(&msg_ids(ns), id);
+}
+
+static inline struct msg_queue *msg_lock_check(struct ipc_namespace *ns,
+ int id)
+{
+ return (struct msg_queue *) ipc_lock_check(&msg_ids(ns), id);
+}
+
static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
{
ipc_rmid(&msg_ids(ns), &s->q_perm);
@@ -445,18 +453,15 @@ asmlinkage long sys_msgctl(int msqid, in
if (!buf)
return -EFAULT;

- memset(&tbuf, 0, sizeof(tbuf));
-
- msq = msg_lock(ns, msqid);
- if (msq == NULL)
- return -EINVAL;
-
if (cmd == MSG_STAT) {
+ msq = msg_lock(ns, msqid);
+ if (IS_ERR(msq))
+ return PTR_ERR(msq);
success_return = msq->q_perm.id;
} else {
- err = -EIDRM;
- if (msg_checkid(ns, msq, msqid))
- goto out_unlock;
+ msq = msg_lock_check(ns, msqid);
+ if (IS_ERR(msq))
+ return PTR_ERR(msq);
success_return = 0;
}
err = -EACCES;
@@ -467,6 +472,8 @@ asmlinkage long sys_msgctl(int msqid, in
if (err)
goto out_unlock;

+ memset(&tbuf, 0, sizeof(tbuf));
+
kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
tbuf.msg_stime = msq->q_stime;
tbuf.msg_rtime = msq->q_rtime;
@@ -494,14 +501,12 @@ asmlinkage long sys_msgctl(int msqid, in
}

mutex_lock(&msg_ids(ns).mutex);
- msq = msg_lock(ns, msqid);
- err = -EINVAL;
- if (msq == NULL)
+ msq = msg_lock_check(ns, msqid);
+ if (IS_ERR(msq)) {
+ err = PTR_ERR(msq);
goto out_up;
+ }

- err = -EIDRM;
- if (msg_checkid(ns, msq, msqid))
- goto out_unlock_up;
ipcp = &msq->q_perm;

err = audit_ipc_obj(ipcp);
@@ -644,14 +649,11 @@ long do_msgsnd(int msqid, long mtype, vo
msg->m_type = mtype;
msg->m_ts = msgsz;

- msq = msg_lock(ns, msqid);
- err = -EINVAL;
- if (msq == NULL)
+ msq = msg_lock_check(ns, msqid);
+ if (IS_ERR(msq)) {
+ err = PTR_ERR(msq);
goto out_free;
-
- err= -EIDRM;
- if (msg_checkid(ns, msq, msqid))
- goto out_unlock_free;
+ }

for (;;) {
struct msg_sender s;
@@ -758,13 +760,9 @@ long do_msgrcv(int msqid, long *pmtype,
mode = convert_mode(&msgtyp, msgflg);
ns = current->nsproxy->ipc_ns;

- msq = msg_lock(ns, msqid);
- if (msq == NULL)
- return -EINVAL;
-
- msg = ERR_PTR(-EIDRM);
- if (msg_checkid(ns, msq, msqid))
- goto out_unlock;
+ msq = msg_lock_check(ns, msqid);
+ if (IS_ERR(msq))
+ return PTR_ERR(msq);

for (;;) {
struct msg_receiver msr_d;
Index: linux-2.6.23-rc2/ipc/sem.c
===================================================================
--- linux-2.6.23-rc2.orig/ipc/sem.c 2007-08-31 11:43:58.000000000 +0200
+++ linux-2.6.23-rc2/ipc/sem.c 2007-08-31 12:38:20.000000000 +0200
@@ -88,7 +88,6 @@

#define sem_ids(ns) (*((ns)->ids[IPC_SEM_IDS]))

-#define sem_lock(ns, id) ((struct sem_array*)ipc_lock(&sem_ids(ns), id))
#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
#define sem_checkid(ns, sma, semid) \
ipc_checkid(&sem_ids(ns),&sma->sem_perm,semid)
@@ -175,6 +174,17 @@ void __init sem_init (void)
IPC_SEM_IDS, sysvipc_sem_proc_show);
}

+static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
+{
+ return (struct sem_array *) ipc_lock(&sem_ids(ns), id);
+}
+
+static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns,
+ int id)
+{
+ return (struct sem_array *) ipc_lock_check(&sem_ids(ns), id);
+}
+
static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
{
ipc_rmid(&sem_ids(ns), &s->sem_perm);
@@ -599,11 +609,9 @@ static int semctl_nolock(struct ipc_name
struct semid64_ds tbuf;
int id;

- memset(&tbuf,0,sizeof(tbuf));
-
sma = sem_lock(ns, semid);
- if(sma == NULL)
- return -EINVAL;
+ if (IS_ERR(sma))
+ return PTR_ERR(sma);

err = -EACCES;
if (ipcperms (&sma->sem_perm, S_IRUGO))
@@ -615,6 +623,8 @@ static int semctl_nolock(struct ipc_name

id = sma->sem_perm.id;

+ memset(&tbuf, 0, sizeof(tbuf));
+
kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
tbuf.sem_otime = sma->sem_otime;
tbuf.sem_ctime = sma->sem_ctime;
@@ -643,16 +653,12 @@ static int semctl_main(struct ipc_namesp
ushort* sem_io = fast_sem_io;
int nsems;

- sma = sem_lock(ns, semid);
- if(sma==NULL)
- return -EINVAL;
+ sma = sem_lock_check(ns, semid);
+ if (IS_ERR(sma))
+ return PTR_ERR(sma);

nsems = sma->sem_nsems;

- err=-EIDRM;
- if (sem_checkid(ns,sma,semid))
- goto out_unlock;
-
err = -EACCES;
if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO))
goto out_unlock;
@@ -864,14 +870,10 @@ static int semctl_down(struct ipc_namesp
if(copy_semid_from_user (&setbuf, arg.buf, version))
return -EFAULT;
}
- sma = sem_lock(ns, semid);
- if(sma==NULL)
- return -EINVAL;
+ sma = sem_lock_check(ns, semid);
+ if (IS_ERR(sma))
+ return PTR_ERR(sma);

- if (sem_checkid(ns,sma,semid)) {
- err=-EIDRM;
- goto out_unlock;
- }
ipcp = &sma->sem_perm;

err = audit_ipc_obj(ipcp);
@@ -1055,15 +1057,10 @@ static struct sem_undo *find_undo(struct
goto out;

/* no undo structure around - allocate one. */
- sma = sem_lock(ns, semid);
- un = ERR_PTR(-EINVAL);
- if(sma==NULL)
- goto out;
- un = ERR_PTR(-EIDRM);
- if (sem_checkid(ns,sma,semid)) {
- sem_unlock(sma);
- goto out;
- }
+ sma = sem_lock_check(ns, semid);
+ if (IS_ERR(sma))
+ return ERR_PTR(PTR_ERR(sma));
+
nsems = sma->sem_nsems;
ipc_rcu_getref(sma);
sem_unlock(sma);
@@ -1169,15 +1166,14 @@ retry_undos:
} else
un = NULL;

- sma = sem_lock(ns, semid);
- error=-EINVAL;
- if(sma==NULL)
+ sma = sem_lock_check(ns, semid);
+ if (IS_ERR(sma)) {
+ error = PTR_ERR(sma);
goto out_free;
- error = -EIDRM;
- if (sem_checkid(ns,sma,semid))
- goto out_unlock_free;
+ }
+
/*
- * semid identifies are not unique - find_undo may have
+ * semid identifiers are not unique - find_undo may have
* allocated an undo structure, it was invalidated by an RMID
* and now a new array with received the same id. Check and retry.
*/
@@ -1243,7 +1239,7 @@ retry_undos:
}

sma = sem_lock(ns, semid);
- if(sma==NULL) {
+ if (IS_ERR(sma)) {
BUG_ON(queue.prev != NULL);
error = -EIDRM;
goto out_free;
@@ -1343,7 +1339,7 @@ void exit_sem(struct task_struct *tsk)
if(semid == -1)
continue;
sma = sem_lock(ns, semid);
- if (sma == NULL)
+ if (IS_ERR(sma))
continue;

if (u->semid == -1)
Index: linux-2.6.23-rc2/ipc/shm.c
===================================================================
--- linux-2.6.23-rc2.orig/ipc/shm.c 2007-08-31 12:13:27.000000000 +0200
+++ linux-2.6.23-rc2/ipc/shm.c 2007-08-31 12:43:28.000000000 +0200
@@ -59,8 +59,6 @@ static struct ipc_ids init_shm_ids;

#define shm_ids(ns) (*((ns)->ids[IPC_SHM_IDS]))

-#define shm_lock(ns, id) \
- ((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id))
#define shm_unlock(shp) \
ipc_unlock(&(shp)->shm_perm)
#define shm_buildid(ns, id, seq) \
@@ -139,12 +137,15 @@ void __init shm_init (void)
IPC_SHM_IDS, sysvipc_shm_proc_show);
}

-static inline int shm_checkid(struct ipc_namespace *ns,
- struct shmid_kernel *s, int id)
+static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
{
- if (ipc_checkid(&shm_ids(ns), &s->shm_perm, id))
- return -EIDRM;
- return 0;
+ return (struct shmid_kernel *) ipc_lock(&shm_ids(ns), id);
+}
+
+static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
+ int id)
+{
+ return (struct shmid_kernel *) ipc_lock_check(&shm_ids(ns), id);
}

static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
@@ -167,7 +168,7 @@ static void shm_open(struct vm_area_stru
struct shmid_kernel *shp;

shp = shm_lock(sfd->ns, sfd->id);
- BUG_ON(!shp);
+ BUG_ON(IS_ERR(shp));
shp->shm_atim = get_seconds();
shp->shm_lprid = current->tgid;
shp->shm_nattch++;
@@ -213,7 +214,7 @@ static void shm_close(struct vm_area_str
mutex_lock(&shm_ids(ns).mutex);
/* remove from the list of attaches of the shm segment */
shp = shm_lock(ns, sfd->id);
- BUG_ON(!shp);
+ BUG_ON(IS_ERR(shp));
shp->shm_lprid = current->tgid;
shp->shm_dtim = get_seconds();
shp->shm_nattch--;
@@ -661,17 +662,25 @@ asmlinkage long sys_shmctl (int shmid, i
{
struct shmid64_ds tbuf;
int result;
- memset(&tbuf, 0, sizeof(tbuf));
- shp = shm_lock(ns, shmid);
- if(shp==NULL) {
- err = -EINVAL;
+
+ if (!buf) {
+ err = -EFAULT;
goto out;
- } else if (cmd == SHM_STAT) {
+ }
+
+ if (cmd == SHM_STAT) {
+ shp = shm_lock(ns, shmid);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
+ goto out;
+ }
result = shp->shm_perm.id;
} else {
- err = shm_checkid(ns, shp,shmid);
- if(err)
- goto out_unlock;
+ shp = shm_lock_check(ns, shmid);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
+ goto out;
+ }
result = 0;
}
err=-EACCES;
@@ -680,6 +689,7 @@ asmlinkage long sys_shmctl (int shmid, i
err = security_shm_shmctl(shp, cmd);
if (err)
goto out_unlock;
+ memset(&tbuf, 0, sizeof(tbuf));
kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
tbuf.shm_segsz = shp->shm_segsz;
tbuf.shm_atime = shp->shm_atim;
@@ -698,14 +708,11 @@ asmlinkage long sys_shmctl (int shmid, i
case SHM_LOCK:
case SHM_UNLOCK:
{
- shp = shm_lock(ns, shmid);
- if(shp==NULL) {
- err = -EINVAL;
+ shp = shm_lock_check(ns, shmid);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
goto out;
}
- err = shm_checkid(ns, shp,shmid);
- if(err)
- goto out_unlock;

err = audit_ipc_obj(&(shp->shm_perm));
if (err)
@@ -755,13 +762,11 @@ asmlinkage long sys_shmctl (int shmid, i
* the name away when the usage hits zero.
*/
mutex_lock(&shm_ids(ns).mutex);
- shp = shm_lock(ns, shmid);
- err = -EINVAL;
- if (shp == NULL)
+ shp = shm_lock_check(ns, shmid);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
goto out_up;
- err = shm_checkid(ns, shp, shmid);
- if(err)
- goto out_unlock_up;
+ }

err = audit_ipc_obj(&(shp->shm_perm));
if (err)
@@ -785,18 +790,21 @@ asmlinkage long sys_shmctl (int shmid, i

case IPC_SET:
{
+ if (!buf) {
+ err = -EFAULT;
+ goto out;
+ }
+
if (copy_shmid_from_user (&setbuf, buf, version)) {
err = -EFAULT;
goto out;
}
mutex_lock(&shm_ids(ns).mutex);
- shp = shm_lock(ns, shmid);
- err=-EINVAL;
- if(shp==NULL)
+ shp = shm_lock_check(ns, shmid);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
goto out_up;
- err = shm_checkid(ns, shp,shmid);
- if(err)
- goto out_unlock_up;
+ }
err = audit_ipc_obj(&(shp->shm_perm));
if (err)
goto out_unlock_up;
@@ -902,13 +910,11 @@ long do_shmat(int shmid, char __user *sh
* additional creator id...
*/
ns = current->nsproxy->ipc_ns;
- shp = shm_lock(ns, shmid);
- if(shp == NULL)
+ shp = shm_lock_check(ns, shmid);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
goto out;
-
- err = shm_checkid(ns, shp,shmid);
- if (err)
- goto out_unlock;
+ }

err = -EACCES;
if (ipcperms(&shp->shm_perm, acc_mode))
@@ -971,7 +977,7 @@ invalid:
out_nattch:
mutex_lock(&shm_ids(ns).mutex);
shp = shm_lock(ns, shmid);
- BUG_ON(!shp);
+ BUG_ON(IS_ERR(shp));
shp->shm_nattch--;
if(shp->shm_nattch == 0 &&
shp->shm_perm.mode & SHM_DEST)
--
-
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