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

From: Nadia . Derbey
Date: Thu Jun 07 2007 - 12:52:53 EST

[PATCH 04/06]


This patch introduces the a change to the ipc_lock() routine interface:
. each time ipc_checkid() is called, this done after calling ipc_lock().
So a new paramameter is added to ipc_lock(). It tells whether or not
a ipc_checkid() is needed, and ipc_checkid() is now called from inside
ipc_lock().


Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>


---
ipc/msg.c | 65 ++++++++++++++++++-------------------------
ipc/sem.c | 74 ++++++++++++++++++++-----------------------------
ipc/shm.c | 92 ++++++++++++++++++++++++++++++-------------------------------
ipc/util.c | 16 +++++++---
ipc/util.h | 6 ++-
5 files changed, 121 insertions(+), 132 deletions(-)

Index: linux-2.6.21/ipc/util.c
===================================================================
--- linux-2.6.21.orig/ipc/util.c 2007-06-07 14:31:00.000000000 +0200
+++ linux-2.6.21/ipc/util.c 2007-06-07 14:57:34.000000000 +0200
@@ -667,7 +667,7 @@ void ipc64_perm_to_ipc_perm (struct ipc6
out->seq = in->seq;
}

-struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
+struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id, int checkid)
{
struct kern_ipc_perm* out;
int lid = id % SEQ_MULTIPLIER;
@@ -675,12 +675,12 @@ struct kern_ipc_perm* ipc_lock(struct ip
rcu_read_lock();
if (lid > ids->max_id) {
rcu_read_unlock();
- return NULL;
+ return ERR_PTR(-EINVAL);
}
out = radix_tree_lookup(&ids->id_tree, lid);
if(out == NULL) {
rcu_read_unlock();
- return NULL;
+ return ERR_PTR(-EINVAL);
}
spin_lock(&out->lock);

@@ -690,8 +690,16 @@ struct kern_ipc_perm* ipc_lock(struct ip
if (out->deleted) {
spin_unlock(&out->lock);
rcu_read_unlock();
- return NULL;
+ return ERR_PTR(-EINVAL);
}
+
+ if (checkid)
+ if (ipc_checkid(ids, out, id)) {
+ spin_unlock(&out->lock);
+ rcu_read_unlock();
+ return ERR_PTR(-EIDRM);
+ }
+
return out;
}

Index: linux-2.6.21/ipc/util.h
===================================================================
--- linux-2.6.21.orig/ipc/util.h 2007-06-07 14:13:42.000000000 +0200
+++ linux-2.6.21/ipc/util.h 2007-06-07 14:57:07.000000000 +0200
@@ -12,9 +12,11 @@

#define USHRT_MAX 0xffff
#define SEQ_MULTIPLIER (IPCMNI)
-
#define IPCS_MAX_SCAN_ENTRIES 256

+#define IPC_CHECKID 1
+#define NO_IPC_CHECKID 0
+
void sem_init (void);
void msg_init (void);
void shm_init (void);
@@ -81,7 +83,7 @@ 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);
+struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int, int);
void ipc_lock_by_ptr(struct kern_ipc_perm *ipcp);
void ipc_unlock(struct kern_ipc_perm* perm);
int ipc_buildid(struct ipc_ids* ids, int id, int seq);
Index: linux-2.6.21/ipc/msg.c
===================================================================
--- linux-2.6.21.orig/ipc/msg.c 2007-06-07 14:03:15.000000000 +0200
+++ linux-2.6.21/ipc/msg.c 2007-06-07 14:40:08.000000000 +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)

@@ -150,6 +147,12 @@ 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,
+ int chk)
+{
+ return (struct msg_queue *) ipc_lock(&msg_ids(ns), id, chk);
+}
+
static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
{
ipc_rmid(&msg_ids(ns), &s->q_perm);
@@ -460,7 +463,7 @@ asmlinkage long sys_msgctl(int msqid, in
return -EFAULT;
return (max_id < 0) ? 0 : max_id;
}
- case MSG_STAT:
+ case MSG_STAT: /* msqid is an index rather than a msg queue id */
case IPC_STAT:
{
struct msqid64_ds tbuf;
@@ -468,21 +471,16 @@ asmlinkage long sys_msgctl(int msqid, in

if (!buf)
return -EFAULT;
- if (cmd == MSG_STAT && msqid > msg_ids(ns).max_id)
- return -EINVAL;
-
- memset(&tbuf, 0, sizeof(tbuf));

- msq = msg_lock(ns, msqid);
- if (msq == NULL)
- return -EINVAL;
-
- if (cmd == MSG_STAT)
+ if (cmd == MSG_STAT) {
+ msq = msg_lock(ns, msqid, NO_IPC_CHECKID);
+ if (IS_ERR(msq) && PTR_ERR(msq) == -EINVAL)
+ return -EINVAL;
success_return = msq->q_perm.id;
- else {
- err = -EIDRM;
- if (msg_checkid(ns, msq, msqid))
- goto out_unlock;
+ } else {
+ msq = msg_lock(ns, msqid, IPC_CHECKID);
+ if (IS_ERR(msq))
+ return PTR_ERR(msq);
success_return = 0;
}
err = -EACCES;
@@ -493,6 +491,8 @@ 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;
@@ -520,14 +520,12 @@ 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(ns, msqid, IPC_CHECKID);
+ 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);
@@ -670,14 +668,11 @@ 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(ns, msqid, IPC_CHECKID);
+ 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;
@@ -784,13 +779,9 @@ 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(ns, msqid, IPC_CHECKID);
+ if (IS_ERR(msq))
+ return PTR_ERR(msq);

for (;;) {
struct msg_receiver msr_d;
Index: linux-2.6.21/ipc/sem.c
===================================================================
--- linux-2.6.21.orig/ipc/sem.c 2007-06-07 14:05:27.000000000 +0200
+++ linux-2.6.21/ipc/sem.c 2007-06-07 14:56:36.000000000 +0200
@@ -89,7 +89,6 @@

#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)
@@ -188,6 +187,12 @@ 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,
+ int chk)
+{
+ return (struct sem_array *) ipc_lock(&sem_ids(ns), id, chk);
+}
+
static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
{
ipc_rmid(&sem_ids(ns), &s->sem_perm);
@@ -620,14 +625,9 @@ static int semctl_nolock(struct ipc_name
struct semid64_ds tbuf;
int id;

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

err = -EACCES;
if (ipcperms (&sma->sem_perm, S_IRUGO))
@@ -639,6 +639,8 @@ 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;
@@ -667,16 +669,12 @@ 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(ns, semid, IPC_CHECKID);
+ 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;
@@ -888,14 +886,10 @@ 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(ns, semid, IPC_CHECKID);
+ 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);
@@ -1079,15 +1073,10 @@ 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(ns, semid, IPC_CHECKID);
+ if (IS_ERR(sma))
+ return ERR_PTR(PTR_ERR(sma));
+
nsems = sma->sem_nsems;
ipc_rcu_getref(sma);
sem_unlock(sma);
@@ -1193,15 +1182,14 @@ retry_undos:
} else
un = NULL;

- sma = sem_lock(ns, semid);
- error=-EINVAL;
- if(sma==NULL)
+ sma = sem_lock(ns, semid, IPC_CHECKID);
+ 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.
*/
@@ -1266,8 +1254,8 @@ retry_undos:
goto out_free;
}

- sma = sem_lock(ns, semid);
- if(sma==NULL) {
+ sma = sem_lock(ns, semid, NO_IPC_CHECKID);
+ if (IS_ERR(sma)) {
BUG_ON(queue.prev != NULL);
error = -EIDRM;
goto out_free;
@@ -1366,8 +1354,8 @@ void exit_sem(struct task_struct *tsk)

if(semid == -1)
continue;
- sma = sem_lock(ns, semid);
- if (sma == NULL)
+ sma = sem_lock(ns, semid, NO_IPC_CHECKID);
+ if (IS_ERR(sma))
continue;

if (u->semid == -1)
Index: linux-2.6.21/ipc/shm.c
===================================================================
--- linux-2.6.21.orig/ipc/shm.c 2007-06-07 14:09:46.000000000 +0200
+++ linux-2.6.21/ipc/shm.c 2007-06-07 14:55:28.000000000 +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) \
@@ -152,12 +150,10 @@ 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,
+ int chk)
{
- if (ipc_checkid(&shm_ids(ns), &s->shm_perm, id))
- return -EIDRM;
- return 0;
+ return (struct shmid_kernel *) ipc_lock(&shm_ids(ns), id, chk);
}

static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
@@ -179,8 +175,8 @@ static void shm_open(struct vm_area_stru
struct shm_file_data *sfd = shm_file_data(file);
struct shmid_kernel *shp;

- shp = shm_lock(sfd->ns, sfd->id);
- BUG_ON(!shp);
+ shp = shm_lock(sfd->ns, sfd->id, NO_IPC_CHECKID);
+ BUG_ON(IS_ERR(shp));
shp->shm_atim = get_seconds();
shp->shm_lprid = current->tgid;
shp->shm_nattch++;
@@ -225,8 +221,8 @@ 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);
+ shp = shm_lock(ns, sfd->id, NO_IPC_CHECKID);
+ BUG_ON(IS_ERR(shp));
shp->shm_lprid = current->tgid;
shp->shm_dtim = get_seconds();
shp->shm_nattch--;
@@ -673,18 +669,25 @@ 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) {
- err = -EINVAL;
+ }
+
+ if (cmd == SHM_STAT) {
+ shp = shm_lock(ns, shmid, NO_IPC_CHECKID);
+ 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(ns, shmid, IPC_CHECKID);
+ if (IS_ERR(shp)) {
+ err = PTR_ERR(shp);
+ goto out;
+ }
result = 0;
}
err=-EACCES;
@@ -693,6 +696,7 @@ 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;
@@ -711,14 +715,11 @@ 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(ns, shmid, IPC_CHECKID);
+ 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)
@@ -768,13 +769,11 @@ 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(ns, shmid, IPC_CHECKID);
+ 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)
@@ -798,18 +797,21 @@ 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(ns, shmid, IPC_CHECKID);
+ 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;
@@ -915,13 +917,11 @@ 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(ns, shmid, IPC_CHECKID);
+ 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))
@@ -983,8 +983,8 @@ invalid:

out_nattch:
mutex_lock(&shm_ids(ns).mutex);
- shp = shm_lock(ns, shmid);
- BUG_ON(!shp);
+ shp = shm_lock(ns, shmid, NO_IPC_CHECKID);
+ BUG_ON(IS_ERR(shp));
shp->shm_nattch--;
if(shp->shm_nattch == 0 &&
shp->shm_perm.mode & SHM_DEST)

--
-
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