1 files changed, 580 insertions, 0 deletions

diff --git a/ipc/util.c b/ipc/util.c
new file mode 100644
index 000000000000..e00c35f7b2b8
--- /dev/null
+++ b/ipc/util.c
@@ -0,0 +1,580 @@
+/*
+ * linux/ipc/util.c
+ * Copyright (C) 1992 Krishna Balasubramanian
+ *
+ * Sep 1997 - Call suser() last after "normal" permission checks so we
+ *            get BSD style process accounting right.
+ *            Occurs in several places in the IPC code.
+ *            Chris Evans, <chris@ferret.lmh.ox.ac.uk>
+ * Nov 1999 - ipc helper functions, unified SMP locking
+ *            Manfred Spraul <manfreds@colorfullife.com>
+ * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
+ *            Mingming Cao <cmm@us.ibm.com>
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/shm.h>
+#include <linux/init.h>
+#include <linux/msg.h>
+#include <linux/smp_lock.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/highuid.h>
+#include <linux/security.h>
+#include <linux/rcupdate.h>
+#include <linux/workqueue.h>
+
+#include <asm/unistd.h>
+
+#include "util.h"
+
+/**
+ *      ipc_init        -       initialise IPC subsystem
+ *
+ *      The various system5 IPC resources (semaphores, messages and shared
+ *      memory are initialised
+ */
+ 
+static int __init ipc_init(void)
+{
+        sem_init();
+        msg_init();
+        shm_init();
+        return 0;
+}
+__initcall(ipc_init);
+
+/**
+ *      ipc_init_ids            -       initialise IPC identifiers
+ *      @ids: Identifier set
+ *      @size: Number of identifiers
+ *
+ *      Given a size for the ipc identifier range (limited below IPCMNI)
+ *      set up the sequence range to use then allocate and initialise the
+ *      array itself. 
+ */
+ 
+void __init ipc_init_ids(struct ipc_ids* ids, int size)
+{
+        int i;
+        sema_init(&ids->sem,1);
+
+        if(size > IPCMNI)
+                size = IPCMNI;
+        ids->in_use = 0;
+        ids->max_id = -1;
+        ids->seq = 0;
+        {
+                int seq_limit = INT_MAX/SEQ_MULTIPLIER;
+                if(seq_limit > USHRT_MAX)
+                        ids->seq_max = USHRT_MAX;
+                 else
+                        ids->seq_max = seq_limit;
+        }
+
+        ids->entries = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*size +
+                                     sizeof(struct ipc_id_ary));
+
+        if(ids->entries == NULL) {
+                printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
+                size = 0;
+                ids->entries = &ids->nullentry;
+        }
+        ids->entries->size = size;
+        for(i=0;i<size;i++)
+                ids->entries->p[i] = NULL;
+}
+
+/**
+ *      ipc_findkey     -       find a key in an ipc identifier set     
+ *      @ids: Identifier set
+ *      @key: The key to find
+ *      
+ *      Requires ipc_ids.sem locked.
+ *      Returns the identifier if found or -1 if not.
+ */
+ 
+int ipc_findkey(struct ipc_ids* ids, key_t key)
+{
+        int id;
+        struct kern_ipc_perm* p;
+        int max_id = ids->max_id;
+
+        /*
+         * rcu_dereference() is not needed here
+         * since ipc_ids.sem is held
+         */
+        for (id = 0; id <= max_id; id++) {
+                p = ids->entries->p[id];
+                if(p==NULL)
+                        continue;
+                if (key == p->key)
+                        return id;
+        }
+        return -1;
+}
+
+/*
+ * Requires ipc_ids.sem locked
+ */
+static int grow_ary(struct ipc_ids* ids, int newsize)
+{
+        struct ipc_id_ary* new;
+        struct ipc_id_ary* old;
+        int i;
+        int size = ids->entries->size;
+
+        if(newsize > IPCMNI)
+                newsize = IPCMNI;
+        if(newsize <= size)
+                return newsize;
+
+        new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +
+                            sizeof(struct ipc_id_ary));
+        if(new == NULL)
+                return size;
+        new->size = newsize;
+        memcpy(new->p, ids->entries->p, sizeof(struct kern_ipc_perm *)*size +
+                                        sizeof(struct ipc_id_ary));
+        for(i=size;i<newsize;i++) {
+                new->p[i] = NULL;
+        }
+        old = ids->entries;
+
+        /*
+         * Use rcu_assign_pointer() to make sure the memcpyed contents
+         * of the new array are visible before the new array becomes visible.
+         */
+        rcu_assign_pointer(ids->entries, new);
+
+        ipc_rcu_putref(old);
+        return newsize;
+}
+
+/**
+ *      ipc_addid       -       add an IPC identifier
+ *      @ids: IPC identifier set
+ *      @new: new IPC permission set
+ *      @size: new size limit for the id array
+ *
+ *      Add an entry 'new' to the IPC arrays. The permissions object is
+ *      initialised and the first free entry is set up and the id assigned
+ *      is returned. The list is returned in a locked state on success.
+ *      On failure the list is not locked and -1 is returned.
+ *
+ *      Called with ipc_ids.sem held.
+ */
+ 
+int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
+{
+        int id;
+
+        size = grow_ary(ids,size);
+
+        /*
+         * rcu_dereference()() is not needed here since
+         * ipc_ids.sem is held
+         */
+        for (id = 0; id < size; id++) {
+                if(ids->entries->p[id] == NULL)
+                        goto found;
+        }
+        return -1;
+found:
+        ids->in_use++;
+        if (id > ids->max_id)
+                ids->max_id = id;
+
+        new->cuid = new->uid = current->euid;
+        new->gid = new->cgid = current->egid;
+
+        new->seq = ids->seq++;
+        if(ids->seq > ids->seq_max)
+                ids->seq = 0;
+
+        spin_lock_init(&new->lock);
+        new->deleted = 0;
+        rcu_read_lock();
+        spin_lock(&new->lock);
+        ids->entries->p[id] = new;
+        return id;
+}
+
+/**
+ *      ipc_rmid        -       remove an IPC identifier
+ *      @ids: identifier set
+ *      @id: Identifier to remove
+ *
+ *      The identifier must be valid, and in use. The kernel will panic if
+ *      fed an invalid identifier. The entry is removed and internal
+ *      variables recomputed. The object associated with the identifier
+ *      is returned.
+ *      ipc_ids.sem and the spinlock for this ID is hold before this function
+ *      is called, and remain locked on the exit.
+ */
+ 
+struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
+{
+        struct kern_ipc_perm* p;
+        int lid = id % SEQ_MULTIPLIER;
+        if(lid >= ids->entries->size)
+                BUG();
+
+        /* 
+         * do not need a rcu_dereference()() here to force ordering
+         * on Alpha, since the ipc_ids.sem is held.
+         */     
+        p = ids->entries->p[lid];
+        ids->entries->p[lid] = NULL;
+        if(p==NULL)
+                BUG();
+        ids->in_use--;
+
+        if (lid == ids->max_id) {
+                do {
+                        lid--;
+                        if(lid == -1)
+                                break;
+                } while (ids->entries->p[lid] == NULL);
+                ids->max_id = lid;
+        }
+        p->deleted = 1;
+        return p;
+}
+
+/**
+ *      ipc_alloc       -       allocate ipc space
+ *      @size: size desired
+ *
+ *      Allocate memory from the appropriate pools and return a pointer to it.
+ *      NULL is returned if the allocation fails
+ */
+ 
+void* ipc_alloc(int size)
+{
+        void* out;
+        if(size > PAGE_SIZE)
+                out = vmalloc(size);
+        else
+                out = kmalloc(size, GFP_KERNEL);
+        return out;
+}
+
+/**
+ *      ipc_free        -       free ipc space
+ *      @ptr: pointer returned by ipc_alloc
+ *      @size: size of block
+ *
+ *      Free a block created with ipc_alloc. The caller must know the size
+ *      used in the allocation call.
+ */
+
+void ipc_free(void* ptr, int size)
+{
+        if(size > PAGE_SIZE)
+                vfree(ptr);
+        else
+                kfree(ptr);
+}
+
+/*
+ * rcu allocations:
+ * There are three headers that are prepended to the actual allocation:
+ * - during use: ipc_rcu_hdr.
+ * - during the rcu grace period: ipc_rcu_grace.
+ * - [only if vmalloc]: ipc_rcu_sched.
+ * Their lifetime doesn't overlap, thus the headers share the same memory.
+ * Unlike a normal union, they are right-aligned, thus some container_of
+ * forward/backward casting is necessary:
+ */
+struct ipc_rcu_hdr
+{
+        int refcount;
+        int is_vmalloc;
+        void *data[0];
+};
+
+
+struct ipc_rcu_grace
+{
+        struct rcu_head rcu;
+        /* "void *" makes sure alignment of following data is sane. */
+        void *data[0];
+};
+
+struct ipc_rcu_sched
+{
+        struct work_struct work;
+        /* "void *" makes sure alignment of following data is sane. */
+        void *data[0];
+};
+
+#define HDRLEN_KMALLOC          (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
+                                        sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
+#define HDRLEN_VMALLOC          (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
+                                        sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
+
+static inline int rcu_use_vmalloc(int size)
+{
+        /* Too big for a single page? */
+        if (HDRLEN_KMALLOC + size > PAGE_SIZE)
+                return 1;
+        return 0;
+}
+
+/**
+ *      ipc_rcu_alloc   -       allocate ipc and rcu space 
+ *      @size: size desired
+ *
+ *      Allocate memory for the rcu header structure +  the object.
+ *      Returns the pointer to the object.
+ *      NULL is returned if the allocation fails. 
+ */
+ 
+void* ipc_rcu_alloc(int size)
+{
+        void* out;
+        /* 
+         * We prepend the allocation with the rcu struct, and
+         * workqueue if necessary (for vmalloc). 
+         */
+        if (rcu_use_vmalloc(size)) {
+                out = vmalloc(HDRLEN_VMALLOC + size);
+                if (out) {
+                        out += HDRLEN_VMALLOC;
+                        container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
+                        container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
+                }
+        } else {
+                out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
+                if (out) {
+                        out += HDRLEN_KMALLOC;
+                        container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
+                        container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
+                }
+        }
+
+        return out;
+}
+
+void ipc_rcu_getref(void *ptr)
+{
+        container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
+}
+
+/**
+ *      ipc_schedule_free       - free ipc + rcu space
+ * 
+ * Since RCU callback function is called in bh,
+ * we need to defer the vfree to schedule_work
+ */
+static void ipc_schedule_free(struct rcu_head *head)
+{
+        struct ipc_rcu_grace *grace =
+                container_of(head, struct ipc_rcu_grace, rcu);
+        struct ipc_rcu_sched *sched =
+                        container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]);
+
+        INIT_WORK(&sched->work, vfree, sched);
+        schedule_work(&sched->work);
+}
+
+/**
+ *      ipc_immediate_free      - free ipc + rcu space
+ *
+ *      Free from the RCU callback context
+ *
+ */
+static void ipc_immediate_free(struct rcu_head *head)
+{
+        struct ipc_rcu_grace *free =
+                container_of(head, struct ipc_rcu_grace, rcu);
+        kfree(free);
+}
+
+void ipc_rcu_putref(void *ptr)
+{
+        if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
+                return;
+
+        if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
+                call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
+                                ipc_schedule_free);
+        } else {
+                call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
+                                ipc_immediate_free);
+        }
+}
+
+/**
+ *      ipcperms        -       check IPC permissions
+ *      @ipcp: IPC permission set
+ *      @flag: desired permission set.
+ *
+ *      Check user, group, other permissions for access
+ *      to ipc resources. return 0 if allowed
+ */
+ 
+int ipcperms (struct kern_ipc_perm *ipcp, short flag)
+{       /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
+        int requested_mode, granted_mode;
+
+        requested_mode = (flag >> 6) | (flag >> 3) | flag;
+        granted_mode = ipcp->mode;
+        if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
+                granted_mode >>= 6;
+        else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
+                granted_mode >>= 3;
+        /* is there some bit set in requested_mode but not in granted_mode? */
+        if ((requested_mode & ~granted_mode & 0007) && 
+            !capable(CAP_IPC_OWNER))
+                return -1;
+
+        return security_ipc_permission(ipcp, flag);
+}
+
+/*
+ * Functions to convert between the kern_ipc_perm structure and the
+ * old/new ipc_perm structures
+ */
+
+/**
+ *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
+ *      @in: kernel permissions
+ *      @out: new style IPC permissions
+ *
+ *      Turn the kernel object 'in' into a set of permissions descriptions
+ *      for returning to userspace (out).
+ */
+ 
+
+void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
+{
+        out->key        = in->key;
+        out->uid        = in->uid;
+        out->gid        = in->gid;
+        out->cuid       = in->cuid;
+        out->cgid       = in->cgid;
+        out->mode       = in->mode;
+        out->seq        = in->seq;
+}
+
+/**
+ *      ipc64_perm_to_ipc_perm  -       convert old ipc permissions to new
+ *      @in: new style IPC permissions
+ *      @out: old style IPC permissions
+ *
+ *      Turn the new style permissions object in into a compatibility
+ *      object and store it into the 'out' pointer.
+ */
+ 
+void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
+{
+        out->key        = in->key;
+        SET_UID(out->uid, in->uid);
+        SET_GID(out->gid, in->gid);
+        SET_UID(out->cuid, in->cuid);
+        SET_GID(out->cgid, in->cgid);
+        out->mode       = in->mode;
+        out->seq        = in->seq;
+}
+
+/*
+ * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
+ * is called with shm_ids.sem locked.  Since grow_ary() is also called with
+ * shm_ids.sem down(for Shared Memory), there is no need to add read 
+ * barriers here to gurantee the writes in grow_ary() are seen in order 
+ * here (for Alpha).
+ *
+ * However ipc_get() itself does not necessary require ipc_ids.sem down. So
+ * if in the future ipc_get() is used by other places without ipc_ids.sem
+ * down, then ipc_get() needs read memery barriers as ipc_lock() does.
+ */
+struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id)
+{
+        struct kern_ipc_perm* out;
+        int lid = id % SEQ_MULTIPLIER;
+        if(lid >= ids->entries->size)
+                return NULL;
+        out = ids->entries->p[lid];
+        return out;
+}
+
+struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
+{
+        struct kern_ipc_perm* out;
+        int lid = id % SEQ_MULTIPLIER;
+        struct ipc_id_ary* entries;
+
+        rcu_read_lock();
+        entries = rcu_dereference(ids->entries);
+        if(lid >= entries->size) {
+                rcu_read_unlock();
+                return NULL;
+        }
+        out = entries->p[lid];
+        if(out == NULL) {
+                rcu_read_unlock();
+                return NULL;
+        }
+        spin_lock(&out->lock);
+        
+        /* ipc_rmid() may have already freed the ID while ipc_lock
+         * was spinning: here verify that the structure is still valid
+         */
+        if (out->deleted) {
+                spin_unlock(&out->lock);
+                rcu_read_unlock();
+                return NULL;
+        }
+        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
+
+
+/**
+ *      ipc_parse_version       -       IPC call version
+ *      @cmd: pointer to command
+ *
+ *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC. 
+ *      The cmd value is turned from an encoding command and version into
+ *      just the command code.
+ */
+ 
+int ipc_parse_version (int *cmd)
+{
+        if (*cmd & IPC_64) {
+                *cmd ^= IPC_64;
+                return IPC_64;
+        } else {
+                return IPC_OLD;
+        }
+}
+
+#endif /* __ARCH_WANT_IPC_PARSE_VERSION */