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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /ipc/util.c
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Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'ipc/util.c')
-rw-r--r--ipc/util.c580
1 files changed, 580 insertions, 0 deletions
diff --git a/ipc/util.c b/ipc/util.c
new file mode 100644
index 00000000000..e00c35f7b2b
--- /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 */