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-rw-r--r--ipc/kdbus/pool.c728
1 files changed, 728 insertions, 0 deletions
diff --git a/ipc/kdbus/pool.c b/ipc/kdbus/pool.c
new file mode 100644
index 000000000..63ccd5571
--- /dev/null
+++ b/ipc/kdbus/pool.c
@@ -0,0 +1,728 @@
+/*
+ * Copyright (C) 2013-2015 Kay Sievers
+ * Copyright (C) 2013-2015 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+ * Copyright (C) 2013-2015 Daniel Mack <daniel@zonque.org>
+ * Copyright (C) 2013-2015 David Herrmann <dh.herrmann@gmail.com>
+ * Copyright (C) 2013-2015 Linux Foundation
+ * Copyright (C) 2014-2015 Djalal Harouni <tixxdz@opendz.org>
+ *
+ * kdbus is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation; either version 2.1 of the License, or (at
+ * your option) any later version.
+ */
+
+#include <linux/aio.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/rbtree.h>
+#include <linux/sched.h>
+#include <linux/shmem_fs.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/uio.h>
+
+#include "pool.h"
+#include "util.h"
+
+/**
+ * struct kdbus_pool - the receiver's buffer
+ * @f: The backing shmem file
+ * @size: The size of the file
+ * @accounted_size: Currently accounted memory in bytes
+ * @lock: Pool data lock
+ * @slices: All slices sorted by address
+ * @slices_busy: Tree of allocated slices
+ * @slices_free: Tree of free slices
+ *
+ * The receiver's buffer, managed as a pool of allocated and free
+ * slices containing the queued messages.
+ *
+ * Messages sent with KDBUS_CMD_SEND are copied directly by the
+ * sending process into the receiver's pool.
+ *
+ * Messages received with KDBUS_CMD_RECV just return the offset
+ * to the data placed in the pool.
+ *
+ * The internally allocated memory needs to be returned by the receiver
+ * with KDBUS_CMD_FREE.
+ */
+struct kdbus_pool {
+ struct file *f;
+ size_t size;
+ size_t accounted_size;
+ struct mutex lock;
+
+ struct list_head slices;
+ struct rb_root slices_busy;
+ struct rb_root slices_free;
+};
+
+/**
+ * struct kdbus_pool_slice - allocated element in kdbus_pool
+ * @pool: Pool this slice belongs to
+ * @off: Offset of slice in the shmem file
+ * @size: Size of slice
+ * @entry: Entry in "all slices" list
+ * @rb_node: Entry in free or busy list
+ * @free: Unused slice
+ * @accounted: Accounted as queue slice
+ * @ref_kernel: Kernel holds a reference
+ * @ref_user: Userspace holds a reference
+ *
+ * The pool has one or more slices, always spanning the entire size of the
+ * pool.
+ *
+ * Every slice is an element in a list sorted by the buffer address, to
+ * provide access to the next neighbor slice.
+ *
+ * Every slice is member in either the busy or the free tree. The free
+ * tree is organized by slice size, the busy tree organized by buffer
+ * offset.
+ */
+struct kdbus_pool_slice {
+ struct kdbus_pool *pool;
+ size_t off;
+ size_t size;
+
+ struct list_head entry;
+ struct rb_node rb_node;
+
+ bool free:1;
+ bool accounted:1;
+ bool ref_kernel:1;
+ bool ref_user:1;
+};
+
+static struct kdbus_pool_slice *kdbus_pool_slice_new(struct kdbus_pool *pool,
+ size_t off, size_t size)
+{
+ struct kdbus_pool_slice *slice;
+
+ slice = kzalloc(sizeof(*slice), GFP_KERNEL);
+ if (!slice)
+ return NULL;
+
+ slice->pool = pool;
+ slice->off = off;
+ slice->size = size;
+ slice->free = true;
+ return slice;
+}
+
+/* insert a slice into the free tree */
+static void kdbus_pool_add_free_slice(struct kdbus_pool *pool,
+ struct kdbus_pool_slice *slice)
+{
+ struct rb_node **n;
+ struct rb_node *pn = NULL;
+
+ n = &pool->slices_free.rb_node;
+ while (*n) {
+ struct kdbus_pool_slice *pslice;
+
+ pn = *n;
+ pslice = rb_entry(pn, struct kdbus_pool_slice, rb_node);
+ if (slice->size < pslice->size)
+ n = &pn->rb_left;
+ else
+ n = &pn->rb_right;
+ }
+
+ rb_link_node(&slice->rb_node, pn, n);
+ rb_insert_color(&slice->rb_node, &pool->slices_free);
+}
+
+/* insert a slice into the busy tree */
+static void kdbus_pool_add_busy_slice(struct kdbus_pool *pool,
+ struct kdbus_pool_slice *slice)
+{
+ struct rb_node **n;
+ struct rb_node *pn = NULL;
+
+ n = &pool->slices_busy.rb_node;
+ while (*n) {
+ struct kdbus_pool_slice *pslice;
+
+ pn = *n;
+ pslice = rb_entry(pn, struct kdbus_pool_slice, rb_node);
+ if (slice->off < pslice->off)
+ n = &pn->rb_left;
+ else if (slice->off > pslice->off)
+ n = &pn->rb_right;
+ else
+ BUG();
+ }
+
+ rb_link_node(&slice->rb_node, pn, n);
+ rb_insert_color(&slice->rb_node, &pool->slices_busy);
+}
+
+static struct kdbus_pool_slice *kdbus_pool_find_slice(struct kdbus_pool *pool,
+ size_t off)
+{
+ struct rb_node *n;
+
+ n = pool->slices_busy.rb_node;
+ while (n) {
+ struct kdbus_pool_slice *s;
+
+ s = rb_entry(n, struct kdbus_pool_slice, rb_node);
+ if (off < s->off)
+ n = n->rb_left;
+ else if (off > s->off)
+ n = n->rb_right;
+ else
+ return s;
+ }
+
+ return NULL;
+}
+
+/**
+ * kdbus_pool_slice_alloc() - allocate memory from a pool
+ * @pool: The receiver's pool
+ * @size: The number of bytes to allocate
+ * @accounted: Whether this slice should be accounted for
+ *
+ * The returned slice is used for kdbus_pool_slice_release() to
+ * free the allocated memory. If either @kvec or @iovec is non-NULL, the data
+ * will be copied from kernel or userspace memory into the new slice at
+ * offset 0.
+ *
+ * Return: the allocated slice on success, ERR_PTR on failure.
+ */
+struct kdbus_pool_slice *kdbus_pool_slice_alloc(struct kdbus_pool *pool,
+ size_t size, bool accounted)
+{
+ size_t slice_size = KDBUS_ALIGN8(size);
+ struct rb_node *n, *found = NULL;
+ struct kdbus_pool_slice *s;
+ int ret = 0;
+
+ if (WARN_ON(!size))
+ return ERR_PTR(-EINVAL);
+
+ /* search a free slice with the closest matching size */
+ mutex_lock(&pool->lock);
+ n = pool->slices_free.rb_node;
+ while (n) {
+ s = rb_entry(n, struct kdbus_pool_slice, rb_node);
+ if (slice_size < s->size) {
+ found = n;
+ n = n->rb_left;
+ } else if (slice_size > s->size) {
+ n = n->rb_right;
+ } else {
+ found = n;
+ break;
+ }
+ }
+
+ /* no slice with the minimum size found in the pool */
+ if (!found) {
+ ret = -EXFULL;
+ goto exit_unlock;
+ }
+
+ /* no exact match, use the closest one */
+ if (!n) {
+ struct kdbus_pool_slice *s_new;
+
+ s = rb_entry(found, struct kdbus_pool_slice, rb_node);
+
+ /* split-off the remainder of the size to its own slice */
+ s_new = kdbus_pool_slice_new(pool, s->off + slice_size,
+ s->size - slice_size);
+ if (!s_new) {
+ ret = -ENOMEM;
+ goto exit_unlock;
+ }
+
+ list_add(&s_new->entry, &s->entry);
+ kdbus_pool_add_free_slice(pool, s_new);
+
+ /* adjust our size now that we split-off another slice */
+ s->size = slice_size;
+ }
+
+ /* move slice from free to the busy tree */
+ rb_erase(found, &pool->slices_free);
+ kdbus_pool_add_busy_slice(pool, s);
+
+ WARN_ON(s->ref_kernel || s->ref_user);
+
+ s->ref_kernel = true;
+ s->free = false;
+ s->accounted = accounted;
+ if (accounted)
+ pool->accounted_size += s->size;
+ mutex_unlock(&pool->lock);
+
+ return s;
+
+exit_unlock:
+ mutex_unlock(&pool->lock);
+ return ERR_PTR(ret);
+}
+
+static void __kdbus_pool_slice_release(struct kdbus_pool_slice *slice)
+{
+ struct kdbus_pool *pool = slice->pool;
+
+ /* don't free the slice if either has a reference */
+ if (slice->ref_kernel || slice->ref_user)
+ return;
+
+ if (WARN_ON(slice->free))
+ return;
+
+ rb_erase(&slice->rb_node, &pool->slices_busy);
+
+ /* merge with the next free slice */
+ if (!list_is_last(&slice->entry, &pool->slices)) {
+ struct kdbus_pool_slice *s;
+
+ s = list_entry(slice->entry.next,
+ struct kdbus_pool_slice, entry);
+ if (s->free) {
+ rb_erase(&s->rb_node, &pool->slices_free);
+ list_del(&s->entry);
+ slice->size += s->size;
+ kfree(s);
+ }
+ }
+
+ /* merge with previous free slice */
+ if (pool->slices.next != &slice->entry) {
+ struct kdbus_pool_slice *s;
+
+ s = list_entry(slice->entry.prev,
+ struct kdbus_pool_slice, entry);
+ if (s->free) {
+ rb_erase(&s->rb_node, &pool->slices_free);
+ list_del(&slice->entry);
+ s->size += slice->size;
+ kfree(slice);
+ slice = s;
+ }
+ }
+
+ slice->free = true;
+ kdbus_pool_add_free_slice(pool, slice);
+}
+
+/**
+ * kdbus_pool_slice_release() - drop kernel-reference on allocated slice
+ * @slice: Slice allocated from the pool
+ *
+ * This releases the kernel-reference on the given slice. If the
+ * kernel-reference and the user-reference on a slice are dropped, the slice is
+ * returned to the pool.
+ *
+ * So far, we do not implement full ref-counting on slices. Each, kernel and
+ * user-space can have exactly one reference to a slice. If both are dropped at
+ * the same time, the slice is released.
+ */
+void kdbus_pool_slice_release(struct kdbus_pool_slice *slice)
+{
+ struct kdbus_pool *pool;
+
+ if (!slice)
+ return;
+
+ /* @slice may be freed, so keep local ptr to @pool */
+ pool = slice->pool;
+
+ mutex_lock(&pool->lock);
+ /* kernel must own a ref to @slice to drop it */
+ WARN_ON(!slice->ref_kernel);
+ slice->ref_kernel = false;
+ /* no longer kernel-owned, de-account slice */
+ if (slice->accounted && !WARN_ON(pool->accounted_size < slice->size))
+ pool->accounted_size -= slice->size;
+ __kdbus_pool_slice_release(slice);
+ mutex_unlock(&pool->lock);
+}
+
+/**
+ * kdbus_pool_release_offset() - release a public offset
+ * @pool: pool to operate on
+ * @off: offset to release
+ *
+ * This should be called whenever user-space frees a slice given to them. It
+ * verifies the slice is available and public, and then drops it. It ensures
+ * correct locking and barriers against queues.
+ *
+ * Return: 0 on success, ENXIO if the offset is invalid or not public.
+ */
+int kdbus_pool_release_offset(struct kdbus_pool *pool, size_t off)
+{
+ struct kdbus_pool_slice *slice;
+ int ret = 0;
+
+ /* 'pool->size' is used as dummy offset for empty slices */
+ if (off == pool->size)
+ return 0;
+
+ mutex_lock(&pool->lock);
+ slice = kdbus_pool_find_slice(pool, off);
+ if (slice && slice->ref_user) {
+ slice->ref_user = false;
+ __kdbus_pool_slice_release(slice);
+ } else {
+ ret = -ENXIO;
+ }
+ mutex_unlock(&pool->lock);
+
+ return ret;
+}
+
+/**
+ * kdbus_pool_publish_empty() - publish empty slice to user-space
+ * @pool: pool to operate on
+ * @off: output storage for offset, or NULL
+ * @size: output storage for size, or NULL
+ *
+ * This is the same as kdbus_pool_slice_publish(), but uses a dummy slice with
+ * size 0. The returned offset points to the end of the pool and is never
+ * returned on real slices.
+ */
+void kdbus_pool_publish_empty(struct kdbus_pool *pool, u64 *off, u64 *size)
+{
+ if (off)
+ *off = pool->size;
+ if (size)
+ *size = 0;
+}
+
+/**
+ * kdbus_pool_slice_publish() - publish slice to user-space
+ * @slice: The slice
+ * @out_offset: Output storage for offset, or NULL
+ * @out_size: Output storage for size, or NULL
+ *
+ * This prepares a slice to be published to user-space.
+ *
+ * This call combines the following operations:
+ * * the memory region is flushed so the user's memory view is consistent
+ * * the slice is marked as referenced by user-space, so user-space has to
+ * call KDBUS_CMD_FREE to release it
+ * * the offset and size of the slice are written to the given output
+ * arguments, if non-NULL
+ */
+void kdbus_pool_slice_publish(struct kdbus_pool_slice *slice,
+ u64 *out_offset, u64 *out_size)
+{
+ mutex_lock(&slice->pool->lock);
+ /* kernel must own a ref to @slice to gain a user-space ref */
+ WARN_ON(!slice->ref_kernel);
+ slice->ref_user = true;
+ mutex_unlock(&slice->pool->lock);
+
+ if (out_offset)
+ *out_offset = slice->off;
+ if (out_size)
+ *out_size = slice->size;
+}
+
+/**
+ * kdbus_pool_slice_offset() - Get a slice's offset inside the pool
+ * @slice: Slice to return the offset of
+ *
+ * Return: The internal offset @slice inside the pool.
+ */
+off_t kdbus_pool_slice_offset(const struct kdbus_pool_slice *slice)
+{
+ return slice->off;
+}
+
+/**
+ * kdbus_pool_slice_size() - get size of a pool slice
+ * @slice: slice to query
+ *
+ * Return: size of the given slice
+ */
+size_t kdbus_pool_slice_size(const struct kdbus_pool_slice *slice)
+{
+ return slice->size;
+}
+
+/**
+ * kdbus_pool_new() - create a new pool
+ * @name: Name of the (deleted) file which shows up in
+ * /proc, used for debugging
+ * @size: Maximum size of the pool
+ *
+ * Return: a new kdbus_pool on success, ERR_PTR on failure.
+ */
+struct kdbus_pool *kdbus_pool_new(const char *name, size_t size)
+{
+ struct kdbus_pool_slice *s;
+ struct kdbus_pool *p;
+ struct file *f;
+ char *n = NULL;
+ int ret;
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return ERR_PTR(-ENOMEM);
+
+ if (name) {
+ n = kasprintf(GFP_KERNEL, KBUILD_MODNAME "-conn:%s", name);
+ if (!n) {
+ ret = -ENOMEM;
+ goto exit_free;
+ }
+ }
+
+ f = shmem_file_setup(n ?: KBUILD_MODNAME "-conn", size, 0);
+ kfree(n);
+
+ if (IS_ERR(f)) {
+ ret = PTR_ERR(f);
+ goto exit_free;
+ }
+
+ ret = get_write_access(file_inode(f));
+ if (ret < 0)
+ goto exit_put_shmem;
+
+ /* allocate first slice spanning the entire pool */
+ s = kdbus_pool_slice_new(p, 0, size);
+ if (!s) {
+ ret = -ENOMEM;
+ goto exit_put_write;
+ }
+
+ p->f = f;
+ p->size = size;
+ p->slices_free = RB_ROOT;
+ p->slices_busy = RB_ROOT;
+ mutex_init(&p->lock);
+
+ INIT_LIST_HEAD(&p->slices);
+ list_add(&s->entry, &p->slices);
+
+ kdbus_pool_add_free_slice(p, s);
+ return p;
+
+exit_put_write:
+ put_write_access(file_inode(f));
+exit_put_shmem:
+ fput(f);
+exit_free:
+ kfree(p);
+ return ERR_PTR(ret);
+}
+
+/**
+ * kdbus_pool_free() - destroy pool
+ * @pool: The receiver's pool
+ */
+void kdbus_pool_free(struct kdbus_pool *pool)
+{
+ struct kdbus_pool_slice *s, *tmp;
+
+ if (!pool)
+ return;
+
+ list_for_each_entry_safe(s, tmp, &pool->slices, entry) {
+ list_del(&s->entry);
+ kfree(s);
+ }
+
+ put_write_access(file_inode(pool->f));
+ fput(pool->f);
+ kfree(pool);
+}
+
+/**
+ * kdbus_pool_accounted() - retrieve accounting information
+ * @pool: pool to query
+ * @size: output for overall pool size
+ * @acc: output for currently accounted size
+ *
+ * This returns accounting information of the pool. Note that the data might
+ * change after the function returns, as the pool lock is dropped. You need to
+ * protect the data via other means, if you need reliable accounting.
+ */
+void kdbus_pool_accounted(struct kdbus_pool *pool, size_t *size, size_t *acc)
+{
+ mutex_lock(&pool->lock);
+ if (size)
+ *size = pool->size;
+ if (acc)
+ *acc = pool->accounted_size;
+ mutex_unlock(&pool->lock);
+}
+
+/**
+ * kdbus_pool_slice_copy_iovec() - copy user memory to a slice
+ * @slice: The slice to write to
+ * @off: Offset in the slice to write to
+ * @iov: iovec array, pointing to data to copy
+ * @iov_len: Number of elements in @iov
+ * @total_len: Total number of bytes described in members of @iov
+ *
+ * User memory referenced by @iov will be copied into @slice at offset @off.
+ *
+ * Return: the numbers of bytes copied, negative errno on failure.
+ */
+ssize_t
+kdbus_pool_slice_copy_iovec(const struct kdbus_pool_slice *slice, loff_t off,
+ struct iovec *iov, size_t iov_len, size_t total_len)
+{
+ struct iov_iter iter;
+ ssize_t len;
+
+ if (WARN_ON(off + total_len > slice->size))
+ return -EFAULT;
+
+ off += slice->off;
+ iov_iter_init(&iter, WRITE, iov, iov_len, total_len);
+ len = vfs_iter_write(slice->pool->f, &iter, &off);
+
+ return (len >= 0 && len != total_len) ? -EFAULT : len;
+}
+
+/**
+ * kdbus_pool_slice_copy_kvec() - copy kernel memory to a slice
+ * @slice: The slice to write to
+ * @off: Offset in the slice to write to
+ * @kvec: kvec array, pointing to data to copy
+ * @kvec_len: Number of elements in @kvec
+ * @total_len: Total number of bytes described in members of @kvec
+ *
+ * Kernel memory referenced by @kvec will be copied into @slice at offset @off.
+ *
+ * Return: the numbers of bytes copied, negative errno on failure.
+ */
+ssize_t kdbus_pool_slice_copy_kvec(const struct kdbus_pool_slice *slice,
+ loff_t off, struct kvec *kvec,
+ size_t kvec_len, size_t total_len)
+{
+ struct iov_iter iter;
+ mm_segment_t old_fs;
+ ssize_t len;
+
+ if (WARN_ON(off + total_len > slice->size))
+ return -EFAULT;
+
+ off += slice->off;
+ iov_iter_kvec(&iter, WRITE | ITER_KVEC, kvec, kvec_len, total_len);
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ len = vfs_iter_write(slice->pool->f, &iter, &off);
+ set_fs(old_fs);
+
+ return (len >= 0 && len != total_len) ? -EFAULT : len;
+}
+
+/**
+ * kdbus_pool_slice_copy() - copy data from one slice into another
+ * @slice_dst: destination slice
+ * @slice_src: source slice
+ *
+ * Return: 0 on success, negative error number on failure.
+ */
+int kdbus_pool_slice_copy(const struct kdbus_pool_slice *slice_dst,
+ const struct kdbus_pool_slice *slice_src)
+{
+ struct file *f_src = slice_src->pool->f;
+ struct file *f_dst = slice_dst->pool->f;
+ struct inode *i_dst = file_inode(f_dst);
+ struct address_space *mapping_dst = f_dst->f_mapping;
+ const struct address_space_operations *aops = mapping_dst->a_ops;
+ unsigned long len = slice_src->size;
+ loff_t off_src = slice_src->off;
+ loff_t off_dst = slice_dst->off;
+ mm_segment_t old_fs;
+ int ret = 0;
+
+ if (WARN_ON(slice_src->size != slice_dst->size) ||
+ WARN_ON(slice_src->free || slice_dst->free))
+ return -EINVAL;
+
+ mutex_lock(&i_dst->i_mutex);
+ old_fs = get_fs();
+ set_fs(get_ds());
+ while (len > 0) {
+ unsigned long page_off;
+ unsigned long copy_len;
+ char __user *kaddr;
+ struct page *page;
+ ssize_t n_read;
+ void *fsdata;
+ long status;
+
+ page_off = off_dst & (PAGE_CACHE_SIZE - 1);
+ copy_len = min_t(unsigned long,
+ PAGE_CACHE_SIZE - page_off, len);
+
+ status = aops->write_begin(f_dst, mapping_dst, off_dst,
+ copy_len, 0, &page, &fsdata);
+ if (unlikely(status < 0)) {
+ ret = status;
+ break;
+ }
+
+ kaddr = (char __force __user *)kmap(page) + page_off;
+ n_read = __vfs_read(f_src, kaddr, copy_len, &off_src);
+ kunmap(page);
+ mark_page_accessed(page);
+ flush_dcache_page(page);
+
+ if (unlikely(n_read != copy_len)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ status = aops->write_end(f_dst, mapping_dst, off_dst,
+ copy_len, copy_len, page, fsdata);
+ if (unlikely(status != copy_len)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ off_dst += copy_len;
+ len -= copy_len;
+ }
+ set_fs(old_fs);
+ mutex_unlock(&i_dst->i_mutex);
+
+ return ret;
+}
+
+/**
+ * kdbus_pool_mmap() - map the pool into the process
+ * @pool: The receiver's pool
+ * @vma: passed by mmap() syscall
+ *
+ * Return: the result of the mmap() call, negative errno on failure.
+ */
+int kdbus_pool_mmap(const struct kdbus_pool *pool, struct vm_area_struct *vma)
+{
+ /* deny write access to the pool */
+ if (vma->vm_flags & VM_WRITE)
+ return -EPERM;
+ vma->vm_flags &= ~VM_MAYWRITE;
+
+ /* do not allow to map more than the size of the file */
+ if ((vma->vm_end - vma->vm_start) > pool->size)
+ return -EFAULT;
+
+ /* replace the connection file with our shmem file */
+ if (vma->vm_file)
+ fput(vma->vm_file);
+ vma->vm_file = get_file(pool->f);
+
+ return pool->f->f_op->mmap(pool->f, vma);
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-17 10:00:27 +0000