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-rw-r--r--fs/read_write.c730
1 files changed, 730 insertions, 0 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
new file mode 100644
index 000000000000..6be4b1a1956b
--- /dev/null
+++ b/fs/read_write.c
@@ -0,0 +1,730 @@
+/*
+ * linux/fs/read_write.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/fcntl.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/smp_lock.h>
+#include <linux/dnotify.h>
+#include <linux/security.h>
+#include <linux/module.h>
+#include <linux/syscalls.h>
+
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+
+struct file_operations generic_ro_fops = {
+ .llseek = generic_file_llseek,
+ .read = generic_file_read,
+ .mmap = generic_file_readonly_mmap,
+ .sendfile = generic_file_sendfile,
+};
+
+EXPORT_SYMBOL(generic_ro_fops);
+
+loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
+{
+ long long retval;
+ struct inode *inode = file->f_mapping->host;
+
+ down(&inode->i_sem);
+ switch (origin) {
+ case 2:
+ offset += inode->i_size;
+ break;
+ case 1:
+ offset += file->f_pos;
+ }
+ retval = -EINVAL;
+ if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ retval = offset;
+ }
+ up(&inode->i_sem);
+ return retval;
+}
+
+EXPORT_SYMBOL(generic_file_llseek);
+
+loff_t remote_llseek(struct file *file, loff_t offset, int origin)
+{
+ long long retval;
+
+ lock_kernel();
+ switch (origin) {
+ case 2:
+ offset += i_size_read(file->f_dentry->d_inode);
+ break;
+ case 1:
+ offset += file->f_pos;
+ }
+ retval = -EINVAL;
+ if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ retval = offset;
+ }
+ unlock_kernel();
+ return retval;
+}
+EXPORT_SYMBOL(remote_llseek);
+
+loff_t no_llseek(struct file *file, loff_t offset, int origin)
+{
+ return -ESPIPE;
+}
+EXPORT_SYMBOL(no_llseek);
+
+loff_t default_llseek(struct file *file, loff_t offset, int origin)
+{
+ long long retval;
+
+ lock_kernel();
+ switch (origin) {
+ case 2:
+ offset += i_size_read(file->f_dentry->d_inode);
+ break;
+ case 1:
+ offset += file->f_pos;
+ }
+ retval = -EINVAL;
+ if (offset >= 0) {
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ retval = offset;
+ }
+ unlock_kernel();
+ return retval;
+}
+EXPORT_SYMBOL(default_llseek);
+
+loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
+{
+ loff_t (*fn)(struct file *, loff_t, int);
+
+ fn = no_llseek;
+ if (file->f_mode & FMODE_LSEEK) {
+ fn = default_llseek;
+ if (file->f_op && file->f_op->llseek)
+ fn = file->f_op->llseek;
+ }
+ return fn(file, offset, origin);
+}
+EXPORT_SYMBOL(vfs_llseek);
+
+asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
+{
+ off_t retval;
+ struct file * file;
+ int fput_needed;
+
+ retval = -EBADF;
+ file = fget_light(fd, &fput_needed);
+ if (!file)
+ goto bad;
+
+ retval = -EINVAL;
+ if (origin <= 2) {
+ loff_t res = vfs_llseek(file, offset, origin);
+ retval = res;
+ if (res != (loff_t)retval)
+ retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
+ }
+ fput_light(file, fput_needed);
+bad:
+ return retval;
+}
+
+#ifdef __ARCH_WANT_SYS_LLSEEK
+asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
+ unsigned long offset_low, loff_t __user * result,
+ unsigned int origin)
+{
+ int retval;
+ struct file * file;
+ loff_t offset;
+ int fput_needed;
+
+ retval = -EBADF;
+ file = fget_light(fd, &fput_needed);
+ if (!file)
+ goto bad;
+
+ retval = -EINVAL;
+ if (origin > 2)
+ goto out_putf;
+
+ offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
+ origin);
+
+ retval = (int)offset;
+ if (offset >= 0) {
+ retval = -EFAULT;
+ if (!copy_to_user(result, &offset, sizeof(offset)))
+ retval = 0;
+ }
+out_putf:
+ fput_light(file, fput_needed);
+bad:
+ return retval;
+}
+#endif
+
+
+int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
+{
+ struct inode *inode;
+ loff_t pos;
+
+ if (unlikely(count > file->f_maxcount))
+ goto Einval;
+ pos = *ppos;
+ if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
+ goto Einval;
+
+ inode = file->f_dentry->d_inode;
+ if (inode->i_flock && MANDATORY_LOCK(inode))
+ return locks_mandatory_area(read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE, inode, file, pos, count);
+ return 0;
+
+Einval:
+ return -EINVAL;
+}
+
+ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
+{
+ struct kiocb kiocb;
+ ssize_t ret;
+
+ init_sync_kiocb(&kiocb, filp);
+ kiocb.ki_pos = *ppos;
+ ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos);
+ if (-EIOCBQUEUED == ret)
+ ret = wait_on_sync_kiocb(&kiocb);
+ *ppos = kiocb.ki_pos;
+ return ret;
+}
+
+EXPORT_SYMBOL(do_sync_read);
+
+ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
+{
+ ssize_t ret;
+
+ if (!(file->f_mode & FMODE_READ))
+ return -EBADF;
+ if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
+ return -EINVAL;
+ if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
+ return -EFAULT;
+
+ ret = rw_verify_area(READ, file, pos, count);
+ if (!ret) {
+ ret = security_file_permission (file, MAY_READ);
+ if (!ret) {
+ if (file->f_op->read)
+ ret = file->f_op->read(file, buf, count, pos);
+ else
+ ret = do_sync_read(file, buf, count, pos);
+ if (ret > 0) {
+ dnotify_parent(file->f_dentry, DN_ACCESS);
+ current->rchar += ret;
+ }
+ current->syscr++;
+ }
+ }
+
+ return ret;
+}
+
+EXPORT_SYMBOL(vfs_read);
+
+ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
+{
+ struct kiocb kiocb;
+ ssize_t ret;
+
+ init_sync_kiocb(&kiocb, filp);
+ kiocb.ki_pos = *ppos;
+ ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos);
+ if (-EIOCBQUEUED == ret)
+ ret = wait_on_sync_kiocb(&kiocb);
+ *ppos = kiocb.ki_pos;
+ return ret;
+}
+
+EXPORT_SYMBOL(do_sync_write);
+
+ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
+{
+ ssize_t ret;
+
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EBADF;
+ if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
+ return -EINVAL;
+ if (unlikely(!access_ok(VERIFY_READ, buf, count)))
+ return -EFAULT;
+
+ ret = rw_verify_area(WRITE, file, pos, count);
+ if (!ret) {
+ ret = security_file_permission (file, MAY_WRITE);
+ if (!ret) {
+ if (file->f_op->write)
+ ret = file->f_op->write(file, buf, count, pos);
+ else
+ ret = do_sync_write(file, buf, count, pos);
+ if (ret > 0) {
+ dnotify_parent(file->f_dentry, DN_MODIFY);
+ current->wchar += ret;
+ }
+ current->syscw++;
+ }
+ }
+
+ return ret;
+}
+
+EXPORT_SYMBOL(vfs_write);
+
+static inline loff_t file_pos_read(struct file *file)
+{
+ return file->f_pos;
+}
+
+static inline void file_pos_write(struct file *file, loff_t pos)
+{
+ file->f_pos = pos;
+}
+
+asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+ int fput_needed;
+
+ file = fget_light(fd, &fput_needed);
+ if (file) {
+ loff_t pos = file_pos_read(file);
+ ret = vfs_read(file, buf, count, &pos);
+ file_pos_write(file, pos);
+ fput_light(file, fput_needed);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(sys_read);
+
+asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+ int fput_needed;
+
+ file = fget_light(fd, &fput_needed);
+ if (file) {
+ loff_t pos = file_pos_read(file);
+ ret = vfs_write(file, buf, count, &pos);
+ file_pos_write(file, pos);
+ fput_light(file, fput_needed);
+ }
+
+ return ret;
+}
+
+asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
+ size_t count, loff_t pos)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+ int fput_needed;
+
+ if (pos < 0)
+ return -EINVAL;
+
+ file = fget_light(fd, &fput_needed);
+ if (file) {
+ ret = -ESPIPE;
+ if (file->f_mode & FMODE_PREAD)
+ ret = vfs_read(file, buf, count, &pos);
+ fput_light(file, fput_needed);
+ }
+
+ return ret;
+}
+
+asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
+ size_t count, loff_t pos)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+ int fput_needed;
+
+ if (pos < 0)
+ return -EINVAL;
+
+ file = fget_light(fd, &fput_needed);
+ if (file) {
+ ret = -ESPIPE;
+ if (file->f_mode & FMODE_PWRITE)
+ ret = vfs_write(file, buf, count, &pos);
+ fput_light(file, fput_needed);
+ }
+
+ return ret;
+}
+
+/*
+ * Reduce an iovec's length in-place. Return the resulting number of segments
+ */
+unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
+{
+ unsigned long seg = 0;
+ size_t len = 0;
+
+ while (seg < nr_segs) {
+ seg++;
+ if (len + iov->iov_len >= to) {
+ iov->iov_len = to - len;
+ break;
+ }
+ len += iov->iov_len;
+ iov++;
+ }
+ return seg;
+}
+
+EXPORT_SYMBOL(iov_shorten);
+
+/* A write operation does a read from user space and vice versa */
+#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
+
+static ssize_t do_readv_writev(int type, struct file *file,
+ const struct iovec __user * uvector,
+ unsigned long nr_segs, loff_t *pos)
+{
+ typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
+ typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
+
+ size_t tot_len;
+ struct iovec iovstack[UIO_FASTIOV];
+ struct iovec *iov=iovstack, *vector;
+ ssize_t ret;
+ int seg;
+ io_fn_t fn;
+ iov_fn_t fnv;
+
+ /*
+ * SuS says "The readv() function *may* fail if the iovcnt argument
+ * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
+ * traditionally returned zero for zero segments, so...
+ */
+ ret = 0;
+ if (nr_segs == 0)
+ goto out;
+
+ /*
+ * First get the "struct iovec" from user memory and
+ * verify all the pointers
+ */
+ ret = -EINVAL;
+ if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
+ goto out;
+ if (!file->f_op)
+ goto out;
+ if (nr_segs > UIO_FASTIOV) {
+ ret = -ENOMEM;
+ iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+ if (!iov)
+ goto out;
+ }
+ ret = -EFAULT;
+ if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
+ goto out;
+
+ /*
+ * Single unix specification:
+ * We should -EINVAL if an element length is not >= 0 and fitting an
+ * ssize_t. The total length is fitting an ssize_t
+ *
+ * Be careful here because iov_len is a size_t not an ssize_t
+ */
+ tot_len = 0;
+ ret = -EINVAL;
+ for (seg = 0; seg < nr_segs; seg++) {
+ void __user *buf = iov[seg].iov_base;
+ ssize_t len = (ssize_t)iov[seg].iov_len;
+
+ if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
+ goto Efault;
+ if (len < 0) /* size_t not fitting an ssize_t .. */
+ goto out;
+ tot_len += len;
+ if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
+ goto out;
+ }
+ if (tot_len == 0) {
+ ret = 0;
+ goto out;
+ }
+
+ ret = rw_verify_area(type, file, pos, tot_len);
+ if (ret)
+ goto out;
+
+ fnv = NULL;
+ if (type == READ) {
+ fn = file->f_op->read;
+ fnv = file->f_op->readv;
+ } else {
+ fn = (io_fn_t)file->f_op->write;
+ fnv = file->f_op->writev;
+ }
+ if (fnv) {
+ ret = fnv(file, iov, nr_segs, pos);
+ goto out;
+ }
+
+ /* Do it by hand, with file-ops */
+ ret = 0;
+ vector = iov;
+ while (nr_segs > 0) {
+ void __user * base;
+ size_t len;
+ ssize_t nr;
+
+ base = vector->iov_base;
+ len = vector->iov_len;
+ vector++;
+ nr_segs--;
+
+ nr = fn(file, base, len, pos);
+
+ if (nr < 0) {
+ if (!ret) ret = nr;
+ break;
+ }
+ ret += nr;
+ if (nr != len)
+ break;
+ }
+out:
+ if (iov != iovstack)
+ kfree(iov);
+ if ((ret + (type == READ)) > 0)
+ dnotify_parent(file->f_dentry,
+ (type == READ) ? DN_ACCESS : DN_MODIFY);
+ return ret;
+Efault:
+ ret = -EFAULT;
+ goto out;
+}
+
+ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
+ unsigned long vlen, loff_t *pos)
+{
+ if (!(file->f_mode & FMODE_READ))
+ return -EBADF;
+ if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
+ return -EINVAL;
+
+ return do_readv_writev(READ, file, vec, vlen, pos);
+}
+
+EXPORT_SYMBOL(vfs_readv);
+
+ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
+ unsigned long vlen, loff_t *pos)
+{
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EBADF;
+ if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
+ return -EINVAL;
+
+ return do_readv_writev(WRITE, file, vec, vlen, pos);
+}
+
+EXPORT_SYMBOL(vfs_writev);
+
+asmlinkage ssize_t
+sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+ int fput_needed;
+
+ file = fget_light(fd, &fput_needed);
+ if (file) {
+ loff_t pos = file_pos_read(file);
+ ret = vfs_readv(file, vec, vlen, &pos);
+ file_pos_write(file, pos);
+ fput_light(file, fput_needed);
+ }
+
+ if (ret > 0)
+ current->rchar += ret;
+ current->syscr++;
+ return ret;
+}
+
+asmlinkage ssize_t
+sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+ int fput_needed;
+
+ file = fget_light(fd, &fput_needed);
+ if (file) {
+ loff_t pos = file_pos_read(file);
+ ret = vfs_writev(file, vec, vlen, &pos);
+ file_pos_write(file, pos);
+ fput_light(file, fput_needed);
+ }
+
+ if (ret > 0)
+ current->wchar += ret;
+ current->syscw++;
+ return ret;
+}
+
+static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
+ size_t count, loff_t max)
+{
+ struct file * in_file, * out_file;
+ struct inode * in_inode, * out_inode;
+ loff_t pos;
+ ssize_t retval;
+ int fput_needed_in, fput_needed_out;
+
+ /*
+ * Get input file, and verify that it is ok..
+ */
+ retval = -EBADF;
+ in_file = fget_light(in_fd, &fput_needed_in);
+ if (!in_file)
+ goto out;
+ if (!(in_file->f_mode & FMODE_READ))
+ goto fput_in;
+ retval = -EINVAL;
+ in_inode = in_file->f_dentry->d_inode;
+ if (!in_inode)
+ goto fput_in;
+ if (!in_file->f_op || !in_file->f_op->sendfile)
+ goto fput_in;
+ retval = -ESPIPE;
+ if (!ppos)
+ ppos = &in_file->f_pos;
+ else
+ if (!(in_file->f_mode & FMODE_PREAD))
+ goto fput_in;
+ retval = rw_verify_area(READ, in_file, ppos, count);
+ if (retval)
+ goto fput_in;
+
+ retval = security_file_permission (in_file, MAY_READ);
+ if (retval)
+ goto fput_in;
+
+ /*
+ * Get output file, and verify that it is ok..
+ */
+ retval = -EBADF;
+ out_file = fget_light(out_fd, &fput_needed_out);
+ if (!out_file)
+ goto fput_in;
+ if (!(out_file->f_mode & FMODE_WRITE))
+ goto fput_out;
+ retval = -EINVAL;
+ if (!out_file->f_op || !out_file->f_op->sendpage)
+ goto fput_out;
+ out_inode = out_file->f_dentry->d_inode;
+ retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
+ if (retval)
+ goto fput_out;
+
+ retval = security_file_permission (out_file, MAY_WRITE);
+ if (retval)
+ goto fput_out;
+
+ if (!max)
+ max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
+
+ pos = *ppos;
+ retval = -EINVAL;
+ if (unlikely(pos < 0))
+ goto fput_out;
+ if (unlikely(pos + count > max)) {
+ retval = -EOVERFLOW;
+ if (pos >= max)
+ goto fput_out;
+ count = max - pos;
+ }
+
+ retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
+
+ if (retval > 0) {
+ current->rchar += retval;
+ current->wchar += retval;
+ }
+ current->syscr++;
+ current->syscw++;
+
+ if (*ppos > max)
+ retval = -EOVERFLOW;
+
+fput_out:
+ fput_light(out_file, fput_needed_out);
+fput_in:
+ fput_light(in_file, fput_needed_in);
+out:
+ return retval;
+}
+
+asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
+{
+ loff_t pos;
+ off_t off;
+ ssize_t ret;
+
+ if (offset) {
+ if (unlikely(get_user(off, offset)))
+ return -EFAULT;
+ pos = off;
+ ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
+ if (unlikely(put_user(pos, offset)))
+ return -EFAULT;
+ return ret;
+ }
+
+ return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
+
+asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
+{
+ loff_t pos;
+ ssize_t ret;
+
+ if (offset) {
+ if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
+ return -EFAULT;
+ ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
+ if (unlikely(put_user(pos, offset)))
+ return -EFAULT;
+ return ret;
+ }
+
+ return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-11 19:57:23 +0000