| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * linux/fs/read_write.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/stat.h> |
| #include <linux/sched/xacct.h> |
| #include <linux/fcntl.h> |
| #include <linux/file.h> |
| #include <linux/uio.h> |
| #include <linux/fsnotify.h> |
| #include <linux/security.h> |
| #include <linux/export.h> |
| #include <linux/syscalls.h> |
| #include <linux/pagemap.h> |
| #include <linux/splice.h> |
| #include <linux/compat.h> |
| #include <linux/mount.h> |
| #include <linux/fs.h> |
| #include "internal.h" |
| |
| #include <linux/uaccess.h> |
| #include <asm/unistd.h> |
| |
| const struct file_operations generic_ro_fops = { |
| .llseek = generic_file_llseek, |
| .read_iter = generic_file_read_iter, |
| .mmap = generic_file_readonly_mmap, |
| .splice_read = generic_file_splice_read, |
| }; |
| |
| EXPORT_SYMBOL(generic_ro_fops); |
| |
| static inline bool unsigned_offsets(struct file *file) |
| { |
| return file->f_mode & FMODE_UNSIGNED_OFFSET; |
| } |
| |
| /** |
| * vfs_setpos - update the file offset for lseek |
| * @file: file structure in question |
| * @offset: file offset to seek to |
| * @maxsize: maximum file size |
| * |
| * This is a low-level filesystem helper for updating the file offset to |
| * the value specified by @offset if the given offset is valid and it is |
| * not equal to the current file offset. |
| * |
| * Return the specified offset on success and -EINVAL on invalid offset. |
| */ |
| loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize) |
| { |
| if (offset < 0 && !unsigned_offsets(file)) |
| return -EINVAL; |
| if (offset > maxsize) |
| return -EINVAL; |
| |
| if (offset != file->f_pos) { |
| file->f_pos = offset; |
| file->f_version = 0; |
| } |
| return offset; |
| } |
| EXPORT_SYMBOL(vfs_setpos); |
| |
| /** |
| * generic_file_llseek_size - generic llseek implementation for regular files |
| * @file: file structure to seek on |
| * @offset: file offset to seek to |
| * @whence: type of seek |
| * @size: max size of this file in file system |
| * @eof: offset used for SEEK_END position |
| * |
| * This is a variant of generic_file_llseek that allows passing in a custom |
| * maximum file size and a custom EOF position, for e.g. hashed directories |
| * |
| * Synchronization: |
| * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms) |
| * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes. |
| * read/writes behave like SEEK_SET against seeks. |
| */ |
| loff_t |
| generic_file_llseek_size(struct file *file, loff_t offset, int whence, |
| loff_t maxsize, loff_t eof) |
| { |
| switch (whence) { |
| case SEEK_END: |
| offset += eof; |
| break; |
| case SEEK_CUR: |
| /* |
| * Here we special-case the lseek(fd, 0, SEEK_CUR) |
| * position-querying operation. Avoid rewriting the "same" |
| * f_pos value back to the file because a concurrent read(), |
| * write() or lseek() might have altered it |
| */ |
| if (offset == 0) |
| return file->f_pos; |
| /* |
| * f_lock protects against read/modify/write race with other |
| * SEEK_CURs. Note that parallel writes and reads behave |
| * like SEEK_SET. |
| */ |
| spin_lock(&file->f_lock); |
| offset = vfs_setpos(file, file->f_pos + offset, maxsize); |
| spin_unlock(&file->f_lock); |
| return offset; |
| case SEEK_DATA: |
| /* |
| * In the generic case the entire file is data, so as long as |
| * offset isn't at the end of the file then the offset is data. |
| */ |
| if ((unsigned long long)offset >= eof) |
| return -ENXIO; |
| break; |
| case SEEK_HOLE: |
| /* |
| * There is a virtual hole at the end of the file, so as long as |
| * offset isn't i_size or larger, return i_size. |
| */ |
| if ((unsigned long long)offset >= eof) |
| return -ENXIO; |
| offset = eof; |
| break; |
| } |
| |
| return vfs_setpos(file, offset, maxsize); |
| } |
| EXPORT_SYMBOL(generic_file_llseek_size); |
| |
| /** |
| * generic_file_llseek - generic llseek implementation for regular files |
| * @file: file structure to seek on |
| * @offset: file offset to seek to |
| * @whence: type of seek |
| * |
| * This is a generic implemenation of ->llseek useable for all normal local |
| * filesystems. It just updates the file offset to the value specified by |
| * @offset and @whence. |
| */ |
| loff_t generic_file_llseek(struct file *file, loff_t offset, int whence) |
| { |
| struct inode *inode = file->f_mapping->host; |
| |
| return generic_file_llseek_size(file, offset, whence, |
| inode->i_sb->s_maxbytes, |
| i_size_read(inode)); |
| } |
| EXPORT_SYMBOL(generic_file_llseek); |
| |
| /** |
| * fixed_size_llseek - llseek implementation for fixed-sized devices |
| * @file: file structure to seek on |
| * @offset: file offset to seek to |
| * @whence: type of seek |
| * @size: size of the file |
| * |
| */ |
| loff_t fixed_size_llseek(struct file *file, loff_t offset, int whence, loff_t size) |
| { |
| switch (whence) { |
| case SEEK_SET: case SEEK_CUR: case SEEK_END: |
| return generic_file_llseek_size(file, offset, whence, |
| size, size); |
| default: |
| return -EINVAL; |
| } |
| } |
| EXPORT_SYMBOL(fixed_size_llseek); |
| |
| /** |
| * no_seek_end_llseek - llseek implementation for fixed-sized devices |
| * @file: file structure to seek on |
| * @offset: file offset to seek to |
| * @whence: type of seek |
| * |
| */ |
| loff_t no_seek_end_llseek(struct file *file, loff_t offset, int whence) |
| { |
| switch (whence) { |
| case SEEK_SET: case SEEK_CUR: |
| return generic_file_llseek_size(file, offset, whence, |
| OFFSET_MAX, 0); |
| default: |
| return -EINVAL; |
| } |
| } |
| EXPORT_SYMBOL(no_seek_end_llseek); |
| |
| /** |
| * no_seek_end_llseek_size - llseek implementation for fixed-sized devices |
| * @file: file structure to seek on |
| * @offset: file offset to seek to |
| * @whence: type of seek |
| * @size: maximal offset allowed |
| * |
| */ |
| loff_t no_seek_end_llseek_size(struct file *file, loff_t offset, int whence, loff_t size) |
| { |
| switch (whence) { |
| case SEEK_SET: case SEEK_CUR: |
| return generic_file_llseek_size(file, offset, whence, |
| size, 0); |
| default: |
| return -EINVAL; |
| } |
| } |
| EXPORT_SYMBOL(no_seek_end_llseek_size); |
| |
| /** |
| * noop_llseek - No Operation Performed llseek implementation |
| * @file: file structure to seek on |
| * @offset: file offset to seek to |
| * @whence: type of seek |
| * |
| * This is an implementation of ->llseek useable for the rare special case when |
| * userspace expects the seek to succeed but the (device) file is actually not |
| * able to perform the seek. In this case you use noop_llseek() instead of |
| * falling back to the default implementation of ->llseek. |
| */ |
| loff_t noop_llseek(struct file *file, loff_t offset, int whence) |
| { |
| return file->f_pos; |
| } |
| EXPORT_SYMBOL(noop_llseek); |
| |
| loff_t no_llseek(struct file *file, loff_t offset, int whence) |
| { |
| return -ESPIPE; |
| } |
| EXPORT_SYMBOL(no_llseek); |
| |
| loff_t default_llseek(struct file *file, loff_t offset, int whence) |
| { |
| struct inode *inode = file_inode(file); |
| loff_t retval; |
| |
| inode_lock(inode); |
| switch (whence) { |
| case SEEK_END: |
| offset += i_size_read(inode); |
| break; |
| case SEEK_CUR: |
| if (offset == 0) { |
| retval = file->f_pos; |
| goto out; |
| } |
| offset += file->f_pos; |
| break; |
| case SEEK_DATA: |
| /* |
| * In the generic case the entire file is data, so as |
| * long as offset isn't at the end of the file then the |
| * offset is data. |
| */ |
| if (offset >= inode->i_size) { |
| retval = -ENXIO; |
| goto out; |
| } |
| break; |
| case SEEK_HOLE: |
| /* |
| * There is a virtual hole at the end of the file, so |
| * as long as offset isn't i_size or larger, return |
| * i_size. |
| */ |
| if (offset >= inode->i_size) { |
| retval = -ENXIO; |
| goto out; |
| } |
| offset = inode->i_size; |
| break; |
| } |
| retval = -EINVAL; |
| if (offset >= 0 || unsigned_offsets(file)) { |
| if (offset != file->f_pos) { |
| file->f_pos = offset; |
| file->f_version = 0; |
| } |
| retval = offset; |
| } |
| out: |
| inode_unlock(inode); |
| return retval; |
| } |
| EXPORT_SYMBOL(default_llseek); |
| |
| loff_t vfs_llseek(struct file *file, loff_t offset, int whence) |
| { |
| loff_t (*fn)(struct file *, loff_t, int); |
| |
| fn = no_llseek; |
| if (file->f_mode & FMODE_LSEEK) { |
| if (file->f_op->llseek) |
| fn = file->f_op->llseek; |
| } |
| return fn(file, offset, whence); |
| } |
| EXPORT_SYMBOL(vfs_llseek); |
| |
| static off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence) |
| { |
| off_t retval; |
| struct fd f = fdget_pos(fd); |
| if (!f.file) |
| return -EBADF; |
| |
| retval = -EINVAL; |
| if (whence <= SEEK_MAX) { |
| loff_t res = vfs_llseek(f.file, offset, whence); |
| retval = res; |
| if (res != (loff_t)retval) |
| retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */ |
| } |
| fdput_pos(f); |
| return retval; |
| } |
| |
| SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence) |
| { |
| return ksys_lseek(fd, offset, whence); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence) |
| { |
| return ksys_lseek(fd, offset, whence); |
| } |
| #endif |
| |
| #if !defined(CONFIG_64BIT) || defined(CONFIG_COMPAT) || \ |
| defined(__ARCH_WANT_SYS_LLSEEK) |
| SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high, |
| unsigned long, offset_low, loff_t __user *, result, |
| unsigned int, whence) |
| { |
| int retval; |
| struct fd f = fdget_pos(fd); |
| loff_t offset; |
| |
| if (!f.file) |
| return -EBADF; |
| |
| retval = -EINVAL; |
| if (whence > SEEK_MAX) |
| goto out_putf; |
| |
| offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low, |
| whence); |
| |
| retval = (int)offset; |
| if (offset >= 0) { |
| retval = -EFAULT; |
| if (!copy_to_user(result, &offset, sizeof(offset))) |
| retval = 0; |
| } |
| out_putf: |
| fdput_pos(f); |
| return retval; |
| } |
| #endif |
| |
| int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count) |
| { |
| struct inode *inode; |
| int retval = -EINVAL; |
| |
| inode = file_inode(file); |
| if (unlikely((ssize_t) count < 0)) |
| return retval; |
| |
| /* |
| * ranged mandatory locking does not apply to streams - it makes sense |
| * only for files where position has a meaning. |
| */ |
| if (ppos) { |
| loff_t pos = *ppos; |
| |
| if (unlikely(pos < 0)) { |
| if (!unsigned_offsets(file)) |
| return retval; |
| if (count >= -pos) /* both values are in 0..LLONG_MAX */ |
| return -EOVERFLOW; |
| } else if (unlikely((loff_t) (pos + count) < 0)) { |
| if (!unsigned_offsets(file)) |
| return retval; |
| } |
| |
| if (unlikely(inode->i_flctx && mandatory_lock(inode))) { |
| retval = locks_mandatory_area(inode, file, pos, pos + count - 1, |
| read_write == READ ? F_RDLCK : F_WRLCK); |
| if (retval < 0) |
| return retval; |
| } |
| } |
| |
| return security_file_permission(file, |
| read_write == READ ? MAY_READ : MAY_WRITE); |
| } |
| |
| static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) |
| { |
| struct iovec iov = { .iov_base = buf, .iov_len = len }; |
| struct kiocb kiocb; |
| struct iov_iter iter; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, filp); |
| kiocb.ki_pos = (ppos ? *ppos : 0); |
| iov_iter_init(&iter, READ, &iov, 1, len); |
| |
| ret = call_read_iter(filp, &kiocb, &iter); |
| BUG_ON(ret == -EIOCBQUEUED); |
| if (ppos) |
| *ppos = kiocb.ki_pos; |
| return ret; |
| } |
| |
| static int warn_unsupported(struct file *file, const char *op) |
| { |
| pr_warn_ratelimited( |
| "kernel %s not supported for file %pD4 (pid: %d comm: %.20s)\n", |
| op, file, current->pid, current->comm); |
| return -EINVAL; |
| } |
| |
| ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) |
| { |
| struct kvec iov = { |
| .iov_base = buf, |
| .iov_len = min_t(size_t, count, MAX_RW_COUNT), |
| }; |
| struct kiocb kiocb; |
| struct iov_iter iter; |
| ssize_t ret; |
| |
| if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ))) |
| return -EINVAL; |
| if (!(file->f_mode & FMODE_CAN_READ)) |
| return -EINVAL; |
| /* |
| * Also fail if ->read_iter and ->read are both wired up as that |
| * implies very convoluted semantics. |
| */ |
| if (unlikely(!file->f_op->read_iter || file->f_op->read)) |
| return warn_unsupported(file, "read"); |
| |
| init_sync_kiocb(&kiocb, file); |
| kiocb.ki_pos = pos ? *pos : 0; |
| iov_iter_kvec(&iter, READ, &iov, 1, iov.iov_len); |
| ret = file->f_op->read_iter(&kiocb, &iter); |
| if (ret > 0) { |
| if (pos) |
| *pos = kiocb.ki_pos; |
| fsnotify_access(file); |
| add_rchar(current, ret); |
| } |
| inc_syscr(current); |
| return ret; |
| } |
| |
| ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) |
| { |
| ssize_t ret; |
| |
| ret = rw_verify_area(READ, file, pos, count); |
| if (ret) |
| return ret; |
| return __kernel_read(file, buf, count, pos); |
| } |
| EXPORT_SYMBOL_NS(kernel_read, ANDROID_GKI_VFS_EXPORT_ONLY); |
| |
| 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_mode & FMODE_CAN_READ)) |
| return -EINVAL; |
| if (unlikely(!access_ok(buf, count))) |
| return -EFAULT; |
| |
| ret = rw_verify_area(READ, file, pos, count); |
| if (ret) |
| return ret; |
| if (count > MAX_RW_COUNT) |
| count = MAX_RW_COUNT; |
| |
| if (file->f_op->read) |
| ret = file->f_op->read(file, buf, count, pos); |
| else if (file->f_op->read_iter) |
| ret = new_sync_read(file, buf, count, pos); |
| else |
| ret = -EINVAL; |
| if (ret > 0) { |
| fsnotify_access(file); |
| add_rchar(current, ret); |
| } |
| inc_syscr(current); |
| return ret; |
| } |
| |
| static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos) |
| { |
| struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len }; |
| struct kiocb kiocb; |
| struct iov_iter iter; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, filp); |
| kiocb.ki_pos = (ppos ? *ppos : 0); |
| iov_iter_init(&iter, WRITE, &iov, 1, len); |
| |
| ret = call_write_iter(filp, &kiocb, &iter); |
| BUG_ON(ret == -EIOCBQUEUED); |
| if (ret > 0 && ppos) |
| *ppos = kiocb.ki_pos; |
| return ret; |
| } |
| |
| /* caller is responsible for file_start_write/file_end_write */ |
| ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos) |
| { |
| struct kvec iov = { |
| .iov_base = (void *)buf, |
| .iov_len = min_t(size_t, count, MAX_RW_COUNT), |
| }; |
| struct kiocb kiocb; |
| struct iov_iter iter; |
| ssize_t ret; |
| |
| if (WARN_ON_ONCE(!(file->f_mode & FMODE_WRITE))) |
| return -EBADF; |
| if (!(file->f_mode & FMODE_CAN_WRITE)) |
| return -EINVAL; |
| /* |
| * Also fail if ->write_iter and ->write are both wired up as that |
| * implies very convoluted semantics. |
| */ |
| if (unlikely(!file->f_op->write_iter || file->f_op->write)) |
| return warn_unsupported(file, "write"); |
| |
| init_sync_kiocb(&kiocb, file); |
| kiocb.ki_pos = pos ? *pos : 0; |
| iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len); |
| ret = file->f_op->write_iter(&kiocb, &iter); |
| if (ret > 0) { |
| if (pos) |
| *pos = kiocb.ki_pos; |
| fsnotify_modify(file); |
| add_wchar(current, ret); |
| } |
| inc_syscw(current); |
| return ret; |
| } |
| /* |
| * This "EXPORT_SYMBOL_GPL()" is more of a "EXPORT_SYMBOL_DONTUSE()", |
| * but autofs is one of the few internal kernel users that actually |
| * wants this _and_ can be built as a module. So we need to export |
| * this symbol for autofs, even though it really isn't appropriate |
| * for any other kernel modules. |
| */ |
| EXPORT_SYMBOL_GPL(__kernel_write); |
| |
| ssize_t kernel_write(struct file *file, const void *buf, size_t count, |
| loff_t *pos) |
| { |
| ssize_t ret; |
| |
| ret = rw_verify_area(WRITE, file, pos, count); |
| if (ret) |
| return ret; |
| |
| file_start_write(file); |
| ret = __kernel_write(file, buf, count, pos); |
| file_end_write(file); |
| return ret; |
| } |
| EXPORT_SYMBOL_NS(kernel_write, ANDROID_GKI_VFS_EXPORT_ONLY); |
| |
| 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_mode & FMODE_CAN_WRITE)) |
| return -EINVAL; |
| if (unlikely(!access_ok(buf, count))) |
| return -EFAULT; |
| |
| ret = rw_verify_area(WRITE, file, pos, count); |
| if (ret) |
| return ret; |
| if (count > MAX_RW_COUNT) |
| count = MAX_RW_COUNT; |
| file_start_write(file); |
| if (file->f_op->write) |
| ret = file->f_op->write(file, buf, count, pos); |
| else if (file->f_op->write_iter) |
| ret = new_sync_write(file, buf, count, pos); |
| else |
| ret = -EINVAL; |
| if (ret > 0) { |
| fsnotify_modify(file); |
| add_wchar(current, ret); |
| } |
| inc_syscw(current); |
| file_end_write(file); |
| return ret; |
| } |
| |
| /* file_ppos returns &file->f_pos or NULL if file is stream */ |
| static inline loff_t *file_ppos(struct file *file) |
| { |
| return file->f_mode & FMODE_STREAM ? NULL : &file->f_pos; |
| } |
| |
| ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count) |
| { |
| struct fd f = fdget_pos(fd); |
| ssize_t ret = -EBADF; |
| |
| if (f.file) { |
| loff_t pos, *ppos = file_ppos(f.file); |
| if (ppos) { |
| pos = *ppos; |
| ppos = &pos; |
| } |
| ret = vfs_read(f.file, buf, count, ppos); |
| if (ret >= 0 && ppos) |
| f.file->f_pos = pos; |
| fdput_pos(f); |
| } |
| return ret; |
| } |
| |
| SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) |
| { |
| return ksys_read(fd, buf, count); |
| } |
| |
| ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count) |
| { |
| struct fd f = fdget_pos(fd); |
| ssize_t ret = -EBADF; |
| |
| if (f.file) { |
| loff_t pos, *ppos = file_ppos(f.file); |
| if (ppos) { |
| pos = *ppos; |
| ppos = &pos; |
| } |
| ret = vfs_write(f.file, buf, count, ppos); |
| if (ret >= 0 && ppos) |
| f.file->f_pos = pos; |
| fdput_pos(f); |
| } |
| |
| return ret; |
| } |
| |
| SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf, |
| size_t, count) |
| { |
| return ksys_write(fd, buf, count); |
| } |
| |
| ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count, |
| loff_t pos) |
| { |
| struct fd f; |
| ssize_t ret = -EBADF; |
| |
| if (pos < 0) |
| return -EINVAL; |
| |
| f = fdget(fd); |
| if (f.file) { |
| ret = -ESPIPE; |
| if (f.file->f_mode & FMODE_PREAD) |
| ret = vfs_read(f.file, buf, count, &pos); |
| fdput(f); |
| } |
| |
| return ret; |
| } |
| |
| SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf, |
| size_t, count, loff_t, pos) |
| { |
| return ksys_pread64(fd, buf, count, pos); |
| } |
| |
| ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf, |
| size_t count, loff_t pos) |
| { |
| struct fd f; |
| ssize_t ret = -EBADF; |
| |
| if (pos < 0) |
| return -EINVAL; |
| |
| f = fdget(fd); |
| if (f.file) { |
| ret = -ESPIPE; |
| if (f.file->f_mode & FMODE_PWRITE) |
| ret = vfs_write(f.file, buf, count, &pos); |
| fdput(f); |
| } |
| |
| return ret; |
| } |
| |
| SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf, |
| size_t, count, loff_t, pos) |
| { |
| return ksys_pwrite64(fd, buf, count, pos); |
| } |
| |
| static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter, |
| loff_t *ppos, int type, rwf_t flags) |
| { |
| struct kiocb kiocb; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, filp); |
| ret = kiocb_set_rw_flags(&kiocb, flags); |
| if (ret) |
| return ret; |
| kiocb.ki_pos = (ppos ? *ppos : 0); |
| |
| if (type == READ) |
| ret = call_read_iter(filp, &kiocb, iter); |
| else |
| ret = call_write_iter(filp, &kiocb, iter); |
| BUG_ON(ret == -EIOCBQUEUED); |
| if (ppos) |
| *ppos = kiocb.ki_pos; |
| return ret; |
| } |
| |
| /* Do it by hand, with file-ops */ |
| static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter, |
| loff_t *ppos, int type, rwf_t flags) |
| { |
| ssize_t ret = 0; |
| |
| if (flags & ~RWF_HIPRI) |
| return -EOPNOTSUPP; |
| |
| while (iov_iter_count(iter)) { |
| struct iovec iovec = iov_iter_iovec(iter); |
| ssize_t nr; |
| |
| if (type == READ) { |
| nr = filp->f_op->read(filp, iovec.iov_base, |
| iovec.iov_len, ppos); |
| } else { |
| nr = filp->f_op->write(filp, iovec.iov_base, |
| iovec.iov_len, ppos); |
| } |
| |
| if (nr < 0) { |
| if (!ret) |
| ret = nr; |
| break; |
| } |
| ret += nr; |
| if (nr != iovec.iov_len) |
| break; |
| iov_iter_advance(iter, nr); |
| } |
| |
| return ret; |
| } |
| |
| static ssize_t do_iter_read(struct file *file, struct iov_iter *iter, |
| loff_t *pos, rwf_t flags) |
| { |
| size_t tot_len; |
| ssize_t ret = 0; |
| |
| if (!(file->f_mode & FMODE_READ)) |
| return -EBADF; |
| if (!(file->f_mode & FMODE_CAN_READ)) |
| return -EINVAL; |
| |
| tot_len = iov_iter_count(iter); |
| if (!tot_len) |
| goto out; |
| ret = rw_verify_area(READ, file, pos, tot_len); |
| if (ret < 0) |
| return ret; |
| |
| if (file->f_op->read_iter) |
| ret = do_iter_readv_writev(file, iter, pos, READ, flags); |
| else |
| ret = do_loop_readv_writev(file, iter, pos, READ, flags); |
| out: |
| if (ret >= 0) |
| fsnotify_access(file); |
| return ret; |
| } |
| |
| ssize_t vfs_iocb_iter_read(struct file *file, struct kiocb *iocb, |
| struct iov_iter *iter) |
| { |
| size_t tot_len; |
| ssize_t ret = 0; |
| |
| if (!file->f_op->read_iter) |
| return -EINVAL; |
| if (!(file->f_mode & FMODE_READ)) |
| return -EBADF; |
| if (!(file->f_mode & FMODE_CAN_READ)) |
| return -EINVAL; |
| |
| tot_len = iov_iter_count(iter); |
| if (!tot_len) |
| goto out; |
| ret = rw_verify_area(READ, file, &iocb->ki_pos, tot_len); |
| if (ret < 0) |
| return ret; |
| |
| ret = call_read_iter(file, iocb, iter); |
| out: |
| if (ret >= 0) |
| fsnotify_access(file); |
| return ret; |
| } |
| EXPORT_SYMBOL(vfs_iocb_iter_read); |
| |
| ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos, |
| rwf_t flags) |
| { |
| if (!file->f_op->read_iter) |
| return -EINVAL; |
| return do_iter_read(file, iter, ppos, flags); |
| } |
| EXPORT_SYMBOL(vfs_iter_read); |
| |
| static ssize_t do_iter_write(struct file *file, struct iov_iter *iter, |
| loff_t *pos, rwf_t flags) |
| { |
| size_t tot_len; |
| ssize_t ret = 0; |
| |
| if (!(file->f_mode & FMODE_WRITE)) |
| return -EBADF; |
| if (!(file->f_mode & FMODE_CAN_WRITE)) |
| return -EINVAL; |
| |
| tot_len = iov_iter_count(iter); |
| if (!tot_len) |
| return 0; |
| ret = rw_verify_area(WRITE, file, pos, tot_len); |
| if (ret < 0) |
| return ret; |
| |
| if (file->f_op->write_iter) |
| ret = do_iter_readv_writev(file, iter, pos, WRITE, flags); |
| else |
| ret = do_loop_readv_writev(file, iter, pos, WRITE, flags); |
| if (ret > 0) |
| fsnotify_modify(file); |
| return ret; |
| } |
| |
| ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb, |
| struct iov_iter *iter) |
| { |
| size_t tot_len; |
| ssize_t ret = 0; |
| |
| if (!file->f_op->write_iter) |
| return -EINVAL; |
| if (!(file->f_mode & FMODE_WRITE)) |
| return -EBADF; |
| if (!(file->f_mode & FMODE_CAN_WRITE)) |
| return -EINVAL; |
| |
| tot_len = iov_iter_count(iter); |
| if (!tot_len) |
| return 0; |
| ret = rw_verify_area(WRITE, file, &iocb->ki_pos, tot_len); |
| if (ret < 0) |
| return ret; |
| |
| ret = call_write_iter(file, iocb, iter); |
| if (ret > 0) |
| fsnotify_modify(file); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(vfs_iocb_iter_write); |
| |
| ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos, |
| rwf_t flags) |
| { |
| if (!file->f_op->write_iter) |
| return -EINVAL; |
| return do_iter_write(file, iter, ppos, flags); |
| } |
| EXPORT_SYMBOL(vfs_iter_write); |
| |
| static ssize_t vfs_readv(struct file *file, const struct iovec __user *vec, |
| unsigned long vlen, loff_t *pos, rwf_t flags) |
| { |
| struct iovec iovstack[UIO_FASTIOV]; |
| struct iovec *iov = iovstack; |
| struct iov_iter iter; |
| ssize_t ret; |
| |
| ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter); |
| if (ret >= 0) { |
| ret = do_iter_read(file, &iter, pos, flags); |
| kfree(iov); |
| } |
| |
| return ret; |
| } |
| |
| static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec, |
| unsigned long vlen, loff_t *pos, rwf_t flags) |
| { |
| struct iovec iovstack[UIO_FASTIOV]; |
| struct iovec *iov = iovstack; |
| struct iov_iter iter; |
| ssize_t ret; |
| |
| ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter); |
| if (ret >= 0) { |
| file_start_write(file); |
| ret = do_iter_write(file, &iter, pos, flags); |
| file_end_write(file); |
| kfree(iov); |
| } |
| return ret; |
| } |
| |
| static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec, |
| unsigned long vlen, rwf_t flags) |
| { |
| struct fd f = fdget_pos(fd); |
| ssize_t ret = -EBADF; |
| |
| if (f.file) { |
| loff_t pos, *ppos = file_ppos(f.file); |
| if (ppos) { |
| pos = *ppos; |
| ppos = &pos; |
| } |
| ret = vfs_readv(f.file, vec, vlen, ppos, flags); |
| if (ret >= 0 && ppos) |
| f.file->f_pos = pos; |
| fdput_pos(f); |
| } |
| |
| if (ret > 0) |
| add_rchar(current, ret); |
| inc_syscr(current); |
| return ret; |
| } |
| |
| static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec, |
| unsigned long vlen, rwf_t flags) |
| { |
| struct fd f = fdget_pos(fd); |
| ssize_t ret = -EBADF; |
| |
| if (f.file) { |
| loff_t pos, *ppos = file_ppos(f.file); |
| if (ppos) { |
| pos = *ppos; |
| ppos = &pos; |
| } |
| ret = vfs_writev(f.file, vec, vlen, ppos, flags); |
| if (ret >= 0 && ppos) |
| f.file->f_pos = pos; |
| fdput_pos(f); |
| } |
| |
| if (ret > 0) |
| add_wchar(current, ret); |
| inc_syscw(current); |
| return ret; |
| } |
| |
| static inline loff_t pos_from_hilo(unsigned long high, unsigned long low) |
| { |
| #define HALF_LONG_BITS (BITS_PER_LONG / 2) |
| return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low; |
| } |
| |
| static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec, |
| unsigned long vlen, loff_t pos, rwf_t flags) |
| { |
| struct fd f; |
| ssize_t ret = -EBADF; |
| |
| if (pos < 0) |
| return -EINVAL; |
| |
| f = fdget(fd); |
| if (f.file) { |
| ret = -ESPIPE; |
| if (f.file->f_mode & FMODE_PREAD) |
| ret = vfs_readv(f.file, vec, vlen, &pos, flags); |
| fdput(f); |
| } |
| |
| if (ret > 0) |
| add_rchar(current, ret); |
| inc_syscr(current); |
| return ret; |
| } |
| |
| static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec, |
| unsigned long vlen, loff_t pos, rwf_t flags) |
| { |
| struct fd f; |
| ssize_t ret = -EBADF; |
| |
| if (pos < 0) |
| return -EINVAL; |
| |
| f = fdget(fd); |
| if (f.file) { |
| ret = -ESPIPE; |
| if (f.file->f_mode & FMODE_PWRITE) |
| ret = vfs_writev(f.file, vec, vlen, &pos, flags); |
| fdput(f); |
| } |
| |
| if (ret > 0) |
| add_wchar(current, ret); |
| inc_syscw(current); |
| return ret; |
| } |
| |
| SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec, |
| unsigned long, vlen) |
| { |
| return do_readv(fd, vec, vlen, 0); |
| } |
| |
| SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec, |
| unsigned long, vlen) |
| { |
| return do_writev(fd, vec, vlen, 0); |
| } |
| |
| SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec, |
| unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h) |
| { |
| loff_t pos = pos_from_hilo(pos_h, pos_l); |
| |
| return do_preadv(fd, vec, vlen, pos, 0); |
| } |
| |
| SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec, |
| unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h, |
| rwf_t, flags) |
| { |
| loff_t pos = pos_from_hilo(pos_h, pos_l); |
| |
| if (pos == -1) |
| return do_readv(fd, vec, vlen, flags); |
| |
| return do_preadv(fd, vec, vlen, pos, flags); |
| } |
| |
| SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec, |
| unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h) |
| { |
| loff_t pos = pos_from_hilo(pos_h, pos_l); |
| |
| return do_pwritev(fd, vec, vlen, pos, 0); |
| } |
| |
| SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec, |
| unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h, |
| rwf_t, flags) |
| { |
| loff_t pos = pos_from_hilo(pos_h, pos_l); |
| |
| if (pos == -1) |
| return do_writev(fd, vec, vlen, flags); |
| |
| return do_pwritev(fd, vec, vlen, pos, flags); |
| } |
| |
| /* |
| * Various compat syscalls. Note that they all pretend to take a native |
| * iovec - import_iovec will properly treat those as compat_iovecs based on |
| * in_compat_syscall(). |
| */ |
| #ifdef CONFIG_COMPAT |
| #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64 |
| COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd, |
| const struct iovec __user *, vec, |
| unsigned long, vlen, loff_t, pos) |
| { |
| return do_preadv(fd, vec, vlen, pos, 0); |
| } |
| #endif |
| |
| COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd, |
| const struct iovec __user *, vec, |
| compat_ulong_t, vlen, u32, pos_low, u32, pos_high) |
| { |
| loff_t pos = ((loff_t)pos_high << 32) | pos_low; |
| |
| return do_preadv(fd, vec, vlen, pos, 0); |
| } |
| |
| #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2 |
| COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd, |
| const struct iovec __user *, vec, |
| unsigned long, vlen, loff_t, pos, rwf_t, flags) |
| { |
| if (pos == -1) |
| return do_readv(fd, vec, vlen, flags); |
| return do_preadv(fd, vec, vlen, pos, flags); |
| } |
| #endif |
| |
| COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd, |
| const struct iovec __user *, vec, |
| compat_ulong_t, vlen, u32, pos_low, u32, pos_high, |
| rwf_t, flags) |
| { |
| loff_t pos = ((loff_t)pos_high << 32) | pos_low; |
| |
| if (pos == -1) |
| return do_readv(fd, vec, vlen, flags); |
| return do_preadv(fd, vec, vlen, pos, flags); |
| } |
| |
| #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64 |
| COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd, |
| const struct iovec __user *, vec, |
| unsigned long, vlen, loff_t, pos) |
| { |
| return do_pwritev(fd, vec, vlen, pos, 0); |
| } |
| #endif |
| |
| COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd, |
| const struct iovec __user *,vec, |
| compat_ulong_t, vlen, u32, pos_low, u32, pos_high) |
| { |
| loff_t pos = ((loff_t)pos_high << 32) | pos_low; |
| |
| return do_pwritev(fd, vec, vlen, pos, 0); |
| } |
| |
| #ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2 |
| COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd, |
| const struct iovec __user *, vec, |
| unsigned long, vlen, loff_t, pos, rwf_t, flags) |
| { |
| if (pos == -1) |
| return do_writev(fd, vec, vlen, flags); |
| return do_pwritev(fd, vec, vlen, pos, flags); |
| } |
| #endif |
| |
| COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd, |
| const struct iovec __user *,vec, |
| compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags) |
| { |
| loff_t pos = ((loff_t)pos_high << 32) | pos_low; |
| |
| if (pos == -1) |
| return do_writev(fd, vec, vlen, flags); |
| return do_pwritev(fd, vec, vlen, pos, flags); |
| } |
| #endif /* CONFIG_COMPAT */ |
| |
| static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, |
| size_t count, loff_t max) |
| { |
| struct fd in, out; |
| struct inode *in_inode, *out_inode; |
| loff_t pos; |
| loff_t out_pos; |
| ssize_t retval; |
| int fl; |
| |
| /* |
| * Get input file, and verify that it is ok.. |
| */ |
| retval = -EBADF; |
| in = fdget(in_fd); |
| if (!in.file) |
| goto out; |
| if (!(in.file->f_mode & FMODE_READ)) |
| goto fput_in; |
| retval = -ESPIPE; |
| if (!ppos) { |
| pos = in.file->f_pos; |
| } else { |
| pos = *ppos; |
| if (!(in.file->f_mode & FMODE_PREAD)) |
| goto fput_in; |
| } |
| retval = rw_verify_area(READ, in.file, &pos, count); |
| if (retval < 0) |
| goto fput_in; |
| if (count > MAX_RW_COUNT) |
| count = MAX_RW_COUNT; |
| |
| /* |
| * Get output file, and verify that it is ok.. |
| */ |
| retval = -EBADF; |
| out = fdget(out_fd); |
| if (!out.file) |
| goto fput_in; |
| if (!(out.file->f_mode & FMODE_WRITE)) |
| goto fput_out; |
| in_inode = file_inode(in.file); |
| out_inode = file_inode(out.file); |
| out_pos = out.file->f_pos; |
| retval = rw_verify_area(WRITE, out.file, &out_pos, count); |
| if (retval < 0) |
| goto fput_out; |
| |
| if (!max) |
| max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes); |
| |
| if (unlikely(pos + count > max)) { |
| retval = -EOVERFLOW; |
| if (pos >= max) |
| goto fput_out; |
| count = max - pos; |
| } |
| |
| fl = 0; |
| #if 0 |
| /* |
| * We need to debate whether we can enable this or not. The |
| * man page documents EAGAIN return for the output at least, |
| * and the application is arguably buggy if it doesn't expect |
| * EAGAIN on a non-blocking file descriptor. |
| */ |
| if (in.file->f_flags & O_NONBLOCK) |
| fl = SPLICE_F_NONBLOCK; |
| #endif |
| file_start_write(out.file); |
| retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl); |
| file_end_write(out.file); |
| |
| if (retval > 0) { |
| add_rchar(current, retval); |
| add_wchar(current, retval); |
| fsnotify_access(in.file); |
| fsnotify_modify(out.file); |
| out.file->f_pos = out_pos; |
| if (ppos) |
| *ppos = pos; |
| else |
| in.file->f_pos = pos; |
| } |
| |
| inc_syscr(current); |
| inc_syscw(current); |
| if (pos > max) |
| retval = -EOVERFLOW; |
| |
| fput_out: |
| fdput(out); |
| fput_in: |
| fdput(in); |
| out: |
| return retval; |
| } |
| |
| SYSCALL_DEFINE4(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); |
| } |
| |
| SYSCALL_DEFINE4(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); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, |
| compat_off_t __user *, offset, compat_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); |
| } |
| |
| COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, |
| compat_loff_t __user *, offset, compat_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); |
| } |
| #endif |
| |
| /** |
| * generic_copy_file_range - copy data between two files |
| * @file_in: file structure to read from |
| * @pos_in: file offset to read from |
| * @file_out: file structure to write data to |
| * @pos_out: file offset to write data to |
| * @len: amount of data to copy |
| * @flags: copy flags |
| * |
| * This is a generic filesystem helper to copy data from one file to another. |
| * It has no constraints on the source or destination file owners - the files |
| * can belong to different superblocks and different filesystem types. Short |
| * copies are allowed. |
| * |
| * This should be called from the @file_out filesystem, as per the |
| * ->copy_file_range() method. |
| * |
| * Returns the number of bytes copied or a negative error indicating the |
| * failure. |
| */ |
| |
| ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in, |
| struct file *file_out, loff_t pos_out, |
| size_t len, unsigned int flags) |
| { |
| return do_splice_direct(file_in, &pos_in, file_out, &pos_out, |
| len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0); |
| } |
| EXPORT_SYMBOL(generic_copy_file_range); |
| |
| /* |
| * Performs necessary checks before doing a file copy |
| * |
| * Can adjust amount of bytes to copy via @req_count argument. |
| * Returns appropriate error code that caller should return or |
| * zero in case the copy should be allowed. |
| */ |
| static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, |
| struct file *file_out, loff_t pos_out, |
| size_t *req_count, unsigned int flags) |
| { |
| struct inode *inode_in = file_inode(file_in); |
| struct inode *inode_out = file_inode(file_out); |
| uint64_t count = *req_count; |
| loff_t size_in; |
| int ret; |
| |
| ret = generic_file_rw_checks(file_in, file_out); |
| if (ret) |
| return ret; |
| |
| /* |
| * We allow some filesystems to handle cross sb copy, but passing |
| * a file of the wrong filesystem type to filesystem driver can result |
| * in an attempt to dereference the wrong type of ->private_data, so |
| * avoid doing that until we really have a good reason. |
| * |
| * nfs and cifs define several different file_system_type structures |
| * and several different sets of file_operations, but they all end up |
| * using the same ->copy_file_range() function pointer. |
| */ |
| if (flags & COPY_FILE_SPLICE) { |
| /* cross sb splice is allowed */ |
| } else if (file_out->f_op->copy_file_range) { |
| if (file_in->f_op->copy_file_range != |
| file_out->f_op->copy_file_range) |
| return -EXDEV; |
| } else if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) { |
| return -EXDEV; |
| } |
| |
| /* Don't touch certain kinds of inodes */ |
| if (IS_IMMUTABLE(inode_out)) |
| return -EPERM; |
| |
| if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out)) |
| return -ETXTBSY; |
| |
| /* Ensure offsets don't wrap. */ |
| if (pos_in + count < pos_in || pos_out + count < pos_out) |
| return -EOVERFLOW; |
| |
| /* Shorten the copy to EOF */ |
| size_in = i_size_read(inode_in); |
| if (pos_in >= size_in) |
| count = 0; |
| else |
| count = min(count, size_in - (uint64_t)pos_in); |
| |
| ret = generic_write_check_limits(file_out, pos_out, &count); |
| if (ret) |
| return ret; |
| |
| /* Don't allow overlapped copying within the same file. */ |
| if (inode_in == inode_out && |
| pos_out + count > pos_in && |
| pos_out < pos_in + count) |
| return -EINVAL; |
| |
| *req_count = count; |
| return 0; |
| } |
| |
| /* |
| * copy_file_range() differs from regular file read and write in that it |
| * specifically allows return partial success. When it does so is up to |
| * the copy_file_range method. |
| */ |
| ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, |
| struct file *file_out, loff_t pos_out, |
| size_t len, unsigned int flags) |
| { |
| ssize_t ret; |
| bool splice = flags & COPY_FILE_SPLICE; |
| |
| if (flags & ~COPY_FILE_SPLICE) |
| return -EINVAL; |
| |
| ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len, |
| flags); |
| if (unlikely(ret)) |
| return ret; |
| |
| ret = rw_verify_area(READ, file_in, &pos_in, len); |
| if (unlikely(ret)) |
| return ret; |
| |
| ret = rw_verify_area(WRITE, file_out, &pos_out, len); |
| if (unlikely(ret)) |
| return ret; |
| |
| if (len == 0) |
| return 0; |
| |
| file_start_write(file_out); |
| |
| /* |
| * Cloning is supported by more file systems, so we implement copy on |
| * same sb using clone, but for filesystems where both clone and copy |
| * are supported (e.g. nfs,cifs), we only call the copy method. |
| */ |
| if (!splice && file_out->f_op->copy_file_range) { |
| ret = file_out->f_op->copy_file_range(file_in, pos_in, |
| file_out, pos_out, |
| len, flags); |
| goto done; |
| } |
| |
| if (!splice && file_in->f_op->remap_file_range && |
| file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) { |
| ret = file_in->f_op->remap_file_range(file_in, pos_in, |
| file_out, pos_out, |
| min_t(loff_t, MAX_RW_COUNT, len), |
| REMAP_FILE_CAN_SHORTEN); |
| if (ret > 0) |
| goto done; |
| } |
| |
| /* |
| * We can get here for same sb copy of filesystems that do not implement |
| * ->copy_file_range() in case filesystem does not support clone or in |
| * case filesystem supports clone but rejected the clone request (e.g. |
| * because it was not block aligned). |
| * |
| * In both cases, fall back to kernel copy so we are able to maintain a |
| * consistent story about which filesystems support copy_file_range() |
| * and which filesystems do not, that will allow userspace tools to |
| * make consistent desicions w.r.t using copy_file_range(). |
| * |
| * We also get here if caller (e.g. nfsd) requested COPY_FILE_SPLICE. |
| */ |
| ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, |
| flags); |
| |
| done: |
| if (ret > 0) { |
| fsnotify_access(file_in); |
| add_rchar(current, ret); |
| fsnotify_modify(file_out); |
| add_wchar(current, ret); |
| } |
| |
| inc_syscr(current); |
| inc_syscw(current); |
| |
| file_end_write(file_out); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(vfs_copy_file_range); |
| |
| SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in, |
| int, fd_out, loff_t __user *, off_out, |
| size_t, len, unsigned int, flags) |
| { |
| loff_t pos_in; |
| loff_t pos_out; |
| struct fd f_in; |
| struct fd f_out; |
| ssize_t ret = -EBADF; |
| |
| f_in = fdget(fd_in); |
| if (!f_in.file) |
| goto out2; |
| |
| f_out = fdget(fd_out); |
| if (!f_out.file) |
| goto out1; |
| |
| ret = -EFAULT; |
| if (off_in) { |
| if (copy_from_user(&pos_in, off_in, sizeof(loff_t))) |
| goto out; |
| } else { |
| pos_in = f_in.file->f_pos; |
| } |
| |
| if (off_out) { |
| if (copy_from_user(&pos_out, off_out, sizeof(loff_t))) |
| goto out; |
| } else { |
| pos_out = f_out.file->f_pos; |
| } |
| |
| ret = -EINVAL; |
| if (flags != 0) |
| goto out; |
| |
| ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len, |
| flags); |
| if (ret > 0) { |
| pos_in += ret; |
| pos_out += ret; |
| |
| if (off_in) { |
| if (copy_to_user(off_in, &pos_in, sizeof(loff_t))) |
| ret = -EFAULT; |
| } else { |
| f_in.file->f_pos = pos_in; |
| } |
| |
| if (off_out) { |
| if (copy_to_user(off_out, &pos_out, sizeof(loff_t))) |
| ret = -EFAULT; |
| } else { |
| f_out.file->f_pos = pos_out; |
| } |
| } |
| |
| out: |
| fdput(f_out); |
| out1: |
| fdput(f_in); |
| out2: |
| return ret; |
| } |
| |
| /* |
| * Don't operate on ranges the page cache doesn't support, and don't exceed the |
| * LFS limits. If pos is under the limit it becomes a short access. If it |
| * exceeds the limit we return -EFBIG. |
| */ |
| int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count) |
| { |
| struct inode *inode = file->f_mapping->host; |
| loff_t max_size = inode->i_sb->s_maxbytes; |
| loff_t limit = rlimit(RLIMIT_FSIZE); |
| |
| if (limit != RLIM_INFINITY) { |
| if (pos >= limit) { |
| send_sig(SIGXFSZ, current, 0); |
| return -EFBIG; |
| } |
| *count = min(*count, limit - pos); |
| } |
| |
| if (!(file->f_flags & O_LARGEFILE)) |
| max_size = MAX_NON_LFS; |
| |
| if (unlikely(pos >= max_size)) |
| return -EFBIG; |
| |
| *count = min(*count, max_size - pos); |
| |
| return 0; |
| } |
| |
| /* |
| * Performs necessary checks before doing a write |
| * |
| * Can adjust writing position or amount of bytes to write. |
| * Returns appropriate error code that caller should return or |
| * zero in case that write should be allowed. |
| */ |
| ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) |
| { |
| struct file *file = iocb->ki_filp; |
| struct inode *inode = file->f_mapping->host; |
| loff_t count; |
| int ret; |
| |
| if (IS_SWAPFILE(inode)) |
| return -ETXTBSY; |
| |
| if (!iov_iter_count(from)) |
| return 0; |
| |
| /* FIXME: this is for backwards compatibility with 2.4 */ |
| if (iocb->ki_flags & IOCB_APPEND) |
| iocb->ki_pos = i_size_read(inode); |
| |
| if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)) |
| return -EINVAL; |
| |
| count = iov_iter_count(from); |
| ret = generic_write_check_limits(file, iocb->ki_pos, &count); |
| if (ret) |
| return ret; |
| |
| iov_iter_truncate(from, count); |
| return iov_iter_count(from); |
| } |
| EXPORT_SYMBOL(generic_write_checks); |
| |
| /* |
| * Performs common checks before doing a file copy/clone |
| * from @file_in to @file_out. |
| */ |
| int generic_file_rw_checks(struct file *file_in, struct file *file_out) |
| { |
| struct inode *inode_in = file_inode(file_in); |
| struct inode *inode_out = file_inode(file_out); |
| |
| /* Don't copy dirs, pipes, sockets... */ |
| if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode)) |
| return -EISDIR; |
| if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) |
| return -EINVAL; |
| |
| if (!(file_in->f_mode & FMODE_READ) || |
| !(file_out->f_mode & FMODE_WRITE) || |
| (file_out->f_flags & O_APPEND)) |
| return -EBADF; |
| |
| return 0; |
| } |