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vmsplice(): lift importing iovec into vmsplice(2) and compat counterpart

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... getting rid of transformations in the latter - just use
compat_import_iovec().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-05-26 21:39:52 -04:00
parent 4faa99965e
commit 87a3002af9
1 changed files with 75 additions and 69 deletions
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144
fs/splice.c
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@ -1242,38 +1242,26 @@ static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
* For lack of a better implementation, implement vmsplice() to userspace
* as a simple copy of the pipes pages to the user iov.
*/
static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
unsigned long nr_segs, unsigned int flags)
static long vmsplice_to_user(struct file *file, struct iov_iter *iter,
unsigned int flags)
{
struct pipe_inode_info *pipe;
struct splice_desc sd;
long ret;
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
struct pipe_inode_info *pipe = get_pipe_info(file);
struct splice_desc sd = {
.total_len = iov_iter_count(iter),
.flags = flags,
.u.data = iter
};
long ret = 0;
pipe = get_pipe_info(file);
if (!pipe)
return -EBADF;
ret = import_iovec(READ, uiov, nr_segs,
ARRAY_SIZE(iovstack), &iov, &iter);
if (ret < 0)
return ret;
sd.total_len = iov_iter_count(&iter);
sd.len = 0;
sd.flags = flags;
sd.u.data = &iter;
sd.pos = 0;
if (sd.total_len) {
pipe_lock(pipe);
ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
pipe_unlock(pipe);
}
kfree(iov);
return ret;
}
@ -1282,14 +1270,11 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
* as splice-from-memory, where the regular splice is splice-from-file (or
* to file). In both cases the output is a pipe, naturally.
*/
static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
unsigned long nr_segs, unsigned int flags)
static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter,
unsigned int flags)
{
struct pipe_inode_info *pipe;
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter from;
long ret;
long ret = 0;
unsigned buf_flag = 0;
if (flags & SPLICE_F_GIFT)
@ -1299,22 +1284,31 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
if (!pipe)
return -EBADF;
ret = import_iovec(WRITE, uiov, nr_segs,
ARRAY_SIZE(iovstack), &iov, &from);
if (ret < 0)
return ret;
pipe_lock(pipe);
ret = wait_for_space(pipe, flags);
if (!ret)
ret = iter_to_pipe(&from, pipe, buf_flag);
ret = iter_to_pipe(iter, pipe, buf_flag);
pipe_unlock(pipe);
if (ret > 0)
wakeup_pipe_readers(pipe);
kfree(iov);
return ret;
}
static int vmsplice_type(struct fd f, int *type)
{
if (!f.file)
return -EBADF;
if (f.file->f_mode & FMODE_WRITE) {
*type = WRITE;
} else if (f.file->f_mode & FMODE_READ) {
*type = READ;
} else {
fdput(f);
return -EBADF;
}
return 0;
}
/*
* Note that vmsplice only really supports true splicing _from_ user memory
* to a pipe, not the other way around. Splicing from user memory is a simple
@ -1331,57 +1325,69 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
* Currently we punt and implement it as a normal copy, see pipe_to_user().
*
*/
static long do_vmsplice(int fd, const struct iovec __user *iov,
unsigned long nr_segs, unsigned int flags)
static long do_vmsplice(struct file *f, struct iov_iter *iter, unsigned int flags)
{
struct fd f;
long error;
if (unlikely(flags & ~SPLICE_F_ALL))
return -EINVAL;
if (unlikely(nr_segs > UIO_MAXIOV))
return -EINVAL;
else if (unlikely(!nr_segs))
if (!iov_iter_count(iter))
return 0;
error = -EBADF;
f = fdget(fd);
if (f.file) {
if (f.file->f_mode & FMODE_WRITE)
error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
else if (f.file->f_mode & FMODE_READ)
error = vmsplice_to_user(f.file, iov, nr_segs, flags);
fdput(f);
}
return error;
if (iov_iter_rw(iter) == WRITE)
return vmsplice_to_pipe(f, iter, flags);
else
return vmsplice_to_user(f, iter, flags);
}
SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov,
unsigned long, nr_segs, unsigned int, flags)
{
return do_vmsplice(fd, iov, nr_segs, flags);
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
long error;
struct fd f;
int type;
f = fdget(fd);
error = vmsplice_type(f, &type);
if (error)
return error;
error = import_iovec(type, uiov, nr_segs,
ARRAY_SIZE(iovstack), &iov, &iter);
if (!error) {
error = do_vmsplice(f.file, &iter, flags);
kfree(iov);
}
fdput(f);
return error;
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
unsigned int, nr_segs, unsigned int, flags)
{
unsigned i;
struct iovec __user *iov;
if (nr_segs > UIO_MAXIOV)
return -EINVAL;
iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
for (i = 0; i < nr_segs; i++) {
struct compat_iovec v;
if (get_user(v.iov_base, &iov32[i].iov_base) ||
get_user(v.iov_len, &iov32[i].iov_len) ||
put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
put_user(v.iov_len, &iov[i].iov_len))
return -EFAULT;
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
long error;
struct fd f;
int type;
f = fdget(fd);
error = vmsplice_type(f, &type);
if (error)
return error;
error = compat_import_iovec(type, iov32, nr_segs,
ARRAY_SIZE(iovstack), &iov, &iter);
if (!error) {
error = do_vmsplice(f.file, &iter, flags);
kfree(iov);
}
return do_vmsplice(fd, iov, nr_segs, flags);
fdput(f);
return error;
}
#endif