On Tue, Feb 1, 2022 at 5:15 AM Warner Losh <i...@bsdimp.com> wrote:
>
> lock_iovec will lock an I/O vec and the memory to which it referrs and
> create a iovec in the host space that referrs to it, with full error
> unwinding.
>
s/referrs/refers/ twice
> Signed-off-by: Warner Losh <i...@bsdimp.com>
> ---
> bsd-user/freebsd/os-syscall.c | 92 +++++++++++++++++++++++++++++++++++
> 1 file changed, 92 insertions(+)
>
Two typos, otherwise seems to LGTM:
Reviewed-by: Kyle Evans <kev...@freebsd.org>
> diff --git a/bsd-user/freebsd/os-syscall.c b/bsd-user/freebsd/os-syscall.c
> index 060134a9ecd..c21759ae7ce 100644
> --- a/bsd-user/freebsd/os-syscall.c
> +++ b/bsd-user/freebsd/os-syscall.c
> @@ -75,6 +75,98 @@ bool is_error(abi_long ret)
> return (abi_ulong)ret >= (abi_ulong)(-4096);
> }
>
> +struct iovec *lock_iovec(int type, abi_ulong target_addr,
> + int count, int copy)
> +{
> + struct target_iovec *target_vec;
> + struct iovec *vec;
> + abi_ulong total_len, max_len;
> + int i;
> + int err = 0;
> + bool bad_address = false;
> +
> + if (count == 0) {
> + errno = 0;
> + return NULL;
> + }
> + if (count < 0 || count > IOV_MAX) {
> + errno = EINVAL;
> + return NULL;
> + }
> +
> + vec = calloc(count, sizeof(struct iovec));
> + if (vec == NULL) {
> + errno = ENOMEM;
> + return NULL;
> + }
> +
> + target_vec = lock_user(VERIFY_READ, target_addr,
> + count * sizeof(struct target_iovec), 1);
> + if (target_vec == NULL) {
> + err = EFAULT;
> + goto fail2;
> + }
> +
> + /*
> + * ??? If host page size > target page size, this will result in a value
> + * larger than what we can actually support.
> + */
> + max_len = 0x7fffffff & TARGET_PAGE_MASK;
> + total_len = 0;
> +
> + for (i = 0; i < count; i++) {
> + abi_ulong base = tswapal(target_vec[i].iov_base);
> + abi_long len = tswapal(target_vec[i].iov_len);
> +
> + if (len < 0) {
> + err = EINVAL;
> + goto fail;
> + } else if (len == 0) {
> + /* Zero length pointer is ignored. */
> + vec[i].iov_base = 0;
> + } else {
> + vec[i].iov_base = lock_user(type, base, len, copy);
> + /*
> + * If the first buffer pointer is bad, this is a fault. But
> + * subsequent bad buffers will result in a partial write; this is
> + * realized by filling the vector with null pointers and zero
> + * lengths.
> + */
> + if (!vec[i].iov_base) {
> + if (i == 0) {
> + err = EFAULT;
> + goto fail;
> + } else {
> + bad_address = true;
> + }
> + }
> + if (bad_address) {
> + len = 0;
> + }
> + if (len > max_len - total_len) {
> + len = max_len - total_len;
> + }
> + }
> + vec[i].iov_len = len;
> + total_len += len;
> + }
> +
> + unlock_user(target_vec, target_addr, 0);
> + return vec;
> +
> + fail:
> + while (--i >= 0) {
> + if (tswapal(target_vec[i].iov_len) > 0) {
> + unlock_user(vec[i].iov_base, tswapal(target_vec[i].iov_base), 0);
> + }
> + }
> + unlock_user(target_vec, target_addr, 0);
> + fail2:
> + free(vec);
> + errno = err;
> + return NULL;
> +}
> +
> /*
> * do_syscall() should always have a single exit point at the end so that
> * actions, such as logging of syscall results, can be performed. All errnos
> --
> 2.33.1
>
