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See http://www.infradead.org/rpr.html X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Kees Cook , linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Don't allow calling ->read or ->write with set_fs as a preparation for killing off set_fs. All the instances that we use kernel_read/write on are using the iter ops already. If a file has both the regular ->read/->write methods and the iter variants those could have different semantics for messed up enough drivers. Also fails the kernel access to them in that case. Signed-off-by: Christoph Hellwig --- fs/read_write.c | 67 +++++++++++++++++++++++++++++++------------------ 1 file changed, 42 insertions(+), 25 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index 5db58b8c78d0dd..702c4301d9eb6b 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -419,27 +419,41 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo 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) { - mm_segment_t old_fs = get_fs(); + 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"); - if (count > MAX_RW_COUNT) - count = MAX_RW_COUNT; - set_fs(KERNEL_DS); - if (file->f_op->read) - ret = file->f_op->read(file, (void __user *)buf, count, pos); - else if (file->f_op->read_iter) - ret = new_sync_read(file, (void __user *)buf, count, pos); - else - ret = -EINVAL; - set_fs(old_fs); + init_sync_kiocb(&kiocb, file); + kiocb.ki_pos = *pos; + iov_iter_kvec(&iter, READ, &iov, 1, iov.iov_len); + ret = file->f_op->read_iter(&kiocb, &iter); if (ret > 0) { + *pos = kiocb.ki_pos; fsnotify_access(file); add_rchar(current, ret); } @@ -510,28 +524,31 @@ static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t /* 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) { - mm_segment_t old_fs; - const char __user *p; + 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"); - old_fs = get_fs(); - set_fs(KERNEL_DS); - p = (__force const char __user *)buf; - if (count > MAX_RW_COUNT) - count = MAX_RW_COUNT; - if (file->f_op->write) - ret = file->f_op->write(file, p, count, pos); - else if (file->f_op->write_iter) - ret = new_sync_write(file, p, count, pos); - else - ret = -EINVAL; - set_fs(old_fs); + init_sync_kiocb(&kiocb, file); + kiocb.ki_pos = *pos; + iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len); + ret = file->f_op->write_iter(&kiocb, &iter); if (ret > 0) { + *pos = kiocb.ki_pos; fsnotify_modify(file); add_wchar(current, ret); } -- 2.28.0