Linux 6.13-rc4

[linux.git] / fs / fuse / ioctl.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2017 Red Hat, Inc.
 */

#include "fuse_i.h"

#include <linux/uio.h>
#include <linux/compat.h>
#include <linux/fileattr.h>
#include <linux/fsverity.h>

#define FUSE_VERITY_ENABLE_ARG_MAX_PAGES 256

static ssize_t fuse_send_ioctl(struct fuse_mount *fm, struct fuse_args *args,
                               struct fuse_ioctl_out *outarg)
{
        ssize_t ret;

        args->out_args[0].size = sizeof(*outarg);
        args->out_args[0].value = outarg;

        ret = fuse_simple_request(fm, args);

        /* Translate ENOSYS, which shouldn't be returned from fs */
        if (ret == -ENOSYS)
                ret = -ENOTTY;

        if (ret >= 0 && outarg->result == -ENOSYS)
                outarg->result = -ENOTTY;

        return ret;
}

/*
 * CUSE servers compiled on 32bit broke on 64bit kernels because the
 * ABI was defined to be 'struct iovec' which is different on 32bit
 * and 64bit.  Fortunately we can determine which structure the server
 * used from the size of the reply.
 */
static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
                                     size_t transferred, unsigned count,
                                     bool is_compat)
{
#ifdef CONFIG_COMPAT
        if (count * sizeof(struct compat_iovec) == transferred) {
                struct compat_iovec *ciov = src;
                unsigned i;

                /*
                 * With this interface a 32bit server cannot support
                 * non-compat (i.e. ones coming from 64bit apps) ioctl
                 * requests
                 */
                if (!is_compat)
                        return -EINVAL;

                for (i = 0; i < count; i++) {
                        dst[i].iov_base = compat_ptr(ciov[i].iov_base);
                        dst[i].iov_len = ciov[i].iov_len;
                }
                return 0;
        }
#endif

        if (count * sizeof(struct iovec) != transferred)
                return -EIO;

        memcpy(dst, src, transferred);
        return 0;
}

/* Make sure iov_length() won't overflow */
static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
                                 size_t count)
{
        size_t n;
        u32 max = fc->max_pages << PAGE_SHIFT;

        for (n = 0; n < count; n++, iov++) {
                if (iov->iov_len > (size_t) max)
                        return -ENOMEM;
                max -= iov->iov_len;
        }
        return 0;
}

static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
                                 void *src, size_t transferred, unsigned count,
                                 bool is_compat)
{
        unsigned i;
        struct fuse_ioctl_iovec *fiov = src;

        if (fc->minor < 16) {
                return fuse_copy_ioctl_iovec_old(dst, src, transferred,
                                                 count, is_compat);
        }

        if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
                return -EIO;

        for (i = 0; i < count; i++) {
                /* Did the server supply an inappropriate value? */
                if (fiov[i].base != (unsigned long) fiov[i].base ||
                    fiov[i].len != (unsigned long) fiov[i].len)
                        return -EIO;

                dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
                dst[i].iov_len = (size_t) fiov[i].len;

#ifdef CONFIG_COMPAT
                if (is_compat &&
                    (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
                     (compat_size_t) dst[i].iov_len != fiov[i].len))
                        return -EIO;
#endif
        }

        return 0;
}

/* For fs-verity, determine iov lengths from input */
static int fuse_setup_measure_verity(unsigned long arg, struct iovec *iov)
{
        __u16 digest_size;
        struct fsverity_digest __user *uarg = (void __user *)arg;

        if (copy_from_user(&digest_size, &uarg->digest_size, sizeof(digest_size)))
                return -EFAULT;

        if (digest_size > SIZE_MAX - sizeof(struct fsverity_digest))
                return -EINVAL;

        iov->iov_len = sizeof(struct fsverity_digest) + digest_size;

        return 0;
}

static int fuse_setup_enable_verity(unsigned long arg, struct iovec *iov,
                                    unsigned int *in_iovs)
{
        struct fsverity_enable_arg enable;
        struct fsverity_enable_arg __user *uarg = (void __user *)arg;
        const __u32 max_buffer_len = FUSE_VERITY_ENABLE_ARG_MAX_PAGES * PAGE_SIZE;

        if (copy_from_user(&enable, uarg, sizeof(enable)))
                return -EFAULT;

        if (enable.salt_size > max_buffer_len || enable.sig_size > max_buffer_len)
                return -ENOMEM;

        if (enable.salt_size > 0) {
                iov++;
                (*in_iovs)++;

                iov->iov_base = u64_to_user_ptr(enable.salt_ptr);
                iov->iov_len = enable.salt_size;
        }

        if (enable.sig_size > 0) {
                iov++;
                (*in_iovs)++;

                iov->iov_base = u64_to_user_ptr(enable.sig_ptr);
                iov->iov_len = enable.sig_size;
        }
        return 0;
}

/*
 * For ioctls, there is no generic way to determine how much memory
 * needs to be read and/or written.  Furthermore, ioctls are allowed
 * to dereference the passed pointer, so the parameter requires deep
 * copying but FUSE has no idea whatsoever about what to copy in or
 * out.
 *
 * This is solved by allowing FUSE server to retry ioctl with
 * necessary in/out iovecs.  Let's assume the ioctl implementation
 * needs to read in the following structure.
 *
 * struct a {
 *      char    *buf;
 *      size_t  buflen;
 * }
 *
 * On the first callout to FUSE server, inarg->in_size and
 * inarg->out_size will be NULL; then, the server completes the ioctl
 * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
 * the actual iov array to
 *
 * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
 *
 * which tells FUSE to copy in the requested area and retry the ioctl.
 * On the second round, the server has access to the structure and
 * from that it can tell what to look for next, so on the invocation,
 * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
 *
 * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
 *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
 *
 * FUSE will copy both struct a and the pointed buffer from the
 * process doing the ioctl and retry ioctl with both struct a and the
 * buffer.
 *
 * This time, FUSE server has everything it needs and completes ioctl
 * without FUSE_IOCTL_RETRY which finishes the ioctl call.
 *
 * Copying data out works the same way.
 *
 * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
 * automatically initializes in and out iovs by decoding @cmd with
 * _IOC_* macros and the server is not allowed to request RETRY.  This
 * limits ioctl data transfers to well-formed ioctls and is the forced
 * behavior for all FUSE servers.
 */
long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
                   unsigned int flags)
{
        struct fuse_file *ff = file->private_data;
        struct fuse_mount *fm = ff->fm;
        struct fuse_ioctl_in inarg = {
                .fh = ff->fh,
                .cmd = cmd,
                .arg = arg,
                .flags = flags
        };
        struct fuse_ioctl_out outarg;
        struct iovec *iov_page = NULL;
        struct iovec *in_iov = NULL, *out_iov = NULL;
        unsigned int in_iovs = 0, out_iovs = 0, max_pages;
        size_t in_size, out_size, c;
        ssize_t transferred;
        int err, i;
        struct iov_iter ii;
        struct fuse_args_pages ap = {};

#if BITS_PER_LONG == 32
        inarg.flags |= FUSE_IOCTL_32BIT;
#else
        if (flags & FUSE_IOCTL_COMPAT) {
                inarg.flags |= FUSE_IOCTL_32BIT;
#ifdef CONFIG_X86_X32_ABI
                if (in_x32_syscall())
                        inarg.flags |= FUSE_IOCTL_COMPAT_X32;
#endif
        }
#endif

        /* assume all the iovs returned by client always fits in a page */
        BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);

        err = -ENOMEM;
        ap.folios = fuse_folios_alloc(fm->fc->max_pages, GFP_KERNEL, &ap.descs);
        iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
        if (!ap.folios || !iov_page)
                goto out;

        fuse_folio_descs_length_init(ap.descs, 0, fm->fc->max_pages);

        /*
         * If restricted, initialize IO parameters as encoded in @cmd.
         * RETRY from server is not allowed.
         */
        if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
                struct iovec *iov = iov_page;

                iov->iov_base = (void __user *)arg;
                iov->iov_len = _IOC_SIZE(cmd);

                if (_IOC_DIR(cmd) & _IOC_WRITE) {
                        in_iov = iov;
                        in_iovs = 1;
                }

                if (_IOC_DIR(cmd) & _IOC_READ) {
                        out_iov = iov;
                        out_iovs = 1;
                }

                err = 0;
                switch (cmd) {
                case FS_IOC_MEASURE_VERITY:
                        err = fuse_setup_measure_verity(arg, iov);
                        break;
                case FS_IOC_ENABLE_VERITY:
                        err = fuse_setup_enable_verity(arg, iov, &in_iovs);
                        break;
                }
                if (err)
                        goto out;
        }

 retry:
        inarg.in_size = in_size = iov_length(in_iov, in_iovs);
        inarg.out_size = out_size = iov_length(out_iov, out_iovs);

        /*
         * Out data can be used either for actual out data or iovs,
         * make sure there always is at least one page.
         */
        out_size = max_t(size_t, out_size, PAGE_SIZE);
        max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);

        /* make sure there are enough buffer pages and init request with them */
        err = -ENOMEM;
        if (max_pages > fm->fc->max_pages)
                goto out;
        while (ap.num_folios < max_pages) {
                ap.folios[ap.num_folios] = folio_alloc(GFP_KERNEL | __GFP_HIGHMEM, 0);
                if (!ap.folios[ap.num_folios])
                        goto out;
                ap.num_folios++;
        }

        /* okay, let's send it to the client */
        ap.args.opcode = FUSE_IOCTL;
        ap.args.nodeid = ff->nodeid;
        ap.args.in_numargs = 1;
        ap.args.in_args[0].size = sizeof(inarg);
        ap.args.in_args[0].value = &inarg;
        if (in_size) {
                ap.args.in_numargs++;
                ap.args.in_args[1].size = in_size;
                ap.args.in_pages = true;

                err = -EFAULT;
                iov_iter_init(&ii, ITER_SOURCE, in_iov, in_iovs, in_size);
                for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_folios); i++) {
                        c = copy_folio_from_iter(ap.folios[i], 0, PAGE_SIZE, &ii);
                        if (c != PAGE_SIZE && iov_iter_count(&ii))
                                goto out;
                }
        }

        ap.args.out_numargs = 2;
        ap.args.out_args[1].size = out_size;
        ap.args.out_pages = true;
        ap.args.out_argvar = true;

        transferred = fuse_send_ioctl(fm, &ap.args, &outarg);
        err = transferred;
        if (transferred < 0)
                goto out;

        /* did it ask for retry? */
        if (outarg.flags & FUSE_IOCTL_RETRY) {
                void *vaddr;

                /* no retry if in restricted mode */
                err = -EIO;
                if (!(flags & FUSE_IOCTL_UNRESTRICTED))
                        goto out;

                in_iovs = outarg.in_iovs;
                out_iovs = outarg.out_iovs;

                /*
                 * Make sure things are in boundary, separate checks
                 * are to protect against overflow.
                 */
                err = -ENOMEM;
                if (in_iovs > FUSE_IOCTL_MAX_IOV ||
                    out_iovs > FUSE_IOCTL_MAX_IOV ||
                    in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
                        goto out;

                vaddr = kmap_local_folio(ap.folios[0], 0);
                err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
                                            transferred, in_iovs + out_iovs,
                                            (flags & FUSE_IOCTL_COMPAT) != 0);
                kunmap_local(vaddr);
                if (err)
                        goto out;

                in_iov = iov_page;
                out_iov = in_iov + in_iovs;

                err = fuse_verify_ioctl_iov(fm->fc, in_iov, in_iovs);
                if (err)
                        goto out;

                err = fuse_verify_ioctl_iov(fm->fc, out_iov, out_iovs);
                if (err)
                        goto out;

                goto retry;
        }

        err = -EIO;
        if (transferred > inarg.out_size)
                goto out;

        err = -EFAULT;
        iov_iter_init(&ii, ITER_DEST, out_iov, out_iovs, transferred);
        for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_folios); i++) {
                c = copy_folio_to_iter(ap.folios[i], 0, PAGE_SIZE, &ii);
                if (c != PAGE_SIZE && iov_iter_count(&ii))
                        goto out;
        }
        err = 0;
 out:
        free_page((unsigned long) iov_page);
        while (ap.num_folios)
                folio_put(ap.folios[--ap.num_folios]);
        kfree(ap.folios);

        return err ? err : outarg.result;
}
EXPORT_SYMBOL_GPL(fuse_do_ioctl);

long fuse_ioctl_common(struct file *file, unsigned int cmd,
                       unsigned long arg, unsigned int flags)
{
        struct inode *inode = file_inode(file);
        struct fuse_conn *fc = get_fuse_conn(inode);

        if (!fuse_allow_current_process(fc))
                return -EACCES;

        if (fuse_is_bad(inode))
                return -EIO;

        return fuse_do_ioctl(file, cmd, arg, flags);
}

long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        return fuse_ioctl_common(file, cmd, arg, 0);
}

long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
        return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
}

static int fuse_priv_ioctl(struct inode *inode, struct fuse_file *ff,
                           unsigned int cmd, void *ptr, size_t size)
{
        struct fuse_mount *fm = ff->fm;
        struct fuse_ioctl_in inarg;
        struct fuse_ioctl_out outarg;
        FUSE_ARGS(args);
        int err;

        memset(&inarg, 0, sizeof(inarg));
        inarg.fh = ff->fh;
        inarg.cmd = cmd;

#if BITS_PER_LONG == 32
        inarg.flags |= FUSE_IOCTL_32BIT;
#endif
        if (S_ISDIR(inode->i_mode))
                inarg.flags |= FUSE_IOCTL_DIR;

        if (_IOC_DIR(cmd) & _IOC_READ)
                inarg.out_size = size;
        if (_IOC_DIR(cmd) & _IOC_WRITE)
                inarg.in_size = size;

        args.opcode = FUSE_IOCTL;
        args.nodeid = ff->nodeid;
        args.in_numargs = 2;
        args.in_args[0].size = sizeof(inarg);
        args.in_args[0].value = &inarg;
        args.in_args[1].size = inarg.in_size;
        args.in_args[1].value = ptr;
        args.out_numargs = 2;
        args.out_args[1].size = inarg.out_size;
        args.out_args[1].value = ptr;

        err = fuse_send_ioctl(fm, &args, &outarg);
        if (!err) {
                if (outarg.result < 0)
                        err = outarg.result;
                else if (outarg.flags & FUSE_IOCTL_RETRY)
                        err = -EIO;
        }
        return err;
}

static struct fuse_file *fuse_priv_ioctl_prepare(struct inode *inode)
{
        struct fuse_mount *fm = get_fuse_mount(inode);
        bool isdir = S_ISDIR(inode->i_mode);

        if (!fuse_allow_current_process(fm->fc))
                return ERR_PTR(-EACCES);

        if (fuse_is_bad(inode))
                return ERR_PTR(-EIO);

        if (!S_ISREG(inode->i_mode) && !isdir)
                return ERR_PTR(-ENOTTY);

        return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
}

static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
{
        fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
}

int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
        struct inode *inode = d_inode(dentry);
        struct fuse_file *ff;
        unsigned int flags;
        struct fsxattr xfa;
        int err;

        ff = fuse_priv_ioctl_prepare(inode);
        if (IS_ERR(ff))
                return PTR_ERR(ff);

        if (fa->flags_valid) {
                err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
                                      &flags, sizeof(flags));
                if (err)
                        goto cleanup;

                fileattr_fill_flags(fa, flags);
        } else {
                err = fuse_priv_ioctl(inode, ff, FS_IOC_FSGETXATTR,
                                      &xfa, sizeof(xfa));
                if (err)
                        goto cleanup;

                fileattr_fill_xflags(fa, xfa.fsx_xflags);
                fa->fsx_extsize = xfa.fsx_extsize;
                fa->fsx_nextents = xfa.fsx_nextents;
                fa->fsx_projid = xfa.fsx_projid;
                fa->fsx_cowextsize = xfa.fsx_cowextsize;
        }
cleanup:
        fuse_priv_ioctl_cleanup(inode, ff);

        return err;
}

int fuse_fileattr_set(struct mnt_idmap *idmap,
                      struct dentry *dentry, struct fileattr *fa)
{
        struct inode *inode = d_inode(dentry);
        struct fuse_file *ff;
        unsigned int flags = fa->flags;
        struct fsxattr xfa;
        int err;

        ff = fuse_priv_ioctl_prepare(inode);
        if (IS_ERR(ff))
                return PTR_ERR(ff);

        if (fa->flags_valid) {
                err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
                                      &flags, sizeof(flags));
                if (err)
                        goto cleanup;
        } else {
                memset(&xfa, 0, sizeof(xfa));
                xfa.fsx_xflags = fa->fsx_xflags;
                xfa.fsx_extsize = fa->fsx_extsize;
                xfa.fsx_nextents = fa->fsx_nextents;
                xfa.fsx_projid = fa->fsx_projid;
                xfa.fsx_cowextsize = fa->fsx_cowextsize;

                err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
                                      &xfa, sizeof(xfa));
        }

cleanup:
        fuse_priv_ioctl_cleanup(inode, ff);

        return err;
}