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vmapbuf: don't smuggle address or length in buf

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Instead, add arguments to vmapbuf.  Since this argument is
always a pointer use a type of void * and cast to vm_offset_t in
vmapbuf.  (In CheriBSD we've altered vm_fault_quick_hold_pages to
take a pointer and check its bounds.)

In no other situtation does b_data contain a user pointer and vmapbuf
replaces b_data with the actual mapping.

Suggested by:	jhb
Reviewed by:	imp, jhb
Obtained from:	CheriBSD
MFC after:	1 week
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D26784
This commit is contained in:
Brooks Davis 2020-10-21 16:00:15 +00:00
parent 7ec2f6bce5
commit 44ca4575ea
5 changed files with 9 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
sys/cam/cam_periph.c
View File

@ -955,18 +955,12 @@ cam_periph_mapmem(union ccb *ccb, struct cam_periph_map_info *mapinfo,
*/
mapinfo->bp[i] = uma_zalloc(pbuf_zone, M_WAITOK);
/* put our pointer in the data slot */
mapinfo->bp[i]->b_data = *data_ptrs[i];
/* set the transfer length, we know it's < MAXPHYS */
mapinfo->bp[i]->b_bufsize = lengths[i];
/* set the direction */
mapinfo->bp[i]->b_iocmd = (dirs[i] == CAM_DIR_OUT) ?
BIO_WRITE : BIO_READ;
/* Map the buffer into kernel memory. */
if (vmapbuf(mapinfo->bp[i], 1) < 0) {
if (vmapbuf(mapinfo->bp[i], *data_ptrs[i], lengths[i], 1) < 0) {
uma_zfree(pbuf_zone, mapinfo->bp[i]);
goto fail;
}

4
sys/dev/nvme/nvme_ctrlr.c
View File

@ -1268,10 +1268,8 @@ nvme_ctrlr_passthrough_cmd(struct nvme_controller *ctrlr,
*/
PHOLD(curproc);
buf = uma_zalloc(pbuf_zone, M_WAITOK);
buf->b_data = pt->buf;
buf->b_bufsize = pt->len;
buf->b_iocmd = pt->is_read ? BIO_READ : BIO_WRITE;
if (vmapbuf(buf, 1) < 0) {
if (vmapbuf(buf, pt->buf, pt->len, 1) < 0) {
ret = EFAULT;
goto err;
}

9
sys/kern/vfs_bio.c
View File

@ -4907,22 +4907,21 @@ vm_hold_free_pages(struct buf *bp, int newbsize)
* This function only works with pager buffers.
*/
int
vmapbuf(struct buf *bp, int mapbuf)
vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf)
{
vm_prot_t prot;
int pidx;
if (bp->b_bufsize < 0)
return (-1);
prot = VM_PROT_READ;
if (bp->b_iocmd == BIO_READ)
prot |= VM_PROT_WRITE; /* Less backwards than it looks */
if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
(vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
(vm_offset_t)uaddr, len, prot, bp->b_pages,
btoc(MAXPHYS))) < 0)
return (-1);
bp->b_bufsize = len;
bp->b_npages = pidx;
bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK;
if (mapbuf || !unmapped_buf_allowed) {
pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
bp->b_data = bp->b_kvabase + bp->b_offset;

2
sys/sys/buf.h
View File

@ -575,7 +575,7 @@ void vfs_bio_set_flags(struct buf *bp, int ioflags);
void vfs_bio_set_valid(struct buf *, int base, int size);
void vfs_busy_pages(struct buf *, int clear_modify);
void vfs_unbusy_pages(struct buf *);
int vmapbuf(struct buf *, int);
int vmapbuf(struct buf *, void *, size_t, int);
void vunmapbuf(struct buf *);
void brelvp(struct buf *);
void bgetvp(struct vnode *, struct buf *);

7
sys/ufs/ffs/ffs_rawread.c
View File

@ -216,7 +216,6 @@ ffs_rawread_readahead(struct vnode *vp,
bp->b_flags = 0; /* XXX necessary ? */
bp->b_iocmd = BIO_READ;
bp->b_iodone = bdone;
bp->b_data = udata;
blockno = offset / bsize;
blockoff = (offset % bsize) / DEV_BSIZE;
if ((daddr_t) blockno != blockno) {
@ -233,9 +232,8 @@ ffs_rawread_readahead(struct vnode *vp,
if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
bp->b_bcount = bsize - blockoff * DEV_BSIZE;
bp->b_bufsize = bp->b_bcount;
if (vmapbuf(bp, 1) < 0)
if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
return EFAULT;
maybe_yield();
@ -252,9 +250,8 @@ ffs_rawread_readahead(struct vnode *vp,
if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
bp->b_bufsize = bp->b_bcount;
if (vmapbuf(bp, 1) < 0)
if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
return EFAULT;
BO_STRATEGY(&dp->v_bufobj, bp);