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Fix a panic(8) implementation:

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hexdump -C < /dev/drum
by simply refusing to do I/O from userland.
a panic.  I'm not sure we even need /dev/drum anymore, it seems
to have been broken for a long time thi
This commit is contained in:
Poul-Henning Kamp 1999-10-08 19:10:18 +00:00
parent 1201869007
commit 6ee0a468fe
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=52035
1 changed files with 17 additions and 5 deletions
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22
sys/vm/vm_swap.c
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@ -73,8 +73,8 @@ static d_strategy_t swstrategy;
static struct cdevsw sw_cdevsw = {
/* open */ swopen,
/* close */ nullclose,
/* read */ physread,
/* write */ physwrite,
/* read */ noread,
/* write */ nowrite,
/* ioctl */ noioctl,
/* poll */ nopoll,
/* mmap */ nommap,
@ -118,7 +118,7 @@ swopen(dev, flag, mode, p)
struct proc *p;
{
if (mode == S_IFBLK || minor(dev))
if (mode == S_IFBLK || minor(dev) != 0)
return (ENXIO);
return (0);
}
@ -132,6 +132,17 @@ swstrategy(bp)
register struct swdevt *sp;
struct vnode *vp;
/*
* XXX: if we allow userland to come through, it will panic
* XXX: so use minor zero for userland and fail it right here
* XXX: and in noread/nowrite.
*/
if (minor(bp->b_dev) == 0) {
bp->b_error = EINVAL;
bp->b_flags |= B_ERROR;
biodone(bp);
return;
}
sz = howmany(bp->b_bcount, PAGE_SIZE);
/*
* Convert interleaved swap into per-device swap. Note that
@ -216,7 +227,6 @@ swapon(p, uap)
static int once;
if (!once) {
cdevsw_add(&sw_cdevsw);
make_dev(&sw_cdevsw, 0, UID_ROOT, GID_KMEM, 0640, "drum");
once++;
}
@ -353,6 +363,7 @@ swaponvp(p, vp, dev, nblks)
if (!swapdev_vp) {
struct vnode *vp1;
struct vnode *nvp;
dev_t dev;
error = getnewvnode(VT_NON, (struct mount *) 0,
spec_vnodeop_p, &nvp);
@ -360,7 +371,8 @@ swaponvp(p, vp, dev, nblks)
panic("Cannot get vnode for swapdev");
vp1 = nvp;
vp1->v_type = VBLK;
addaliasu(vp1, makeudev(BDEV_MAJOR, 0));
dev = make_dev(&sw_cdevsw, 1, UID_ROOT, GID_KMEM, 0640, "swapdev");
addalias(vp1, dev);
swapdev_vp = vp1;
}
return (0);