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Delay permission checks for VCHR vnodes until after vnode is locked in

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vm_mmap_vnode function, where we can safely check for a special /dev/zero
case. Rev. 1.180 has reordered checks and introduced a regression.

Submitted by:	alc
Was broken by:	kan
This commit is contained in:
kan 2004-04-05 04:54:22 +00:00
parent 6ce9793803
commit 4cdcf07096
1 changed files with 7 additions and 2 deletions
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9
sys/vm/vm_mmap.c
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@ -341,14 +341,14 @@ mmap(td, uap)
* permission although we opened it without asking
* for it, bail out.
*/
if ((flags & MAP_SHARED) != 0 || vp->v_type == VCHR) {
if ((flags & MAP_SHARED) != 0) {
if ((fp->f_flag & FWRITE) != 0) {
maxprot |= VM_PROT_WRITE;
} else if ((prot & PROT_WRITE) != 0) {
error = EACCES;
goto done;
}
} else {
} else if (vp->v_type != VCHR || (fp->f_flag & FWRITE) != 0) {
maxprot |= VM_PROT_WRITE;
}
handle = (void *)vp;
@ -1113,6 +1113,11 @@ vm_mmap_vnode(struct thread *td, vm_size_t objsize,
/*
* cdevs does not provide private mappings of any kind.
*/
if ((*maxprotp & VM_PROT_WRITE) == 0 &&
(prot & PROT_WRITE) != 0) {
error = EACCES;
goto done;
}
/*
* However, for XIG X server to continue to work,
* we should allow the superuser to do it anyway.