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Introduce kern_mmap_req().

Browse Source 
This presents an extensible interface to the generic mmap(2)
implementation via a struct pointer intended to use a designated
initializer or compount literal.  We take advantage of the mandatory
zeroing of fields not listed in the initializer.

Remove kern_mmap_fpcheck() and use kern_mmap_req().

The motivation for this change is a desire to keep the core
implementation from growing an ever-increasing number of arguments
that must be specified in the correct order for the lowest-level
implementations.  In CheriBSD we have already added two more arguments.

Reviewed by:	kib
Discussed with:	kevans
Obtained from:	CheriBSD
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D23164
This commit is contained in:
Brooks Davis 2020-03-04 21:27:12 +00:00
parent a2037dba7e
commit d718de812f
3 changed files with 49 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
sys/compat/linux/linux_mmap.c
View File

@ -77,6 +77,7 @@ int
linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
int flags, int fd, off_t pos)
{
struct mmap_req mr, mr_fixed;
struct proc *p = td->td_proc;
struct vmspace *vms = td->td_proc->p_vmspace;
int bsd_flags, error;
@ -201,17 +202,25 @@ linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
* address is not zero, try with MAP_FIXED and MAP_EXCL first,
* and fall back to the normal behaviour if that fails.
*/
mr = (struct mmap_req) {
.mr_hint = addr,
.mr_len = len,
.mr_prot = prot,
.mr_flags = bsd_flags,
.mr_fd = fd,
.mr_pos = pos,
.mr_check_fp_fn = linux_mmap_check_fp,
};
if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
(bsd_flags & MAP_EXCL) == 0) {
error = kern_mmap_fpcheck(td, addr, len, prot,
bsd_flags | MAP_FIXED | MAP_EXCL, fd, pos,
linux_mmap_check_fp);
mr_fixed = mr;
mr_fixed.mr_flags |= MAP_FIXED | MAP_EXCL;
error = kern_mmap_req(td, &mr_fixed);
if (error == 0)
goto out;
}
error = kern_mmap_fpcheck(td, addr, len, prot, bsd_flags, fd, pos,
linux_mmap_check_fp);
error = kern_mmap_req(td, &mr);
out:
LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);

16
sys/sys/syscallsubr.h
View File

@ -65,6 +65,18 @@ struct uio;
typedef int (*mmap_check_fp_fn)(struct file *, int, int, int);
struct mmap_req {
vm_offset_t mr_hint;
vm_size_t mr_len;
int mr_prot;
int mr_flags;
int mr_fd;
off_t mr_pos;
mmap_check_fp_fn mr_check_fp_fn;
};
int kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg,
size_t buflen, size_t path_max);
int kern_accept(struct thread *td, int s, struct sockaddr **name,
socklen_t *namelen, struct file **fp);
int kern_accept4(struct thread *td, int s, struct sockaddr **name,
@ -182,9 +194,7 @@ int kern_mlock(struct proc *proc, struct ucred *cred, uintptr_t addr,
size_t len);
int kern_mmap(struct thread *td, uintptr_t addr, size_t len, int prot,
int flags, int fd, off_t pos);
int kern_mmap_fpcheck(struct thread *td, uintptr_t addr, size_t len,
int prot, int flags, int fd, off_t pos,
mmap_check_fp_fn check_fp_fn);
int kern_mmap_req(struct thread *td, const struct mmap_req *mrp);
int kern_mmap_maxprot(struct proc *p, int prot);
int kern_mprotect(struct thread *td, uintptr_t addr, size_t size, int prot);
int kern_msgctl(struct thread *, int, int, struct msqid_ds *);

32
sys/vm/vm_mmap.c
View File

@ -199,26 +199,39 @@ int
kern_mmap(struct thread *td, uintptr_t addr0, size_t len, int prot, int flags,
int fd, off_t pos)
{
struct mmap_req mr = {
.mr_hint = addr0,
.mr_len = len,
.mr_prot = prot,
.mr_flags = flags,
.mr_fd = fd,
.mr_pos = pos
};
return (kern_mmap_fpcheck(td, addr0, len, prot, flags, fd, pos, NULL));
return (kern_mmap_req(td, &mr));
}
/*
* When mmap'ing a file, check_fp_fn may be used for the caller to do any
* last-minute validation based on the referenced file in a non-racy way.
*/
int
kern_mmap_fpcheck(struct thread *td, uintptr_t addr0, size_t len, int prot,
int flags, int fd, off_t pos, mmap_check_fp_fn check_fp_fn)
kern_mmap_req(struct thread *td, const struct mmap_req *mrp)
{
struct vmspace *vms;
struct file *fp;
struct proc *p;
off_t pos;
vm_offset_t addr;
vm_size_t pageoff, size;
vm_size_t len, pageoff, size;
vm_prot_t cap_maxprot;
int align, error, max_prot;
int align, error, fd, flags, max_prot, prot;
cap_rights_t rights;
mmap_check_fp_fn check_fp_fn;
addr = mrp->mr_hint;
len = mrp->mr_len;
prot = mrp->mr_prot;
flags = mrp->mr_flags;
fd = mrp->mr_fd;
pos = mrp->mr_pos;
check_fp_fn = mrp->mr_check_fp_fn;
if ((prot & ~(_PROT_ALL | PROT_MAX(_PROT_ALL))) != 0)
return (EINVAL);
@ -239,7 +252,6 @@ kern_mmap_fpcheck(struct thread *td, uintptr_t addr0, size_t len, int prot,
vms = p->p_vmspace;
fp = NULL;
AUDIT_ARG_FD(fd);
addr = addr0;
/*
* Ignore old flags that used to be defined but did not do anything.