procfs, linprocfs: ensure target process vmspace stability

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D57497

sys/compat/linprocfs/linprocfs.c

@@ -1311,19 +1311,13 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 	struct vattr vat;
 	bool private;
 
-	PROC_LOCK(p);
-	error = p_candebug(td, p);
-	PROC_UNLOCK(p);
-	if (error)
-		return (error);
-
 	if (uio->uio_rw != UIO_READ)
 		return (EOPNOTSUPP);
 
-	error = 0;
-	vm = vmspace_acquire_ref(p);
-	if (vm == NULL)
-		return (ESRCH);
+	error = proc_vmspace_ref(td, p, PRVM_BLOCK_EXEC | PRVM_CHECK_DEBUG,
+	    &vm);
+	if (error != 0)
+		return (error);
 
 	if (SV_CURPROC_FLAG(SV_LP64))
 		l_map_str = l64_map_str;
@@ -1421,7 +1415,7 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 		}
 	}
 	vm_map_unlock_read(map);
-	vmspace_free(vm);
+	proc_vmspace_unref(td, p, PRVM_CHECK_DEBUG | PRVM_BLOCK_EXEC, vm);
 
 	return (error);
 }

sys/fs/procfs/procfs_map.c

@@ -40,6 +40,7 @@
 #include <sys/malloc.h>
 #include <sys/mount.h>
 #include <sys/proc.h>
+#include <sys/ptrace.h>
 #include <sys/resourcevar.h>
 #include <sys/rwlock.h>
 #include <sys/sbuf.h>
@@ -93,15 +94,14 @@ procfs_doprocmap(PFS_FILL_ARGS)
 	bool wrap32;
 #endif
 
-	PROC_LOCK(p);
-	error = p_candebug(td, p);
-	PROC_UNLOCK(p);
-	if (error)
-		return (error);
-
 	if (uio->uio_rw != UIO_READ)
 		return (EOPNOTSUPP);
 
+	error = proc_vmspace_ref(td, p, PRVM_BLOCK_EXEC | PRVM_CHECK_DEBUG,
+	    &vm);
+	if (error != 0)
+		return (error);
+
 #ifdef COMPAT_FREEBSD32
 	wrap32 = false;
 	if (SV_CURPROC_FLAG(SV_ILP32)) {
@@ -111,9 +111,6 @@ procfs_doprocmap(PFS_FILL_ARGS)
 	}
 #endif
 
-	vm = vmspace_acquire_ref(p);
-	if (vm == NULL)
-		return (ESRCH);
 	map = &vm->vm_map;
 	vm_map_lock_read(map);
 	VM_MAP_ENTRY_FOREACH(entry, map) {
@@ -238,6 +235,6 @@ procfs_doprocmap(PFS_FILL_ARGS)
 		}
 	}
 	vm_map_unlock_read(map);
-	vmspace_free(vm);
+	proc_vmspace_unref(td, p, PRVM_BLOCK_EXEC | PRVM_CHECK_DEBUG, vm);
 	return (error);
 }

sys/fs/procfs/procfs_mem.c

@@ -60,11 +60,7 @@ procfs_doprocmem(PFS_FILL_ARGS)
 	if (uio->uio_resid == 0)
 		return (0);
 
-	PROC_LOCK(p);
-	error = p_candebug(td, p);
-	PROC_UNLOCK(p);
-	if (error == 0)
-		error = proc_rwmem(p, uio, 0);
+	error = proc_rwmem(p, uio, PRVM_CHECK_DEBUG | PRVM_BLOCK_EXEC);
 
 	return (error);
 }