As discussed on tech-kern:
Factor out common code of chroot-like syscalls into change_root() and export that function for use in other parts of the kernel. Rename change_dir() to chdir_lookup() as the latter describes better what the function does. While there, move the namei_data initialisation into chdir_lookup(), too. And export chdir_lookup().
This commit is contained in:
bad
parent
d582bd909a
commit
02bcf17298
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@ -1,4 +1,4 @@
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/* $NetBSD: vfs_syscalls.c,v 1.396 2009/07/02 12:53:47 pooka Exp $ */
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/* $NetBSD: vfs_syscalls.c,v 1.397 2009/08/01 21:17:11 bad Exp $ */
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/*-
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* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
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@ -66,7 +66,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.396 2009/07/02 12:53:47 pooka Exp $");
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__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.397 2009/08/01 21:17:11 bad Exp $");
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#ifdef _KERNEL_OPT
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#include "opt_fileassoc.h"
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@ -110,7 +110,6 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.396 2009/07/02 12:53:47 pooka Exp
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MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount struct");
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static int change_dir(struct nameidata *, struct lwp *);
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static int change_flags(struct vnode *, u_long, struct lwp *);
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static int change_mode(struct vnode *, int, struct lwp *l);
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static int change_owner(struct vnode *, uid_t, gid_t, struct lwp *, int);
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@ -1126,7 +1125,6 @@ int
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sys_fchroot(struct lwp *l, const struct sys_fchroot_args *uap, register_t *retval)
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{
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struct proc *p = l->l_proc;
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struct cwdinfo *cwdi;
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struct vnode *vp;
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file_t *fp;
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int error, fd = SCARG(uap, fd);
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@ -1135,7 +1133,7 @@ sys_fchroot(struct lwp *l, const struct sys_fchroot_args *uap, register_t *retva
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KAUTH_REQ_SYSTEM_CHROOT_FCHROOT, NULL, NULL, NULL)) != 0)
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return error;
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/* fd_getvnode() will use the descriptor for us */
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if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
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if ((error = fd_getvnode(fd, &fp)) != 0)
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return error;
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vp = fp->f_data;
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vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
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@ -1148,27 +1146,7 @@ sys_fchroot(struct lwp *l, const struct sys_fchroot_args *uap, register_t *retva
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goto out;
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VREF(vp);
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/*
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* Prevent escaping from chroot by putting the root under
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* the working directory. Silently chdir to / if we aren't
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* already there.
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*/
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cwdi = p->p_cwdi;
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rw_enter(&cwdi->cwdi_lock, RW_WRITER);
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if (!vn_isunder(cwdi->cwdi_cdir, vp, l)) {
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/*
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* XXX would be more failsafe to change directory to a
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* deadfs node here instead
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*/
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vrele(cwdi->cwdi_cdir);
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VREF(vp);
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cwdi->cwdi_cdir = vp;
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}
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if (cwdi->cwdi_rdir != NULL)
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vrele(cwdi->cwdi_rdir);
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cwdi->cwdi_rdir = vp;
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rw_exit(&cwdi->cwdi_lock);
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change_root(p->p_cwdi, vp, l);
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out:
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fd_putfile(fd);
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@ -1188,16 +1166,15 @@ sys_chdir(struct lwp *l, const struct sys_chdir_args *uap, register_t *retval)
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struct proc *p = l->l_proc;
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struct cwdinfo *cwdi;
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int error;
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struct nameidata nd;
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struct vnode *vp;
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NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
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SCARG(uap, path));
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if ((error = change_dir(&nd, l)) != 0)
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if ((error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE,
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&vp, l)) != 0)
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return (error);
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cwdi = p->p_cwdi;
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rw_enter(&cwdi->cwdi_lock, RW_WRITER);
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vrele(cwdi->cwdi_cdir);
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cwdi->cwdi_cdir = nd.ni_vp;
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cwdi->cwdi_cdir = vp;
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rw_exit(&cwdi->cwdi_lock);
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return (0);
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}
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@ -1213,24 +1190,31 @@ sys_chroot(struct lwp *l, const struct sys_chroot_args *uap, register_t *retval)
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syscallarg(const char *) path;
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} */
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struct proc *p = l->l_proc;
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struct cwdinfo *cwdi;
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struct vnode *vp;
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int error;
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struct nameidata nd;
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struct vnode *vp;
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if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_CHROOT,
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KAUTH_REQ_SYSTEM_CHROOT_CHROOT, NULL, NULL, NULL)) != 0)
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return (error);
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NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, UIO_USERSPACE,
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SCARG(uap, path));
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if ((error = change_dir(&nd, l)) != 0)
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if ((error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE,
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&vp, l)) != 0)
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return (error);
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cwdi = p->p_cwdi;
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change_root(p->p_cwdi, vp, l);
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return (0);
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}
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/*
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* Common routine for chroot and fchroot.
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*/
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void
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change_root(struct cwdinfo *cwdi, struct vnode *vp, struct lwp *l)
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{
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rw_enter(&cwdi->cwdi_lock, RW_WRITER);
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if (cwdi->cwdi_rdir != NULL)
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vrele(cwdi->cwdi_rdir);
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vp = nd.ni_vp;
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cwdi->cwdi_rdir = vp;
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/*
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@ -1248,31 +1232,31 @@ sys_chroot(struct lwp *l, const struct sys_chroot_args *uap, register_t *retval)
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cwdi->cwdi_cdir = vp;
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}
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rw_exit(&cwdi->cwdi_lock);
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return (0);
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}
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/*
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* Common routine for chroot and chdir.
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*/
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static int
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change_dir(struct nameidata *ndp, struct lwp *l)
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int
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chdir_lookup(const char *path, int where, struct vnode **vpp, struct lwp *l)
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{
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struct vnode *vp;
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struct nameidata nd;
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int error;
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if ((error = namei(ndp)) != 0)
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NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT, where,
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path);
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if ((error = namei(&nd)) != 0)
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return (error);
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vp = ndp->ni_vp;
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if (vp->v_type != VDIR)
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*vpp = nd.ni_vp;
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if ((*vpp)->v_type != VDIR)
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error = ENOTDIR;
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else
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error = VOP_ACCESS(vp, VEXEC, l->l_cred);
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error = VOP_ACCESS(*vpp, VEXEC, l->l_cred);
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if (error)
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vput(vp);
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vput(*vpp);
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else
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VOP_UNLOCK(vp, 0);
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VOP_UNLOCK(*vpp, 0);
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return (error);
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}
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@ -1,4 +1,4 @@
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/* $NetBSD: vfs_syscalls.h,v 1.11 2009/07/02 12:56:40 pooka Exp $ */
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/* $NetBSD: vfs_syscalls.h,v 1.12 2009/08/01 21:17:12 bad Exp $ */
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/*
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* Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
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@ -65,4 +65,7 @@ int do_sys_rename(const char *, const char *, enum uio_seg, int);
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int do_sys_mknod(struct lwp *l, const char *, mode_t, dev_t, register_t *);
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int do_sys_mkdir(const char *, mode_t);
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int chdir_lookup(const char *, int, struct vnode **, struct lwp *);
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void change_root(struct cwdinfo *, struct vnode *, struct lwp *);
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#endif /* _SYS_VFS_SYSCALLS_H_ */
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