示例#1
0
static int
nullfs_readlink(struct vnop_readlink_args * ap)
{
	NULLFSDEBUG("%s %p\n", __FUNCTION__, ap->a_vp);
	int error;
	struct vnode *vp, *lvp;

	if (nullfs_checkspecialvp(ap->a_vp)) {
		return ENOTSUP; /* the special vnodes aren't links */
	}

	vp  = ap->a_vp;
	lvp = NULLVPTOLOWERVP(vp);

	error = vnode_getwithref(lvp);
	if (error == 0) {
		error = VNOP_READLINK(lvp, ap->a_uio, ap->a_context);
		vnode_put(lvp);

		if (error) {
			NULLFSDEBUG("readlink failed: %d\n", error);
		}
	}

	return error;
}
示例#2
0
文件: vfs_lookup.c 项目: Algozjb/xnu
/*
 * Takes ni_vp and ni_dvp non-NULL.  Returns with *new_dp set to the location
 * at which to start a lookup with a resolved path, and all other iocounts dropped.
 */
int 
lookup_handle_symlink(struct nameidata *ndp, vnode_t *new_dp, vfs_context_t ctx)
{
	int error;
	char *cp;		/* pointer into pathname argument */
	uio_t auio;
	char uio_buf[ UIO_SIZEOF(1) ];
	int need_newpathbuf;
	u_int linklen;
	struct componentname *cnp = &ndp->ni_cnd;
	vnode_t dp;
	char *tmppn;

#if CONFIG_VFS_FUNNEL
	if ((cnp->cn_flags & FSNODELOCKHELD)) {
		cnp->cn_flags &= ~FSNODELOCKHELD;
		unlock_fsnode(ndp->ni_dvp, NULL);
	}	
#endif /* CONFIG_VFS_FUNNEL */

	if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
		return ELOOP;
	}
#if CONFIG_MACF
	if ((error = mac_vnode_check_readlink(ctx, ndp->ni_vp)) != 0)
		return error;
#endif /* MAC */
	if (ndp->ni_pathlen > 1 || !(cnp->cn_flags & HASBUF))
		need_newpathbuf = 1;
	else
		need_newpathbuf = 0;

	if (need_newpathbuf) {
		MALLOC_ZONE(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
		if (cp == NULL) {
			return ENOMEM;
		}
	} else {
		cp = cnp->cn_pnbuf;
	}
	auio = uio_createwithbuffer(1, 0, UIO_SYSSPACE, UIO_READ, &uio_buf[0], sizeof(uio_buf));

	uio_addiov(auio, CAST_USER_ADDR_T(cp), MAXPATHLEN);

	error = VNOP_READLINK(ndp->ni_vp, auio, ctx);
	if (error) {
		if (need_newpathbuf)
			FREE_ZONE(cp, MAXPATHLEN, M_NAMEI);
		return error;
	}

	/* 
	 * Safe to set unsigned with a [larger] signed type here
	 * because 0 <= uio_resid <= MAXPATHLEN and MAXPATHLEN
	 * is only 1024.
	 */
	linklen = MAXPATHLEN - (u_int)uio_resid(auio);
	if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
		if (need_newpathbuf)
			FREE_ZONE(cp, MAXPATHLEN, M_NAMEI);

		return ENAMETOOLONG;
	}
	if (need_newpathbuf) {
		long len = cnp->cn_pnlen;

		tmppn = cnp->cn_pnbuf;
		bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
		cnp->cn_pnbuf = cp;
		cnp->cn_pnlen = MAXPATHLEN;

		if ( (cnp->cn_flags & HASBUF) )
			FREE_ZONE(tmppn, len, M_NAMEI);
		else
			cnp->cn_flags |= HASBUF;
	} else
		cnp->cn_pnbuf[linklen] = '\0';

	ndp->ni_pathlen += linklen;
	cnp->cn_nameptr = cnp->cn_pnbuf;

	/*
	 * starting point for 'relative'
	 * symbolic link path
	 */
	dp = ndp->ni_dvp;

	/*
	 * get rid of references returned via 'lookup'
	 */
	vnode_put(ndp->ni_vp);
	vnode_put(ndp->ni_dvp);	/* ALWAYS have a dvp for a symlink */

	ndp->ni_vp = NULLVP;
	ndp->ni_dvp = NULLVP;

	/*
	 * Check if symbolic link restarts us at the root
	 */
	if (*(cnp->cn_nameptr) == '/') {
		while (*(cnp->cn_nameptr) == '/') {
			cnp->cn_nameptr++;
			ndp->ni_pathlen--;
		}
		if ((dp = ndp->ni_rootdir) == NULLVP) {
			return ENOENT;
		}
	}

	*new_dp = dp;

	return 0;
}
示例#3
0
/*
 * Convert a pathname into a pointer to a locked inode.
 *
 * The FOLLOW flag is set when symbolic links are to be followed
 * when they occur at the end of the name translation process.
 * Symbolic links are always followed for all other pathname
 * components other than the last.
 *
 * The segflg defines whether the name is to be copied from user
 * space or kernel space.
 *
 * Overall outline of namei:
 *
 *	copy in name
 *	get starting directory
 *	while (!done && !error) {
 *		call lookup to search path.
 *		if symbolic link, massage name in buffer and continue
 *	}
 *
 * Returns:	0			Success
 *		ENOENT			No such file or directory
 *		ELOOP			Too many levels of symbolic links
 *		ENAMETOOLONG		Filename too long
 *		copyinstr:EFAULT	Bad address
 *		copyinstr:ENAMETOOLONG	Filename too long
 *		lookup:EBADF		Bad file descriptor
 *		lookup:EROFS
 *		lookup:EACCES
 *		lookup:EPERM
 *		lookup:ERECYCLE	 vnode was recycled from underneath us in lookup.
 *						 This means we should re-drive lookup from this point.
 *		lookup: ???
 *		VNOP_READLINK:???
 */
int
namei(struct nameidata *ndp)
{
	struct filedesc *fdp;	/* pointer to file descriptor state */
	char *cp;		/* pointer into pathname argument */
	struct vnode *dp;	/* the directory we are searching */
	struct vnode *usedvp = ndp->ni_dvp;  /* store pointer to vp in case we must loop due to
										   	heavy vnode pressure */
	u_long cnpflags = ndp->ni_cnd.cn_flags; /* store in case we have to restore after loop */
	uio_t auio;
	int error;
	struct componentname *cnp = &ndp->ni_cnd;
	vfs_context_t ctx = cnp->cn_context;
	proc_t p = vfs_context_proc(ctx);
/* XXX ut should be from context */
	uthread_t ut = (struct uthread *)get_bsdthread_info(current_thread());
	char *tmppn;
	char uio_buf[ UIO_SIZEOF(1) ];

#if DIAGNOSTIC
	if (!vfs_context_ucred(ctx) || !p)
		panic ("namei: bad cred/proc");
	if (cnp->cn_nameiop & (~OPMASK))
		panic ("namei: nameiop contaminated with flags");
	if (cnp->cn_flags & OPMASK)
		panic ("namei: flags contaminated with nameiops");
#endif
	fdp = p->p_fd;

vnode_recycled:

	/*
	 * Get a buffer for the name to be translated, and copy the
	 * name into the buffer.
	 */
	if ((cnp->cn_flags & HASBUF) == 0) {
		cnp->cn_pnbuf = ndp->ni_pathbuf;
		cnp->cn_pnlen = PATHBUFLEN;
	}
#if LP64_DEBUG
	if (IS_VALID_UIO_SEGFLG(ndp->ni_segflg) == 0) {
		panic("%s :%d - invalid ni_segflg\n", __FILE__, __LINE__); 
	}
#endif /* LP64_DEBUG */

retry_copy:
	if (UIO_SEG_IS_USER_SPACE(ndp->ni_segflg)) {
		error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
			    cnp->cn_pnlen, (size_t *)&ndp->ni_pathlen);
	} else {
		error = copystr(CAST_DOWN(void *, ndp->ni_dirp), cnp->cn_pnbuf,
			    cnp->cn_pnlen, (size_t *)&ndp->ni_pathlen);
	}
	if (error == ENAMETOOLONG && !(cnp->cn_flags & HASBUF)) {
		MALLOC_ZONE(cnp->cn_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
		if (cnp->cn_pnbuf == NULL) {
			error = ENOMEM;
			goto error_out;
		}

		cnp->cn_flags |= HASBUF;
		cnp->cn_pnlen = MAXPATHLEN;
		
		goto retry_copy;
	}
	if (error)
	        goto error_out;

#if CONFIG_VOLFS
 	/*
	 * Check for legacy volfs style pathnames.
	 *
	 * For compatibility reasons we currently allow these paths,
	 * but future versions of the OS may not support them.
	 */
	if (ndp->ni_pathlen >= VOLFS_MIN_PATH_LEN &&
	    cnp->cn_pnbuf[0] == '/' &&
	    cnp->cn_pnbuf[1] == '.' &&
	    cnp->cn_pnbuf[2] == 'v' &&
	    cnp->cn_pnbuf[3] == 'o' &&
	    cnp->cn_pnbuf[4] == 'l' &&
	    cnp->cn_pnbuf[5] == '/' ) {
		char * realpath;
		int realpath_err;
		/* Attempt to resolve a legacy volfs style pathname. */
		MALLOC_ZONE(realpath, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
		if (realpath) {
			if ((realpath_err= vfs_getrealpath(&cnp->cn_pnbuf[6], realpath, MAXPATHLEN, ctx))) {
				FREE_ZONE(realpath, MAXPATHLEN, M_NAMEI);
				if (realpath_err == ENOSPC){
					error = ENAMETOOLONG;
					goto error_out;
				}
			} else {
				if (cnp->cn_flags & HASBUF) {
					FREE_ZONE(cnp->cn_pnbuf, cnp->cn_pnlen, M_NAMEI);
				}
				cnp->cn_pnbuf = realpath;
				cnp->cn_pnlen = MAXPATHLEN;
				ndp->ni_pathlen = strlen(realpath) + 1;
				cnp->cn_flags |= HASBUF | CN_VOLFSPATH;
			}
		}
	}
 #endif /* CONFIG_VOLFS */

	/* If we are auditing the kernel pathname, save the user pathname */
	if (cnp->cn_flags & AUDITVNPATH1)
		AUDIT_ARG(upath, ut->uu_cdir, cnp->cn_pnbuf, ARG_UPATH1); 
	if (cnp->cn_flags & AUDITVNPATH2)
		AUDIT_ARG(upath, ut->uu_cdir, cnp->cn_pnbuf, ARG_UPATH2); 

	/*
	 * Do not allow empty pathnames
	 */
	if (*cnp->cn_pnbuf == '\0') {
		error = ENOENT;
		goto error_out;
	}
	ndp->ni_loopcnt = 0;

	/*
	 * determine the starting point for the translation.
	 */
	if ((ndp->ni_rootdir = fdp->fd_rdir) == NULLVP) {
	        if ( !(fdp->fd_flags & FD_CHROOT))
		        ndp->ni_rootdir = rootvnode;
	}
	cnp->cn_nameptr = cnp->cn_pnbuf;

	ndp->ni_usedvp = NULLVP;

	if (*(cnp->cn_nameptr) == '/') {
	        while (*(cnp->cn_nameptr) == '/') {
		        cnp->cn_nameptr++;
			ndp->ni_pathlen--;
		}
		dp = ndp->ni_rootdir;
	} else if (cnp->cn_flags & USEDVP) {
	        dp = ndp->ni_dvp;
		ndp->ni_usedvp = dp;
	} else
	        dp = vfs_context_cwd(ctx);

	if (dp == NULLVP || (dp->v_lflag & VL_DEAD)) {
	        error = ENOENT;
		goto error_out;
	}
	ndp->ni_dvp = NULLVP;
	ndp->ni_vp  = NULLVP;

	for (;;) {
	        int need_newpathbuf;
		int linklen;

		ndp->ni_startdir = dp;

		if ( (error = lookup(ndp)) ) {
			goto error_out;
		}
		/*
		 * Check for symbolic link
		 */
		if ((cnp->cn_flags & ISSYMLINK) == 0) {
			return (0);
		}
		if ((cnp->cn_flags & FSNODELOCKHELD)) {
		        cnp->cn_flags &= ~FSNODELOCKHELD;
			unlock_fsnode(ndp->ni_dvp, NULL);
		}	
		if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
			error = ELOOP;
			break;
		}
#if CONFIG_MACF
		if ((error = mac_vnode_check_readlink(ctx, ndp->ni_vp)) != 0)
			break;
#endif /* MAC */
		if (ndp->ni_pathlen > 1 || !(cnp->cn_flags & HASBUF))
		        need_newpathbuf = 1;
		else
		        need_newpathbuf = 0;

		if (need_newpathbuf) {
			MALLOC_ZONE(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
			if (cp == NULL) {
				error = ENOMEM;
				break;
			}
		} else {
			cp = cnp->cn_pnbuf;
		}
		auio = uio_createwithbuffer(1, 0, UIO_SYSSPACE, UIO_READ, &uio_buf[0], sizeof(uio_buf));

		uio_addiov(auio, CAST_USER_ADDR_T(cp), MAXPATHLEN);

		error = VNOP_READLINK(ndp->ni_vp, auio, ctx);
		if (error) {
			if (need_newpathbuf)
				FREE_ZONE(cp, MAXPATHLEN, M_NAMEI);
			break;
		}
		// LP64todo - fix this
		linklen = MAXPATHLEN - uio_resid(auio);
		if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
			if (need_newpathbuf)
				FREE_ZONE(cp, MAXPATHLEN, M_NAMEI);

			error = ENAMETOOLONG;
			break;
		}
		if (need_newpathbuf) {
			long len = cnp->cn_pnlen;

			tmppn = cnp->cn_pnbuf;
			bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
			cnp->cn_pnbuf = cp;
			cnp->cn_pnlen = MAXPATHLEN;

			if ( (cnp->cn_flags & HASBUF) )
			        FREE_ZONE(tmppn, len, M_NAMEI);
			else
			        cnp->cn_flags |= HASBUF;
		} else
			cnp->cn_pnbuf[linklen] = '\0';

		ndp->ni_pathlen += linklen;
		cnp->cn_nameptr = cnp->cn_pnbuf;

		/*
		 * starting point for 'relative'
		 * symbolic link path
		 */
		dp = ndp->ni_dvp;
	        /*
		 * get rid of references returned via 'lookup'
		 */
		vnode_put(ndp->ni_vp);
		vnode_put(ndp->ni_dvp);

		ndp->ni_vp = NULLVP;
		ndp->ni_dvp = NULLVP;

		/*
		 * Check if symbolic link restarts us at the root
		 */
		if (*(cnp->cn_nameptr) == '/') {
			while (*(cnp->cn_nameptr) == '/') {
				cnp->cn_nameptr++;
				ndp->ni_pathlen--;
			}
			if ((dp = ndp->ni_rootdir) == NULLVP) {
			        error = ENOENT;
				goto error_out;
			}
		}
	}
	/*
	 * only come here if we fail to handle a SYMLINK...
	 * if either ni_dvp or ni_vp is non-NULL, then
	 * we need to drop the iocount that was picked
	 * up in the lookup routine
	 */
	if (ndp->ni_dvp)
	        vnode_put(ndp->ni_dvp);
	if (ndp->ni_vp)
	        vnode_put(ndp->ni_vp);
 error_out:
	if ( (cnp->cn_flags & HASBUF) ) {
		cnp->cn_flags &= ~HASBUF;
		FREE_ZONE(cnp->cn_pnbuf, cnp->cn_pnlen, M_NAMEI);
	}
	cnp->cn_pnbuf = NULL;
	ndp->ni_vp = NULLVP;
	if (error == ERECYCLE){
		/* vnode was recycled underneath us. re-drive lookup to start at 
		   the beginning again, since recycling invalidated last lookup*/
		ndp->ni_cnd.cn_flags = cnpflags;
		ndp->ni_dvp = usedvp;
		goto vnode_recycled;
	}


	return (error);
}