1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. 24 */ 25 26 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */ 27 /* All Rights Reserved */ 28 29 /* 30 * Portions of this source code were derived from Berkeley 4.3 BSD 31 * under license from the Regents of the University of California. 32 */ 33 34 #include <sys/param.h> 35 #include <sys/isa_defs.h> 36 #include <sys/types.h> 37 #include <sys/sysmacros.h> 38 #include <sys/cred.h> 39 #include <sys/systm.h> 40 #include <sys/errno.h> 41 #include <sys/pathname.h> 42 #include <sys/vnode.h> 43 #include <sys/file.h> 44 #include <sys/fcntl.h> 45 #include <sys/uio.h> 46 #include <sys/debug.h> 47 #include <fs/fs_subr.h> 48 #include <c2/audit.h> 49 50 /* 51 * Read the contents of a symbolic link. 52 */ 53 ssize_t 54 readlinkat(int dfd, char *name, char *buf, size_t count) 55 { 56 vnode_t *startvp; 57 vnode_t *vp; 58 struct iovec aiov; 59 struct uio auio; 60 int error; 61 struct vattr vattr; 62 ssize_t cnt; 63 int estale_retry = 0; 64 65 if ((cnt = (ssize_t)count) < 0) 66 return (set_errno(EINVAL)); 67 if (name == NULL) 68 return (set_errno(EFAULT)); 69 if ((error = fgetstartvp(dfd, name, &startvp)) != 0) 70 return (set_errno(error)); 71 72 lookup: 73 if (AU_AUDITING() && startvp != NULL) 74 audit_setfsat_path(1); 75 if (error = lookupnameat(name, UIO_USERSPACE, NO_FOLLOW, 76 NULLVPP, &vp, startvp)) { 77 if (error == ESTALE && fs_need_estale_retry(estale_retry++)) 78 goto lookup; 79 goto out; 80 } 81 82 if (vp->v_type != VLNK) { 83 /* 84 * Ask the underlying filesystem if it wants this 85 * object to look like a symlink at user-level. 86 */ 87 vattr.va_mask = AT_TYPE; 88 error = VOP_GETATTR(vp, &vattr, 0, CRED(), NULL); 89 if (error || vattr.va_type != VLNK) { 90 VN_RELE(vp); 91 if ((error == ESTALE) && 92 fs_need_estale_retry(estale_retry++)) 93 goto lookup; 94 error = EINVAL; 95 goto out; 96 } 97 } 98 aiov.iov_base = buf; 99 aiov.iov_len = cnt; 100 auio.uio_iov = &aiov; 101 auio.uio_iovcnt = 1; 102 auio.uio_loffset = 0; 103 auio.uio_segflg = UIO_USERSPACE; 104 auio.uio_extflg = UIO_COPY_CACHED; 105 auio.uio_resid = cnt; 106 error = VOP_READLINK(vp, &auio, CRED(), NULL); 107 VN_RELE(vp); 108 if (error == ESTALE && fs_need_estale_retry(estale_retry++)) 109 goto lookup; 110 out: 111 if (startvp != NULL) 112 VN_RELE(startvp); 113 if (error) 114 return (set_errno(error)); 115 return ((ssize_t)(cnt - auio.uio_resid)); 116 } 117 118 ssize_t 119 readlink(char *name, char *buf, size_t count) 120 { 121 return (readlinkat(AT_FDCWD, name, buf, count)); 122 } 123 124 #ifdef _SYSCALL32_IMPL 125 /* 126 * readlink32() intentionally returns a ssize_t rather than ssize32_t; 127 * see the comments above read32 for details. 128 */ 129 130 ssize_t 131 readlinkat32(int dfd, caddr32_t name, caddr32_t buf, size32_t count) 132 { 133 return ((ssize32_t)readlinkat(dfd, (char *)(uintptr_t)name, 134 (char *)(uintptr_t)buf, (ssize32_t)count)); 135 } 136 137 ssize_t 138 readlink32(caddr32_t name, caddr32_t buf, size32_t count) 139 { 140 return ((ssize32_t)readlinkat(AT_FDCWD, (char *)(uintptr_t)name, 141 (char *)(uintptr_t)buf, (ssize32_t)count)); 142 } 143 144 #endif /* _SYSCALL32_IMPL */ 145