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 2010 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/param.h> 29 #include <sys/sysmacros.h> 30 #include <sys/signal.h> 31 #include <sys/cred.h> 32 #include <sys/user.h> 33 #include <sys/errno.h> 34 #include <sys/vnode.h> 35 #include <sys/proc.h> 36 #include <sys/cmn_err.h> 37 #include <sys/debug.h> 38 #include <sys/pathname.h> 39 #include <sys/disp.h> 40 #include <sys/exec.h> 41 #include <sys/kmem.h> 42 #include <sys/note.h> 43 44 /* 45 * This is the loadable module wrapper. 46 */ 47 #include <sys/modctl.h> 48 49 /* Local prototypes */ 50 static int 51 shbinexec( 52 struct vnode *vp, 53 struct execa *uap, 54 struct uarg *args, 55 struct intpdata *idatap, 56 int level, 57 long *execsz, 58 int setid, 59 caddr_t exec_file, 60 struct cred *cred, 61 int brand_action); 62 63 #define SHBIN_CNTL(x) ((x)&037) 64 #define SHBINMAGIC_LEN 4 65 extern char shbinmagicstr[]; 66 67 /* 68 * Our list where we may find a copy of ksh93. The ordering is: 69 * 1. 64bit (may not be installed or not supported in hardware) 70 * 2. 32bit 71 * 3. Use /sbin/ksh93 when /usr is not available 72 * 73 * ([1] and [2] explicitly bypass /usr/bin/ksh93 to avoid the 74 * isaexec overhead). 75 */ 76 static char *shell_list[] = 77 { 78 /* Bypass /usr/bin/ksh93 (which is "isaexec") for performance */ 79 #if defined(__sparc) 80 "/usr/bin/sparcv9/ksh93", 81 "/usr/bin/sparcv7/ksh93", 82 #elif defined(__x86) 83 "/usr/bin/amd64/ksh93", 84 "/usr/bin/i86/ksh93", 85 #else 86 #error "Unrecognized platform/CPU (use /usr/bin/ksh93 when in doubt)." 87 #endif 88 "/sbin/ksh93", 89 NULL 90 }; 91 92 static struct execsw esw = { 93 shbinmagicstr, 94 0, 95 SHBINMAGIC_LEN, 96 shbinexec, 97 NULL 98 }; 99 100 /* 101 * Module linkage information for the kernel. 102 */ 103 extern struct mod_ops mod_execops; 104 105 static struct modlexec modlexec = { 106 &mod_execops, "exec mod for shell binaries (ksh93)", &esw 107 }; 108 109 static struct modlinkage modlinkage = { 110 MODREV_1, (void *)&modlexec, NULL 111 }; 112 113 int 114 _init(void) 115 { 116 return (mod_install(&modlinkage)); 117 } 118 119 int 120 _fini(void) 121 { 122 return (mod_remove(&modlinkage)); 123 } 124 125 int 126 _info(struct modinfo *modinfop) 127 { 128 return (mod_info(&modlinkage, modinfop)); 129 } 130 131 static int 132 checkshbinmagic(struct vnode *vp) 133 { 134 int error; 135 char linep[SHBINMAGIC_LEN]; 136 ssize_t resid; 137 138 /* 139 * Read the entire line and confirm that it starts with the magic 140 * sequence for compiled ksh93 shell scripts. 141 */ 142 if (error = vn_rdwr(UIO_READ, vp, linep, sizeof (linep), (offset_t)0, 143 UIO_SYSSPACE, 0, (rlim64_t)0, CRED(), &resid)) 144 return (error); 145 146 if (memcmp(linep, shbinmagicstr, SHBINMAGIC_LEN) != 0) 147 return (ENOEXEC); 148 149 return (0); 150 } 151 152 static int 153 shbinexec( 154 struct vnode *vp, 155 struct execa *uap, 156 struct uarg *args, 157 struct intpdata *idatap, 158 int level, 159 long *execsz, 160 int setid, 161 caddr_t exec_file, 162 struct cred *cred, 163 int brand_action) 164 { 165 _NOTE(ARGUNUSED(brand_action)) 166 vnode_t *nvp; 167 int error = 0; 168 struct intpdata idata; 169 struct pathname intppn; 170 struct pathname resolvepn; 171 char *opath; 172 char devfd[19]; /* 32-bit int fits in 10 digits + 8 for "/dev/fd/" */ 173 int fd = -1; 174 int i; 175 176 if (level) { /* Can't recurse */ 177 error = ENOEXEC; 178 goto bad; 179 } 180 181 ASSERT(idatap == (struct intpdata *)NULL); 182 183 /* 184 * Check whether the executable has the correct magic value. 185 */ 186 if (error = checkshbinmagic(vp)) 187 goto fail; 188 189 pn_alloc(&resolvepn); 190 191 /* 192 * Travel the list of shells and look for one which is available... 193 */ 194 for (i = 0; shell_list[i] != NULL; i++) { 195 error = pn_get(shell_list[i], UIO_SYSSPACE, &intppn); 196 if (error != 0) { 197 break; 198 } 199 200 error = lookuppn(&intppn, &resolvepn, FOLLOW, NULLVPP, &nvp); 201 if (!error) { 202 /* Found match */ 203 break; 204 } 205 206 /* No match found ? Then continue with the next item... */ 207 pn_free(&intppn); 208 } 209 210 if (error) { 211 pn_free(&resolvepn); 212 goto fail; 213 } 214 215 /* 216 * Set up interpreter data 217 * "--" is passed to mark the end-of-arguments before adding 218 * the script's file name, preventing problems when a 219 * script's name starts with a '-' character. 220 */ 221 bzero(&idata, sizeof (intpdata_t)); 222 idata.intp = NULL; 223 idata.intp_name[0] = shell_list[i]; 224 idata.intp_arg[0] = "--"; 225 226 opath = args->pathname; 227 args->pathname = resolvepn.pn_path; 228 /* don't free resolvepn until we are done with args */ 229 pn_free(&intppn); 230 231 /* 232 * When we're executing a set-uid script resulting in uids 233 * mismatching or when we execute with additional privileges, 234 * we close the "replace script between exec and open by shell" 235 * hole by passing the script as /dev/fd parameter. 236 */ 237 if ((setid & EXECSETID_PRIVS) != 0 || 238 (setid & (EXECSETID_UGIDS|EXECSETID_SETID)) == 239 (EXECSETID_UGIDS|EXECSETID_SETID)) { 240 (void) strcpy(devfd, "/dev/fd/"); 241 if (error = execopen(&vp, &fd)) 242 goto done; 243 numtos(fd, &devfd[8]); 244 args->fname = devfd; 245 } 246 247 error = gexec(&nvp, uap, args, &idata, ++level, execsz, exec_file, cred, 248 EBA_NONE); 249 250 if (!error) { 251 /* 252 * Close this script as the sh interpreter 253 * will open and close it later on. 254 */ 255 (void) VOP_CLOSE(vp, FREAD, 1, (offset_t)0, cred, NULL); 256 } 257 done: 258 VN_RELE(nvp); 259 args->pathname = opath; 260 pn_free(&resolvepn); 261 fail: 262 if (error && fd != -1) 263 (void) execclose(fd); 264 bad: 265 return (error); 266 } 267