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(__amd64) 83 "/usr/bin/amd64/ksh93", 84 "/usr/bin/i86/ksh93", 85 #elif defined(__i386) 86 "/usr/bin/i86/ksh93", 87 #else 88 #error "Unrecognized platform/CPU (use /usr/bin/ksh93 when in doubt)." 89 #endif 90 "/sbin/ksh93", 91 NULL 92 }; 93 94 static struct execsw esw = { 95 shbinmagicstr, 96 0, 97 SHBINMAGIC_LEN, 98 shbinexec, 99 NULL 100 }; 101 102 /* 103 * Module linkage information for the kernel. 104 */ 105 extern struct mod_ops mod_execops; 106 107 static struct modlexec modlexec = { 108 &mod_execops, "exec mod for shell binaries (ksh93)", &esw 109 }; 110 111 static struct modlinkage modlinkage = { 112 MODREV_1, (void *)&modlexec, NULL 113 }; 114 115 int 116 _init(void) 117 { 118 return (mod_install(&modlinkage)); 119 } 120 121 int 122 _fini(void) 123 { 124 return (mod_remove(&modlinkage)); 125 } 126 127 int 128 _info(struct modinfo *modinfop) 129 { 130 return (mod_info(&modlinkage, modinfop)); 131 } 132 133 static int 134 checkshbinmagic(struct vnode *vp) 135 { 136 int error; 137 char linep[SHBINMAGIC_LEN]; 138 ssize_t resid; 139 140 /* 141 * Read the entire line and confirm that it starts with the magic 142 * sequence for compiled ksh93 shell scripts. 143 */ 144 if (error = vn_rdwr(UIO_READ, vp, linep, sizeof (linep), (offset_t)0, 145 UIO_SYSSPACE, 0, (rlim64_t)0, CRED(), &resid)) 146 return (error); 147 148 if (memcmp(linep, shbinmagicstr, SHBINMAGIC_LEN) != 0) 149 return (ENOEXEC); 150 151 return (0); 152 } 153 154 static int 155 shbinexec( 156 struct vnode *vp, 157 struct execa *uap, 158 struct uarg *args, 159 struct intpdata *idatap, 160 int level, 161 long *execsz, 162 int setid, 163 caddr_t exec_file, 164 struct cred *cred, 165 int brand_action) 166 { 167 _NOTE(ARGUNUSED(brand_action)) 168 vnode_t *nvp; 169 int error = 0; 170 struct intpdata idata; 171 struct pathname intppn; 172 struct pathname resolvepn; 173 char *opath; 174 char devfd[19]; /* 32-bit int fits in 10 digits + 8 for "/dev/fd/" */ 175 int fd = -1; 176 int i; 177 178 if (level) { /* Can't recurse */ 179 error = ENOEXEC; 180 goto bad; 181 } 182 183 ASSERT(idatap == (struct intpdata *)NULL); 184 185 /* 186 * Check whether the executable has the correct magic value. 187 */ 188 if (error = checkshbinmagic(vp)) 189 goto fail; 190 191 pn_alloc(&resolvepn); 192 193 /* 194 * Travel the list of shells and look for one which is available... 195 */ 196 for (i = 0; shell_list[i] != NULL; i++) { 197 error = pn_get(shell_list[i], UIO_SYSSPACE, &intppn); 198 if (error != 0) { 199 break; 200 } 201 202 error = lookuppn(&intppn, &resolvepn, FOLLOW, NULLVPP, &nvp); 203 if (!error) { 204 /* Found match */ 205 break; 206 } 207 208 /* No match found ? Then continue with the next item... */ 209 pn_free(&intppn); 210 } 211 212 if (error) { 213 pn_free(&resolvepn); 214 goto fail; 215 } 216 217 /* 218 * Setup interpreter data 219 * "--" is passed to mark the end-of-arguments before adding 220 * the scripts file name, preventing problems when a 221 * a script's name starts with a '-' character. 222 */ 223 idata.intp = NULL; 224 idata.intp_name = shell_list[i]; 225 idata.intp_arg = "--"; 226 227 opath = args->pathname; 228 args->pathname = resolvepn.pn_path; 229 /* don't free resolvepn until we are done with args */ 230 pn_free(&intppn); 231 232 /* 233 * When we're executing a set-uid script resulting in uids 234 * mismatching or when we execute with additional privileges, 235 * we close the "replace script between exec and open by shell" 236 * hole by passing the script as /dev/fd parameter. 237 */ 238 if ((setid & EXECSETID_PRIVS) != 0 || 239 (setid & (EXECSETID_UGIDS|EXECSETID_SETID)) == 240 (EXECSETID_UGIDS|EXECSETID_SETID)) { 241 (void) strcpy(devfd, "/dev/fd/"); 242 if (error = execopen(&vp, &fd)) 243 goto done; 244 numtos(fd, &devfd[8]); 245 args->fname = devfd; 246 } 247 248 error = gexec(&nvp, uap, args, &idata, ++level, execsz, exec_file, cred, 249 EBA_NONE); 250 251 if (!error) { 252 /* 253 * Close this script as the sh interpreter 254 * will open and close it later on. 255 */ 256 (void) VOP_CLOSE(vp, FREAD, 1, (offset_t)0, cred, NULL); 257 } 258 done: 259 VN_RELE(nvp); 260 args->pathname = opath; 261 pn_free(&resolvepn); 262 fail: 263 if (error && fd != -1) 264 (void) execclose(fd); 265 bad: 266 return (error); 267 } 268