1 /*- 2 * perm.c - check user permission for at(1) 3 * 4 * SPDX-License-Identifier: BSD-2-Clause 5 * 6 * Copyright (C) 1994 Thomas Koenig 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. The name of the author(s) may not be used to endorse or promote 14 * products derived from this software without specific prior written 15 * permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 /* System Headers */ 31 32 #include <sys/types.h> 33 #include <err.h> 34 #include <errno.h> 35 #include <pwd.h> 36 #include <stddef.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <unistd.h> 41 42 /* Local headers */ 43 44 #include "at.h" 45 #include "perm.h" 46 #include "privs.h" 47 48 /* Macros */ 49 50 #define MAXUSERID 10 51 52 /* Structures and unions */ 53 54 /* Function declarations */ 55 56 static int check_for_user(FILE *fp,const char *name); 57 58 /* Local functions */ 59 60 static int check_for_user(FILE *fp,const char *name) 61 { 62 char *buffer; 63 size_t len; 64 int found = 0; 65 66 len = strlen(name); 67 if ((buffer = malloc(len+2)) == NULL) 68 errx(EXIT_FAILURE, "virtual memory exhausted"); 69 70 while(fgets(buffer, len+2, fp) != NULL) 71 { 72 if ((strncmp(name, buffer, len) == 0) && 73 (buffer[len] == '\n')) 74 { 75 found = 1; 76 break; 77 } 78 } 79 fclose(fp); 80 free(buffer); 81 return found; 82 } 83 /* Global functions */ 84 int check_permission(void) 85 { 86 FILE *fp; 87 uid_t uid = geteuid(); 88 struct passwd *pentry; 89 90 if (uid==0) 91 return 1; 92 93 if ((pentry = getpwuid(uid)) == NULL) 94 err(EXIT_FAILURE, "cannot access user database"); 95 96 PRIV_START 97 98 fp=fopen(PERM_PATH "at.allow","r"); 99 100 PRIV_END 101 102 if (fp != NULL) 103 { 104 return check_for_user(fp, pentry->pw_name); 105 } 106 else if (errno == ENOENT) 107 { 108 109 PRIV_START 110 111 fp=fopen(PERM_PATH "at.deny", "r"); 112 113 PRIV_END 114 115 if (fp != NULL) 116 { 117 return !check_for_user(fp, pentry->pw_name); 118 } 119 else if (errno != ENOENT) 120 warn("at.deny"); 121 } 122 else 123 warn("at.allow"); 124 return 0; 125 } 126