1/* access.c 2 Check access to files by the user and by the daemon. */ 3 4#include "uucp.h" 5 6#include "uudefs.h" 7#include "sysdep.h" 8#include "system.h" 9 10#include <errno.h> 11 12/* See if the user has access to a file, to prevent the setuid uucp 13 and uux programs handing out unauthorized access. */ 14 15boolean 16fsysdep_access (zfile) 17 const char *zfile; 18{ 19 if (access (zfile, R_OK) == 0) 20 return TRUE; 21 ulog (LOG_ERROR, "%s: %s", zfile, strerror (errno)); 22 return FALSE; 23} 24 25/* See if the daemon has access to a file. This is called if a file 26 is not being transferred to the spool directory, since if the 27 daemon does not have access the later transfer will fail. We 28 assume that the daemon will have the same euid (or egid) as the one 29 we are running under. If our uid (gid) and euid (egid) are the 30 same, we assume that we have access. Note that is not important 31 for security, since the check will be (implicitly) done again when 32 the daemon tries to transfer the file. This routine should work 33 whether the UUCP programs are installed setuid or setgid. */ 34 35boolean 36fsysdep_daemon_access (zfile) 37 const char *zfile; 38{ 39 struct stat s; 40 uid_t ieuid, iuid, iegid, igid; 41 boolean fok; 42 43 ieuid = geteuid (); 44 if (ieuid == 0) 45 return TRUE; 46 iuid = getuid (); 47 iegid = getegid (); 48 igid = getgid (); 49 50 /* If our effective uid and gid are the same as our real uid and 51 gid, we assume the daemon will have access to the file. */ 52 if (ieuid == iuid && iegid == igid) 53 return TRUE; 54 55 if (stat ((char *) zfile, &s) != 0) 56 { 57 /* If we get an EACCES error, we can't read the file using our 58 euid. Therefore, the daemon will not have access to the file. */ 59 if (errno == EACCES) 60 ulog (LOG_ERROR, "%s: cannot be read by daemon", zfile); 61 else 62 ulog (LOG_ERROR, "stat (%s): %s", zfile, strerror (errno)); 63 return FALSE; 64 } 65 66 /* If our euid is not our uid, but it is the file's uid, see if the 67 owner has read access. Otherwise, if our egid is not our gid, 68 but it is the file's gid, see if the group has read access. 69 Otherwise, see if the world has read access. We know from the 70 above check that at least one of our euid and egid are different, 71 so that is the only one we want to check. This check could fail 72 if the UUCP programs were both setuid and setgid, but why would 73 they be? */ 74 if (ieuid != iuid && ieuid == s.st_uid) 75 fok = (s.st_mode & S_IRUSR) != 0; 76 else if (iegid != igid && iegid == s.st_gid) 77 fok = (s.st_mode & S_IRGRP) != 0; 78 else 79 fok = (s.st_mode & S_IROTH) != 0; 80 81 if (! fok) 82 { 83 ulog (LOG_ERROR, "%s: cannot be read by daemon", zfile); 84 return FALSE; 85 } 86 87 return TRUE; 88} 89