1 /* Change the ownership and mode bits of a directory. 2 3 Copyright (C) 2006-2021 Free Software Foundation, Inc. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 17 18 /* Written by Paul Eggert. */ 19 20 #include <config.h> 21 22 #include "dirchownmod.h" 23 24 #include <errno.h> 25 #include <sys/types.h> 26 #include <sys/stat.h> 27 #include <unistd.h> 28 29 #include "stat-macros.h" 30 31 #ifndef HAVE_FCHMOD 32 # define HAVE_FCHMOD 0 33 # undef fchmod 34 # define fchmod(fd, mode) (-1) 35 #endif 36 37 /* Change the ownership and mode bits of a directory. If FD is 38 nonnegative, it should be a file descriptor associated with the 39 directory; close it before returning. DIR is the name of the 40 directory. 41 42 If MKDIR_MODE is not (mode_t) -1, mkdir (DIR, MKDIR_MODE) has just 43 been executed successfully with umask zero, so DIR should be a 44 directory (not a symbolic link). 45 46 First, set the file's owner to OWNER and group to GROUP, but leave 47 the owner alone if OWNER is (uid_t) -1, and similarly for GROUP. 48 49 Then, set the file's mode bits to MODE, except preserve any of the 50 bits that correspond to zero bits in MODE_BITS. In other words, 51 MODE_BITS is a mask that specifies which of the file's mode bits 52 should be set or cleared. MODE should be a subset of MODE_BITS, 53 which in turn should be a subset of CHMOD_MODE_BITS. 54 55 This implementation assumes the current umask is zero. 56 57 Return 0 if successful, -1 (setting errno) otherwise. Unsuccessful 58 calls may do the chown but not the chmod. */ 59 60 int 61 dirchownmod (int fd, char const *dir, mode_t mkdir_mode, /* */ 62 uid_t owner, gid_t group, 63 mode_t mode, mode_t mode_bits) 64 { 65 struct stat st; 66 int result = (fd < 0 ? stat (dir, &st) : fstat (fd, &st)); 67 68 if (result == 0) 69 { 70 mode_t dir_mode = st.st_mode; 71 72 /* Check whether DIR is a directory. If FD is nonnegative, this 73 check avoids changing the ownership and mode bits of the 74 wrong file in many cases. This doesn't fix all the race 75 conditions, but it is better than nothing. */ 76 if (! S_ISDIR (dir_mode)) 77 { 78 errno = ENOTDIR; 79 result = -1; 80 } 81 else 82 { 83 /* If at least one of the S_IXUGO bits are set, chown might 84 clear the S_ISUID and S_SGID bits. Keep track of any 85 file mode bits whose values are indeterminate due to this 86 issue. */ 87 mode_t indeterminate = 0; 88 89 /* On some systems, chown clears S_ISUID and S_ISGID, so do 90 chown before chmod. On older System V hosts, ordinary 91 users can give their files away via chown; don't worry 92 about that here, since users shouldn't do that. */ 93 94 if ((owner != (uid_t) -1 && owner != st.st_uid) 95 || (group != (gid_t) -1 && group != st.st_gid)) 96 { 97 result = (0 <= fd 98 ? fchown (fd, owner, group) 99 : mkdir_mode != (mode_t) -1 100 ? lchown (dir, owner, group) 101 : chown (dir, owner, group)); 102 103 /* Either the user cares about an indeterminate bit and 104 it'll be set properly by chmod below, or the user 105 doesn't care and it's OK to use the bit's pre-chown 106 value. So there's no need to re-stat DIR here. */ 107 108 if (result == 0 && (dir_mode & S_IXUGO)) 109 indeterminate = dir_mode & (S_ISUID | S_ISGID); 110 } 111 112 /* If the file mode bits might not be right, use chmod to 113 change them. Don't change bits the user doesn't care 114 about. */ 115 if (result == 0 && (((dir_mode ^ mode) | indeterminate) & mode_bits)) 116 { 117 mode_t chmod_mode = 118 mode | (dir_mode & CHMOD_MODE_BITS & ~mode_bits); 119 result = (HAVE_FCHMOD && 0 <= fd 120 ? fchmod (fd, chmod_mode) 121 : mkdir_mode != (mode_t) -1 122 ? lchmod (dir, chmod_mode) 123 : chmod (dir, chmod_mode)); 124 } 125 } 126 } 127 128 if (0 <= fd) 129 { 130 if (result == 0) 131 result = close (fd); 132 else 133 { 134 int e = errno; 135 close (fd); 136 errno = e; 137 } 138 } 139 140 return result; 141 }