1 /* 2 * linux/fs/attr.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * changes by Thomas Schoebel-Theuer 6 */ 7 8 #include <linux/module.h> 9 #include <linux/time.h> 10 #include <linux/mm.h> 11 #include <linux/string.h> 12 #include <linux/capability.h> 13 #include <linux/fsnotify.h> 14 #include <linux/fcntl.h> 15 #include <linux/quotaops.h> 16 #include <linux/security.h> 17 18 /* Taken over from the old code... */ 19 20 /* POSIX UID/GID verification for setting inode attributes. */ 21 int inode_change_ok(struct inode *inode, struct iattr *attr) 22 { 23 int retval = -EPERM; 24 unsigned int ia_valid = attr->ia_valid; 25 26 /* If force is set do it anyway. */ 27 if (ia_valid & ATTR_FORCE) 28 goto fine; 29 30 /* Make sure a caller can chown. */ 31 if ((ia_valid & ATTR_UID) && 32 (current->fsuid != inode->i_uid || 33 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN)) 34 goto error; 35 36 /* Make sure caller can chgrp. */ 37 if ((ia_valid & ATTR_GID) && 38 (current->fsuid != inode->i_uid || 39 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) && 40 !capable(CAP_CHOWN)) 41 goto error; 42 43 /* Make sure a caller can chmod. */ 44 if (ia_valid & ATTR_MODE) { 45 if (!is_owner_or_cap(inode)) 46 goto error; 47 /* Also check the setgid bit! */ 48 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : 49 inode->i_gid) && !capable(CAP_FSETID)) 50 attr->ia_mode &= ~S_ISGID; 51 } 52 53 /* Check for setting the inode time. */ 54 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) { 55 if (!is_owner_or_cap(inode)) 56 goto error; 57 } 58 fine: 59 retval = 0; 60 error: 61 return retval; 62 } 63 64 EXPORT_SYMBOL(inode_change_ok); 65 66 int inode_setattr(struct inode * inode, struct iattr * attr) 67 { 68 unsigned int ia_valid = attr->ia_valid; 69 70 if (ia_valid & ATTR_SIZE && 71 attr->ia_size != i_size_read(inode)) { 72 int error = vmtruncate(inode, attr->ia_size); 73 if (error) 74 return error; 75 } 76 77 if (ia_valid & ATTR_UID) 78 inode->i_uid = attr->ia_uid; 79 if (ia_valid & ATTR_GID) 80 inode->i_gid = attr->ia_gid; 81 if (ia_valid & ATTR_ATIME) 82 inode->i_atime = timespec_trunc(attr->ia_atime, 83 inode->i_sb->s_time_gran); 84 if (ia_valid & ATTR_MTIME) 85 inode->i_mtime = timespec_trunc(attr->ia_mtime, 86 inode->i_sb->s_time_gran); 87 if (ia_valid & ATTR_CTIME) 88 inode->i_ctime = timespec_trunc(attr->ia_ctime, 89 inode->i_sb->s_time_gran); 90 if (ia_valid & ATTR_MODE) { 91 umode_t mode = attr->ia_mode; 92 93 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 94 mode &= ~S_ISGID; 95 inode->i_mode = mode; 96 } 97 mark_inode_dirty(inode); 98 99 return 0; 100 } 101 EXPORT_SYMBOL(inode_setattr); 102 103 int notify_change(struct dentry * dentry, struct iattr * attr) 104 { 105 struct inode *inode = dentry->d_inode; 106 mode_t mode = inode->i_mode; 107 int error; 108 struct timespec now; 109 unsigned int ia_valid = attr->ia_valid; 110 111 now = current_fs_time(inode->i_sb); 112 113 attr->ia_ctime = now; 114 if (!(ia_valid & ATTR_ATIME_SET)) 115 attr->ia_atime = now; 116 if (!(ia_valid & ATTR_MTIME_SET)) 117 attr->ia_mtime = now; 118 if (ia_valid & ATTR_KILL_PRIV) { 119 attr->ia_valid &= ~ATTR_KILL_PRIV; 120 ia_valid &= ~ATTR_KILL_PRIV; 121 error = security_inode_need_killpriv(dentry); 122 if (error > 0) 123 error = security_inode_killpriv(dentry); 124 if (error) 125 return error; 126 } 127 128 /* 129 * We now pass ATTR_KILL_S*ID to the lower level setattr function so 130 * that the function has the ability to reinterpret a mode change 131 * that's due to these bits. This adds an implicit restriction that 132 * no function will ever call notify_change with both ATTR_MODE and 133 * ATTR_KILL_S*ID set. 134 */ 135 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && 136 (ia_valid & ATTR_MODE)) 137 BUG(); 138 139 if (ia_valid & ATTR_KILL_SUID) { 140 if (mode & S_ISUID) { 141 ia_valid = attr->ia_valid |= ATTR_MODE; 142 attr->ia_mode = (inode->i_mode & ~S_ISUID); 143 } 144 } 145 if (ia_valid & ATTR_KILL_SGID) { 146 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 147 if (!(ia_valid & ATTR_MODE)) { 148 ia_valid = attr->ia_valid |= ATTR_MODE; 149 attr->ia_mode = inode->i_mode; 150 } 151 attr->ia_mode &= ~S_ISGID; 152 } 153 } 154 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) 155 return 0; 156 157 if (ia_valid & ATTR_SIZE) 158 down_write(&dentry->d_inode->i_alloc_sem); 159 160 if (inode->i_op && inode->i_op->setattr) { 161 error = security_inode_setattr(dentry, attr); 162 if (!error) 163 error = inode->i_op->setattr(dentry, attr); 164 } else { 165 error = inode_change_ok(inode, attr); 166 if (!error) 167 error = security_inode_setattr(dentry, attr); 168 if (!error) { 169 if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) || 170 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) 171 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0; 172 if (!error) 173 error = inode_setattr(inode, attr); 174 } 175 } 176 177 if (ia_valid & ATTR_SIZE) 178 up_write(&dentry->d_inode->i_alloc_sem); 179 180 if (!error) 181 fsnotify_change(dentry, ia_valid); 182 183 return error; 184 } 185 186 EXPORT_SYMBOL(notify_change); 187