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/security.h> 16 17 /* Taken over from the old code... */ 18 19 /* POSIX UID/GID verification for setting inode attributes. */ 20 int inode_change_ok(const struct inode *inode, struct iattr *attr) 21 { 22 int retval = -EPERM; 23 unsigned int ia_valid = attr->ia_valid; 24 25 /* If force is set do it anyway. */ 26 if (ia_valid & ATTR_FORCE) 27 goto fine; 28 29 /* Make sure a caller can chown. */ 30 if ((ia_valid & ATTR_UID) && 31 (current_fsuid() != inode->i_uid || 32 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN)) 33 goto error; 34 35 /* Make sure caller can chgrp. */ 36 if ((ia_valid & ATTR_GID) && 37 (current_fsuid() != inode->i_uid || 38 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) && 39 !capable(CAP_CHOWN)) 40 goto error; 41 42 /* Make sure a caller can chmod. */ 43 if (ia_valid & ATTR_MODE) { 44 if (!is_owner_or_cap(inode)) 45 goto error; 46 /* Also check the setgid bit! */ 47 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : 48 inode->i_gid) && !capable(CAP_FSETID)) 49 attr->ia_mode &= ~S_ISGID; 50 } 51 52 /* Check for setting the inode time. */ 53 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) { 54 if (!is_owner_or_cap(inode)) 55 goto error; 56 } 57 fine: 58 retval = 0; 59 error: 60 return retval; 61 } 62 EXPORT_SYMBOL(inode_change_ok); 63 64 /** 65 * inode_newsize_ok - may this inode be truncated to a given size 66 * @inode: the inode to be truncated 67 * @offset: the new size to assign to the inode 68 * @Returns: 0 on success, -ve errno on failure 69 * 70 * inode_newsize_ok must be called with i_mutex held. 71 * 72 * inode_newsize_ok will check filesystem limits and ulimits to check that the 73 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ 74 * when necessary. Caller must not proceed with inode size change if failure is 75 * returned. @inode must be a file (not directory), with appropriate 76 * permissions to allow truncate (inode_newsize_ok does NOT check these 77 * conditions). 78 */ 79 int inode_newsize_ok(const struct inode *inode, loff_t offset) 80 { 81 if (inode->i_size < offset) { 82 unsigned long limit; 83 84 limit = rlimit(RLIMIT_FSIZE); 85 if (limit != RLIM_INFINITY && offset > limit) 86 goto out_sig; 87 if (offset > inode->i_sb->s_maxbytes) 88 goto out_big; 89 } else { 90 /* 91 * truncation of in-use swapfiles is disallowed - it would 92 * cause subsequent swapout to scribble on the now-freed 93 * blocks. 94 */ 95 if (IS_SWAPFILE(inode)) 96 return -ETXTBSY; 97 } 98 99 return 0; 100 out_sig: 101 send_sig(SIGXFSZ, current, 0); 102 out_big: 103 return -EFBIG; 104 } 105 EXPORT_SYMBOL(inode_newsize_ok); 106 107 /** 108 * generic_setattr - copy simple metadata updates into the generic inode 109 * @inode: the inode to be updated 110 * @attr: the new attributes 111 * 112 * generic_setattr must be called with i_mutex held. 113 * 114 * generic_setattr updates the inode's metadata with that specified 115 * in attr. Noticably missing is inode size update, which is more complex 116 * as it requires pagecache updates. See simple_setsize. 117 * 118 * The inode is not marked as dirty after this operation. The rationale is 119 * that for "simple" filesystems, the struct inode is the inode storage. 120 * The caller is free to mark the inode dirty afterwards if needed. 121 */ 122 void generic_setattr(struct inode *inode, const struct iattr *attr) 123 { 124 unsigned int ia_valid = attr->ia_valid; 125 126 if (ia_valid & ATTR_UID) 127 inode->i_uid = attr->ia_uid; 128 if (ia_valid & ATTR_GID) 129 inode->i_gid = attr->ia_gid; 130 if (ia_valid & ATTR_ATIME) 131 inode->i_atime = timespec_trunc(attr->ia_atime, 132 inode->i_sb->s_time_gran); 133 if (ia_valid & ATTR_MTIME) 134 inode->i_mtime = timespec_trunc(attr->ia_mtime, 135 inode->i_sb->s_time_gran); 136 if (ia_valid & ATTR_CTIME) 137 inode->i_ctime = timespec_trunc(attr->ia_ctime, 138 inode->i_sb->s_time_gran); 139 if (ia_valid & ATTR_MODE) { 140 umode_t mode = attr->ia_mode; 141 142 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 143 mode &= ~S_ISGID; 144 inode->i_mode = mode; 145 } 146 } 147 EXPORT_SYMBOL(generic_setattr); 148 149 /* 150 * note this function is deprecated, the new truncate sequence should be 151 * used instead -- see eg. simple_setsize, generic_setattr. 152 */ 153 int inode_setattr(struct inode *inode, const struct iattr *attr) 154 { 155 unsigned int ia_valid = attr->ia_valid; 156 157 if (ia_valid & ATTR_SIZE && 158 attr->ia_size != i_size_read(inode)) { 159 int error; 160 161 error = vmtruncate(inode, attr->ia_size); 162 if (error) 163 return error; 164 } 165 166 generic_setattr(inode, attr); 167 168 mark_inode_dirty(inode); 169 170 return 0; 171 } 172 EXPORT_SYMBOL(inode_setattr); 173 174 int notify_change(struct dentry * dentry, struct iattr * attr) 175 { 176 struct inode *inode = dentry->d_inode; 177 mode_t mode = inode->i_mode; 178 int error; 179 struct timespec now; 180 unsigned int ia_valid = attr->ia_valid; 181 182 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { 183 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 184 return -EPERM; 185 } 186 187 now = current_fs_time(inode->i_sb); 188 189 attr->ia_ctime = now; 190 if (!(ia_valid & ATTR_ATIME_SET)) 191 attr->ia_atime = now; 192 if (!(ia_valid & ATTR_MTIME_SET)) 193 attr->ia_mtime = now; 194 if (ia_valid & ATTR_KILL_PRIV) { 195 attr->ia_valid &= ~ATTR_KILL_PRIV; 196 ia_valid &= ~ATTR_KILL_PRIV; 197 error = security_inode_need_killpriv(dentry); 198 if (error > 0) 199 error = security_inode_killpriv(dentry); 200 if (error) 201 return error; 202 } 203 204 /* 205 * We now pass ATTR_KILL_S*ID to the lower level setattr function so 206 * that the function has the ability to reinterpret a mode change 207 * that's due to these bits. This adds an implicit restriction that 208 * no function will ever call notify_change with both ATTR_MODE and 209 * ATTR_KILL_S*ID set. 210 */ 211 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && 212 (ia_valid & ATTR_MODE)) 213 BUG(); 214 215 if (ia_valid & ATTR_KILL_SUID) { 216 if (mode & S_ISUID) { 217 ia_valid = attr->ia_valid |= ATTR_MODE; 218 attr->ia_mode = (inode->i_mode & ~S_ISUID); 219 } 220 } 221 if (ia_valid & ATTR_KILL_SGID) { 222 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 223 if (!(ia_valid & ATTR_MODE)) { 224 ia_valid = attr->ia_valid |= ATTR_MODE; 225 attr->ia_mode = inode->i_mode; 226 } 227 attr->ia_mode &= ~S_ISGID; 228 } 229 } 230 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) 231 return 0; 232 233 error = security_inode_setattr(dentry, attr); 234 if (error) 235 return error; 236 237 if (ia_valid & ATTR_SIZE) 238 down_write(&dentry->d_inode->i_alloc_sem); 239 240 if (inode->i_op && inode->i_op->setattr) { 241 error = inode->i_op->setattr(dentry, attr); 242 } else { 243 error = inode_change_ok(inode, attr); 244 if (!error) 245 error = inode_setattr(inode, attr); 246 } 247 248 if (ia_valid & ATTR_SIZE) 249 up_write(&dentry->d_inode->i_alloc_sem); 250 251 if (!error) 252 fsnotify_change(dentry, ia_valid); 253 254 return error; 255 } 256 257 EXPORT_SYMBOL(notify_change); 258