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(const 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 | ATTR_TIMES_SET)) { 55 if (!is_owner_or_cap(inode)) 56 goto error; 57 } 58 fine: 59 retval = 0; 60 error: 61 return retval; 62 } 63 EXPORT_SYMBOL(inode_change_ok); 64 65 /** 66 * inode_newsize_ok - may this inode be truncated to a given size 67 * @inode: the inode to be truncated 68 * @offset: the new size to assign to the inode 69 * @Returns: 0 on success, -ve errno on failure 70 * 71 * inode_newsize_ok will check filesystem limits and ulimits to check that the 72 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ 73 * when necessary. Caller must not proceed with inode size change if failure is 74 * returned. @inode must be a file (not directory), with appropriate 75 * permissions to allow truncate (inode_newsize_ok does NOT check these 76 * conditions). 77 * 78 * inode_newsize_ok must be called with i_mutex held. 79 */ 80 int inode_newsize_ok(const struct inode *inode, loff_t offset) 81 { 82 if (inode->i_size < offset) { 83 unsigned long limit; 84 85 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 86 if (limit != RLIM_INFINITY && offset > limit) 87 goto out_sig; 88 if (offset > inode->i_sb->s_maxbytes) 89 goto out_big; 90 } else { 91 /* 92 * truncation of in-use swapfiles is disallowed - it would 93 * cause subsequent swapout to scribble on the now-freed 94 * blocks. 95 */ 96 if (IS_SWAPFILE(inode)) 97 return -ETXTBSY; 98 } 99 100 return 0; 101 out_sig: 102 send_sig(SIGXFSZ, current, 0); 103 out_big: 104 return -EFBIG; 105 } 106 EXPORT_SYMBOL(inode_newsize_ok); 107 108 int inode_setattr(struct inode * inode, struct iattr * attr) 109 { 110 unsigned int ia_valid = attr->ia_valid; 111 112 if (ia_valid & ATTR_SIZE && 113 attr->ia_size != i_size_read(inode)) { 114 int error = vmtruncate(inode, attr->ia_size); 115 if (error) 116 return error; 117 } 118 119 if (ia_valid & ATTR_UID) 120 inode->i_uid = attr->ia_uid; 121 if (ia_valid & ATTR_GID) 122 inode->i_gid = attr->ia_gid; 123 if (ia_valid & ATTR_ATIME) 124 inode->i_atime = timespec_trunc(attr->ia_atime, 125 inode->i_sb->s_time_gran); 126 if (ia_valid & ATTR_MTIME) 127 inode->i_mtime = timespec_trunc(attr->ia_mtime, 128 inode->i_sb->s_time_gran); 129 if (ia_valid & ATTR_CTIME) 130 inode->i_ctime = timespec_trunc(attr->ia_ctime, 131 inode->i_sb->s_time_gran); 132 if (ia_valid & ATTR_MODE) { 133 umode_t mode = attr->ia_mode; 134 135 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 136 mode &= ~S_ISGID; 137 inode->i_mode = mode; 138 } 139 mark_inode_dirty(inode); 140 141 return 0; 142 } 143 EXPORT_SYMBOL(inode_setattr); 144 145 int notify_change(struct dentry * dentry, struct iattr * attr) 146 { 147 struct inode *inode = dentry->d_inode; 148 mode_t mode = inode->i_mode; 149 int error; 150 struct timespec now; 151 unsigned int ia_valid = attr->ia_valid; 152 153 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { 154 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 155 return -EPERM; 156 } 157 158 now = current_fs_time(inode->i_sb); 159 160 attr->ia_ctime = now; 161 if (!(ia_valid & ATTR_ATIME_SET)) 162 attr->ia_atime = now; 163 if (!(ia_valid & ATTR_MTIME_SET)) 164 attr->ia_mtime = now; 165 if (ia_valid & ATTR_KILL_PRIV) { 166 attr->ia_valid &= ~ATTR_KILL_PRIV; 167 ia_valid &= ~ATTR_KILL_PRIV; 168 error = security_inode_need_killpriv(dentry); 169 if (error > 0) 170 error = security_inode_killpriv(dentry); 171 if (error) 172 return error; 173 } 174 175 /* 176 * We now pass ATTR_KILL_S*ID to the lower level setattr function so 177 * that the function has the ability to reinterpret a mode change 178 * that's due to these bits. This adds an implicit restriction that 179 * no function will ever call notify_change with both ATTR_MODE and 180 * ATTR_KILL_S*ID set. 181 */ 182 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && 183 (ia_valid & ATTR_MODE)) 184 BUG(); 185 186 if (ia_valid & ATTR_KILL_SUID) { 187 if (mode & S_ISUID) { 188 ia_valid = attr->ia_valid |= ATTR_MODE; 189 attr->ia_mode = (inode->i_mode & ~S_ISUID); 190 } 191 } 192 if (ia_valid & ATTR_KILL_SGID) { 193 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 194 if (!(ia_valid & ATTR_MODE)) { 195 ia_valid = attr->ia_valid |= ATTR_MODE; 196 attr->ia_mode = inode->i_mode; 197 } 198 attr->ia_mode &= ~S_ISGID; 199 } 200 } 201 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) 202 return 0; 203 204 error = security_inode_setattr(dentry, attr); 205 if (error) 206 return error; 207 208 if (ia_valid & ATTR_SIZE) 209 down_write(&dentry->d_inode->i_alloc_sem); 210 211 if (inode->i_op && inode->i_op->setattr) { 212 error = inode->i_op->setattr(dentry, attr); 213 } else { 214 error = inode_change_ok(inode, attr); 215 if (!error) { 216 if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) || 217 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) 218 error = vfs_dq_transfer(inode, attr) ? 219 -EDQUOT : 0; 220 if (!error) 221 error = inode_setattr(inode, attr); 222 } 223 } 224 225 if (ia_valid & ATTR_SIZE) 226 up_write(&dentry->d_inode->i_alloc_sem); 227 228 if (!error) 229 fsnotify_change(dentry, ia_valid); 230 231 return error; 232 } 233 234 EXPORT_SYMBOL(notify_change); 235