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 will check filesystem limits and ulimits to check that the 71 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ 72 * when necessary. Caller must not proceed with inode size change if failure is 73 * returned. @inode must be a file (not directory), with appropriate 74 * permissions to allow truncate (inode_newsize_ok does NOT check these 75 * conditions). 76 * 77 * inode_newsize_ok must be called with i_mutex held. 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 int inode_setattr(struct inode * inode, struct iattr * attr) 108 { 109 unsigned int ia_valid = attr->ia_valid; 110 111 if (ia_valid & ATTR_SIZE && 112 attr->ia_size != i_size_read(inode)) { 113 int error = vmtruncate(inode, attr->ia_size); 114 if (error) 115 return error; 116 } 117 118 if (ia_valid & ATTR_UID) 119 inode->i_uid = attr->ia_uid; 120 if (ia_valid & ATTR_GID) 121 inode->i_gid = attr->ia_gid; 122 if (ia_valid & ATTR_ATIME) 123 inode->i_atime = timespec_trunc(attr->ia_atime, 124 inode->i_sb->s_time_gran); 125 if (ia_valid & ATTR_MTIME) 126 inode->i_mtime = timespec_trunc(attr->ia_mtime, 127 inode->i_sb->s_time_gran); 128 if (ia_valid & ATTR_CTIME) 129 inode->i_ctime = timespec_trunc(attr->ia_ctime, 130 inode->i_sb->s_time_gran); 131 if (ia_valid & ATTR_MODE) { 132 umode_t mode = attr->ia_mode; 133 134 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 135 mode &= ~S_ISGID; 136 inode->i_mode = mode; 137 } 138 mark_inode_dirty(inode); 139 140 return 0; 141 } 142 EXPORT_SYMBOL(inode_setattr); 143 144 int notify_change(struct dentry * dentry, struct iattr * attr) 145 { 146 struct inode *inode = dentry->d_inode; 147 mode_t mode = inode->i_mode; 148 int error; 149 struct timespec now; 150 unsigned int ia_valid = attr->ia_valid; 151 152 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { 153 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 154 return -EPERM; 155 } 156 157 now = current_fs_time(inode->i_sb); 158 159 attr->ia_ctime = now; 160 if (!(ia_valid & ATTR_ATIME_SET)) 161 attr->ia_atime = now; 162 if (!(ia_valid & ATTR_MTIME_SET)) 163 attr->ia_mtime = now; 164 if (ia_valid & ATTR_KILL_PRIV) { 165 attr->ia_valid &= ~ATTR_KILL_PRIV; 166 ia_valid &= ~ATTR_KILL_PRIV; 167 error = security_inode_need_killpriv(dentry); 168 if (error > 0) 169 error = security_inode_killpriv(dentry); 170 if (error) 171 return error; 172 } 173 174 /* 175 * We now pass ATTR_KILL_S*ID to the lower level setattr function so 176 * that the function has the ability to reinterpret a mode change 177 * that's due to these bits. This adds an implicit restriction that 178 * no function will ever call notify_change with both ATTR_MODE and 179 * ATTR_KILL_S*ID set. 180 */ 181 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && 182 (ia_valid & ATTR_MODE)) 183 BUG(); 184 185 if (ia_valid & ATTR_KILL_SUID) { 186 if (mode & S_ISUID) { 187 ia_valid = attr->ia_valid |= ATTR_MODE; 188 attr->ia_mode = (inode->i_mode & ~S_ISUID); 189 } 190 } 191 if (ia_valid & ATTR_KILL_SGID) { 192 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 193 if (!(ia_valid & ATTR_MODE)) { 194 ia_valid = attr->ia_valid |= ATTR_MODE; 195 attr->ia_mode = inode->i_mode; 196 } 197 attr->ia_mode &= ~S_ISGID; 198 } 199 } 200 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) 201 return 0; 202 203 error = security_inode_setattr(dentry, attr); 204 if (error) 205 return error; 206 207 if (ia_valid & ATTR_SIZE) 208 down_write(&dentry->d_inode->i_alloc_sem); 209 210 if (inode->i_op && inode->i_op->setattr) { 211 error = inode->i_op->setattr(dentry, attr); 212 } else { 213 error = inode_change_ok(inode, attr); 214 if (!error) 215 error = inode_setattr(inode, attr); 216 } 217 218 if (ia_valid & ATTR_SIZE) 219 up_write(&dentry->d_inode->i_alloc_sem); 220 221 if (!error) 222 fsnotify_change(dentry, ia_valid); 223 224 return error; 225 } 226 227 EXPORT_SYMBOL(notify_change); 228