* would have been wasted for padding to the nearest minimal I/O unit boundary.
* Instead, data first goes to the write-buffer and is flushed when the
* buffer is full or when it is not used for some time (by timer). This is
- * similarto the mechanism is used by JFFS2.
+ * similar to the mechanism is used by JFFS2.
*
* Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
* mutexes defined inside these objects. Since sometimes upper-level code
#include "ubifs.h"
/**
+ * ubifs_ro_mode - switch UBIFS to read read-only mode.
+ * @c: UBIFS file-system description object
+ * @err: error code which is the reason of switching to R/O mode
+ */
+void ubifs_ro_mode(struct ubifs_info *c, int err)
+{
+ if (!c->ro_media) {
+ c->ro_media = 1;
+ c->no_chk_data_crc = 0;
+ ubifs_warn("switched to read-only mode, error %d", err);
+ dbg_dump_stack();
+ }
+}
+
+/**
* ubifs_check_node - check node.
* @c: UBIFS file-system description object
* @buf: node to check
* @lnum: logical eraseblock number
* @offs: offset within the logical eraseblock
* @quiet: print no messages
+ * @must_chk_crc: indicates whether to always check the CRC
*
* This function checks node magic number and CRC checksum. This function also
* validates node length to prevent UBIFS from becoming crazy when an attacker
* node length in the common header could cause UBIFS to read memory outside of
* allocated buffer when checking the CRC checksum.
*
- * This function returns zero in case of success %-EUCLEAN in case of bad CRC
- * or magic.
+ * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
+ * true, which is controlled by corresponding UBIFS mount option. However, if
+ * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
+ * checked. Similarly, if @c->always_chk_crc is true, @c->no_chk_data_crc is
+ * ignored and CRC is checked.
+ *
+ * This function returns zero in case of success and %-EUCLEAN in case of bad
+ * CRC or magic.
*/
int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
- int offs, int quiet)
+ int offs, int quiet, int must_chk_crc)
{
int err = -EINVAL, type, node_len;
uint32_t crc, node_crc, magic;
node_len > c->ranges[type].max_len)
goto out_len;
+ if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->always_chk_crc &&
+ c->no_chk_data_crc)
+ return 0;
+
crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
node_crc = le32_to_cpu(ch->crc);
if (crc != node_crc) {
goto out;
}
- err = ubifs_check_node(c, buf, lnum, offs, 0);
+ err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
if (err) {
ubifs_err("expected node type %d", type);
return err;
goto out;
}
- err = ubifs_check_node(c, buf, lnum, offs, 0);
+ err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
if (err) {
ubifs_err("expected node type %d", type);
return err;