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authorRoberto Sassu <roberto.sassu@huawei.com>2017-05-16 14:53:41 +0200
committerMimi Zohar <zohar@linux.vnet.ibm.com>2017-06-21 14:37:12 -0400
commitb17fd9ecf854e8f695e911d3ff9e1fe33bb1c76c (patch)
tree5c71fb519515435bd8753edb0f329c2a688c3f55 /security/integrity
parent82e3bb4d44be21daefe8af857a68d3c9118c1048 (diff)
ima: introduce ima_parse_buf()
ima_parse_buf() takes as input the buffer start and end pointers, and stores the result in a static array of ima_field_data structures, where the len field contains the length parsed from the buffer, and the data field contains the address of the buffer just after the length. Optionally, the function returns the current value of the buffer pointer and the number of array elements written. A bitmap has been added as parameter of ima_parse_buf() to handle the cases where the length is not prepended to data. Each bit corresponds to an element of the ima_field_data array. If a bit is set, the length is not parsed from the buffer, but is read from the corresponding element of the array (the length must be set before calling the function). ima_parse_buf() can perform three checks upon request by callers, depending on the enforce mask passed to it: - ENFORCE_FIELDS: matching of number of fields (length-data combination) - there must be enough data in the buffer to parse the number of fields requested (output: current value of buffer pointer) - ENFORCE_BUFEND: matching of buffer end - the ima_field_data array must be large enough to contain lengths and data pointers for the amount of data requested (output: number of fields written) - ENFORCE_FIELDS | ENFORCE_BUFEND: matching of both Use cases - measurement entry header: ENFORCE_FIELDS | ENFORCE_BUFEND - four fields must be parsed: pcr, digest, template name, template data - ENFORCE_BUFEND is enforced only for the last measurement entry - template digest (Crypto Agile): ENFORCE_BUFEND - since only the total template digest length is known, the function parses length-data combinations until the buffer end is reached - template data: ENFORCE_FIELDS | ENFORCE_BUFEND - since the number of fields and the total template data length are known, the function can perform both checks Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Diffstat (limited to 'security/integrity')
-rw-r--r--security/integrity/ima/ima_template_lib.c61
-rw-r--r--security/integrity/ima/ima_template_lib.h6
2 files changed, 67 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index f9ba37b3928d..28af43f63572 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -159,6 +159,67 @@ void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
}
+/**
+ * ima_parse_buf() - Parses lengths and data from an input buffer
+ * @bufstartp: Buffer start address.
+ * @bufendp: Buffer end address.
+ * @bufcurp: Pointer to remaining (non-parsed) data.
+ * @maxfields: Length of fields array.
+ * @fields: Array containing lengths and pointers of parsed data.
+ * @curfields: Number of array items containing parsed data.
+ * @len_mask: Bitmap (if bit is set, data length should not be parsed).
+ * @enforce_mask: Check if curfields == maxfields and/or bufcurp == bufendp.
+ * @bufname: String identifier of the input buffer.
+ *
+ * Return: 0 on success, -EINVAL on error.
+ */
+int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
+ int maxfields, struct ima_field_data *fields, int *curfields,
+ unsigned long *len_mask, int enforce_mask, char *bufname)
+{
+ void *bufp = bufstartp;
+ int i;
+
+ for (i = 0; i < maxfields; i++) {
+ if (len_mask == NULL || !test_bit(i, len_mask)) {
+ if (bufp > (bufendp - sizeof(u32)))
+ break;
+
+ fields[i].len = *(u32 *)bufp;
+ if (ima_canonical_fmt)
+ fields[i].len = le32_to_cpu(fields[i].len);
+
+ bufp += sizeof(u32);
+ }
+
+ if (bufp > (bufendp - fields[i].len))
+ break;
+
+ fields[i].data = bufp;
+ bufp += fields[i].len;
+ }
+
+ if ((enforce_mask & ENFORCE_FIELDS) && i != maxfields) {
+ pr_err("%s: nr of fields mismatch: expected: %d, current: %d\n",
+ bufname, maxfields, i);
+ return -EINVAL;
+ }
+
+ if ((enforce_mask & ENFORCE_BUFEND) && bufp != bufendp) {
+ pr_err("%s: buf end mismatch: expected: %p, current: %p\n",
+ bufname, bufendp, bufp);
+ return -EINVAL;
+ }
+
+ if (curfields)
+ *curfields = i;
+
+ if (bufcurp)
+ *bufcurp = bufp;
+
+ return 0;
+}
+
static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
struct ima_field_data *field_data)
{
diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h
index c344530c1d69..6a3d8b831deb 100644
--- a/security/integrity/ima/ima_template_lib.h
+++ b/security/integrity/ima/ima_template_lib.h
@@ -18,6 +18,9 @@
#include <linux/seq_file.h>
#include "ima.h"
+#define ENFORCE_FIELDS 0x00000001
+#define ENFORCE_BUFEND 0x00000002
+
void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
struct ima_field_data *field_data);
void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
@@ -26,6 +29,9 @@ void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
struct ima_field_data *field_data);
void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
struct ima_field_data *field_data);
+int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
+ int maxfields, struct ima_field_data *fields, int *curfields,
+ unsigned long *len_mask, int enforce_mask, char *bufname);
int ima_eventdigest_init(struct ima_event_data *event_data,
struct ima_field_data *field_data);
int ima_eventname_init(struct ima_event_data *event_data,