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Subject[PATCH 2/3 v5] add a new template field buf to contain the buffer
Date
From: Prakhar Srivastava <prsriva02@gmail.com>

The buffer(cmdline args) added to the ima log cannot be attested
without having the actual buffer. Thus to make the measured buffer
available to stroe/read a new ima temaplate (buf) is added.
The cmdline args used for soft reboot can then be read and attested
later.

The patch adds a new template field buf to store/read the buffer
used while measuring kexec_cmdline args in the
[PATCH 1/2 v5]: "add a new ima hook and policy to measure the cmdline".
Signed-off-by: Prakhar Srivastava <prsriva02@gmail.com>
---
security/integrity/ima/ima_main.c | 23 +++++++++++++++++++++++
security/integrity/ima/ima_template.c | 2 ++
security/integrity/ima/ima_template_lib.c | 21 +++++++++++++++++++++
security/integrity/ima/ima_template_lib.h | 4 ++++
security/integrity/integrity.h | 1 +
5 files changed, 51 insertions(+)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 1d186bda25fe..ca12885ca241 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -605,10 +605,32 @@ static int process_buffer_measurement(const void *buf, int size,
int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
int action = 0;

+ struct buffer_xattr {
+ enum evm_ima_xattr_type type;
+ u16 buf_length;
+ unsigned char buf[0];
+ };
+ struct buffer_xattr *buffer_event_data = NULL;
+ int alloc_length = 0;
+
action = ima_get_action(NULL, cred, secid, 0, KEXEC_CMDLINE, &pcr);
if (!(action & IMA_AUDIT) && !(action & IMA_MEASURE))
goto out;

+ alloc_length = sizeof(struct buffer_xattr) + size;
+ buffer_event_data = kzalloc(alloc_length, GFP_KERNEL);
+ if (!buffer_event_data) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ buffer_event_data->type = IMA_XATTR_BUFFER;
+ buffer_event_data->buf_length = size;
+ memcpy(buffer_event_data->buf, buf, size);
+
+ event_data.xattr_value = (struct evm_ima_xattr_data *)buffer_event_data;
+ event_data.xattr_len = alloc_length;
+
memset(iint, 0, sizeof(*iint));
memset(&hash, 0, sizeof(hash));

@@ -638,6 +660,7 @@ static int process_buffer_measurement(const void *buf, int size,
}

out:
+ kfree(buffer_event_data);
return ret;
}

diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index b631b8bc7624..a76d1c04162a 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -43,6 +43,8 @@ static const struct ima_template_field supported_fields[] = {
.field_show = ima_show_template_string},
{.field_id = "sig", .field_init = ima_eventsig_init,
.field_show = ima_show_template_sig},
+ {.field_id = "buf", .field_init = ima_eventbuf_init,
+ .field_show = ima_show_template_buf},
};
#define MAX_TEMPLATE_NAME_LEN 15

diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index 513b457ae900..95a827f42c18 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -162,6 +162,11 @@ 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);
}

+void ima_show_template_buf(struct seq_file *m, enum ima_show_type show,
+ struct ima_field_data *field_data)
+{
+ 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.
@@ -389,3 +394,19 @@ int ima_eventsig_init(struct ima_event_data *event_data,
return ima_write_template_field_data(xattr_value, event_data->xattr_len,
DATA_FMT_HEX, field_data);
}
+
+/*
+ * ima_eventbuf_init - include the buffer(kexec-cmldine) as part of the
+ * template data.
+ */
+int ima_eventbuf_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data)
+{
+ struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
+
+ if ((!xattr_value) || (xattr_value->type != IMA_XATTR_BUFFER))
+ return 0;
+
+ return ima_write_template_field_data(xattr_value, event_data->xattr_len,
+ DATA_FMT_HEX, field_data);
+}
diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h
index 6a3d8b831deb..12f1a8578b31 100644
--- a/security/integrity/ima/ima_template_lib.h
+++ b/security/integrity/ima/ima_template_lib.h
@@ -29,6 +29,8 @@ 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);
+void ima_show_template_buf(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);
@@ -42,4 +44,6 @@ int ima_eventname_ng_init(struct ima_event_data *event_data,
struct ima_field_data *field_data);
int ima_eventsig_init(struct ima_event_data *event_data,
struct ima_field_data *field_data);
+int ima_eventbuf_init(struct ima_event_data *event_data,
+ struct ima_field_data *field_data);
#endif /* __LINUX_IMA_TEMPLATE_LIB_H */
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 7de59f44cba3..14ef904f091d 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -74,6 +74,7 @@ enum evm_ima_xattr_type {
EVM_IMA_XATTR_DIGSIG,
IMA_XATTR_DIGEST_NG,
EVM_XATTR_PORTABLE_DIGSIG,
+ IMA_XATTR_BUFFER,
IMA_XATTR_LAST
};

--
2.20.1
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