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Message-Id: <20190510223228.9966-2-prsriva02@gmail.com>
Date: Fri, 10 May 2019 15:32:26 -0700
From: Prakhar Srivastava <prsriva02@...il.com>
To: linux-integrity@...r.kernel.org,
inux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: zohar@...ux.ibm.com, ebiederm@...ssion.com, vgoyal@...hat.com,
prsriva@...rosoft.com, Prakhar Srivastava <prsriva02@...il.com>
Subject: [PATCH 1/3 v5] add a new ima hook and policy to measure the cmdline
From: Prakhar Srivastava <prsriva02@...il.com>
For this reason, this patch adds support for measuring these
parameters during kexec. To achive this, a new ima policy and
hook id, defined KEXEC_CMDLINE and ima_kexec_cmdline respectively,
are added.
Signed-off-by: Prakhar Srivastava <prsriva02@...il.com>
---
Documentation/ABI/testing/ima_policy | 1 +
include/linux/ima.h | 2 +
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_api.c | 1 +
security/integrity/ima/ima_main.c | 84 ++++++++++++++++++++++++++++
security/integrity/ima/ima_policy.c | 9 +++
6 files changed, 98 insertions(+)
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 74c6702de74e..62e7cd687e9c 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -29,6 +29,7 @@ Description:
base: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
[FIRMWARE_CHECK]
[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
+ [KEXEC_CMDLINE]
mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
[[^]MAY_EXEC]
fsmagic:= hex value
diff --git a/include/linux/ima.h b/include/linux/ima.h
index dc12fbcf484c..2e2c77280be8 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -26,6 +26,7 @@ extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
enum kernel_read_file_id id);
extern void ima_post_path_mknod(struct dentry *dentry);
+extern void ima_kexec_cmdline(const void *buf, int size);
#ifdef CONFIG_IMA_KEXEC
extern void ima_add_kexec_buffer(struct kimage *image);
@@ -92,6 +93,7 @@ static inline void ima_post_path_mknod(struct dentry *dentry)
return;
}
+static inline void ima_kexec_cmdline(const void *buf, int size) {}
#endif /* CONFIG_IMA */
#ifndef CONFIG_IMA_KEXEC
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index d213e835c498..226a26d8de09 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -184,6 +184,7 @@ static inline unsigned long ima_hash_key(u8 *digest)
hook(KEXEC_KERNEL_CHECK) \
hook(KEXEC_INITRAMFS_CHECK) \
hook(POLICY_CHECK) \
+ hook(KEXEC_CMDLINE) \
hook(MAX_CHECK)
#define __ima_hook_enumify(ENUM) ENUM,
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index c7505fb122d4..800d965232e5 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -169,6 +169,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
* subj=, obj=, type=, func=, mask=, fsmagic=
* subj,obj, and type: are LSM specific.
* func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK
+ * | KEXEC_CMDLINE
* mask: contains the permission mask
* fsmagic: hex value
*
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 357edd140c09..1d186bda25fe 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -576,6 +576,90 @@ int ima_load_data(enum kernel_load_data_id id)
return 0;
}
+/*
+ * process_buffer_measurement - Measure the buffer passed to ima log.
+ * (Instead of using the file hash use the buffer hash).
+ * @buf - The buffer that needs to be added to the log
+ * @size - size of buffer(in bytes)
+ * @eventname - event name to be used for buffer.
+ *
+ * The buffer passed is added to the ima log.
+ *
+ * On success return 0.
+ * On error cases surface errors from ima calls.
+ */
+static int process_buffer_measurement(const void *buf, int size,
+ const char *eventname, const struct cred *cred,
+ u32 secid)
+{
+ int ret = 0;
+ struct ima_template_entry *entry = NULL;
+ struct integrity_iint_cache tmp_iint, *iint = &tmp_iint;
+ struct ima_event_data event_data = {iint, NULL, NULL,
+ NULL, 0, NULL};
+ struct {
+ struct ima_digest_data hdr;
+ char digest[IMA_MAX_DIGEST_SIZE];
+ } hash;
+ int violation = 0;
+ int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
+ int action = 0;
+
+ action = ima_get_action(NULL, cred, secid, 0, KEXEC_CMDLINE, &pcr);
+ if (!(action & IMA_AUDIT) && !(action & IMA_MEASURE))
+ goto out;
+
+ memset(iint, 0, sizeof(*iint));
+ memset(&hash, 0, sizeof(hash));
+
+ event_data.filename = eventname;
+
+ iint->ima_hash = &hash.hdr;
+ iint->ima_hash->algo = ima_hash_algo;
+ iint->ima_hash->length = hash_digest_size[ima_hash_algo];
+
+ ret = ima_calc_buffer_hash(buf, size, iint->ima_hash);
+ if (ret < 0)
+ goto out;
+
+ ret = ima_alloc_init_template(&event_data, &entry);
+ if (ret < 0)
+ goto out;
+
+ if (action & IMA_MEASURE)
+ ret = ima_store_template(entry, violation, NULL, buf, pcr);
+
+ if (action & IMA_AUDIT)
+ ima_audit_measurement(iint, event_data.filename);
+
+ if (ret < 0) {
+ ima_free_template_entry(entry);
+ goto out;
+ }
+
+out:
+ return ret;
+}
+
+/**
+ * ima_kexec_cmdline - based on policy, store kexec cmdline args
+ * @buf: pointer to buffer
+ * @size: size of buffer
+ *
+ * Buffers can only be measured, not appraised.
+ */
+void ima_kexec_cmdline(const void *buf, int size)
+{
+ u32 secid;
+
+ if (buf && size != 0) {
+ security_task_getsecid(current, &secid);
+ process_buffer_measurement(buf, size, "kexec-cmdline",
+ current_cred(), secid);
+ }
+}
+
+
static int __init init_ima(void)
{
int error;
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index e0cc323f948f..413e5921b248 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -291,6 +291,13 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
{
int i;
+ /* only incase of KEXEC_CMDLINE, inode is NULL */
+ if (func == KEXEC_CMDLINE) {
+ if ((rule->flags & IMA_FUNC) &&
+ (rule->func == func) && (!inode))
+ return true;
+ return false;
+ }
if ((rule->flags & IMA_FUNC) &&
(rule->func != func && func != POST_SETATTR))
return false;
@@ -869,6 +876,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
entry->func = KEXEC_INITRAMFS_CHECK;
else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
entry->func = POLICY_CHECK;
+ else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
+ entry->func = KEXEC_CMDLINE;
else
result = -EINVAL;
if (!result)
--
2.20.1
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