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* [PATCHv2] added ima hook for buffer, being enabled as a policy
@ 2019-04-20  0:00 Prakhar Srivastava
  2019-04-20  0:00 ` [PATCHv2] use event name instead of enum to make the call generic Prakhar Srivastava
  2019-04-20  0:00 ` [PATCHv2] since cmdline args can be same for multiple kexec, log entry hash will collide. Prepend the kernel file name to the cmdline args to distinguish between cmdline args passed to subsequent kexec calls Prakhar Srivastava
  0 siblings, 2 replies; 3+ messages in thread
From: Prakhar Srivastava @ 2019-04-20  0:00 UTC (permalink / raw)
  To: linux-security-module, linux-kernel
  Cc: zohar, Prakhar Srivastava, Prakhar Srivastava

From: Prakhar Srivastava <prsriva02@gmail.com>

Signed-off-by: Prakhar Srivastava <prsriva@microsoft.com>
---

This adds a new ima hook ima_buffer_check and a policy entry BUFFER_CHECK.
This enables buffer has measurements into ima log

 Documentation/ABI/testing/ima_policy |  1 +
 include/linux/ima.h                  | 13 +++-
 security/integrity/ima/ima.h         |  1 +
 security/integrity/ima/ima_main.c    | 95 ++++++++++++++++++++++++++++
 security/integrity/ima/ima_policy.c  | 14 +++-
 5 files changed, 122 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index bb0f9a135e21..676088c7ab26 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -28,6 +28,7 @@ Description:
 		base: 	func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
 				[FIRMWARE_CHECK]
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
+				[BUFFER_CHECK]
 			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 7f6952f8d6aa..733d0cb9dedc 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -14,6 +14,12 @@
 #include <linux/kexec.h>
 struct linux_binprm;
 
+enum __buffer_id {
+	KERNEL_VERSION,
+	KEXEC_CMDLINE,
+	MAX_BUFFER_ID = KEXEC_CMDLINE
+} buffer_id;
+
 #ifdef CONFIG_IMA
 extern int ima_bprm_check(struct linux_binprm *bprm);
 extern int ima_file_check(struct file *file, int mask, int opened);
@@ -23,7 +29,7 @@ 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_buffer_check(const void *buff, int size, enum buffer_id id);
 #ifdef CONFIG_IMA_KEXEC
 extern void ima_add_kexec_buffer(struct kimage *image);
 #endif
@@ -65,6 +71,11 @@ static inline void ima_post_path_mknod(struct dentry *dentry)
 	return;
 }
 
+static inline void ima_buffer_check(const void *buff, int size,
+			enum buffer_id id)
+{
+	return;
+}
 #endif /* CONFIG_IMA */
 
 #ifndef CONFIG_IMA_KEXEC
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b563fbd4d122..b71f2f6f7421 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -181,6 +181,7 @@ enum ima_hooks {
 	FIRMWARE_CHECK,
 	KEXEC_KERNEL_CHECK,
 	KEXEC_INITRAMFS_CHECK,
+	BUFFER_CHECK,
 	POLICY_CHECK,
 	MAX_CHECK
 };
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 2aebb7984437..6408cadaadbb 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -155,6 +155,84 @@ void ima_file_free(struct file *file)
 	ima_check_last_writer(iint, inode, file);
 }
 
+/*
+ * process_buffer_measurement - Measure the buffer passed to ima log.
+ * (Instead of using the file hash the buffer hash is used).
+ * @buff - The buffer that needs to be added to the log
+ * @size - size of buffer(in bytes)
+ * @id - buffer id, this is differentiator for the various buffers
+ * that can be measured.
+ *
+ * The buffer passed is added to the ima logs.
+ * If the sig template is used, then the sig field contains the buffer.
+ *
+ * On success return 0.
+ * On error cases surface errors from ima calls.
+ */
+static int process_buffer_measurement(const void *buff, int size,
+				enum buffer_id id)
+{
+	int ret = -EINVAL;
+	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;
+	char *name = NULL;
+	int violation = 0;
+	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
+
+	if (!buff || size ==  0)
+		goto err_out;
+
+	if (ima_get_action(NULL, 0, BUFFER_CHECK, &pcr) != IMA_MEASURE)
+		goto err_out;
+
+	switch (buffer_id) {
+	case KERNEL_VERSION:
+		name = "Kernel-version";
+		break;
+	case KEXEC_CMDLINE:
+		name = "Kexec-cmdline";
+		break;
+	default:
+		goto err_out;
+	}
+
+	memset(iint, 0, sizeof(*iint));
+	memset(&hash, 0, sizeof(hash));
+
+	event_data.filename = name;
+
+	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(buff, size, iint->ima_hash);
+	if (ret < 0)
+		goto err_out;
+
+	ret = ima_alloc_init_template(&event_data, &entry);
+	if (ret < 0)
+		goto err_out;
+
+	ret = ima_store_template(entry, violation, NULL,
+					buff, pcr);
+	if (ret < 0) {
+		ima_free_template_entry(entry);
+		goto err_out;
+	}
+
+	return 0;
+
+err_out:
+	pr_err("Error in adding buffer measure: %d\n", ret);
+	return ret;
+}
+
 static int process_measurement(struct file *file, char *buf, loff_t size,
 			       int mask, enum ima_hooks func, int opened)
 {
@@ -370,6 +448,23 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 	return 0;
 }
 
+/**
+ * ima_buffer_check - based on policy, collect & store buffer measurement
+ * @buf: pointer to buffer
+ * @size: size of buffer
+ * @buffer_id: caller identifier
+ *
+ * Buffers can only be measured, not appraised.  The buffer identifier
+ * is used as the measurement list entry name (eg. boot_cmdline).
+ */
+void ima_buffer_check(const void *buf, int size, enum buffer_id id)
+{
+	if (buf && size != 0)
+		process_buffer_measurement(buf, size, id);
+
+	return;
+}
+
 static int read_idmap[READING_MAX_ID] = {
 	[READING_FIRMWARE] = FIRMWARE_CHECK,
 	[READING_MODULE] = MODULE_CHECK,
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 3ab1067db624..cefe1a188f31 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -231,6 +231,12 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 	const struct cred *cred = current_cred();
 	int i;
 
+	// Incase of BUFFER_CHECK, Inode is NULL
+	if (!inode) {
+		if ((rule->flags & IMA_FUNC) && (rule->func == func))
+			return true;
+		return false;
+	}
 	if ((rule->flags & IMA_FUNC) &&
 	    (rule->func != func && func != POST_SETATTR))
 		return false;
@@ -665,6 +671,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
 				 == 0)
 				entry->func = KEXEC_INITRAMFS_CHECK;
+			else if (strcmp(args[0].from, "BUFFER_CHECK") == 0)
+				entry->func = BUFFER_CHECK;
 			else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
 				entry->func = POLICY_CHECK;
 			else
@@ -944,7 +952,7 @@ enum {
 	func_file = 0, func_mmap, func_bprm,
 	func_module, func_firmware, func_post,
 	func_kexec_kernel, func_kexec_initramfs,
-	func_policy
+	func_buffer, func_policy
 };
 
 static char *func_tokens[] = {
@@ -956,6 +964,7 @@ static char *func_tokens[] = {
 	"POST_SETATTR",
 	"KEXEC_KERNEL_CHECK",
 	"KEXEC_INITRAMFS_CHECK",
+	"BUFFER_CHECK",
 	"POLICY_CHECK"
 };
 
@@ -1027,6 +1036,9 @@ static void policy_func_show(struct seq_file *m, enum ima_hooks func)
 	case KEXEC_INITRAMFS_CHECK:
 		seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
 		break;
+	case BUFFER_CHECK:
+		seq_printf(m, pt(Opt_func), ft(func_buffer));
+		break;
 	case POLICY_CHECK:
 		seq_printf(m, pt(Opt_func), ft(func_policy));
 		break;
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* [PATCHv2] use event name instead of enum to make the call generic
  2019-04-20  0:00 [PATCHv2] added ima hook for buffer, being enabled as a policy Prakhar Srivastava
@ 2019-04-20  0:00 ` Prakhar Srivastava
  2019-04-20  0:00 ` [PATCHv2] since cmdline args can be same for multiple kexec, log entry hash will collide. Prepend the kernel file name to the cmdline args to distinguish between cmdline args passed to subsequent kexec calls Prakhar Srivastava
  1 sibling, 0 replies; 3+ messages in thread
From: Prakhar Srivastava @ 2019-04-20  0:00 UTC (permalink / raw)
  To: linux-security-module, linux-kernel
  Cc: zohar, Prakhar Srivastava, Prakhar Srivastava

From: Prakhar Srivastava <prsriva02@gmail.com>

Signed-off-by: Prakhar Srivastava <prsriva@microsoft.com>
---

remove enaums to control type of buffers entries, instead pass the event name to be used.

 include/linux/ima.h               | 10 ++--------
 kernel/kexec_file.c               |  3 +++
 security/integrity/ima/ima.h      |  2 +-
 security/integrity/ima/ima_main.c | 30 ++++++++++--------------------
 4 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 733d0cb9dedc..5e41507c57e5 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -14,12 +14,6 @@
 #include <linux/kexec.h>
 struct linux_binprm;
 
-enum __buffer_id {
-	KERNEL_VERSION,
-	KEXEC_CMDLINE,
-	MAX_BUFFER_ID = KEXEC_CMDLINE
-} buffer_id;
-
 #ifdef CONFIG_IMA
 extern int ima_bprm_check(struct linux_binprm *bprm);
 extern int ima_file_check(struct file *file, int mask, int opened);
@@ -29,7 +23,7 @@ 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_buffer_check(const void *buff, int size, enum buffer_id id);
+extern void ima_buffer_check(const void *buff, int size, char *eventname);
 #ifdef CONFIG_IMA_KEXEC
 extern void ima_add_kexec_buffer(struct kimage *image);
 #endif
@@ -72,7 +66,7 @@ static inline void ima_post_path_mknod(struct dentry *dentry)
 }
 
 static inline void ima_buffer_check(const void *buff, int size,
-			enum buffer_id id)
+			char *eventname)
 {
 	return;
 }
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b118735fea9d..2a5234eb4b28 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -182,6 +182,9 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 			ret = -EINVAL;
 			goto out;
 		}
+
+		ima_buffer_check(image->cmdline_buf, cmdline_len - 1,
+				"kexec_cmdline");
 	}
 
 	/* Call arch image load handlers */
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b71f2f6f7421..fcade3c103ed 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -181,8 +181,8 @@ enum ima_hooks {
 	FIRMWARE_CHECK,
 	KEXEC_KERNEL_CHECK,
 	KEXEC_INITRAMFS_CHECK,
-	BUFFER_CHECK,
 	POLICY_CHECK,
+	BUFFER_CHECK,
 	MAX_CHECK
 };
 
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 6408cadaadbb..da82c705a5ed 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -160,8 +160,7 @@ void ima_file_free(struct file *file)
  * (Instead of using the file hash the buffer hash is used).
  * @buff - The buffer that needs to be added to the log
  * @size - size of buffer(in bytes)
- * @id - buffer id, this is differentiator for the various buffers
- * that can be measured.
+ * @id - eventname, event name to be used for buffer measurement.
  *
  * The buffer passed is added to the ima logs.
  * If the sig template is used, then the sig field contains the buffer.
@@ -170,7 +169,7 @@ void ima_file_free(struct file *file)
  * On error cases surface errors from ima calls.
  */
 static int process_buffer_measurement(const void *buff, int size,
-				enum buffer_id id)
+				char *eventname)
 {
 	int ret = -EINVAL;
 	struct ima_template_entry *entry = NULL;
@@ -185,23 +184,13 @@ static int process_buffer_measurement(const void *buff, int size,
 	int violation = 0;
 	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 
-	if (!buff || size ==  0)
+	if (!buff || size ==  0 || !eventname)
 		goto err_out;
 
 	if (ima_get_action(NULL, 0, BUFFER_CHECK, &pcr) != IMA_MEASURE)
 		goto err_out;
 
-	switch (buffer_id) {
-	case KERNEL_VERSION:
-		name = "Kernel-version";
-		break;
-	case KEXEC_CMDLINE:
-		name = "Kexec-cmdline";
-		break;
-	default:
-		goto err_out;
-	}
-
+	name = eventname;
 	memset(iint, 0, sizeof(*iint));
 	memset(&hash, 0, sizeof(hash));
 
@@ -452,15 +441,16 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
  * ima_buffer_check - based on policy, collect & store buffer measurement
  * @buf: pointer to buffer
  * @size: size of buffer
- * @buffer_id: caller identifier
+ * @eventname: caller identifier
  *
  * Buffers can only be measured, not appraised.  The buffer identifier
- * is used as the measurement list entry name (eg. boot_cmdline).
+ * is used as the measurement list entry name (eg. boot_cmdline,
+ * kernel_version).
  */
-void ima_buffer_check(const void *buf, int size, enum buffer_id id)
+void ima_buffer_check(const void *buf, int size, char *eventname)
 {
-	if (buf && size != 0)
-		process_buffer_measurement(buf, size, id);
+	if (buf && size != 0 && eventname)
+		process_buffer_measurement(buf, size, eventname);
 
 	return;
 }
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* [PATCHv2] since cmdline args can be same for multiple kexec, log entry hash will collide. Prepend the kernel file name to the cmdline args to distinguish between cmdline args passed to subsequent kexec calls
  2019-04-20  0:00 [PATCHv2] added ima hook for buffer, being enabled as a policy Prakhar Srivastava
  2019-04-20  0:00 ` [PATCHv2] use event name instead of enum to make the call generic Prakhar Srivastava
@ 2019-04-20  0:00 ` Prakhar Srivastava
  1 sibling, 0 replies; 3+ messages in thread
From: Prakhar Srivastava @ 2019-04-20  0:00 UTC (permalink / raw)
  To: linux-security-module, linux-kernel
  Cc: zohar, Prakhar Srivastava, Prakhar Srivastava

From: Prakhar Srivastava <prsriva02@gmail.com>

Signed-off-by: Prakhar Srivastava <prsriva@microsoft.com>
---
since cmdline args can be same for multiple kexec, log entry
hash will collide. Prepend the kernel file name to the cmdline args to
distinguish between cmdline args passed to subsequent kexec calls

 kernel/kexec_core.c     | 57 +++++++++++++++++++++++++++++++++++++++++
 kernel/kexec_file.c     | 14 ++++++++--
 kernel/kexec_internal.h |  3 +++
 3 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index ae1a3ba24df5..97b77c780311 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1151,3 +1151,60 @@ void __weak arch_kexec_protect_crashkres(void)
 
 void __weak arch_kexec_unprotect_crashkres(void)
 {}
+
+/**
+ * kexec_cmdline_prepend_img_name - prepare the buffer with cmdline
+ * that needs to be measured
+ * @outbuf - out buffer that contains the formated string
+ * @kernel_fd - the file identifier for the kerenel image
+ * @cmdline_ptr - ptr to the cmdline buffer
+ * @cmdline_len - len of the buffer.
+ *
+ * This generates a buffer in the format Kerenelfilename::cmdline
+ *
+ * On success return 0.
+ * On failure return -EINVAL.
+ */
+int kexec_cmdline_prepend_img_name(char **outbuf, int kernel_fd,
+				const char *cmdline_ptr,
+				unsigned long cmdline_len)
+{
+	int ret = -EINVAL;
+	struct fd f = {};
+	int size = 0;
+	char *buf = NULL;
+	char delimiter[] = "::";
+
+	if (!outbuf || !cmdline_ptr)
+		goto out;
+
+	f = fdget(kernel_fd);
+	if (!f.file)
+		goto out;
+
+	size = (f.file->f_path.dentry->d_name.len + cmdline_len - 1+
+			ARRAY_SIZE(delimiter)) - 1;
+
+	buf = kzalloc(size, GFP_KERNEL);
+	if (!buf)
+		goto out;
+
+	memcpy(buf, f.file->f_path.dentry->d_name.name,
+		f.file->f_path.dentry->d_name.len);
+	memcpy(buf + f.file->f_path.dentry->d_name.len,
+		delimiter, ARRAY_SIZE(delimiter) - 1);
+	memcpy(buf + f.file->f_path.dentry->d_name.len +
+		ARRAY_SIZE(delimiter) - 1,
+		cmdline_ptr, cmdline_len - 1);
+
+	*outbuf = buf;
+	ret = size;
+
+	pr_debug("kexec cmdline buff: %s\n", buf);
+
+out:
+	if (f.file)
+		fdput(f);
+
+	return ret;
+}
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 2a5234eb4b28..a487491d55b9 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -126,6 +126,8 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 	int ret = 0;
 	void *ldata;
 	loff_t size;
+	char *buff_to_measure = NULL;
+	int buff_to_measure_size = 0;
 
 	ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
 				       &size, INT_MAX, READING_KEXEC_IMAGE);
@@ -183,8 +185,13 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 			goto out;
 		}
 
-		ima_buffer_check(image->cmdline_buf, cmdline_len - 1,
-				"kexec_cmdline");
+		/* IMA measures the cmdline args passed to the next kernel*/
+		buff_to_measure_size = kexec_cmdline_prepend_img_name(&buff_to_measure,
+			kernel_fd, image->cmdline_buf, image->cmdline_buf_len);
+
+		ima_buffer_check(buff_to_measure, buff_to_measure_size,
+					"kexec_cmdline");
+
 	}
 
 	/* Call arch image load handlers */
@@ -200,6 +207,9 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 	/* In case of error, free up all allocated memory in this function */
 	if (ret)
 		kimage_file_post_load_cleanup(image);
+
+	kfree(buff_to_measure);
+
 	return ret;
 }
 
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 799a8a452187..4d34a8ef4637 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -11,6 +11,9 @@ int kimage_load_segment(struct kimage *image, struct kexec_segment *segment);
 void kimage_terminate(struct kimage *image);
 int kimage_is_destination_range(struct kimage *image,
 				unsigned long start, unsigned long end);
+int kexec_cmdline_prepend_img_name(char **outbuf, int kernel_fd,
+				const char *cmdline_ptr,
+				unsigned long cmdline_len);
 
 extern struct mutex kexec_mutex;
 
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2019-04-20  0:01 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-04-20  0:00 [PATCHv2] added ima hook for buffer, being enabled as a policy Prakhar Srivastava
2019-04-20  0:00 ` [PATCHv2] use event name instead of enum to make the call generic Prakhar Srivastava
2019-04-20  0:00 ` [PATCHv2] since cmdline args can be same for multiple kexec, log entry hash will collide. Prepend the kernel file name to the cmdline args to distinguish between cmdline args passed to subsequent kexec calls Prakhar Srivastava

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