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authorMimi Zohar <zohar@linux.vnet.ibm.com>2018-07-13 14:05:58 -0400
committerJames Morris <james.morris@microsoft.com>2018-07-16 15:31:57 -0400
commit16c267aac86b463b1fcccd43c89f4c8e5c5c86fa (patch)
tree550e6fcb00d732a3c018b3258302f8ffd61a4379
parenta210fd32a46bae6d05b43860fe3b47732501d63b (diff)
ima: based on policy require signed kexec kernel images
The original kexec_load syscall can not verify file signatures, nor can the kexec image be measured. Based on policy, deny the kexec_load syscall. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.morris@microsoft.com>
-rw-r--r--include/linux/ima.h7
-rw-r--r--security/integrity/ima/ima.h1
-rw-r--r--security/integrity/ima/ima_main.c27
-rw-r--r--security/integrity/ima/ima_policy.c2
-rw-r--r--security/security.c7
5 files changed, 43 insertions, 1 deletions
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 0e4647e0eb60..84806b54b50a 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -11,6 +11,7 @@
11#define _LINUX_IMA_H 11#define _LINUX_IMA_H
12 12
13#include <linux/fs.h> 13#include <linux/fs.h>
14#include <linux/security.h>
14#include <linux/kexec.h> 15#include <linux/kexec.h>
15struct linux_binprm; 16struct linux_binprm;
16 17
@@ -19,6 +20,7 @@ extern int ima_bprm_check(struct linux_binprm *bprm);
19extern int ima_file_check(struct file *file, int mask, int opened); 20extern int ima_file_check(struct file *file, int mask, int opened);
20extern void ima_file_free(struct file *file); 21extern void ima_file_free(struct file *file);
21extern int ima_file_mmap(struct file *file, unsigned long prot); 22extern int ima_file_mmap(struct file *file, unsigned long prot);
23extern int ima_load_data(enum kernel_load_data_id id);
22extern int ima_read_file(struct file *file, enum kernel_read_file_id id); 24extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
23extern int ima_post_read_file(struct file *file, void *buf, loff_t size, 25extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
24 enum kernel_read_file_id id); 26 enum kernel_read_file_id id);
@@ -49,6 +51,11 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot)
49 return 0; 51 return 0;
50} 52}
51 53
54static inline int ima_load_data(enum kernel_load_data_id id)
55{
56 return 0;
57}
58
52static inline int ima_read_file(struct file *file, enum kernel_read_file_id id) 59static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
53{ 60{
54 return 0; 61 return 0;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 354bb5716ce3..78c15264b17b 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -232,6 +232,7 @@ int ima_policy_show(struct seq_file *m, void *v);
232#define IMA_APPRAISE_MODULES 0x08 232#define IMA_APPRAISE_MODULES 0x08
233#define IMA_APPRAISE_FIRMWARE 0x10 233#define IMA_APPRAISE_FIRMWARE 0x10
234#define IMA_APPRAISE_POLICY 0x20 234#define IMA_APPRAISE_POLICY 0x20
235#define IMA_APPRAISE_KEXEC 0x40
235 236
236#ifdef CONFIG_IMA_APPRAISE 237#ifdef CONFIG_IMA_APPRAISE
237int ima_appraise_measurement(enum ima_hooks func, 238int ima_appraise_measurement(enum ima_hooks func,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index dca44cf7838e..71fecfef0939 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -496,6 +496,33 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
496 MAY_READ, func, 0); 496 MAY_READ, func, 0);
497} 497}
498 498
499/**
500 * ima_load_data - appraise decision based on policy
501 * @id: kernel load data caller identifier
502 *
503 * Callers of this LSM hook can not measure, appraise, or audit the
504 * data provided by userspace. Enforce policy rules requring a file
505 * signature (eg. kexec'ed kernel image).
506 *
507 * For permission return 0, otherwise return -EACCES.
508 */
509int ima_load_data(enum kernel_load_data_id id)
510{
511 if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
512 return 0;
513
514 switch (id) {
515 case LOADING_KEXEC_IMAGE:
516 if (ima_appraise & IMA_APPRAISE_KEXEC) {
517 pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
518 return -EACCES; /* INTEGRITY_UNKNOWN */
519 }
520 default:
521 break;
522 }
523 return 0;
524}
525
499static int __init init_ima(void) 526static int __init init_ima(void)
500{ 527{
501 int error; 528 int error;
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index cdcc9a7b4e24..d5b4958decc5 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -448,6 +448,8 @@ static int ima_appraise_flag(enum ima_hooks func)
448 return IMA_APPRAISE_FIRMWARE; 448 return IMA_APPRAISE_FIRMWARE;
449 else if (func == POLICY_CHECK) 449 else if (func == POLICY_CHECK)
450 return IMA_APPRAISE_POLICY; 450 return IMA_APPRAISE_POLICY;
451 else if (func == KEXEC_KERNEL_CHECK)
452 return IMA_APPRAISE_KEXEC;
451 return 0; 453 return 0;
452} 454}
453 455
diff --git a/security/security.c b/security/security.c
index c2de2f134854..4927e7cc7d96 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1058,7 +1058,12 @@ EXPORT_SYMBOL_GPL(security_kernel_post_read_file);
1058 1058
1059int security_kernel_load_data(enum kernel_load_data_id id) 1059int security_kernel_load_data(enum kernel_load_data_id id)
1060{ 1060{
1061 return call_int_hook(kernel_load_data, 0, id); 1061 int ret;
1062
1063 ret = call_int_hook(kernel_load_data, 0, id);
1064 if (ret)
1065 return ret;
1066 return ima_load_data(id);
1062} 1067}
1063 1068
1064int security_task_fix_setuid(struct cred *new, const struct cred *old, 1069int security_task_fix_setuid(struct cred *new, const struct cred *old,