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authorPetko Manolov <petkan@mip-labs.com>2015-12-02 17:47:56 +0200
committerOleksandr Suvorov <oleksandr.suvorov@toradex.com>2020-05-25 13:57:21 +0300
commit11485a13d38000c64471bdf6338536be52b761f9 (patch)
tree19f8e7d5f5bdae494368a6b1eeafe8d5b2e8d62f
parent72d6cdc59c00405719b62eb3dedf0def2b6e028e (diff)
IMA: allow reading back the current IMA policy
commit 80eae209d63ac6361c7b445f7e7e41f39c044772 upstream It is often useful to be able to read back the IMA policy. It is even more important after introducing CONFIG_IMA_WRITE_POLICY. This option allows the root user to see the current policy rules. Signed-off-by: Zbigniew Jasinski <z.jasinski@samsung.com> Signed-off-by: Petko Manolov <petkan@mip-labs.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
-rw-r--r--security/integrity/ima/Kconfig10
-rw-r--r--security/integrity/ima/ima.h15
-rw-r--r--security/integrity/ima/ima_fs.c29
-rw-r--r--security/integrity/ima/ima_policy.c207
4 files changed, 253 insertions, 8 deletions
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index b13068d54343..1d4dbae64f8c 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -119,6 +119,16 @@ config IMA_WRITE_POLICY
If unsure, say N.
+config IMA_READ_POLICY
+ bool "Enable reading back the current IMA policy"
+ depends on IMA
+ default y if IMA_WRITE_POLICY
+ default n if !IMA_WRITE_POLICY
+ help
+ It is often useful to be able to read back the IMA policy. It is
+ even more important after introducing CONFIG_IMA_WRITE_POLICY.
+ This option allows the root user to see the current policy rules.
+
config IMA_APPRAISE
bool "Appraise integrity measurements"
depends on IMA
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 9e82367f5190..917407fb7e94 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -166,6 +166,10 @@ void ima_update_policy(void);
void ima_update_policy_flag(void);
ssize_t ima_parse_add_rule(char *);
void ima_delete_rules(void);
+void *ima_policy_start(struct seq_file *m, loff_t *pos);
+void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos);
+void ima_policy_stop(struct seq_file *m, void *v);
+int ima_policy_show(struct seq_file *m, void *v);
/* Appraise integrity measurements */
#define IMA_APPRAISE_ENFORCE 0x01
@@ -250,5 +254,12 @@ static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
{
return -EINVAL;
}
-#endif /* CONFIG_IMA_LSM_RULES */
-#endif
+#endif /* CONFIG_IMA_TRUSTED_KEYRING */
+
+#ifdef CONFIG_IMA_READ_POLICY
+#define POLICY_FILE_FLAGS (S_IWUSR | S_IRUSR)
+#else
+#define POLICY_FILE_FLAGS S_IWUSR
+#endif /* CONFIG_IMA_WRITE_POLICY */
+
+#endif /* __LINUX_IMA_H */
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 777867d42d27..6816ef259e7e 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -311,14 +311,31 @@ enum ima_fs_flags {
static unsigned long ima_fs_flags;
+#ifdef CONFIG_IMA_READ_POLICY
+static const struct seq_operations ima_policy_seqops = {
+ .start = ima_policy_start,
+ .next = ima_policy_next,
+ .stop = ima_policy_stop,
+ .show = ima_policy_show,
+};
+#endif
+
/*
* ima_open_policy: sequentialize access to the policy file
*/
static int ima_open_policy(struct inode *inode, struct file *filp)
{
- /* No point in being allowed to open it if you aren't going to write */
- if (!(filp->f_flags & O_WRONLY))
+ if (!(filp->f_flags & O_WRONLY)) {
+#ifndef CONFIG_IMA_READ_POLICY
return -EACCES;
+#else
+ if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
+ return -EACCES;
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return seq_open(filp, &ima_policy_seqops);
+#endif
+ }
if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
return -EBUSY;
return 0;
@@ -335,6 +352,9 @@ static int ima_release_policy(struct inode *inode, struct file *file)
{
const char *cause = valid_policy ? "completed" : "failed";
+ if ((file->f_flags & O_ACCMODE) == O_RDONLY)
+ return 0;
+
pr_info("IMA: policy update %s\n", cause);
integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
"policy_update", cause, !valid_policy, 0);
@@ -345,6 +365,7 @@ static int ima_release_policy(struct inode *inode, struct file *file)
clear_bit(IMA_FS_BUSY, &ima_fs_flags);
return 0;
}
+
ima_update_policy();
#ifndef CONFIG_IMA_WRITE_POLICY
securityfs_remove(ima_policy);
@@ -358,6 +379,7 @@ static int ima_release_policy(struct inode *inode, struct file *file)
static const struct file_operations ima_measure_policy_ops = {
.open = ima_open_policy,
.write = ima_write_policy,
+ .read = seq_read,
.release = ima_release_policy,
.llseek = generic_file_llseek,
};
@@ -395,8 +417,7 @@ int __init ima_fs_init(void)
if (IS_ERR(violations))
goto out;
- ima_policy = securityfs_create_file("policy",
- S_IWUSR,
+ ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS,
ima_dir, NULL,
&ima_measure_policy_ops);
if (IS_ERR(ima_policy))
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 10a0a9b9e22d..2f4e0f5f31e2 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -18,6 +18,7 @@
#include <linux/slab.h>
#include <linux/rculist.h>
#include <linux/genhd.h>
+#include <linux/seq_file.h>
#include "ima.h"
@@ -458,8 +459,8 @@ enum {
Opt_obj_user, Opt_obj_role, Opt_obj_type,
Opt_subj_user, Opt_subj_role, Opt_subj_type,
Opt_func, Opt_mask, Opt_fsmagic,
- Opt_uid, Opt_euid, Opt_fowner,
- Opt_appraise_type, Opt_fsuuid, Opt_permit_directio
+ Opt_fsuuid, Opt_uid, Opt_euid, Opt_fowner,
+ Opt_appraise_type, Opt_permit_directio
};
static match_table_t policy_tokens = {
@@ -828,3 +829,205 @@ void ima_delete_rules(void)
kfree(entry);
}
}
+
+#ifdef CONFIG_IMA_READ_POLICY
+enum {
+ mask_exec = 0, mask_write, mask_read, mask_append
+};
+
+static char *mask_tokens[] = {
+ "MAY_EXEC",
+ "MAY_WRITE",
+ "MAY_READ",
+ "MAY_APPEND"
+};
+
+enum {
+ func_file = 0, func_mmap, func_bprm,
+ func_module, func_firmware, func_post
+};
+
+static char *func_tokens[] = {
+ "FILE_CHECK",
+ "MMAP_CHECK",
+ "BPRM_CHECK",
+ "MODULE_CHECK",
+ "FIRMWARE_CHECK",
+ "POST_SETATTR"
+};
+
+void *ima_policy_start(struct seq_file *m, loff_t *pos)
+{
+ loff_t l = *pos;
+ struct ima_rule_entry *entry;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(entry, ima_rules, list) {
+ if (!l--) {
+ rcu_read_unlock();
+ return entry;
+ }
+ }
+ rcu_read_unlock();
+ return NULL;
+}
+
+void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct ima_rule_entry *entry = v;
+
+ rcu_read_lock();
+ entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
+ rcu_read_unlock();
+ (*pos)++;
+
+ return (&entry->list == ima_rules) ? NULL : entry;
+}
+
+void ima_policy_stop(struct seq_file *m, void *v)
+{
+}
+
+#define pt(token) policy_tokens[token + Opt_err].pattern
+#define mt(token) mask_tokens[token]
+#define ft(token) func_tokens[token]
+
+int ima_policy_show(struct seq_file *m, void *v)
+{
+ struct ima_rule_entry *entry = v;
+ int i = 0;
+ char tbuf[64] = {0,};
+
+ rcu_read_lock();
+
+ if (entry->action & MEASURE)
+ seq_puts(m, pt(Opt_measure));
+ if (entry->action & DONT_MEASURE)
+ seq_puts(m, pt(Opt_dont_measure));
+ if (entry->action & APPRAISE)
+ seq_puts(m, pt(Opt_appraise));
+ if (entry->action & DONT_APPRAISE)
+ seq_puts(m, pt(Opt_dont_appraise));
+ if (entry->action & AUDIT)
+ seq_puts(m, pt(Opt_audit));
+
+ seq_puts(m, " ");
+
+ if (entry->flags & IMA_FUNC) {
+ switch (entry->func) {
+ case FILE_CHECK:
+ seq_printf(m, pt(Opt_func), ft(func_file));
+ break;
+ case MMAP_CHECK:
+ seq_printf(m, pt(Opt_func), ft(func_mmap));
+ break;
+ case BPRM_CHECK:
+ seq_printf(m, pt(Opt_func), ft(func_bprm));
+ break;
+ case MODULE_CHECK:
+ seq_printf(m, pt(Opt_func), ft(func_module));
+ break;
+ case FIRMWARE_CHECK:
+ seq_printf(m, pt(Opt_func), ft(func_firmware));
+ break;
+ case POST_SETATTR:
+ seq_printf(m, pt(Opt_func), ft(func_post));
+ break;
+ default:
+ snprintf(tbuf, sizeof(tbuf), "%d", entry->func);
+ seq_printf(m, pt(Opt_func), tbuf);
+ break;
+ }
+ seq_puts(m, " ");
+ }
+
+ if (entry->flags & IMA_MASK) {
+ if (entry->mask & MAY_EXEC)
+ seq_printf(m, pt(Opt_mask), mt(mask_exec));
+ if (entry->mask & MAY_WRITE)
+ seq_printf(m, pt(Opt_mask), mt(mask_write));
+ if (entry->mask & MAY_READ)
+ seq_printf(m, pt(Opt_mask), mt(mask_read));
+ if (entry->mask & MAY_APPEND)
+ seq_printf(m, pt(Opt_mask), mt(mask_append));
+ seq_puts(m, " ");
+ }
+
+ if (entry->flags & IMA_FSMAGIC) {
+ snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
+ seq_printf(m, pt(Opt_fsmagic), tbuf);
+ seq_puts(m, " ");
+ }
+
+ if (entry->flags & IMA_FSUUID) {
+ seq_puts(m, "fsuuid=");
+ for (i = 0; i < ARRAY_SIZE(entry->fsuuid); ++i) {
+ switch (i) {
+ case 4:
+ case 6:
+ case 8:
+ case 10:
+ seq_puts(m, "-");
+ }
+ seq_printf(m, "%x", entry->fsuuid[i]);
+ }
+ seq_puts(m, " ");
+ }
+
+ if (entry->flags & IMA_UID) {
+ snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
+ seq_printf(m, pt(Opt_uid), tbuf);
+ seq_puts(m, " ");
+ }
+
+ if (entry->flags & IMA_EUID) {
+ snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
+ seq_printf(m, pt(Opt_euid), tbuf);
+ seq_puts(m, " ");
+ }
+
+ if (entry->flags & IMA_FOWNER) {
+ snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
+ seq_printf(m, pt(Opt_fowner), tbuf);
+ seq_puts(m, " ");
+ }
+
+ for (i = 0; i < MAX_LSM_RULES; i++) {
+ if (entry->lsm[i].rule) {
+ switch (i) {
+ case LSM_OBJ_USER:
+ seq_printf(m, pt(Opt_obj_user),
+ (char *)entry->lsm[i].args_p);
+ break;
+ case LSM_OBJ_ROLE:
+ seq_printf(m, pt(Opt_obj_role),
+ (char *)entry->lsm[i].args_p);
+ break;
+ case LSM_OBJ_TYPE:
+ seq_printf(m, pt(Opt_obj_type),
+ (char *)entry->lsm[i].args_p);
+ break;
+ case LSM_SUBJ_USER:
+ seq_printf(m, pt(Opt_subj_user),
+ (char *)entry->lsm[i].args_p);
+ break;
+ case LSM_SUBJ_ROLE:
+ seq_printf(m, pt(Opt_subj_role),
+ (char *)entry->lsm[i].args_p);
+ break;
+ case LSM_SUBJ_TYPE:
+ seq_printf(m, pt(Opt_subj_type),
+ (char *)entry->lsm[i].args_p);
+ break;
+ }
+ }
+ }
+ if (entry->flags & IMA_DIGSIG_REQUIRED)
+ seq_puts(m, "appraise_type=imasig ");
+ if (entry->flags & IMA_PERMIT_DIRECTIO)
+ seq_puts(m, "permit_directio ");
+ rcu_read_unlock();
+ seq_puts(m, "\n");
+ return 0;
+}
+#endif /* CONFIG_IMA_READ_POLICY */