[apparmor] [PATCH] apparmor: add the ability to report a crypto hash of loaded policy
John Johansen
john.johansen at canonical.com
Fri Aug 9 00:41:31 UTC 2013
Provide userspace the ability to validate what policy is loaded via
an exported crypto hash value.
Signed-off-by: John Johansen <john.johansen at canonical.com>
Header from folded patch 'convert-to-sha1.patch':
Signed-off-by: John Johansen <john.johansen at canonical.com>
---
security/apparmor/Kconfig | 12 +++++
security/apparmor/Makefile | 1 +
security/apparmor/apparmorfs.c | 37 ++++++++++++++
security/apparmor/crypto.c | 90 ++++++++++++++++++++++++++++++++++
security/apparmor/include/apparmorfs.h | 1 +
security/apparmor/include/crypto.h | 35 +++++++++++++
security/apparmor/include/policy.h | 1 +
security/apparmor/policy_unpack.c | 20 +++++---
8 files changed, 191 insertions(+), 6 deletions(-)
create mode 100644 security/apparmor/crypto.c
create mode 100644 security/apparmor/include/crypto.h
diff --git a/security/apparmor/Kconfig b/security/apparmor/Kconfig
index 9b9013b..216b528 100644
--- a/security/apparmor/Kconfig
+++ b/security/apparmor/Kconfig
@@ -29,3 +29,15 @@ config SECURITY_APPARMOR_BOOTPARAM_VALUE
boot.
If you are unsure how to answer this question, answer 1.
+
+config SECURITY_APPARMOR_HASH
+ bool "SHA1 hash of loaded profiles"
+ depends on SECURITY_APPARMOR
+ depends on CRYPTO
+ select CRYPTO_SHA1
+ default n
+
+ help
+ This option selects whether sha1 hashing is done against loaded
+ profiles and exported for inspection to user space via the apparmor
+ filesystem.
diff --git a/security/apparmor/Makefile b/security/apparmor/Makefile
index 0831e04..d693df8 100644
--- a/security/apparmor/Makefile
+++ b/security/apparmor/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor.o
apparmor-y := apparmorfs.o audit.o capability.o context.o ipc.o lib.o match.o \
path.o domain.o policy.o policy_unpack.o procattr.o lsm.o \
resource.o sid.o file.o
+apparmor-$(CONFIG_SECURITY_APPARMOR_HASH) += crypto.o
clean-files := capability_names.h rlim_names.h
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index d708a55..683baa2 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -26,6 +26,7 @@
#include "include/apparmorfs.h"
#include "include/audit.h"
#include "include/context.h"
+#include "include/crypto.h"
#include "include/policy.h"
#include "include/resource.h"
@@ -319,6 +320,33 @@ static const struct file_operations aa_fs_profattach_fops = {
.release = aa_fs_seq_profile_release,
};
+static int aa_fs_seq_hash_show(struct seq_file *seq, void *v)
+{
+ unsigned char *string = seq->private;
+ unsigned int i;
+
+ if (string) {
+ for (i = 0; i < aa_hash_size(); i++)
+ seq_printf(seq, "%.2x", string[i]);
+ seq_printf(seq, "\n");
+ }
+
+ return 0;
+}
+
+static int aa_fs_seq_hash_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, aa_fs_seq_hash_show, inode->i_private);
+}
+
+static const struct file_operations aa_fs_seq_hash_fops = {
+ .owner = THIS_MODULE,
+ .open = aa_fs_seq_hash_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
/** fns to setup dynamic per profile/namespace files **/
void __aa_fs_profile_rmdir(struct aa_profile *profile)
{
@@ -420,6 +448,15 @@ int __aa_fs_profile_mkdir(struct aa_profile *profile, struct dentry *parent)
goto fail;
profile->dents[AAFS_PROF_ATTACH] = dent;
+ if (profile->hash) {
+ dent = securityfs_create_file("sha1", S_IFREG | 0444, dir,
+ &profile->hash,
+ &aa_fs_seq_hash_fops);
+ if (IS_ERR(dent))
+ goto fail;
+ profile->dents[AAFS_PROF_HASH] = dent;
+ }
+
list_for_each_entry(child, &profile->base.profiles, base.list) {
error = __aa_fs_profile_mkdir(child, prof_child_dir(profile));
if (error)
diff --git a/security/apparmor/crypto.c b/security/apparmor/crypto.c
new file mode 100644
index 0000000..8c2484d
--- /dev/null
+++ b/security/apparmor/crypto.c
@@ -0,0 +1,90 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor policy loading interface function definitions.
+ *
+ * Copyright 2013 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ * Fns to provide a cryptographic checksum of policy that has been loaded
+ * this can be compared to userspace policy compiles to verify loaded
+ * policy is what it should be.
+ */
+
+#include <linux/crypto.h>
+
+#include "include/apparmor.h"
+#include "include/crypto.h"
+
+static unsigned int apparmor_hash_size;
+
+static struct crypto_hash *apparmor_tfm;
+
+unsigned int aa_hash_size(void)
+{
+ return apparmor_hash_size;
+}
+
+int aa_calc_profile_hash(struct aa_profile *profile, void *start, size_t len)
+{
+ struct scatterlist sg;
+ struct hash_desc desc = {
+ .tfm = apparmor_tfm,
+ .flags = 0
+ };
+ int error = -ENOMEM;
+
+ if (!apparmor_tfm)
+ return 0;
+
+ sg_init_one(&sg, (u8 *) start, len);
+
+ profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
+ if (!profile->hash)
+ goto fail;
+
+ error = crypto_hash_init(&desc);
+ if (error)
+ goto fail;
+ error = crypto_hash_update(&desc, &sg, len);
+ if (error)
+ goto fail;
+ error = crypto_hash_final(&desc, profile->hash);
+ if (error)
+ goto fail;
+
+ return 0;
+
+fail:
+ kfree(profile->hash);
+ profile->hash = NULL;
+
+ return error;
+}
+
+static int __init init_profile_hash(void)
+{
+ struct crypto_hash *tfm;
+
+ if (!apparmor_initialized)
+ return 0;
+
+ tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(tfm)) {
+ int error = PTR_ERR(tfm);
+ AA_ERROR("failed to setup profile sha1 hashing: %d\n", error);
+ return error;
+ }
+ apparmor_tfm = tfm;
+ apparmor_hash_size = crypto_hash_digestsize(apparmor_tfm);
+
+ aa_info_message("AppArmor cryptographic sha1 policy hashing Enabled");
+
+ return 0;
+}
+
+late_initcall(init_profile_hash);
diff --git a/security/apparmor/include/apparmorfs.h b/security/apparmor/include/apparmorfs.h
index f91712c..414e568 100644
--- a/security/apparmor/include/apparmorfs.h
+++ b/security/apparmor/include/apparmorfs.h
@@ -82,6 +82,7 @@ enum aafs_prof_type {
AAFS_PROF_NAME,
AAFS_PROF_MODE,
AAFS_PROF_ATTACH,
+ AAFS_PROF_HASH,
AAFS_PROF_SIZEOF,
};
diff --git a/security/apparmor/include/crypto.h b/security/apparmor/include/crypto.h
new file mode 100644
index 0000000..613944d
--- /dev/null
+++ b/security/apparmor/include/crypto.h
@@ -0,0 +1,35 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor policy loading interface function definitions.
+ *
+ * Copyright 2013 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#ifndef __APPARMOR_CRYPTO_H
+#define __APPARMOR_CRYPTO_H
+
+#include "policy.h"
+
+#ifdef CONFIG_SECURITY_APPARMOR_HASH
+unsigned int aa_hash_size(void);
+int aa_calc_profile_hash(struct aa_profile *profile, void *start, size_t len);
+#else
+static inline int aa_calc_profile_hash(struct aa_profile *profile, void *start,
+ size_t len)
+{
+ return 0;
+}
+
+static inline unsigned int aa_hash_size(void)
+{
+ return 0;
+}
+#endif
+
+#endif /* __APPARMOR_CRYPTO_H */
diff --git a/security/apparmor/include/policy.h b/security/apparmor/include/policy.h
index 59b3637..f2d4b63 100644
--- a/security/apparmor/include/policy.h
+++ b/security/apparmor/include/policy.h
@@ -219,6 +219,7 @@ struct aa_profile {
struct aa_caps caps;
struct aa_rlimit rlimits;
+ unsigned char *hash;
char *dirname;
struct dentry *dents[AAFS_PROF_SIZEOF];
};
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index 80050b3..bb7acc7 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -24,6 +24,7 @@
#include "include/apparmor.h"
#include "include/audit.h"
#include "include/context.h"
+#include "include/crypto.h"
#include "include/match.h"
#include "include/policy.h"
#include "include/policy_unpack.h"
@@ -66,6 +67,7 @@ struct aa_ext {
u32 version;
};
+
/* audit callback for unpack fields */
static void audit_cb(struct audit_buffer *ab, void *va)
{
@@ -757,12 +759,14 @@ int aa_unpack(void *udata, size_t size, struct list_head *lh, const char **ns)
*ns = NULL;
while (e.pos < e.end) {
+ void *start;
error = verify_header(&e, e.pos == e.start, ns);
if (error)
goto fail;
/* alignment adjust needed by dfa unpack */
e.adj = (e.pos - e.start) & 7;
+ start = e.pos;
profile = unpack_profile(&e);
if (IS_ERR(profile)) {
error = PTR_ERR(profile);
@@ -770,16 +774,17 @@ int aa_unpack(void *udata, size_t size, struct list_head *lh, const char **ns)
}
error = verify_profile(profile);
- if (error) {
- aa_free_profile(profile);
- goto fail;
- }
+ if (error)
+ goto fail_profile;
+
+ error = aa_calc_profile_hash(profile, start, e.pos - start);
+ if (error)
+ goto fail_profile;
ent = aa_load_ent_alloc();
if (!ent) {
error = -ENOMEM;
- aa_put_profile(profile);
- goto fail;
+ goto fail_profile;
}
ent->new = profile;
@@ -788,6 +793,9 @@ int aa_unpack(void *udata, size_t size, struct list_head *lh, const char **ns)
return 0;
+fail_profile:
+ aa_put_profile(profile);
+
fail:
list_for_each_entry_safe(ent, tmp, lh, list) {
list_del_init(&ent->list);
--
1.8.1.2
More information about the AppArmor
mailing list