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-rw-r--r--security/integrity/evm/Kconfig75
-rw-r--r--security/integrity/evm/Makefile8
-rw-r--r--security/integrity/evm/evm.h67
-rw-r--r--security/integrity/evm/evm_crypto.c435
-rw-r--r--security/integrity/evm/evm_main.c963
-rw-r--r--security/integrity/evm/evm_posix_acl.c23
-rw-r--r--security/integrity/evm/evm_secfs.c334
7 files changed, 1905 insertions, 0 deletions
diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
new file mode 100644
index 0000000000..fba9ee359b
--- /dev/null
+++ b/security/integrity/evm/Kconfig
@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config EVM
+ bool "EVM support"
+ select KEYS
+ select ENCRYPTED_KEYS
+ select CRYPTO_HMAC
+ select CRYPTO_SHA1
+ select CRYPTO_HASH_INFO
+ default n
+ help
+ EVM protects a file's security extended attributes against
+ integrity attacks.
+
+ If you are unsure how to answer this question, answer N.
+
+config EVM_ATTR_FSUUID
+ bool "FSUUID (version 2)"
+ default y
+ depends on EVM
+ help
+ Include filesystem UUID for HMAC calculation.
+
+ Default value is 'selected', which is former version 2.
+ if 'not selected', it is former version 1
+
+ WARNING: changing the HMAC calculation method or adding
+ additional info to the calculation, requires existing EVM
+ labeled file systems to be relabeled.
+
+config EVM_EXTRA_SMACK_XATTRS
+ bool "Additional SMACK xattrs"
+ depends on EVM && SECURITY_SMACK
+ default n
+ help
+ Include additional SMACK xattrs for HMAC calculation.
+
+ In addition to the original security xattrs (eg. security.selinux,
+ security.SMACK64, security.capability, and security.ima) included
+ in the HMAC calculation, enabling this option includes newly defined
+ Smack xattrs: security.SMACK64EXEC, security.SMACK64TRANSMUTE and
+ security.SMACK64MMAP.
+
+ WARNING: changing the HMAC calculation method or adding
+ additional info to the calculation, requires existing EVM
+ labeled file systems to be relabeled.
+
+config EVM_ADD_XATTRS
+ bool "Add additional EVM extended attributes at runtime"
+ depends on EVM
+ default n
+ help
+ Allow userland to provide additional xattrs for HMAC calculation.
+
+ When this option is enabled, root can add additional xattrs to the
+ list used by EVM by writing them into
+ /sys/kernel/security/integrity/evm/evm_xattrs.
+
+config EVM_LOAD_X509
+ bool "Load an X509 certificate onto the '.evm' trusted keyring"
+ depends on EVM && INTEGRITY_TRUSTED_KEYRING
+ default n
+ help
+ Load an X509 certificate onto the '.evm' trusted keyring.
+
+ This option enables X509 certificate loading from the kernel
+ onto the '.evm' trusted keyring. A public key can be used to
+ verify EVM integrity starting from the 'init' process. The
+ key must have digitalSignature usage set.
+
+config EVM_X509_PATH
+ string "EVM X509 certificate path"
+ depends on EVM_LOAD_X509
+ default "/etc/keys/x509_evm.der"
+ help
+ This option defines X509 certificate path.
diff --git a/security/integrity/evm/Makefile b/security/integrity/evm/Makefile
new file mode 100644
index 0000000000..a56f5613be
--- /dev/null
+++ b/security/integrity/evm/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for building the Extended Verification Module(EVM)
+#
+obj-$(CONFIG_EVM) += evm.o
+
+evm-y := evm_main.o evm_crypto.o evm_secfs.o
+evm-$(CONFIG_FS_POSIX_ACL) += evm_posix_acl.o
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
new file mode 100644
index 0000000000..53bd7fec93
--- /dev/null
+++ b/security/integrity/evm/evm.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2005-2010 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.com>
+ *
+ * File: evm.h
+ */
+
+#ifndef __INTEGRITY_EVM_H
+#define __INTEGRITY_EVM_H
+
+#include <linux/xattr.h>
+#include <linux/security.h>
+
+#include "../integrity.h"
+
+#define EVM_INIT_HMAC 0x0001
+#define EVM_INIT_X509 0x0002
+#define EVM_ALLOW_METADATA_WRITES 0x0004
+#define EVM_SETUP_COMPLETE 0x80000000 /* userland has signaled key load */
+
+#define EVM_KEY_MASK (EVM_INIT_HMAC | EVM_INIT_X509)
+#define EVM_INIT_MASK (EVM_INIT_HMAC | EVM_INIT_X509 | EVM_SETUP_COMPLETE | \
+ EVM_ALLOW_METADATA_WRITES)
+
+struct xattr_list {
+ struct list_head list;
+ char *name;
+ bool enabled;
+};
+
+extern int evm_initialized;
+
+#define EVM_ATTR_FSUUID 0x0001
+
+extern int evm_hmac_attrs;
+
+/* List of EVM protected security xattrs */
+extern struct list_head evm_config_xattrnames;
+
+struct evm_digest {
+ struct ima_digest_data hdr;
+ char digest[IMA_MAX_DIGEST_SIZE];
+} __packed;
+
+int evm_protected_xattr(const char *req_xattr_name);
+
+int evm_init_key(void);
+int evm_update_evmxattr(struct dentry *dentry,
+ const char *req_xattr_name,
+ const char *req_xattr_value,
+ size_t req_xattr_value_len);
+int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
+ const char *req_xattr_value,
+ size_t req_xattr_value_len, struct evm_digest *data);
+int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
+ const char *req_xattr_value,
+ size_t req_xattr_value_len, char type,
+ struct evm_digest *data);
+int evm_init_hmac(struct inode *inode, const struct xattr *xattrs,
+ char *hmac_val);
+int evm_init_secfs(void);
+
+#endif
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
new file mode 100644
index 0000000000..b1ffd4cc0b
--- /dev/null
+++ b/security/integrity/evm/evm_crypto.c
@@ -0,0 +1,435 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2005-2010 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.com>
+ *
+ * File: evm_crypto.c
+ * Using root's kernel master key (kmk), calculate the HMAC
+ */
+
+#define pr_fmt(fmt) "EVM: "fmt
+
+#include <linux/export.h>
+#include <linux/crypto.h>
+#include <linux/xattr.h>
+#include <linux/evm.h>
+#include <keys/encrypted-type.h>
+#include <crypto/hash.h>
+#include <crypto/hash_info.h>
+#include "evm.h"
+
+#define EVMKEY "evm-key"
+#define MAX_KEY_SIZE 128
+static unsigned char evmkey[MAX_KEY_SIZE];
+static const int evmkey_len = MAX_KEY_SIZE;
+
+static struct crypto_shash *hmac_tfm;
+static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
+
+static DEFINE_MUTEX(mutex);
+
+#define EVM_SET_KEY_BUSY 0
+
+static unsigned long evm_set_key_flags;
+
+static const char evm_hmac[] = "hmac(sha1)";
+
+/**
+ * evm_set_key() - set EVM HMAC key from the kernel
+ * @key: pointer to a buffer with the key data
+ * @keylen: length of the key data
+ *
+ * This function allows setting the EVM HMAC key from the kernel
+ * without using the "encrypted" key subsystem keys. It can be used
+ * by the crypto HW kernel module which has its own way of managing
+ * keys.
+ *
+ * key length should be between 32 and 128 bytes long
+ */
+int evm_set_key(void *key, size_t keylen)
+{
+ int rc;
+
+ rc = -EBUSY;
+ if (test_and_set_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags))
+ goto busy;
+ rc = -EINVAL;
+ if (keylen > MAX_KEY_SIZE)
+ goto inval;
+ memcpy(evmkey, key, keylen);
+ evm_initialized |= EVM_INIT_HMAC;
+ pr_info("key initialized\n");
+ return 0;
+inval:
+ clear_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags);
+busy:
+ pr_err("key initialization failed\n");
+ return rc;
+}
+EXPORT_SYMBOL_GPL(evm_set_key);
+
+static struct shash_desc *init_desc(char type, uint8_t hash_algo)
+{
+ long rc;
+ const char *algo;
+ struct crypto_shash **tfm, *tmp_tfm;
+ struct shash_desc *desc;
+
+ if (type == EVM_XATTR_HMAC) {
+ if (!(evm_initialized & EVM_INIT_HMAC)) {
+ pr_err_once("HMAC key is not set\n");
+ return ERR_PTR(-ENOKEY);
+ }
+ tfm = &hmac_tfm;
+ algo = evm_hmac;
+ } else {
+ if (hash_algo >= HASH_ALGO__LAST)
+ return ERR_PTR(-EINVAL);
+
+ tfm = &evm_tfm[hash_algo];
+ algo = hash_algo_name[hash_algo];
+ }
+
+ if (*tfm)
+ goto alloc;
+ mutex_lock(&mutex);
+ if (*tfm)
+ goto unlock;
+
+ tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
+ if (IS_ERR(tmp_tfm)) {
+ pr_err("Can not allocate %s (reason: %ld)\n", algo,
+ PTR_ERR(tmp_tfm));
+ mutex_unlock(&mutex);
+ return ERR_CAST(tmp_tfm);
+ }
+ if (type == EVM_XATTR_HMAC) {
+ rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len);
+ if (rc) {
+ crypto_free_shash(tmp_tfm);
+ mutex_unlock(&mutex);
+ return ERR_PTR(rc);
+ }
+ }
+ *tfm = tmp_tfm;
+unlock:
+ mutex_unlock(&mutex);
+alloc:
+ desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
+ GFP_KERNEL);
+ if (!desc)
+ return ERR_PTR(-ENOMEM);
+
+ desc->tfm = *tfm;
+
+ rc = crypto_shash_init(desc);
+ if (rc) {
+ kfree(desc);
+ return ERR_PTR(rc);
+ }
+ return desc;
+}
+
+/* Protect against 'cutting & pasting' security.evm xattr, include inode
+ * specific info.
+ *
+ * (Additional directory/file metadata needs to be added for more complete
+ * protection.)
+ */
+static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
+ char type, char *digest)
+{
+ struct h_misc {
+ unsigned long ino;
+ __u32 generation;
+ uid_t uid;
+ gid_t gid;
+ umode_t mode;
+ } hmac_misc;
+
+ memset(&hmac_misc, 0, sizeof(hmac_misc));
+ /* Don't include the inode or generation number in portable
+ * signatures
+ */
+ if (type != EVM_XATTR_PORTABLE_DIGSIG) {
+ hmac_misc.ino = inode->i_ino;
+ hmac_misc.generation = inode->i_generation;
+ }
+ /* The hmac uid and gid must be encoded in the initial user
+ * namespace (not the filesystems user namespace) as encoding
+ * them in the filesystems user namespace allows an attack
+ * where first they are written in an unprivileged fuse mount
+ * of a filesystem and then the system is tricked to mount the
+ * filesystem for real on next boot and trust it because
+ * everything is signed.
+ */
+ hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
+ hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
+ hmac_misc.mode = inode->i_mode;
+ crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
+ if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
+ type != EVM_XATTR_PORTABLE_DIGSIG)
+ crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
+ crypto_shash_final(desc, digest);
+
+ pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
+ (int)sizeof(struct h_misc), &hmac_misc);
+}
+
+/*
+ * Dump large security xattr values as a continuous ascii hexademical string.
+ * (pr_debug is limited to 64 bytes.)
+ */
+static void dump_security_xattr_l(const char *prefix, const void *src,
+ size_t count)
+{
+#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
+ char *asciihex, *p;
+
+ p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
+ if (!asciihex)
+ return;
+
+ p = bin2hex(p, src, count);
+ *p = 0;
+ pr_debug("%s: (%zu) %.*s\n", prefix, count, (int)count * 2, asciihex);
+ kfree(asciihex);
+#endif
+}
+
+static void dump_security_xattr(const char *name, const char *value,
+ size_t value_len)
+{
+ if (value_len < 64)
+ pr_debug("%s: (%zu) [%*phN]\n", name, value_len,
+ (int)value_len, value);
+ else
+ dump_security_xattr_l(name, value, value_len);
+}
+
+/*
+ * Calculate the HMAC value across the set of protected security xattrs.
+ *
+ * Instead of retrieving the requested xattr, for performance, calculate
+ * the hmac using the requested xattr value. Don't alloc/free memory for
+ * each xattr, but attempt to re-use the previously allocated memory.
+ */
+static int evm_calc_hmac_or_hash(struct dentry *dentry,
+ const char *req_xattr_name,
+ const char *req_xattr_value,
+ size_t req_xattr_value_len,
+ uint8_t type, struct evm_digest *data)
+{
+ struct inode *inode = d_backing_inode(dentry);
+ struct xattr_list *xattr;
+ struct shash_desc *desc;
+ size_t xattr_size = 0;
+ char *xattr_value = NULL;
+ int error;
+ int size, user_space_size;
+ bool ima_present = false;
+
+ if (!(inode->i_opflags & IOP_XATTR) ||
+ inode->i_sb->s_user_ns != &init_user_ns)
+ return -EOPNOTSUPP;
+
+ desc = init_desc(type, data->hdr.algo);
+ if (IS_ERR(desc))
+ return PTR_ERR(desc);
+
+ data->hdr.length = crypto_shash_digestsize(desc->tfm);
+
+ error = -ENODATA;
+ list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+ bool is_ima = false;
+
+ if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
+ is_ima = true;
+
+ /*
+ * Skip non-enabled xattrs for locally calculated
+ * signatures/HMACs.
+ */
+ if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled)
+ continue;
+
+ if ((req_xattr_name && req_xattr_value)
+ && !strcmp(xattr->name, req_xattr_name)) {
+ error = 0;
+ crypto_shash_update(desc, (const u8 *)req_xattr_value,
+ req_xattr_value_len);
+ if (is_ima)
+ ima_present = true;
+
+ dump_security_xattr(req_xattr_name,
+ req_xattr_value,
+ req_xattr_value_len);
+ continue;
+ }
+ size = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr->name,
+ &xattr_value, xattr_size, GFP_NOFS);
+ if (size == -ENOMEM) {
+ error = -ENOMEM;
+ goto out;
+ }
+ if (size < 0)
+ continue;
+
+ user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
+ xattr->name, NULL, 0);
+ if (user_space_size != size)
+ pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
+ dentry->d_name.name, xattr->name, size,
+ user_space_size);
+ error = 0;
+ xattr_size = size;
+ crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
+ if (is_ima)
+ ima_present = true;
+
+ dump_security_xattr(xattr->name, xattr_value, xattr_size);
+ }
+ hmac_add_misc(desc, inode, type, data->digest);
+
+ /* Portable EVM signatures must include an IMA hash */
+ if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
+ error = -EPERM;
+out:
+ kfree(xattr_value);
+ kfree(desc);
+ return error;
+}
+
+int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
+ const char *req_xattr_value, size_t req_xattr_value_len,
+ struct evm_digest *data)
+{
+ return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
+ req_xattr_value_len, EVM_XATTR_HMAC, data);
+}
+
+int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
+ const char *req_xattr_value, size_t req_xattr_value_len,
+ char type, struct evm_digest *data)
+{
+ return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
+ req_xattr_value_len, type, data);
+}
+
+static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
+{
+ const struct evm_ima_xattr_data *xattr_data = NULL;
+ struct integrity_iint_cache *iint;
+ int rc = 0;
+
+ iint = integrity_iint_find(inode);
+ if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
+ return 1;
+
+ /* Do this the hard way */
+ rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_EVM,
+ (char **)&xattr_data, 0, GFP_NOFS);
+ if (rc <= 0) {
+ if (rc == -ENODATA)
+ rc = 0;
+ goto out;
+ }
+ if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
+ rc = 1;
+ else
+ rc = 0;
+
+out:
+ kfree(xattr_data);
+ return rc;
+}
+
+
+/*
+ * Calculate the hmac and update security.evm xattr
+ *
+ * Expects to be called with i_mutex locked.
+ */
+int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
+ const char *xattr_value, size_t xattr_value_len)
+{
+ struct inode *inode = d_backing_inode(dentry);
+ struct evm_digest data;
+ int rc = 0;
+
+ /*
+ * Don't permit any transformation of the EVM xattr if the signature
+ * is of an immutable type
+ */
+ rc = evm_is_immutable(dentry, inode);
+ if (rc < 0)
+ return rc;
+ if (rc)
+ return -EPERM;
+
+ data.hdr.algo = HASH_ALGO_SHA1;
+ rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
+ xattr_value_len, &data);
+ if (rc == 0) {
+ data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
+ rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry,
+ XATTR_NAME_EVM,
+ &data.hdr.xattr.data[1],
+ SHA1_DIGEST_SIZE + 1, 0);
+ } else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
+ rc = __vfs_removexattr(&nop_mnt_idmap, dentry, XATTR_NAME_EVM);
+ }
+ return rc;
+}
+
+int evm_init_hmac(struct inode *inode, const struct xattr *xattrs,
+ char *hmac_val)
+{
+ struct shash_desc *desc;
+ const struct xattr *xattr;
+
+ desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
+ if (IS_ERR(desc)) {
+ pr_info("init_desc failed\n");
+ return PTR_ERR(desc);
+ }
+
+ for (xattr = xattrs; xattr->name; xattr++) {
+ if (!evm_protected_xattr(xattr->name))
+ continue;
+
+ crypto_shash_update(desc, xattr->value, xattr->value_len);
+ }
+
+ hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
+ kfree(desc);
+ return 0;
+}
+
+/*
+ * Get the key from the TPM for the SHA1-HMAC
+ */
+int evm_init_key(void)
+{
+ struct key *evm_key;
+ struct encrypted_key_payload *ekp;
+ int rc;
+
+ evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
+ if (IS_ERR(evm_key))
+ return -ENOENT;
+
+ down_read(&evm_key->sem);
+ ekp = evm_key->payload.data[0];
+
+ rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
+
+ /* burn the original key contents */
+ memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
+ up_read(&evm_key->sem);
+ key_put(evm_key);
+ return rc;
+}
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
new file mode 100644
index 0000000000..ff9a939dad
--- /dev/null
+++ b/security/integrity/evm/evm_main.c
@@ -0,0 +1,963 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2005-2010 IBM Corporation
+ *
+ * Author:
+ * Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.com>
+ *
+ * File: evm_main.c
+ * implements evm_inode_setxattr, evm_inode_post_setxattr,
+ * evm_inode_removexattr, evm_verifyxattr, and evm_inode_set_acl.
+ */
+
+#define pr_fmt(fmt) "EVM: "fmt
+
+#include <linux/init.h>
+#include <linux/crypto.h>
+#include <linux/audit.h>
+#include <linux/xattr.h>
+#include <linux/integrity.h>
+#include <linux/evm.h>
+#include <linux/magic.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/lsm_hooks.h>
+
+#include <crypto/hash.h>
+#include <crypto/hash_info.h>
+#include <crypto/algapi.h>
+#include "evm.h"
+
+int evm_initialized;
+
+static const char * const integrity_status_msg[] = {
+ "pass", "pass_immutable", "fail", "fail_immutable", "no_label",
+ "no_xattrs", "unknown"
+};
+int evm_hmac_attrs;
+
+static struct xattr_list evm_config_default_xattrnames[] = {
+ {
+ .name = XATTR_NAME_SELINUX,
+ .enabled = IS_ENABLED(CONFIG_SECURITY_SELINUX)
+ },
+ {
+ .name = XATTR_NAME_SMACK,
+ .enabled = IS_ENABLED(CONFIG_SECURITY_SMACK)
+ },
+ {
+ .name = XATTR_NAME_SMACKEXEC,
+ .enabled = IS_ENABLED(CONFIG_EVM_EXTRA_SMACK_XATTRS)
+ },
+ {
+ .name = XATTR_NAME_SMACKTRANSMUTE,
+ .enabled = IS_ENABLED(CONFIG_EVM_EXTRA_SMACK_XATTRS)
+ },
+ {
+ .name = XATTR_NAME_SMACKMMAP,
+ .enabled = IS_ENABLED(CONFIG_EVM_EXTRA_SMACK_XATTRS)
+ },
+ {
+ .name = XATTR_NAME_APPARMOR,
+ .enabled = IS_ENABLED(CONFIG_SECURITY_APPARMOR)
+ },
+ {
+ .name = XATTR_NAME_IMA,
+ .enabled = IS_ENABLED(CONFIG_IMA_APPRAISE)
+ },
+ {
+ .name = XATTR_NAME_CAPS,
+ .enabled = true
+ },
+};
+
+LIST_HEAD(evm_config_xattrnames);
+
+static int evm_fixmode __ro_after_init;
+static int __init evm_set_fixmode(char *str)
+{
+ if (strncmp(str, "fix", 3) == 0)
+ evm_fixmode = 1;
+ else
+ pr_err("invalid \"%s\" mode", str);
+
+ return 1;
+}
+__setup("evm=", evm_set_fixmode);
+
+static void __init evm_init_config(void)
+{
+ int i, xattrs;
+
+ xattrs = ARRAY_SIZE(evm_config_default_xattrnames);
+
+ pr_info("Initialising EVM extended attributes:\n");
+ for (i = 0; i < xattrs; i++) {
+ pr_info("%s%s\n", evm_config_default_xattrnames[i].name,
+ !evm_config_default_xattrnames[i].enabled ?
+ " (disabled)" : "");
+ list_add_tail(&evm_config_default_xattrnames[i].list,
+ &evm_config_xattrnames);
+ }
+
+#ifdef CONFIG_EVM_ATTR_FSUUID
+ evm_hmac_attrs |= EVM_ATTR_FSUUID;
+#endif
+ pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
+}
+
+static bool evm_key_loaded(void)
+{
+ return (bool)(evm_initialized & EVM_KEY_MASK);
+}
+
+/*
+ * This function determines whether or not it is safe to ignore verification
+ * errors, based on the ability of EVM to calculate HMACs. If the HMAC key
+ * is not loaded, and it cannot be loaded in the future due to the
+ * EVM_SETUP_COMPLETE initialization flag, allowing an operation despite the
+ * attrs/xattrs being found invalid will not make them valid.
+ */
+static bool evm_hmac_disabled(void)
+{
+ if (evm_initialized & EVM_INIT_HMAC)
+ return false;
+
+ if (!(evm_initialized & EVM_SETUP_COMPLETE))
+ return false;
+
+ return true;
+}
+
+static int evm_find_protected_xattrs(struct dentry *dentry)
+{
+ struct inode *inode = d_backing_inode(dentry);
+ struct xattr_list *xattr;
+ int error;
+ int count = 0;
+
+ if (!(inode->i_opflags & IOP_XATTR))
+ return -EOPNOTSUPP;
+
+ list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+ error = __vfs_getxattr(dentry, inode, xattr->name, NULL, 0);
+ if (error < 0) {
+ if (error == -ENODATA)
+ continue;
+ return error;
+ }
+ count++;
+ }
+
+ return count;
+}
+
+/*
+ * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
+ *
+ * Compute the HMAC on the dentry's protected set of extended attributes
+ * and compare it against the stored security.evm xattr.
+ *
+ * For performance:
+ * - use the previoulsy retrieved xattr value and length to calculate the
+ * HMAC.)
+ * - cache the verification result in the iint, when available.
+ *
+ * Returns integrity status
+ */
+static enum integrity_status evm_verify_hmac(struct dentry *dentry,
+ const char *xattr_name,
+ char *xattr_value,
+ size_t xattr_value_len,
+ struct integrity_iint_cache *iint)
+{
+ struct evm_ima_xattr_data *xattr_data = NULL;
+ struct signature_v2_hdr *hdr;
+ enum integrity_status evm_status = INTEGRITY_PASS;
+ struct evm_digest digest;
+ struct inode *inode;
+ int rc, xattr_len, evm_immutable = 0;
+
+ if (iint && (iint->evm_status == INTEGRITY_PASS ||
+ iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
+ return iint->evm_status;
+
+ /* if status is not PASS, try to check again - against -ENOMEM */
+
+ /* first need to know the sig type */
+ rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_EVM,
+ (char **)&xattr_data, 0, GFP_NOFS);
+ if (rc <= 0) {
+ evm_status = INTEGRITY_FAIL;
+ if (rc == -ENODATA) {
+ rc = evm_find_protected_xattrs(dentry);
+ if (rc > 0)
+ evm_status = INTEGRITY_NOLABEL;
+ else if (rc == 0)
+ evm_status = INTEGRITY_NOXATTRS; /* new file */
+ } else if (rc == -EOPNOTSUPP) {
+ evm_status = INTEGRITY_UNKNOWN;
+ }
+ goto out;
+ }
+
+ xattr_len = rc;
+
+ /* check value type */
+ switch (xattr_data->type) {
+ case EVM_XATTR_HMAC:
+ if (xattr_len != sizeof(struct evm_xattr)) {
+ evm_status = INTEGRITY_FAIL;
+ goto out;
+ }
+
+ digest.hdr.algo = HASH_ALGO_SHA1;
+ rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
+ xattr_value_len, &digest);
+ if (rc)
+ break;
+ rc = crypto_memneq(xattr_data->data, digest.digest,
+ SHA1_DIGEST_SIZE);
+ if (rc)
+ rc = -EINVAL;
+ break;
+ case EVM_XATTR_PORTABLE_DIGSIG:
+ evm_immutable = 1;
+ fallthrough;
+ case EVM_IMA_XATTR_DIGSIG:
+ /* accept xattr with non-empty signature field */
+ if (xattr_len <= sizeof(struct signature_v2_hdr)) {
+ evm_status = INTEGRITY_FAIL;
+ goto out;
+ }
+
+ hdr = (struct signature_v2_hdr *)xattr_data;
+ digest.hdr.algo = hdr->hash_algo;
+ rc = evm_calc_hash(dentry, xattr_name, xattr_value,
+ xattr_value_len, xattr_data->type, &digest);
+ if (rc)
+ break;
+ rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
+ (const char *)xattr_data, xattr_len,
+ digest.digest, digest.hdr.length);
+ if (!rc) {
+ inode = d_backing_inode(dentry);
+
+ if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
+ if (iint)
+ iint->flags |= EVM_IMMUTABLE_DIGSIG;
+ evm_status = INTEGRITY_PASS_IMMUTABLE;
+ } else if (!IS_RDONLY(inode) &&
+ !(inode->i_sb->s_readonly_remount) &&
+ !IS_IMMUTABLE(inode)) {
+ evm_update_evmxattr(dentry, xattr_name,
+ xattr_value,
+ xattr_value_len);
+ }
+ }
+ break;
+ default:
+ rc = -EINVAL;
+ break;
+ }
+
+ if (rc) {
+ if (rc == -ENODATA)
+ evm_status = INTEGRITY_NOXATTRS;
+ else if (evm_immutable)
+ evm_status = INTEGRITY_FAIL_IMMUTABLE;
+ else
+ evm_status = INTEGRITY_FAIL;
+ }
+ pr_debug("digest: (%d) [%*phN]\n", digest.hdr.length, digest.hdr.length,
+ digest.digest);
+out:
+ if (iint)
+ iint->evm_status = evm_status;
+ kfree(xattr_data);
+ return evm_status;
+}
+
+static int evm_protected_xattr_common(const char *req_xattr_name,
+ bool all_xattrs)
+{
+ int namelen;
+ int found = 0;
+ struct xattr_list *xattr;
+
+ namelen = strlen(req_xattr_name);
+ list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+ if (!all_xattrs && !xattr->enabled)
+ continue;
+
+ if ((strlen(xattr->name) == namelen)
+ && (strncmp(req_xattr_name, xattr->name, namelen) == 0)) {
+ found = 1;
+ break;
+ }
+ if (strncmp(req_xattr_name,
+ xattr->name + XATTR_SECURITY_PREFIX_LEN,
+ strlen(req_xattr_name)) == 0) {
+ found = 1;
+ break;
+ }
+ }
+
+ return found;
+}
+
+int evm_protected_xattr(const char *req_xattr_name)
+{
+ return evm_protected_xattr_common(req_xattr_name, false);
+}
+
+int evm_protected_xattr_if_enabled(const char *req_xattr_name)
+{
+ return evm_protected_xattr_common(req_xattr_name, true);
+}
+
+/**
+ * evm_read_protected_xattrs - read EVM protected xattr names, lengths, values
+ * @dentry: dentry of the read xattrs
+ * @buffer: buffer xattr names, lengths or values are copied to
+ * @buffer_size: size of buffer
+ * @type: n: names, l: lengths, v: values
+ * @canonical_fmt: data format (true: little endian, false: native format)
+ *
+ * Read protected xattr names (separated by |), lengths (u32) or values for a
+ * given dentry and return the total size of copied data. If buffer is NULL,
+ * just return the total size.
+ *
+ * Returns the total size on success, a negative value on error.
+ */
+int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
+ int buffer_size, char type, bool canonical_fmt)
+{
+ struct xattr_list *xattr;
+ int rc, size, total_size = 0;
+
+ list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+ rc = __vfs_getxattr(dentry, d_backing_inode(dentry),
+ xattr->name, NULL, 0);
+ if (rc < 0 && rc == -ENODATA)
+ continue;
+ else if (rc < 0)
+ return rc;
+
+ switch (type) {
+ case 'n':
+ size = strlen(xattr->name) + 1;
+ if (buffer) {
+ if (total_size)
+ *(buffer + total_size - 1) = '|';
+
+ memcpy(buffer + total_size, xattr->name, size);
+ }
+ break;
+ case 'l':
+ size = sizeof(u32);
+ if (buffer) {
+ if (canonical_fmt)
+ rc = (__force int)cpu_to_le32(rc);
+
+ *(u32 *)(buffer + total_size) = rc;
+ }
+ break;
+ case 'v':
+ size = rc;
+ if (buffer) {
+ rc = __vfs_getxattr(dentry,
+ d_backing_inode(dentry), xattr->name,
+ buffer + total_size,
+ buffer_size - total_size);
+ if (rc < 0)
+ return rc;
+ }
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ total_size += size;
+ }
+
+ return total_size;
+}
+
+/**
+ * evm_verifyxattr - verify the integrity of the requested xattr
+ * @dentry: object of the verify xattr
+ * @xattr_name: requested xattr
+ * @xattr_value: requested xattr value
+ * @xattr_value_len: requested xattr value length
+ * @iint: inode integrity metadata
+ *
+ * Calculate the HMAC for the given dentry and verify it against the stored
+ * security.evm xattr. For performance, use the xattr value and length
+ * previously retrieved to calculate the HMAC.
+ *
+ * Returns the xattr integrity status.
+ *
+ * This function requires the caller to lock the inode's i_mutex before it
+ * is executed.
+ */
+enum integrity_status evm_verifyxattr(struct dentry *dentry,
+ const char *xattr_name,
+ void *xattr_value, size_t xattr_value_len,
+ struct integrity_iint_cache *iint)
+{
+ if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
+ return INTEGRITY_UNKNOWN;
+
+ if (!iint) {
+ iint = integrity_iint_find(d_backing_inode(dentry));
+ if (!iint)
+ return INTEGRITY_UNKNOWN;
+ }
+ return evm_verify_hmac(dentry, xattr_name, xattr_value,
+ xattr_value_len, iint);
+}
+EXPORT_SYMBOL_GPL(evm_verifyxattr);
+
+/*
+ * evm_verify_current_integrity - verify the dentry's metadata integrity
+ * @dentry: pointer to the affected dentry
+ *
+ * Verify and return the dentry's metadata integrity. The exceptions are
+ * before EVM is initialized or in 'fix' mode.
+ */
+static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
+{
+ struct inode *inode = d_backing_inode(dentry);
+
+ if (!evm_key_loaded() || !S_ISREG(inode->i_mode) || evm_fixmode)
+ return INTEGRITY_PASS;
+ return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
+}
+
+/*
+ * evm_xattr_change - check if passed xattr value differs from current value
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: requested xattr
+ * @xattr_value: requested xattr value
+ * @xattr_value_len: requested xattr value length
+ *
+ * Check if passed xattr value differs from current value.
+ *
+ * Returns 1 if passed xattr value differs from current value, 0 otherwise.
+ */
+static int evm_xattr_change(struct mnt_idmap *idmap,
+ struct dentry *dentry, const char *xattr_name,
+ const void *xattr_value, size_t xattr_value_len)
+{
+ char *xattr_data = NULL;
+ int rc = 0;
+
+ rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr_name, &xattr_data,
+ 0, GFP_NOFS);
+ if (rc < 0) {
+ rc = 1;
+ goto out;
+ }
+
+ if (rc == xattr_value_len)
+ rc = !!memcmp(xattr_value, xattr_data, rc);
+ else
+ rc = 1;
+
+out:
+ kfree(xattr_data);
+ return rc;
+}
+
+/*
+ * evm_protect_xattr - protect the EVM extended attribute
+ *
+ * Prevent security.evm from being modified or removed without the
+ * necessary permissions or when the existing value is invalid.
+ *
+ * The posix xattr acls are 'system' prefixed, which normally would not
+ * affect security.evm. An interesting side affect of writing posix xattr
+ * acls is their modifying of the i_mode, which is included in security.evm.
+ * For posix xattr acls only, permit security.evm, even if it currently
+ * doesn't exist, to be updated unless the EVM signature is immutable.
+ */
+static int evm_protect_xattr(struct mnt_idmap *idmap,
+ struct dentry *dentry, const char *xattr_name,
+ const void *xattr_value, size_t xattr_value_len)
+{
+ enum integrity_status evm_status;
+
+ if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ } else if (!evm_protected_xattr(xattr_name)) {
+ if (!posix_xattr_acl(xattr_name))
+ return 0;
+ evm_status = evm_verify_current_integrity(dentry);
+ if ((evm_status == INTEGRITY_PASS) ||
+ (evm_status == INTEGRITY_NOXATTRS))
+ return 0;
+ goto out;
+ }
+
+ evm_status = evm_verify_current_integrity(dentry);
+ if (evm_status == INTEGRITY_NOXATTRS) {
+ struct integrity_iint_cache *iint;
+
+ /* Exception if the HMAC is not going to be calculated. */
+ if (evm_hmac_disabled())
+ return 0;
+
+ iint = integrity_iint_find(d_backing_inode(dentry));
+ if (iint && (iint->flags & IMA_NEW_FILE))
+ return 0;
+
+ /* exception for pseudo filesystems */
+ if (dentry->d_sb->s_magic == TMPFS_MAGIC
+ || dentry->d_sb->s_magic == SYSFS_MAGIC)
+ return 0;
+
+ integrity_audit_msg(AUDIT_INTEGRITY_METADATA,
+ dentry->d_inode, dentry->d_name.name,
+ "update_metadata",
+ integrity_status_msg[evm_status],
+ -EPERM, 0);
+ }
+out:
+ /* Exception if the HMAC is not going to be calculated. */
+ if (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
+ evm_status == INTEGRITY_UNKNOWN))
+ return 0;
+
+ /*
+ * Writing other xattrs is safe for portable signatures, as portable
+ * signatures are immutable and can never be updated.
+ */
+ if (evm_status == INTEGRITY_FAIL_IMMUTABLE)
+ return 0;
+
+ if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
+ !evm_xattr_change(idmap, dentry, xattr_name, xattr_value,
+ xattr_value_len))
+ return 0;
+
+ if (evm_status != INTEGRITY_PASS &&
+ evm_status != INTEGRITY_PASS_IMMUTABLE)
+ integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
+ dentry->d_name.name, "appraise_metadata",
+ integrity_status_msg[evm_status],
+ -EPERM, 0);
+ return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
+}
+
+/**
+ * evm_inode_setxattr - protect the EVM extended attribute
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ * @xattr_value: pointer to the new extended attribute value
+ * @xattr_value_len: pointer to the new extended attribute value length
+ *
+ * Before allowing the 'security.evm' protected xattr to be updated,
+ * verify the existing value is valid. As only the kernel should have
+ * access to the EVM encrypted key needed to calculate the HMAC, prevent
+ * userspace from writing HMAC value. Writing 'security.evm' requires
+ * requires CAP_SYS_ADMIN privileges.
+ */
+int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
+ const char *xattr_name, const void *xattr_value,
+ size_t xattr_value_len)
+{
+ const struct evm_ima_xattr_data *xattr_data = xattr_value;
+
+ /* Policy permits modification of the protected xattrs even though
+ * there's no HMAC key loaded
+ */
+ if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+ return 0;
+
+ if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+ if (!xattr_value_len)
+ return -EINVAL;
+ if (xattr_data->type != EVM_IMA_XATTR_DIGSIG &&
+ xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
+ return -EPERM;
+ }
+ return evm_protect_xattr(idmap, dentry, xattr_name, xattr_value,
+ xattr_value_len);
+}
+
+/**
+ * evm_inode_removexattr - protect the EVM extended attribute
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ *
+ * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
+ * the current value is valid.
+ */
+int evm_inode_removexattr(struct mnt_idmap *idmap,
+ struct dentry *dentry, const char *xattr_name)
+{
+ /* Policy permits modification of the protected xattrs even though
+ * there's no HMAC key loaded
+ */
+ if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+ return 0;
+
+ return evm_protect_xattr(idmap, dentry, xattr_name, NULL, 0);
+}
+
+#ifdef CONFIG_FS_POSIX_ACL
+static int evm_inode_set_acl_change(struct mnt_idmap *idmap,
+ struct dentry *dentry, const char *name,
+ struct posix_acl *kacl)
+{
+ int rc;
+
+ umode_t mode;
+ struct inode *inode = d_backing_inode(dentry);
+
+ if (!kacl)
+ return 1;
+
+ rc = posix_acl_update_mode(idmap, inode, &mode, &kacl);
+ if (rc || (inode->i_mode != mode))
+ return 1;
+
+ return 0;
+}
+#else
+static inline int evm_inode_set_acl_change(struct mnt_idmap *idmap,
+ struct dentry *dentry,
+ const char *name,
+ struct posix_acl *kacl)
+{
+ return 0;
+}
+#endif
+
+/**
+ * evm_inode_set_acl - protect the EVM extended attribute from posix acls
+ * @idmap: idmap of the idmapped mount
+ * @dentry: pointer to the affected dentry
+ * @acl_name: name of the posix acl
+ * @kacl: pointer to the posix acls
+ *
+ * Prevent modifying posix acls causing the EVM HMAC to be re-calculated
+ * and 'security.evm' xattr updated, unless the existing 'security.evm' is
+ * valid.
+ */
+int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+ const char *acl_name, struct posix_acl *kacl)
+{
+ enum integrity_status evm_status;
+
+ /* Policy permits modification of the protected xattrs even though
+ * there's no HMAC key loaded
+ */
+ if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+ return 0;
+
+ evm_status = evm_verify_current_integrity(dentry);
+ if ((evm_status == INTEGRITY_PASS) ||
+ (evm_status == INTEGRITY_NOXATTRS))
+ return 0;
+
+ /* Exception if the HMAC is not going to be calculated. */
+ if (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
+ evm_status == INTEGRITY_UNKNOWN))
+ return 0;
+
+ /*
+ * Writing other xattrs is safe for portable signatures, as portable
+ * signatures are immutable and can never be updated.
+ */
+ if (evm_status == INTEGRITY_FAIL_IMMUTABLE)
+ return 0;
+
+ if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
+ !evm_inode_set_acl_change(idmap, dentry, acl_name, kacl))
+ return 0;
+
+ if (evm_status != INTEGRITY_PASS_IMMUTABLE)
+ integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
+ dentry->d_name.name, "appraise_metadata",
+ integrity_status_msg[evm_status],
+ -EPERM, 0);
+ return -EPERM;
+}
+
+static void evm_reset_status(struct inode *inode)
+{
+ struct integrity_iint_cache *iint;
+
+ iint = integrity_iint_find(inode);
+ if (iint)
+ iint->evm_status = INTEGRITY_UNKNOWN;
+}
+
+/**
+ * evm_revalidate_status - report whether EVM status re-validation is necessary
+ * @xattr_name: pointer to the affected extended attribute name
+ *
+ * Report whether callers of evm_verifyxattr() should re-validate the
+ * EVM status.
+ *
+ * Return true if re-validation is necessary, false otherwise.
+ */
+bool evm_revalidate_status(const char *xattr_name)
+{
+ if (!evm_key_loaded())
+ return false;
+
+ /* evm_inode_post_setattr() passes NULL */
+ if (!xattr_name)
+ return true;
+
+ if (!evm_protected_xattr(xattr_name) && !posix_xattr_acl(xattr_name) &&
+ strcmp(xattr_name, XATTR_NAME_EVM))
+ return false;
+
+ return true;
+}
+
+/**
+ * evm_inode_post_setxattr - update 'security.evm' to reflect the changes
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ * @xattr_value: pointer to the new extended attribute value
+ * @xattr_value_len: pointer to the new extended attribute value length
+ *
+ * Update the HMAC stored in 'security.evm' to reflect the change.
+ *
+ * No need to take the i_mutex lock here, as this function is called from
+ * __vfs_setxattr_noperm(). The caller of which has taken the inode's
+ * i_mutex lock.
+ */
+void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
+ const void *xattr_value, size_t xattr_value_len)
+{
+ if (!evm_revalidate_status(xattr_name))
+ return;
+
+ evm_reset_status(dentry->d_inode);
+
+ if (!strcmp(xattr_name, XATTR_NAME_EVM))
+ return;
+
+ if (!(evm_initialized & EVM_INIT_HMAC))
+ return;
+
+ evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
+}
+
+/**
+ * evm_inode_post_removexattr - update 'security.evm' after removing the xattr
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ *
+ * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
+ *
+ * No need to take the i_mutex lock here, as this function is called from
+ * vfs_removexattr() which takes the i_mutex.
+ */
+void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
+{
+ if (!evm_revalidate_status(xattr_name))
+ return;
+
+ evm_reset_status(dentry->d_inode);
+
+ if (!strcmp(xattr_name, XATTR_NAME_EVM))
+ return;
+
+ if (!(evm_initialized & EVM_INIT_HMAC))
+ return;
+
+ evm_update_evmxattr(dentry, xattr_name, NULL, 0);
+}
+
+static int evm_attr_change(struct mnt_idmap *idmap,
+ struct dentry *dentry, struct iattr *attr)
+{
+ struct inode *inode = d_backing_inode(dentry);
+ unsigned int ia_valid = attr->ia_valid;
+
+ if (!i_uid_needs_update(idmap, attr, inode) &&
+ !i_gid_needs_update(idmap, attr, inode) &&
+ (!(ia_valid & ATTR_MODE) || attr->ia_mode == inode->i_mode))
+ return 0;
+
+ return 1;
+}
+
+/**
+ * evm_inode_setattr - prevent updating an invalid EVM extended attribute
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @attr: iattr structure containing the new file attributes
+ *
+ * Permit update of file attributes when files have a valid EVM signature,
+ * except in the case of them having an immutable portable signature.
+ */
+int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+ struct iattr *attr)
+{
+ unsigned int ia_valid = attr->ia_valid;
+ enum integrity_status evm_status;
+
+ /* Policy permits modification of the protected attrs even though
+ * there's no HMAC key loaded
+ */
+ if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+ return 0;
+
+ if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
+ return 0;
+ evm_status = evm_verify_current_integrity(dentry);
+ /*
+ * Writing attrs is safe for portable signatures, as portable signatures
+ * are immutable and can never be updated.
+ */
+ if ((evm_status == INTEGRITY_PASS) ||
+ (evm_status == INTEGRITY_NOXATTRS) ||
+ (evm_status == INTEGRITY_FAIL_IMMUTABLE) ||
+ (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
+ evm_status == INTEGRITY_UNKNOWN)))
+ return 0;
+
+ if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
+ !evm_attr_change(idmap, dentry, attr))
+ return 0;
+
+ integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
+ dentry->d_name.name, "appraise_metadata",
+ integrity_status_msg[evm_status], -EPERM, 0);
+ return -EPERM;
+}
+
+/**
+ * evm_inode_post_setattr - update 'security.evm' after modifying metadata
+ * @dentry: pointer to the affected dentry
+ * @ia_valid: for the UID and GID status
+ *
+ * For now, update the HMAC stored in 'security.evm' to reflect UID/GID
+ * changes.
+ *
+ * This function is called from notify_change(), which expects the caller
+ * to lock the inode's i_mutex.
+ */
+void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
+{
+ if (!evm_revalidate_status(NULL))
+ return;
+
+ evm_reset_status(dentry->d_inode);
+
+ if (!(evm_initialized & EVM_INIT_HMAC))
+ return;
+
+ if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
+ evm_update_evmxattr(dentry, NULL, NULL, 0);
+}
+
+/*
+ * evm_inode_init_security - initializes security.evm HMAC value
+ */
+int evm_inode_init_security(struct inode *inode, struct inode *dir,
+ const struct qstr *qstr, struct xattr *xattrs,
+ int *xattr_count)
+{
+ struct evm_xattr *xattr_data;
+ struct xattr *xattr, *evm_xattr;
+ bool evm_protected_xattrs = false;
+ int rc;
+
+ if (!(evm_initialized & EVM_INIT_HMAC) || !xattrs)
+ return 0;
+
+ /*
+ * security_inode_init_security() makes sure that the xattrs array is
+ * contiguous, there is enough space for security.evm, and that there is
+ * a terminator at the end of the array.
+ */
+ for (xattr = xattrs; xattr->name; xattr++) {
+ if (evm_protected_xattr(xattr->name))
+ evm_protected_xattrs = true;
+ }
+
+ /* EVM xattr not needed. */
+ if (!evm_protected_xattrs)
+ return 0;
+
+ evm_xattr = lsm_get_xattr_slot(xattrs, xattr_count);
+ /*
+ * Array terminator (xattr name = NULL) must be the first non-filled
+ * xattr slot.
+ */
+ WARN_ONCE(evm_xattr != xattr,
+ "%s: xattrs terminator is not the first non-filled slot\n",
+ __func__);
+
+ xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
+ if (!xattr_data)
+ return -ENOMEM;
+
+ xattr_data->data.type = EVM_XATTR_HMAC;
+ rc = evm_init_hmac(inode, xattrs, xattr_data->digest);
+ if (rc < 0)
+ goto out;
+
+ evm_xattr->value = xattr_data;
+ evm_xattr->value_len = sizeof(*xattr_data);
+ evm_xattr->name = XATTR_EVM_SUFFIX;
+ return 0;
+out:
+ kfree(xattr_data);
+ return rc;
+}
+EXPORT_SYMBOL_GPL(evm_inode_init_security);
+
+#ifdef CONFIG_EVM_LOAD_X509
+void __init evm_load_x509(void)
+{
+ int rc;
+
+ rc = integrity_load_x509(INTEGRITY_KEYRING_EVM, CONFIG_EVM_X509_PATH);
+ if (!rc)
+ evm_initialized |= EVM_INIT_X509;
+}
+#endif
+
+static int __init init_evm(void)
+{
+ int error;
+ struct list_head *pos, *q;
+
+ evm_init_config();
+
+ error = integrity_init_keyring(INTEGRITY_KEYRING_EVM);
+ if (error)
+ goto error;
+
+ error = evm_init_secfs();
+ if (error < 0) {
+ pr_info("Error registering secfs\n");
+ goto error;
+ }
+
+error:
+ if (error != 0) {
+ if (!list_empty(&evm_config_xattrnames)) {
+ list_for_each_safe(pos, q, &evm_config_xattrnames)
+ list_del(pos);
+ }
+ }
+
+ return error;
+}
+
+late_initcall(init_evm);
diff --git a/security/integrity/evm/evm_posix_acl.c b/security/integrity/evm/evm_posix_acl.c
new file mode 100644
index 0000000000..37275800c0
--- /dev/null
+++ b/security/integrity/evm/evm_posix_acl.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 IBM Corporation
+ *
+ * Author:
+ * Mimi Zohar <zohar@us.ibm.com>
+ */
+
+#include <linux/xattr.h>
+#include <linux/evm.h>
+
+int posix_xattr_acl(const char *xattr)
+{
+ int xattr_len = strlen(xattr);
+
+ if ((strlen(XATTR_NAME_POSIX_ACL_ACCESS) == xattr_len)
+ && (strncmp(XATTR_NAME_POSIX_ACL_ACCESS, xattr, xattr_len) == 0))
+ return 1;
+ if ((strlen(XATTR_NAME_POSIX_ACL_DEFAULT) == xattr_len)
+ && (strncmp(XATTR_NAME_POSIX_ACL_DEFAULT, xattr, xattr_len) == 0))
+ return 1;
+ return 0;
+}
diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c
new file mode 100644
index 0000000000..9b907c2fee
--- /dev/null
+++ b/security/integrity/evm/evm_secfs.c
@@ -0,0 +1,334 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2010 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ *
+ * File: evm_secfs.c
+ * - Used to signal when key is on keyring
+ * - Get the key and enable EVM
+ */
+
+#include <linux/audit.h>
+#include <linux/uaccess.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include "evm.h"
+
+static struct dentry *evm_dir;
+static struct dentry *evm_init_tpm;
+static struct dentry *evm_symlink;
+
+#ifdef CONFIG_EVM_ADD_XATTRS
+static struct dentry *evm_xattrs;
+static DEFINE_MUTEX(xattr_list_mutex);
+static int evm_xattrs_locked;
+#endif
+
+/**
+ * evm_read_key - read() for <securityfs>/evm
+ *
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @count: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t evm_read_key(struct file *filp, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ char temp[80];
+ ssize_t rc;
+
+ if (*ppos != 0)
+ return 0;
+
+ sprintf(temp, "%d", (evm_initialized & ~EVM_SETUP_COMPLETE));
+ rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+
+ return rc;
+}
+
+/**
+ * evm_write_key - write() for <securityfs>/evm
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Used to signal that key is on the kernel key ring.
+ * - get the integrity hmac key from the kernel key ring
+ * - create list of hmac protected extended attributes
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t evm_write_key(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ unsigned int i;
+ int ret;
+
+ if (!capable(CAP_SYS_ADMIN) || (evm_initialized & EVM_SETUP_COMPLETE))
+ return -EPERM;
+
+ ret = kstrtouint_from_user(buf, count, 0, &i);
+
+ if (ret)
+ return ret;
+
+ /* Reject invalid values */
+ if (!i || (i & ~EVM_INIT_MASK) != 0)
+ return -EINVAL;
+
+ /*
+ * Don't allow a request to enable metadata writes if
+ * an HMAC key is loaded.
+ */
+ if ((i & EVM_ALLOW_METADATA_WRITES) &&
+ (evm_initialized & EVM_INIT_HMAC) != 0)
+ return -EPERM;
+
+ if (i & EVM_INIT_HMAC) {
+ ret = evm_init_key();
+ if (ret != 0)
+ return ret;
+ /* Forbid further writes after the symmetric key is loaded */
+ i |= EVM_SETUP_COMPLETE;
+ }
+
+ evm_initialized |= i;
+
+ /* Don't allow protected metadata modification if a symmetric key
+ * is loaded
+ */
+ if (evm_initialized & EVM_INIT_HMAC)
+ evm_initialized &= ~(EVM_ALLOW_METADATA_WRITES);
+
+ return count;
+}
+
+static const struct file_operations evm_key_ops = {
+ .read = evm_read_key,
+ .write = evm_write_key,
+};
+
+#ifdef CONFIG_EVM_ADD_XATTRS
+/**
+ * evm_read_xattrs - read() for <securityfs>/evm_xattrs
+ *
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @count: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t evm_read_xattrs(struct file *filp, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ char *temp;
+ int offset = 0;
+ ssize_t rc, size = 0;
+ struct xattr_list *xattr;
+
+ if (*ppos != 0)
+ return 0;
+
+ rc = mutex_lock_interruptible(&xattr_list_mutex);
+ if (rc)
+ return -ERESTARTSYS;
+
+ list_for_each_entry(xattr, &evm_config_xattrnames, list) {
+ if (!xattr->enabled)
+ continue;
+
+ size += strlen(xattr->name) + 1;
+ }
+
+ temp = kmalloc(size + 1, GFP_KERNEL);
+ if (!temp) {
+ mutex_unlock(&xattr_list_mutex);
+ return -ENOMEM;
+ }
+
+ list_for_each_entry(xattr, &evm_config_xattrnames, list) {
+ if (!xattr->enabled)
+ continue;
+
+ sprintf(temp + offset, "%s\n", xattr->name);
+ offset += strlen(xattr->name) + 1;
+ }
+
+ mutex_unlock(&xattr_list_mutex);
+ rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+
+ kfree(temp);
+
+ return rc;
+}
+
+/**
+ * evm_write_xattrs - write() for <securityfs>/evm_xattrs
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t evm_write_xattrs(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ int len, err;
+ struct xattr_list *xattr, *tmp;
+ struct audit_buffer *ab;
+ struct iattr newattrs;
+ struct inode *inode;
+
+ if (!capable(CAP_SYS_ADMIN) || evm_xattrs_locked)
+ return -EPERM;
+
+ if (*ppos != 0)
+ return -EINVAL;
+
+ if (count > XATTR_NAME_MAX)
+ return -E2BIG;
+
+ ab = audit_log_start(audit_context(), GFP_KERNEL,
+ AUDIT_INTEGRITY_EVM_XATTR);
+ if (!ab && IS_ENABLED(CONFIG_AUDIT))
+ return -ENOMEM;
+
+ xattr = kmalloc(sizeof(struct xattr_list), GFP_KERNEL);
+ if (!xattr) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ xattr->enabled = true;
+ xattr->name = memdup_user_nul(buf, count);
+ if (IS_ERR(xattr->name)) {
+ err = PTR_ERR(xattr->name);
+ xattr->name = NULL;
+ goto out;
+ }
+
+ /* Remove any trailing newline */
+ len = strlen(xattr->name);
+ if (len && xattr->name[len-1] == '\n')
+ xattr->name[len-1] = '\0';
+
+ audit_log_format(ab, "xattr=");
+ audit_log_untrustedstring(ab, xattr->name);
+
+ if (strcmp(xattr->name, ".") == 0) {
+ evm_xattrs_locked = 1;
+ newattrs.ia_mode = S_IFREG | 0440;
+ newattrs.ia_valid = ATTR_MODE;
+ inode = evm_xattrs->d_inode;
+ inode_lock(inode);
+ err = simple_setattr(&nop_mnt_idmap, evm_xattrs, &newattrs);
+ inode_unlock(inode);
+ if (!err)
+ err = count;
+ goto out;
+ }
+
+ if (strncmp(xattr->name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN) != 0) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * xattr_list_mutex guards against races in evm_read_xattrs().
+ * Entries are only added to the evm_config_xattrnames list
+ * and never deleted. Therefore, the list is traversed
+ * using list_for_each_entry_lockless() without holding
+ * the mutex in evm_calc_hmac_or_hash(), evm_find_protected_xattrs()
+ * and evm_protected_xattr().
+ */
+ mutex_lock(&xattr_list_mutex);
+ list_for_each_entry(tmp, &evm_config_xattrnames, list) {
+ if (strcmp(xattr->name, tmp->name) == 0) {
+ err = -EEXIST;
+ if (!tmp->enabled) {
+ tmp->enabled = true;
+ err = count;
+ }
+ mutex_unlock(&xattr_list_mutex);
+ goto out;
+ }
+ }
+ list_add_tail_rcu(&xattr->list, &evm_config_xattrnames);
+ mutex_unlock(&xattr_list_mutex);
+
+ audit_log_format(ab, " res=0");
+ audit_log_end(ab);
+ return count;
+out:
+ audit_log_format(ab, " res=%d", (err < 0) ? err : 0);
+ audit_log_end(ab);
+ if (xattr) {
+ kfree(xattr->name);
+ kfree(xattr);
+ }
+ return err;
+}
+
+static const struct file_operations evm_xattr_ops = {
+ .read = evm_read_xattrs,
+ .write = evm_write_xattrs,
+};
+
+static int evm_init_xattrs(void)
+{
+ evm_xattrs = securityfs_create_file("evm_xattrs", 0660, evm_dir, NULL,
+ &evm_xattr_ops);
+ if (!evm_xattrs || IS_ERR(evm_xattrs))
+ return -EFAULT;
+
+ return 0;
+}
+#else
+static int evm_init_xattrs(void)
+{
+ return 0;
+}
+#endif
+
+int __init evm_init_secfs(void)
+{
+ int error = 0;
+
+ evm_dir = securityfs_create_dir("evm", integrity_dir);
+ if (!evm_dir || IS_ERR(evm_dir))
+ return -EFAULT;
+
+ evm_init_tpm = securityfs_create_file("evm", 0660,
+ evm_dir, NULL, &evm_key_ops);
+ if (!evm_init_tpm || IS_ERR(evm_init_tpm)) {
+ error = -EFAULT;
+ goto out;
+ }
+
+ evm_symlink = securityfs_create_symlink("evm", NULL,
+ "integrity/evm/evm", NULL);
+ if (!evm_symlink || IS_ERR(evm_symlink)) {
+ error = -EFAULT;
+ goto out;
+ }
+
+ if (evm_init_xattrs() != 0) {
+ error = -EFAULT;
+ goto out;
+ }
+
+ return 0;
+out:
+ securityfs_remove(evm_symlink);
+ securityfs_remove(evm_init_tpm);
+ securityfs_remove(evm_dir);
+ return error;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-19 16:01:23 +0000