TOMOYO: Add environment variable name restriction support.

This patch adds support for checking environment variable's names.
Although TOMOYO already provides ability to check argv[]/envp[] passed to
execve() requests,

  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="bar"

will reject execution of /bin/sh if environment variable LD_LIBRARY_PATH is not
defined. To grant execution of /bin/sh if LD_LIBRARY_PATH is not defined,
administrators have to specify like

  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="/system/lib"
  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]=NULL

. Since there are many environment variables whereas conditional checks are
applied as "&&", it is difficult to cover all combinations. Therefore, this
patch supports conditional checks that are applied as "||", by specifying like

  file execute /bin/sh
  misc env LD_LIBRARY_PATH exec.envp["LD_LIBRARY_PATH"]="/system/lib"

which means "grant execution of /bin/sh if environment variable is not defined
or is defined and its value is /system/lib".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

security/tomoyo/Makefile

@@ -1,4 +1,4 @@
-obj-y = audit.o common.o condition.o domain.o file.o gc.o group.o load_policy.o memory.o mount.o realpath.o securityfs_if.o tomoyo.o util.o
+obj-y = audit.o common.o condition.o domain.o environ.o file.o gc.o group.o load_policy.o memory.o mount.o realpath.o securityfs_if.o tomoyo.o util.o
 
 $(obj)/policy/profile.conf:
 	@mkdir -p $(obj)/policy/

security/tomoyo/common.c

@@ -20,6 +20,7 @@ const char * const tomoyo_mode[TOMOYO_CONFIG_MAX_MODE] = {
 /* String table for /sys/kernel/security/tomoyo/profile */
 const char * const tomoyo_mac_keywords[TOMOYO_MAX_MAC_INDEX
 				       + TOMOYO_MAX_MAC_CATEGORY_INDEX] = {
+	/* CONFIG::file group */
 	[TOMOYO_MAC_FILE_EXECUTE]    = "execute",
 	[TOMOYO_MAC_FILE_OPEN]       = "open",
 	[TOMOYO_MAC_FILE_CREATE]     = "create",
@@ -43,7 +44,11 @@ const char * const tomoyo_mac_keywords[TOMOYO_MAX_MAC_INDEX
 	[TOMOYO_MAC_FILE_MOUNT]      = "mount",
 	[TOMOYO_MAC_FILE_UMOUNT]     = "unmount",
 	[TOMOYO_MAC_FILE_PIVOT_ROOT] = "pivot_root",
+	/* CONFIG::misc group */
+	[TOMOYO_MAC_ENVIRON] = "env",
+	/* CONFIG group */
 	[TOMOYO_MAX_MAC_INDEX + TOMOYO_MAC_CATEGORY_FILE] = "file",
+	[TOMOYO_MAX_MAC_INDEX + TOMOYO_MAC_CATEGORY_MISC] = "misc",
 };
 
 /* String table for conditions. */
@@ -133,7 +138,8 @@ const char * const tomoyo_path_keyword[TOMOYO_MAX_PATH_OPERATION] = {
 /* String table for categories. */
 static const char * const tomoyo_category_keywords
 [TOMOYO_MAX_MAC_CATEGORY_INDEX] = {
-	[TOMOYO_MAC_CATEGORY_FILE]       = "file",
+	[TOMOYO_MAC_CATEGORY_FILE] = "file",
+	[TOMOYO_MAC_CATEGORY_MISC] = "misc",
 };
 
 /* Permit policy management by non-root user? */
@@ -1036,11 +1042,13 @@ static int tomoyo_write_domain2(struct tomoyo_policy_namespace *ns,
 	static const struct {
 		const char *keyword;
 		int (*write) (struct tomoyo_acl_param *);
-	} tomoyo_callback[1] = {
+	} tomoyo_callback[2] = {
 		{ "file ", tomoyo_write_file },
+		{ "misc ", tomoyo_write_misc },
 	};
 	u8 i;
-	for (i = 0; i < 1; i++) {
+
+	for (i = 0; i < ARRAY_SIZE(tomoyo_callback); i++) {
 		if (!tomoyo_str_starts(&param.data,
 				       tomoyo_callback[i].keyword))
 			continue;
@@ -1375,6 +1383,12 @@ static bool tomoyo_print_entry(struct tomoyo_io_buffer *head,
 		tomoyo_print_name_union(head, &ptr->dir_name);
 		tomoyo_print_name_union(head, &ptr->fs_type);
 		tomoyo_print_number_union(head, &ptr->flags);
+	} else if (acl_type == TOMOYO_TYPE_ENV_ACL) {
+		struct tomoyo_env_acl *ptr =
+			container_of(acl, typeof(*ptr), head);
+
+		tomoyo_set_group(head, "misc env ");
+		tomoyo_set_string(head, ptr->env->name);
 	}
 	if (acl->cond) {
 		head->r.print_cond_part = true;

security/tomoyo/common.h

@@ -196,6 +196,7 @@ enum tomoyo_acl_entry_type_index {
 	TOMOYO_TYPE_PATH_NUMBER_ACL,
 	TOMOYO_TYPE_MKDEV_ACL,
 	TOMOYO_TYPE_MOUNT_ACL,
+	TOMOYO_TYPE_ENV_ACL,
 };
 
 /* Index numbers for access controls with one pathname. */
@@ -300,12 +301,14 @@ enum tomoyo_mac_index {
 	TOMOYO_MAC_FILE_MOUNT,
 	TOMOYO_MAC_FILE_UMOUNT,
 	TOMOYO_MAC_FILE_PIVOT_ROOT,
+	TOMOYO_MAC_ENVIRON,
 	TOMOYO_MAX_MAC_INDEX
 };
 
 /* Index numbers for category of functionality. */
 enum tomoyo_mac_category_index {
 	TOMOYO_MAC_CATEGORY_FILE,
+	TOMOYO_MAC_CATEGORY_MISC,
 	TOMOYO_MAX_MAC_CATEGORY_INDEX
 };
 
@@ -396,6 +399,9 @@ struct tomoyo_request_info {
 			 */
 			u8 operation;
 		} path_number;
+		struct {
+			const struct tomoyo_path_info *name;
+		} environ;
 		struct {
 			const struct tomoyo_path_info *type;
 			const struct tomoyo_path_info *dir;
@@ -638,6 +644,12 @@ struct tomoyo_mount_acl {
 	struct tomoyo_number_union flags;
 };
 
+/* Structure for "misc env" directive in domain policy. */
+struct tomoyo_env_acl {
+	struct tomoyo_acl_info head;        /* type = TOMOYO_TYPE_ENV_ACL  */
+	const struct tomoyo_path_info *env; /* environment variable */
+};
+
 /* Structure for holding a line from /sys/kernel/security/tomoyo/ interface. */
 struct tomoyo_acl_param {
 	char *data;
@@ -820,6 +832,7 @@ const struct tomoyo_path_info *tomoyo_path_matches_group
 int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 				 struct path *path, const int flag);
 int tomoyo_close_control(struct tomoyo_io_buffer *head);
+int tomoyo_env_perm(struct tomoyo_request_info *r, const char *env);
 int tomoyo_find_next_domain(struct linux_binprm *bprm);
 int tomoyo_get_mode(const struct tomoyo_policy_namespace *ns, const u8 profile,
 		    const u8 index);
@@ -860,6 +873,7 @@ int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
 int tomoyo_write_aggregator(struct tomoyo_acl_param *param);
 int tomoyo_write_file(struct tomoyo_acl_param *param);
 int tomoyo_write_group(struct tomoyo_acl_param *param, const u8 type);
+int tomoyo_write_misc(struct tomoyo_acl_param *param);
 int tomoyo_write_transition_control(struct tomoyo_acl_param *param,
 				    const u8 type);
 ssize_t tomoyo_read_control(struct tomoyo_io_buffer *head, char __user *buffer,

security/tomoyo/domain.c

@@ -562,6 +562,92 @@ out:
 	return entry;
 }
 
+/**
+ * tomoyo_environ - Check permission for environment variable names.
+ *
+ * @ee: Pointer to "struct tomoyo_execve".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_environ(struct tomoyo_execve *ee)
+{
+	struct tomoyo_request_info *r = &ee->r;
+	struct linux_binprm *bprm = ee->bprm;
+	/* env_page.data is allocated by tomoyo_dump_page(). */
+	struct tomoyo_page_dump env_page = { };
+	char *arg_ptr; /* Size is TOMOYO_EXEC_TMPSIZE bytes */
+	int arg_len = 0;
+	unsigned long pos = bprm->p;
+	int offset = pos % PAGE_SIZE;
+	int argv_count = bprm->argc;
+	int envp_count = bprm->envc;
+	int error = -ENOMEM;
+
+	ee->r.type = TOMOYO_MAC_ENVIRON;
+	ee->r.profile = r->domain->profile;
+	ee->r.mode = tomoyo_get_mode(r->domain->ns, ee->r.profile,
+				     TOMOYO_MAC_ENVIRON);
+	if (!r->mode || !envp_count)
+		return 0;
+	arg_ptr = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
+	if (!arg_ptr)
+		goto out;
+	while (error == -ENOMEM) {
+		if (!tomoyo_dump_page(bprm, pos, &env_page))
+			goto out;
+		pos += PAGE_SIZE - offset;
+		/* Read. */
+		while (argv_count && offset < PAGE_SIZE) {
+			if (!env_page.data[offset++])
+				argv_count--;
+		}
+		if (argv_count) {
+			offset = 0;
+			continue;
+		}
+		while (offset < PAGE_SIZE) {
+			const unsigned char c = env_page.data[offset++];
+
+			if (c && arg_len < TOMOYO_EXEC_TMPSIZE - 10) {
+				if (c == '=') {
+					arg_ptr[arg_len++] = '\0';
+				} else if (c == '\\') {
+					arg_ptr[arg_len++] = '\\';
+					arg_ptr[arg_len++] = '\\';
+				} else if (c > ' ' && c < 127) {
+					arg_ptr[arg_len++] = c;
+				} else {
+					arg_ptr[arg_len++] = '\\';
+					arg_ptr[arg_len++] = (c >> 6) + '0';
+					arg_ptr[arg_len++]
+						= ((c >> 3) & 7) + '0';
+					arg_ptr[arg_len++] = (c & 7) + '0';
+				}
+			} else {
+				arg_ptr[arg_len] = '\0';
+			}
+			if (c)
+				continue;
+			if (tomoyo_env_perm(r, arg_ptr)) {
+				error = -EPERM;
+				break;
+			}
+			if (!--envp_count) {
+				error = 0;
+				break;
+			}
+			arg_len = 0;
+		}
+		offset = 0;
+	}
+out:
+	if (r->mode != TOMOYO_CONFIG_ENFORCING)
+		error = 0;
+	kfree(env_page.data);
+	kfree(arg_ptr);
+	return error;
+}
+
 /**
  * tomoyo_find_next_domain - Find a domain.
  *
@@ -581,6 +667,7 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 	bool reject_on_transition_failure = false;
 	struct tomoyo_path_info rn = { }; /* real name */
 	struct tomoyo_execve *ee = kzalloc(sizeof(*ee), GFP_NOFS);
+
 	if (!ee)
 		return -ENOMEM;
 	ee->tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
@@ -713,6 +800,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 	bprm->cred->security = domain;
 	if (need_kfree)
 		kfree(rn.name);
+	if (!retval) {
+		ee->r.domain = domain;
+		retval = tomoyo_environ(ee);
+	}
 	kfree(ee->tmp);
 	kfree(ee->dump.data);
 	kfree(ee);
@@ -732,7 +823,8 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
 		      struct tomoyo_page_dump *dump)
 {
 	struct page *page;
-	/* dump->data is released by tomoyo_finish_execve(). */
+
+	/* dump->data is released by tomoyo_find_next_domain(). */
 	if (!dump->data) {
 		dump->data = kzalloc(PAGE_SIZE, GFP_NOFS);
 		if (!dump->data)
@@ -753,6 +845,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
 		 * So do I.
 		 */
 		char *kaddr = kmap_atomic(page, KM_USER0);
+
 		dump->page = page;
 		memcpy(dump->data + offset, kaddr + offset,
 		       PAGE_SIZE - offset);

security/tomoyo/environ.c

@@ -0,0 +1,122 @@
+/*
+ * security/tomoyo/environ.c
+ *
+ * Copyright (C) 2005-2011  NTT DATA CORPORATION
+ */
+
+#include "common.h"
+
+/**
+ * tomoyo_check_env_acl - Check permission for environment variable's name.
+ *
+ * @r:   Pointer to "struct tomoyo_request_info".
+ * @ptr: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if granted, false otherwise.
+ */
+static bool tomoyo_check_env_acl(struct tomoyo_request_info *r,
+				 const struct tomoyo_acl_info *ptr)
+{
+	const struct tomoyo_env_acl *acl =
+		container_of(ptr, typeof(*acl), head);
+
+	return tomoyo_path_matches_pattern(r->param.environ.name, acl->env);
+}
+
+/**
+ * tomoyo_audit_env_log - Audit environment variable name log.
+ *
+ * @r: Pointer to "struct tomoyo_request_info".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_audit_env_log(struct tomoyo_request_info *r)
+{
+	return tomoyo_supervisor(r, "misc env %s\n",
+				 r->param.environ.name->name);
+}
+
+/**
+ * tomoyo_env_perm - Check permission for environment variable's name.
+ *
+ * @r:   Pointer to "struct tomoyo_request_info".
+ * @env: The name of environment variable.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_env_perm(struct tomoyo_request_info *r, const char *env)
+{
+	struct tomoyo_path_info environ;
+	int error;
+
+	if (!env || !*env)
+		return 0;
+	environ.name = env;
+	tomoyo_fill_path_info(&environ);
+	r->param_type = TOMOYO_TYPE_ENV_ACL;
+	r->param.environ.name = &environ;
+	do {
+		tomoyo_check_acl(r, tomoyo_check_env_acl);
+		error = tomoyo_audit_env_log(r);
+	} while (error == TOMOYO_RETRY_REQUEST);
+	return error;
+}
+
+/**
+ * tomoyo_same_env_acl - Check for duplicated "struct tomoyo_env_acl" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_info".
+ * @b: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static bool tomoyo_same_env_acl(const struct tomoyo_acl_info *a,
+				const struct tomoyo_acl_info *b)
+{
+	const struct tomoyo_env_acl *p1 = container_of(a, typeof(*p1), head);
+	const struct tomoyo_env_acl *p2 = container_of(b, typeof(*p2), head);
+
+	return p1->env == p2->env;
+}
+
+/**
+ * tomoyo_write_env - Write "struct tomoyo_env_acl" list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+static int tomoyo_write_env(struct tomoyo_acl_param *param)
+{
+	struct tomoyo_env_acl e = { .head.type = TOMOYO_TYPE_ENV_ACL };
+	int error = -ENOMEM;
+	const char *data = tomoyo_read_token(param);
+
+	if (!tomoyo_correct_word(data) || strchr(data, '='))
+		return -EINVAL;
+	e.env = tomoyo_get_name(data);
+	if (!e.env)
+		return error;
+	error = tomoyo_update_domain(&e.head, sizeof(e), param,
+				  tomoyo_same_env_acl, NULL);
+	tomoyo_put_name(e.env);
+	return error;
+}
+
+/**
+ * tomoyo_write_misc - Update environment variable list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_misc(struct tomoyo_acl_param *param)
+{
+	if (tomoyo_str_starts(&param->data, "env "))
+		return tomoyo_write_env(param);
+	return -EINVAL;
+}

security/tomoyo/gc.c

@@ -36,6 +36,7 @@ static const u8 tomoyo_acl_size[] = {
 	[TOMOYO_TYPE_PATH_NUMBER_ACL] = sizeof(struct tomoyo_path_number_acl),
 	[TOMOYO_TYPE_MKDEV_ACL] = sizeof(struct tomoyo_mkdev_acl),
 	[TOMOYO_TYPE_MOUNT_ACL] = sizeof(struct tomoyo_mount_acl),
+	[TOMOYO_TYPE_ENV_ACL] = sizeof(struct tomoyo_env_acl),
 };
 
 /**
@@ -293,6 +294,14 @@ static void tomoyo_del_acl(struct list_head *element)
 			tomoyo_put_number_union(&entry->flags);
 		}
 		break;
+	case TOMOYO_TYPE_ENV_ACL:
+		{
+			struct tomoyo_env_acl *entry =
+				container_of(acl, typeof(*entry), head);
+
+			tomoyo_put_name(entry->env);
+		}
+		break;
 	}
 }
 

security/tomoyo/util.c

@@ -42,6 +42,8 @@ const u8 tomoyo_index2category[TOMOYO_MAX_MAC_INDEX] = {
 	[TOMOYO_MAC_FILE_MOUNT]      = TOMOYO_MAC_CATEGORY_FILE,
 	[TOMOYO_MAC_FILE_UMOUNT]     = TOMOYO_MAC_CATEGORY_FILE,
 	[TOMOYO_MAC_FILE_PIVOT_ROOT] = TOMOYO_MAC_CATEGORY_FILE,
+	/* CONFIG::misc group */
+	[TOMOYO_MAC_ENVIRON]         = TOMOYO_MAC_CATEGORY_MISC,
 };
 
 /**
@@ -920,15 +922,17 @@ int tomoyo_get_mode(const struct tomoyo_policy_namespace *ns, const u8 profile,
 		    const u8 index)
 {
 	u8 mode;
-	const u8 category = TOMOYO_MAC_CATEGORY_FILE;
+	struct tomoyo_profile *p;
+
 	if (!tomoyo_policy_loaded)
 		return TOMOYO_CONFIG_DISABLED;
-	mode = tomoyo_profile(ns, profile)->config[index];
+	p = tomoyo_profile(ns, profile);
+	mode = p->config[index];
 	if (mode == TOMOYO_CONFIG_USE_DEFAULT)
-		mode = tomoyo_profile(ns, profile)->config
-			[category + TOMOYO_MAX_MAC_INDEX];
+		mode = p->config[tomoyo_index2category[index]
+				 + TOMOYO_MAX_MAC_INDEX];
 	if (mode == TOMOYO_CONFIG_USE_DEFAULT)
-		mode = tomoyo_profile(ns, profile)->default_config;
+		mode = p->default_config;
 	return mode & 3;
 }