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Mon, 6 Apr 2020 22:14:54 +0000 (UTC) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by relay.mimecast.com with ESMTP id us-mta-142-3VlvHYLFO2uJsgCjMsJqEA-1; Mon, 06 Apr 2020 18:14:49 -0400 X-MC-Unique: 3VlvHYLFO2uJsgCjMsJqEA-1 Received: from dede-linux.corp.microsoft.com (unknown [131.107.147.242]) by linux.microsoft.com (Postfix) with ESMTPSA id 926C520BBF9E; Mon, 6 Apr 2020 15:14:47 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 926C520BBF9E From: deven.desai@linux.microsoft.com To: agk@redhat.com, axboe@kernel.dk, snitzer@redhat.com, jmorris@namei.org, serge@hallyn.com, zohar@linux.ibm.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, dm-devel@redhat.com, linux-block@vger.kernel.org Date: Mon, 6 Apr 2020 15:14:30 -0700 Message-Id: <20200406221439.1469862-4-deven.desai@linux.microsoft.com> In-Reply-To: <20200406221439.1469862-1-deven.desai@linux.microsoft.com> References: <20200406221439.1469862-1-deven.desai@linux.microsoft.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 036MEvDA018693 X-loop: dm-devel@redhat.com Cc: sashal@kernel.org, pasha.tatashin@soleen.com, mdsakib@linux.microsoft.com, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, tyhicks@linux.microsoft.com, jaskarankhurana@linux.microsoft.com Subject: [dm-devel] [RFC PATCH v2 03/12] security: add ipe lsm policy parser and policy loading X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com From: Deven Bowers Adds the policy parser and the policy loading to IPE, along with the related sysfs and securityfs entries. Signed-off-by: Deven Bowers --- security/ipe/Kconfig | 2 +- security/ipe/Makefile | 3 + security/ipe/ipe-parse.c | 898 ++++++++++++++++++++++++++++++++++++++ security/ipe/ipe-parse.h | 35 ++ security/ipe/ipe-policy.c | 180 ++++++++ security/ipe/ipe-policy.h | 54 +++ security/ipe/ipe-secfs.c | 814 ++++++++++++++++++++++++++++++++++ security/ipe/ipe-secfs.h | 25 ++ security/ipe/ipe-sysfs.c | 86 ++++ security/ipe/ipe.c | 13 + security/ipe/ipe.h | 1 + 11 files changed, 2110 insertions(+), 1 deletion(-) create mode 100644 security/ipe/ipe-parse.c create mode 100644 security/ipe/ipe-parse.h create mode 100644 security/ipe/ipe-policy.c create mode 100644 security/ipe/ipe-secfs.c create mode 100644 security/ipe/ipe-secfs.h diff --git a/security/ipe/Kconfig b/security/ipe/Kconfig index 0c67cd049d0c..ef6fb019be6f 100644 --- a/security/ipe/Kconfig +++ b/security/ipe/Kconfig @@ -5,7 +5,7 @@ menuconfig SECURITY_IPE bool "Integrity Policy Enforcement (IPE)" - depends on SECURITY && AUDIT + depends on SECURITY && AUDIT && SECURITYFS select SYSTEM_DATA_VERIFICATION help This option enables the Integrity Policy Enforcement subsystem, diff --git a/security/ipe/Makefile b/security/ipe/Makefile index aaa2e2c0b2f4..4dcfc5b26b58 100644 --- a/security/ipe/Makefile +++ b/security/ipe/Makefile @@ -19,8 +19,11 @@ obj-$(CONFIG_SECURITY_IPE) += \ ipe-audit.o \ ipe-bp.o \ ipe-engine.o \ + ipe-parse.o \ + ipe-policy.o \ ipe-property.o \ ipe-hooks.o \ + ipe-secfs.o \ ipe-sysfs.o \ clean-files := ipe-bp.c diff --git a/security/ipe/ipe-parse.c b/security/ipe/ipe-parse.c new file mode 100644 index 000000000000..c5e0111b9c8b --- /dev/null +++ b/security/ipe/ipe-parse.c @@ -0,0 +1,898 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include "ipe.h" +#include "ipe-prop-internal.h" +#include "ipe-hooks.h" +#include "ipe-parse.h" +#include "ipe-property.h" +#include "ipe-audit.h" + +#include +#include +#include +#include +#include +#include +#include +#include + +#define ALLOW_ACTION "ALLOW" +#define DENY_ACTION "DENY" +#define COMMENT_CHAR '#' +#define VER_FSTR "%hu.%hu.%hu" + +/* Internal Type Definitions */ +enum property_priority { + other = 0, + action = 1, + op = 2, + default_action = 3, + policy_ver = 4, + policy_name = 5, +}; + +struct token { + struct list_head next_tok; + const char *key; + enum property_priority key_priority; + const char *val; +}; + +/* Utility Functions */ +static inline bool is_quote(char c) +{ + return c == '"' || c == '\''; +} + +static inline bool valid_token(char *s) +{ + return !s || !strpbrk(s, "\"\'"); +} + +static inline bool is_default(const struct token *t) +{ + return !t->val && t->key_priority == default_action; +} + +static inline bool is_operation(const struct token *t) +{ + return t->val && t->key_priority == op; +} + +static inline bool is_action(const struct token *t) +{ + return t->val && t->key_priority == action; +} + +static inline bool is_name(const struct token *t) +{ + return t->val && t->key_priority == policy_name; +} + +static inline bool is_ver(const struct token *t) +{ + return t->val && t->key_priority == policy_ver; +} + +static int cmp_pri(void *priv, struct list_head *a, struct list_head *b) +{ + struct token *t_a = container_of(a, struct token, next_tok); + struct token *t_b = container_of(b, struct token, next_tok); + + return t_b->key_priority - t_a->key_priority; +} + +static char *trim_quotes(char *str) +{ + char s; + size_t len; + + if (!str) + return str; + + s = *str; + + if (is_quote(s)) { + len = strlen(str) - 1; + + if (str[len] != s) + return NULL; + + str[len] = '\0'; + ++str; + } + + return str; +} + +/** + * ipe_set_action: Set an action with error checking. + * @src: Valid pointer to the source location to set wih the result + * @set: Value to apply to @src, if valid + * + * Return: + * 0 - OK + * -EBADMSG - Attempting to set something that is already set + */ +static int ipe_set_action(enum ipe_action *src, enum ipe_action set) +{ + if (*src != ipe_action_unset) + return -EBADMSG; + + *src = set; + + return 0; +} + +/** + * ipe_insert_token: Allocate and append the key=value pair indicated by @val, + * to the list represented by @head. + * @val: Token to parse, of form "key=val". + * @head: Head of the list to insert the token structure into. + * + * If "=val" is omitted, this function will succeed, and the value set will be + * NULL. + * + * Return: + * 0 - OK + * -EBADMSG - Invalid policy syntax + * -ENOMEM - No Memory + */ +static int ipe_insert_token(char *val, struct list_head *head) +{ + char *key; + substring_t match[MAX_OPT_ARGS]; + struct token *tok; + const match_table_t prop_priorities = { + { policy_name, IPE_HEADER_POLICY_NAME }, + { policy_ver, IPE_HEADER_POLICY_VERSION}, + { op, IPE_PROPERTY_OPERATION }, + { default_action, IPE_PROPERTY_DEFAULT }, + { action, IPE_PROPERTY_ACTION }, + { other, NULL }, + }; + + key = strsep(&val, "="); + if (!key) + return -EBADMSG; + + tok = kzalloc(sizeof(*tok), GFP_KERNEL); + if (!tok) + return -ENOMEM; + + tok->key = key; + tok->val = trim_quotes(val); + tok->key_priority = match_token(key, prop_priorities, match); + INIT_LIST_HEAD(&tok->next_tok); + + list_add_tail(&tok->next_tok, head); + + return 0; +} + +/** + * ipe_tokenize_line: Parse a line of text into a list of token structures. + * @line: Line to parse. + * @list: Head of the list to insert the token structure into. + * + * The final result will be sorted in the priority order definted by + * enum property_priorities to enforce policy structure. + * + * Return: + * 0 - OK + * -EBADMSG - Invalid policy syntax + * -ENOMEM - No Memory + * -ENOENT - No tokens were parsed + */ +static int ipe_tokenize_line(char *line, struct list_head *list) +{ + int rc = 0; + size_t i = 0; + size_t len = 0; + char *tok = NULL; + char quote = '\0'; + + len = strlen(line); + + for (i = 0; i < len; ++i) { + if (quote == '\0' && is_quote(line[i])) { + quote = line[i]; + continue; + } + + if (quote != '\0' && line[i] == quote) { + quote = '\0'; + continue; + } + + if (quote == '\0' && line[i] == COMMENT_CHAR) { + tok = NULL; + break; + } + + if (isgraph(line[i]) && !tok) + tok = &line[i]; + + if (quote == '\0' && isspace(line[i])) { + line[i] = '\0'; + + if (!tok) + continue; + + rc = ipe_insert_token(tok, list); + if (rc != 0) + return rc; + + tok = NULL; + } + } + + if (quote != '\0') + return -EBADMSG; + + if (tok) + ipe_insert_token(tok, list); + + if (list_empty(list)) + return -ENOENT; + + list_sort(NULL, list, cmp_pri); + + return 0; +} + +static inline int ipe_parse_version(const char *val, struct ipe_pol_ver *ver) +{ + if (sscanf(val, VER_FSTR, &ver->major, &ver->minor, &ver->rev) != 3) + return -EBADMSG; + + return 0; +} + +/** + * ipe_parse_action: Given a token, parse the value as if it were an 'action' + * token. + * @action: Token to parse to determine the action. + * + * Action tokens are of the form: action=(ALLOW|DENY) for more information + * about IPE policy, please see the documentation. + * + * Return: + * ipe_action_allow - OK + * ipe_action_deny - OK + * ipe_action_unset - ERR + */ +static enum ipe_action ipe_parse_action(struct token *action) +{ + if (!action->val) + return ipe_action_unset; + else if (!strcmp(action->val, ALLOW_ACTION)) + return ipe_action_allow; + else if (!strcmp(action->val, DENY_ACTION)) + return ipe_action_deny; + + return ipe_action_unset; +} + +/** + * ipe_parse_op: Given a token, parse the value as if it were an 'op' token. + * @op: Token to parse to determine the operation. + * + * "op" tokens are of the form: op=(EXECUTE|FIRMWARE|KEXEC_IMAGE|...) + * for more information about IPE policy, please see the documentation. + * + * Return: + * ipe_op_max - ERR + * otherwise - OK + */ +static enum ipe_op ipe_parse_op(struct token *op) +{ + substring_t match[MAX_OPT_ARGS]; + const match_table_t ops = { + { ipe_op_execute, IPE_OP_EXECUTE }, + { ipe_op_firmware, IPE_OP_FIRMWARE }, + { ipe_op_kexec_image, IPE_OP_KEXEC_IMAGE }, + { ipe_op_kexec_initramfs, IPE_OP_KEXEC_INITRAMFS }, + { ipe_op_x509, IPE_OP_X509_CERTIFICATE }, + { ipe_op_policy, IPE_OP_POLICY }, + { ipe_op_kmodule, IPE_OP_KMODULE }, + { ipe_op_kernel_read, IPE_OP_KERNEL_READ }, + { ipe_op_max, NULL }, + }; + + return match_token((char *)op->val, ops, match); +} + +/** + * ipe_set_default: Set the default of the policy, at various scope levels + * depending on the value of op. + * @op: Operation that was parsed. + * @pol: Policy to modify with the newly-parsed default action. + * @a: Action token (see parse_action) to parse to determine + * the default. + * + * Return: + * 0 - OK + * -EBADMSG - Invalid policy format + */ +static int ipe_set_default(enum ipe_op op, struct ipe_policy *pol, + struct token *a) +{ + int rc = 0; + size_t i = 0; + enum ipe_action act = ipe_parse_action(a); + + if (act == ipe_action_unset) + return -EBADMSG; + + if (op == ipe_op_max) + return ipe_set_action(&pol->def, act); + + if (op == ipe_op_kernel_read) { + for (i = ipe_op_firmware; i <= ipe_op_kmodule; ++i) { + rc = ipe_set_action(&pol->ops[i].def, act); + if (rc != 0) + return rc; + } + return 0; + } + + return ipe_set_action(&pol->ops[op].def, act); +} + +/** + * ipe_parse_default: Parse a default statement of an IPE policy modify @pol + * with the proper changes + * @tokens: List of tokens parsed from the line + * @pol: Policy to modify with the newly-parsed default action + * + * + * Return: + * 0 - OK + * -EBADMSG - Invalid policy format + * -ENOENT - Unknown policy structure + */ +static int ipe_parse_default(struct list_head *tokens, + struct ipe_policy *pol) +{ + struct token *f = NULL; + struct token *s = NULL; + struct token *t = NULL; + enum ipe_op i = ipe_op_max; + + f = list_first_entry(tokens, struct token, next_tok); + s = list_next_entry(f, next_tok); + if (is_action(s)) + return ipe_set_default(ipe_op_max, pol, s); + + i = ipe_parse_op(s); + if (i == ipe_op_max) + return -ENOENT; + + t = list_next_entry(s, next_tok); + if (is_action(t)) { + t = list_next_entry(s, next_tok); + return ipe_set_default(i, pol, t); + } + + return -ENOENT; +} + +/** + * ipe_free_token_list - Free a list of tokens, and then reinitialize @list + * dropping all tokens. + * @list: List to be freed. + */ +static void ipe_free_token_list(struct list_head *list) +{ + struct token *ptr, *next; + + list_for_each_entry_safe(ptr, next, list, next_tok) + kfree(ptr); + + INIT_LIST_HEAD(list); +} + +/** + * ipe_free_prop - Deallocator for an ipe_prop_container structure. + * @cont: Object to free. + */ +static void ipe_free_prop(struct ipe_prop_container *cont) +{ + if (IS_ERR_OR_NULL(cont)) + return; + + if (cont->prop->free_val) + cont->prop->free_val(&cont->value); + kfree(cont); +} + +/** + * ipe_alloc_prop: Allocator for a ipe_prop_container structure. + * @tok: Token structure representing the "key=value" pair of the property. + * + * Return: + * Pointer to ipe_rule - OK + * ERR_PTR(-ENOMEM) - Allocation failed + */ +static struct ipe_prop_container *ipe_alloc_prop(const struct token *tok) +{ + int rc = 0; + const struct ipe_property *prop = NULL; + struct ipe_prop_container *cont = NULL; + + prop = ipe_lookup_prop(tok->key); + if (!prop) { + rc = -ENOENT; + goto err; + } + + cont = kzalloc(sizeof(*cont), GFP_KERNEL); + if (!cont) { + rc = -ENOMEM; + goto err; + } + + INIT_LIST_HEAD(&cont->next); + + rc = prop->parse(tok->val, &cont->value); + if (rc != 0) + goto err; + + cont->prop = prop; + + return cont; +err: + ipe_free_prop(cont); + return ERR_PTR(rc); +} + +/** + * ipe_free_rule: Deallocator for an ipe_rule structure. + * @rule: Object to free. + */ +static void ipe_free_rule(struct ipe_rule *rule) +{ + struct ipe_prop_container *ptr; + struct list_head *l_ptr, *l_next; + + if (IS_ERR_OR_NULL(rule)) + return; + + list_for_each_safe(l_ptr, l_next, &rule->props) { + ptr = container_of(l_ptr, struct ipe_prop_container, next); + list_del(l_ptr); + ipe_free_prop(ptr); + } + + kfree(rule); +} + +/** + * ipe_alloc_rule: Allocate a ipe_rule structure, for operation @op, parsed + * from the first token in list @head. + * @op: Operation parsed from the first token in @head. + * @t: The first token in @head that was parsed. + * @head: List of remaining tokens to parse. + * + * Return: + * Valid ipe_rule pointer - OK + * ERR_PTR(-EBADMSG) - Invalid syntax + * ERR_PTR(-ENOMEM) - Out of memory + */ +static struct ipe_rule *ipe_alloc_rule(enum ipe_op op, struct token *t, + struct list_head *head) +{ + int rc = 0; + struct token *ptr; + enum ipe_action act; + struct ipe_rule *rule = NULL; + struct ipe_prop_container *prop = NULL; + + ptr = list_next_entry(t, next_tok); + if (!is_action(ptr)) { + rc = -EBADMSG; + goto err; + } + + act = ipe_parse_action(ptr); + if (act == ipe_action_unset) { + rc = -EBADMSG; + goto err; + } + + rule = kzalloc(sizeof(*rule), GFP_KERNEL); + if (!rule) { + rc = -ENOMEM; + goto err; + } + + INIT_LIST_HEAD(&rule->props); + INIT_LIST_HEAD(&rule->next); + rule->action = act; + rule->op = op; + + list_for_each_entry_continue(ptr, head, next_tok) { + prop = ipe_alloc_prop(ptr); + + if (IS_ERR(prop)) { + rc = PTR_ERR(prop); + goto err; + } + + list_add_tail(&prop->next, &rule->props); + } + + return rule; +err: + ipe_free_prop(prop); + ipe_free_rule(rule); + return ERR_PTR(rc); +} + +/** + * ipe_dup_prop: Duplicate an ipe_prop_container structure + * @p: Container to duplicate. + * + * This function is used to duplicate individual properties within a rule. + * It should only be called in operations that actually map to one or more + * operations. + * + * Return: + * Valid ipe_prop_container - OK + * ERR_PTR(-ENOMEM) - Out of memory + * Other Errors - see various property duplicator functions + */ +static +struct ipe_prop_container *ipe_dup_prop(const struct ipe_prop_container *p) +{ + int rc = 0; + struct ipe_prop_container *dup; + + dup = kzalloc(sizeof(*dup), GFP_KERNEL); + if (!dup) { + rc = -ENOMEM; + goto err; + } + + dup->prop = p->prop; + INIT_LIST_HEAD(&dup->next); + + rc = p->prop->dup(p->value, &dup->value); + if (rc != 0) + goto err; + + return dup; +err: + ipe_free_prop(dup); + return ERR_PTR(rc); +} + +/** + * ipe_dup_rule: Duplicate a policy rule, used for pseudo hooks like + * KERNEL_READ to map a policy rule across all hooks. + * @r: Rule to duplicate. + * + * Return: + * valid ipe_rule - OK + * ERR_PTR(-ENOMEM) - Out of memory + * Other Errors - See ipe_dup_prop + */ +static struct ipe_rule *ipe_dup_rule(const struct ipe_rule *r) +{ + int rc = 0; + struct ipe_rule *dup; + struct ipe_prop_container *ptr; + + dup = kzalloc(sizeof(*dup), GFP_KERNEL); + if (!dup) { + rc = -ENOMEM; + goto err; + } + + dup->op = r->op; + dup->action = r->action; + INIT_LIST_HEAD(&dup->props); + INIT_LIST_HEAD(&dup->next); + + list_for_each_entry(ptr, &r->props, next) { + struct ipe_prop_container *prop2; + + prop2 = ipe_dup_prop(ptr); + if (IS_ERR(prop2)) { + rc = PTR_ERR(prop2); + goto err; + } + + list_add_tail(&prop2->next, &dup->props); + } + + return dup; +err: + ipe_free_rule(dup); + return ERR_PTR(rc); +} + +/** + * ipe_free_policy: Deallocate an ipe_policy structure. + * @pol: Policy to free. + */ +void ipe_free_policy(struct ipe_policy *pol) +{ + size_t i; + struct ipe_rule *ptr; + struct ipe_rule_table *op; + struct list_head *l_ptr, *l_next; + + if (IS_ERR_OR_NULL(pol)) + return; + + for (i = 0; i < ARRAY_SIZE(pol->ops); ++i) { + op = &pol->ops[i]; + + list_for_each_safe(l_ptr, l_next, &op->rules) { + ptr = list_entry(l_ptr, struct ipe_rule, next); + list_del(l_ptr); + ipe_free_rule(ptr); + } + } + + kfree(pol->policy_name); + kfree(pol); + pol = NULL; +} + +/** + * ipe_alloc_policy: Give a list of tokens representing the first line of the + * token, attempt to parse it as an IPE policy header, and + * allocate a policy structure based on those values. + * @tokens: List of tokens parsed from the first line of the policy + * + * Return: + * Valid ipe_policy pointer - OK + * ERR_PTR(-ENOMEM) - Out of memory + * ERR_PTR(-EBADMSG) - Invalid policy syntax + */ +static struct ipe_policy *ipe_alloc_policy(struct list_head *tokens) +{ + size_t i; + int rc = 0; + struct token *name = NULL; + struct token *ver = NULL; + struct ipe_policy *lp = NULL; + + name = list_first_entry(tokens, struct token, next_tok); + if (!is_name(name)) { + rc = -EBADMSG; + goto err; + } + + if (list_is_singular(tokens)) { + rc = -EBADMSG; + goto err; + } + + ver = list_next_entry(name, next_tok); + if (!is_ver(ver)) { + rc = -EBADMSG; + goto err; + } + + lp = kzalloc(sizeof(*lp), GFP_KERNEL); + if (!lp) { + rc = -ENOMEM; + goto err; + } + + lp->policy_name = kstrdup(name->val, GFP_KERNEL); + if (!lp->policy_name) { + rc = -ENOMEM; + goto err; + } + + rc = ipe_parse_version(ver->val, &lp->policy_version); + if (rc != 0) + goto err; + + for (i = 0; i < ARRAY_SIZE(lp->ops); ++i) { + lp->ops[i].def = ipe_action_unset; + INIT_LIST_HEAD(&lp->ops[i].rules); + } + + lp->def = ipe_action_unset; + + return lp; +err: + ipe_free_policy(lp); + return ERR_PTR(rc); +} + +/** + * ipe_add_rule_for_range: Given a ipe_rule @r, duplicate @r and add the rule + * to @pol for the operation range @start to @end. + * @start: The starting point of the range to add the rule to. + * @end: The ending point of the range to add the rule to. + * @r: The rule to copy. + * @pol: Policy structure to modify with the result. + * + * This is @start to @end, inclusive. @r is still valid after this function, + * and should be freed if appropriate. + * + * Return: + * 0 - OK + * Other Errors - See ipe_dup_prop + */ +static int ipe_add_rule_for_range(enum ipe_op start, enum ipe_op end, + struct ipe_rule *r, struct ipe_policy *pol) +{ + enum ipe_op i; + struct ipe_rule *cpy = NULL; + + for (i = start; i <= end; ++i) { + cpy = ipe_dup_rule(r); + if (IS_ERR(cpy)) + return PTR_ERR(cpy); + + list_add_tail(&cpy->next, &pol->ops[i].rules); + } + + return 0; +} + +/** + * ipe_parse_line: Given a list of tokens, attempt to parse it into a rule + * structure, and add it to the passed-in ipe_policy structure. + * @tokens: List of tokens that were parsed. + * @pol: Policy structure to modify with the result. + * + * Return: + * 0 - OK + * -ENOENT - Unrecognized property + * -ENOMEM - Out of memory + * Other Errors - See ipe_dup_prop + */ +static int ipe_parse_line(struct list_head *tokens, + struct ipe_policy *pol) +{ + int rc = 0; + struct token *f; + enum ipe_op i = ipe_op_max; + struct ipe_rule *rule = NULL; + + f = list_first_entry(tokens, struct token, next_tok); + + switch (f->key_priority) { + case default_action: + rc = ipe_parse_default(tokens, pol); + break; + case op: + i = ipe_parse_op(f); + if (i == ipe_op_max) + return -ENOENT; + + if (list_is_singular(tokens)) + return -EBADMSG; + + rule = ipe_alloc_rule(i, f, tokens); + if (IS_ERR(rule)) { + rc = PTR_ERR(rule); + goto cleanup; + } + + if (i == ipe_op_kernel_read) { + rc = ipe_add_rule_for_range(ipe_op_firmware, + ipe_op_kmodule, rule, pol); + if (rc != 0) + goto cleanup; + } else { + list_add_tail(&rule->next, &pol->ops[i].rules); + rule = NULL; + } + break; + default: + return -ENOENT; + } + +cleanup: + ipe_free_rule(rule); + return rc; +} + +/** + * ipe_remap_policy_defaults: Remap all defaults not specified by policy to + * 'allow' to preserve compatibility. + * @p: Policy to modify. + * + * This function's behavior changes when strict_parse is set. When the strict + * parser is enabled, this function will break backwards policy compatibility, + * erroring on an unset default. + * + * Return: + * 0 - OK + * -EBADMSG - (Only with strict parse) A default was left unset. + */ +static int ipe_remap_policy_defaults(struct ipe_policy *p) +{ + size_t i; + + if (p->def == ipe_action_unset) { + for (i = 0; i < ARRAY_SIZE(p->ops); ++i) { + if (p->ops[i].def == ipe_action_unset) { + ipe_audit_unset_remap((enum ipe_op)i); + if (strict_parse) + return -EBADMSG; + p->ops[i].def = ipe_action_allow; + } + } + } + + return 0; +} + +/** + * ipe_parse_policy: Given a string, parse the string into an IPE policy + * structure. + * @policy: NULL terminated string to parse. + * + * This function's behavior changes when strict_parse is set. When the strict + * parser is enabled, this function will break backwards policy compatibility, + * erroring on unknown syntax. This function will modify @policy. + * + * Return: + * Valid ipe_policy structure - OK + * ERR_PTR(-EBADMSG) - Invalid Policy Syntax (Unrecoverable) + * ERR_PTR(-ENOMEM) - Out of Memory + */ +struct ipe_policy *ipe_parse_policy(char *policy) +{ + int rc = 0; + size_t i = 1; + char *p = NULL; + LIST_HEAD(t_list); + struct ipe_policy *local_p = NULL; + + while ((p = strsep(&policy, "\n\0")) != NULL) { + rc = ipe_tokenize_line(p, &t_list); + if (rc == -ENOENT) { + ++i; + continue; + } + if (rc != 0) + goto err; + + if (!local_p) { + local_p = ipe_alloc_policy(&t_list); + if (IS_ERR(local_p)) { + rc = PTR_ERR(local_p); + goto err; + } + } else { + rc = ipe_parse_line(&t_list, local_p); + if (rc == -ENOENT) { + ipe_audit_ignore_line(i); + if (strict_parse) { + rc = -EBADMSG; + goto err; + } + } else if (rc != 0) { + goto err; + } + } + + ipe_free_token_list(&t_list); + ++i; + } + + rc = ipe_remap_policy_defaults(local_p); + if (rc != 0) + goto err; + + return local_p; +err: + ipe_free_token_list(&t_list); + ipe_free_policy(local_p); + return ERR_PTR(rc); +} diff --git a/security/ipe/ipe-parse.h b/security/ipe/ipe-parse.h new file mode 100644 index 000000000000..99310b5c3e00 --- /dev/null +++ b/security/ipe/ipe-parse.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include "ipe-policy.h" + +#include + +#ifndef IPE_PARSE_H +#define IPE_PARSE_H + +/** + * ipe_parse_policy: Given a string, parse the string into an IPE policy + * structure. + * @policy: NULL terminated string to parse. + * + * This function's behavior changes when strict_parse is set. When the strict + * parser is enabled, this function will break backwards policy compatibility, + * erroring on unknown syntax. This function will modify @policy. + * + * Return: + * Valid ipe_policy structure - OK + * ERR_PTR(-EBADMSG) - Invalid Policy Syntax (Unrecoverable) + * ERR_PTR(-ENOMEM) - Out of Memory + */ +struct ipe_policy *ipe_parse_policy(char *policy); + +/** + * ipe_free_policy: Deallocate an ipe_policy structure. + * @pol: Policy to free. + */ +void ipe_free_policy(struct ipe_policy *pol); + +#endif /* IPE_AUDIT_H */ diff --git a/security/ipe/ipe-policy.c b/security/ipe/ipe-policy.c new file mode 100644 index 000000000000..f39282160095 --- /dev/null +++ b/security/ipe/ipe-policy.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include "ipe.h" +#include "ipe-secfs.h" +#include "ipe-policy.h" +#include "ipe-parse.h" +#include "ipe-audit.h" + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static DEFINE_MUTEX(policy_lock); + +#define VER_TO_UINT64(_major, _minor, _rev) \ + ((((((u64)(_major)) << 16) | ((u64)(_minor))) << 16) | ((u64)(_rev))) + +/** + * ipe_is_version_allowed: Determine if @new has a greater or equal + * policy version than @old. + * @old: The policy to compare against. + * @new: The policy staged to replace @old. + * + * Return: + * true - @new has a policy version >= than @old + * false - @new does not have a policy version >= than @old + */ +static bool ipe_is_version_allowed(const struct ipe_pol_ver *old, + const struct ipe_pol_ver *new) +{ + u64 old_ver = VER_TO_UINT64(old->major, old->minor, old->rev); + u64 new_ver = VER_TO_UINT64(new->major, new->minor, new->rev); + + return new_ver >= old_ver; +} + +/** + * ipe_is_valid_policy: determine if @old is allowed to replace @new. + * @old: policy that the @new is supposed to replace. Can be NULL. + * @new: the policy that is supposed to replace @new. + * + * Return: + * true - @new can replace @old + * false - @new cannot replace @old + */ +bool ipe_is_valid_policy(const struct ipe_policy *old, + const struct ipe_policy *new) +{ + if (old) + return ipe_is_version_allowed(&old->policy_version, + &new->policy_version); + return true; +} + +/** + * ipe_is_active_policy: Determine if @policy is the currently active policy. + * @policy: Policy to check if it's the active policy. + * + * NOTE: If this attribute is needed to be consistent over a critical section, + * do not use this function, as it does not hold the read lock over the + * entirety of the critical section. + * + * Return: + * true - @policy is the active policy + * false - @policy is not the active policy + */ +bool ipe_is_active_policy(const struct ipe_policy *policy) +{ + bool result; + + rcu_read_lock(); + + result = rcu_dereference(ipe_active_policy) == policy; + + rcu_read_unlock(); + + return result; +} + +/** + * ipe_update_active_policy: Determine if @old is the active policy, and update + * the active policy if necessary. + * @old: The previous policy that the update is trying to replace. + * @new: The new policy attempting to replace @old. + * + * If @old is not the active policy, nothing will be done. + * + * Return: + * 0 - OK + * -EBADMSG - Invalid Policy + */ +int ipe_update_active_policy(const struct ipe_policy *old, + const struct ipe_policy *new) +{ + int rc = 0; + const struct ipe_policy *curr_policy = NULL; + + /* no active policy, safe to update */ + if (!ipe_active_policy) + return 0; + + mutex_lock(&policy_lock); + + curr_policy = rcu_dereference_protected(ipe_active_policy, + lockdep_is_held(&policy_lock)); + + if (curr_policy == old) { + if (!ipe_is_valid_policy(curr_policy, new)) { + rc = -EBADMSG; + goto cleanup; + } + + ipe_audit_policy_activation(new); + + (void)rcu_replace_pointer(ipe_active_policy, new, + lockdep_is_held(&policy_lock)); + } + + mutex_unlock(&policy_lock); + synchronize_rcu(); + + return rc; +cleanup: + mutex_unlock(&policy_lock); + return rc; +} + +/** + * ipe_activate_policy: Set a specific policy as the active policy. + * @pol: The policy to set as the active policy. + * + * This is only called by the sysctl "ipe.active_policy". + * + * Return: + * 0 - OK + * -EINVAL - Policy that is being activated is lower in version than + * currently running policy. + */ +int ipe_activate_policy(const struct ipe_policy *pol) +{ + int rc = 0; + const struct ipe_policy *curr_policy = NULL; + + mutex_lock(&policy_lock); + + curr_policy = rcu_dereference_protected(ipe_active_policy, + lockdep_is_held(&policy_lock)); + + /* + * User-set policies must be >= to current running policy. + */ + if (!ipe_is_valid_policy(curr_policy, pol)) { + rc = -EINVAL; + goto cleanup; + } + + ipe_audit_policy_activation(pol); + + /* cleanup of this pointer is handled by the secfs removal */ + (void)rcu_replace_pointer(ipe_active_policy, pol, + lockdep_is_held(&policy_lock)); + + mutex_unlock(&policy_lock); + synchronize_rcu(); + + return 0; +cleanup: + mutex_unlock(&policy_lock); + return rc; +} diff --git a/security/ipe/ipe-policy.h b/security/ipe/ipe-policy.h index c0c9f2962c92..c9da982ef2d4 100644 --- a/security/ipe/ipe-policy.h +++ b/security/ipe/ipe-policy.h @@ -59,4 +59,58 @@ struct ipe_policy { struct ipe_rule_table ops[ipe_op_max - 1]; }; +/** + * ipe_is_valid_policy: determine if @old is allowed to replace @new. + * @old: policy that the @new is supposed to replace. Can be NULL. + * @new: the policy that is supposed to replace @new. + * + * Return: + * true - @new can replace @old + * false - @new cannot replace @old + */ +bool ipe_is_valid_policy(const struct ipe_policy *old, + const struct ipe_policy *new); + +/** + * ipe_is_active_policy: Determine if @policy is the currently active policy. + * @policy: Policy to check if it's the active policy. + * + * NOTE: If this attribute is needed to be consistent over a critical section, + * do not use this function, as it does not hold the read lock over the + * entirety of the critical section. + * + * Return: + * true - @policy is the active policy + * false - @policy is not the active policy + */ +bool ipe_is_active_policy(const struct ipe_policy *policy); + +/** + * ipe_update_active_policy: Determine if @old is the active policy, and update + * the active policy if necessary. + * @old: The previous policy that the update is trying to replace. + * @new: The new policy attempting to replace @old. + * + * If @old is not the active policy, nothing will be done. + * + * Return: + * 0 - OK + * -EBADMSG - Invalid Policy + */ +int ipe_update_active_policy(const struct ipe_policy *old, + const struct ipe_policy *new); + +/** + * ipe_activate_policy: Set a specific policy as the active policy. + * @pol: The policy to set as the active policy. + * + * This is only called by the sysctl "ipe.active_policy". + * + * Return: + * 0 - OK + * -EINVAL - Policy that is being activated is lower in version than + * currently running policy. + */ +int ipe_activate_policy(const struct ipe_policy *policy); + #endif /* IPE_POLICY_H */ diff --git a/security/ipe/ipe-secfs.c b/security/ipe/ipe-secfs.c new file mode 100644 index 000000000000..1c9c41e143ab --- /dev/null +++ b/security/ipe/ipe-secfs.c @@ -0,0 +1,814 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include "ipe.h" +#include "ipe-parse.h" +#include "ipe-secfs.h" +#include "ipe-policy.h" +#include "ipe-audit.h" + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define IPE_ROOT "ipe" +#define IPE_FULL_CONTENT "raw" +#define IPE_INNER_CONTENT "content" +#define IPE_POLICIES "policies" +#define IPE_NEW_POLICY "new_policy" +#define IPE_DELETE_POLICY "del_policy" + +struct ipe_policy_node { + u8 *data; + size_t data_len; + const u8 *content; + size_t content_size; + + struct ipe_policy *parsed; +}; + +/* root directory */ +static struct dentry *ipe_secfs_root __ro_after_init; + +/* subdirectory containing policies */ +static struct dentry *ipe_policies_root __ro_after_init; + +/* boot policy */ +static struct dentry *boot_policy_node __ro_after_init; + +/* top-level policy commands */ +static struct dentry *ipe_new_policy __ro_after_init; +static struct dentry *ipe_del_policy __ro_after_init; + +static ssize_t ipe_secfs_new_policy(struct file *f, const char __user *data, + size_t len, loff_t *offset); + +static ssize_t ipe_secfs_del_policy(struct file *f, const char __user *data, + size_t len, loff_t *offset); + +static ssize_t ipe_secfs_rd_policy(struct file *f, char __user *data, + size_t len, loff_t *offset); + +static ssize_t ipe_secfs_ud_policy(struct file *f, const char __user *data, + size_t len, loff_t *offset); + +static ssize_t ipe_secfs_rd_content(struct file *f, char __user *data, + size_t len, loff_t *offset); + +const static struct file_operations new_policy_ops = { + .write = ipe_secfs_new_policy +}; + +const static struct file_operations del_policy_ops = { + .write = ipe_secfs_del_policy +}; + +const static struct file_operations policy_raw_ops = { + .read = ipe_secfs_rd_policy, + .write = ipe_secfs_ud_policy +}; + +const static struct file_operations policy_content_ops = { + .read = ipe_secfs_rd_content +}; + +/** + * ipe_free_policy_node: Free an ipe_policy_node structure allocated by + * ipe_alloc_policy_node. + * @n: Ipe_policy_node to free + */ +static void ipe_free_policy_node(struct ipe_policy_node *n) +{ + if (IS_ERR_OR_NULL(n)) + return; + + ipe_free_policy(n->parsed); + kfree(n->data); + + kfree(n); +} + +/** + * alloc_callback: Callback given to verify_pkcs7_signature function to set + * the inner content reference and parse the policy. + * @ctx: "ipe_policy_node" to set inner content, size and parsed policy of. + * @data: Start of PKCS#7 inner content. + * @len: Length of @data. + * @asn1hdrlen: Unused. + * + * Return: + * 0 - OK + * ERR_PTR(-EBADMSG) - Invalid policy syntax + * ERR_PTR(-ENOMEM) - Out of memory + */ +static int alloc_callback(void *ctx, const void *data, size_t len, + size_t asn1hdrlen) +{ + char *cpy = NULL; + struct ipe_policy *pol = NULL; + struct ipe_policy_node *n = (struct ipe_policy_node *)ctx; + + n->content = (const u8 *)data; + n->content_size = len; + + if (len == 0) + return -EBADMSG; + + cpy = kzalloc(len + 1, GFP_KERNEL); + if (!cpy) + return -ENOMEM; + + (void)strncpy(cpy, data, len); + + pol = ipe_parse_policy(cpy); + if (IS_ERR(pol)) { + kfree(cpy); + return PTR_ERR(pol); + } + + n->parsed = pol; + kfree(cpy); + return 0; +} + +/** + * ipe_alloc_policy_node: Allocate a new ipe_policy_node structure. + * @data: Raw enveloped PKCS#7 data that represents the policy. + * @len: Length of @data. + * + * Return: + * valid ipe_policy_node - OK + * ERR_PTR(-EBADMSG) - Invalid policy syntax + * ERR_PTR(-ENOMEM) - Out of memory + */ +static struct ipe_policy_node *ipe_alloc_policy_node(const u8 *data, + size_t len) +{ + int rc = 0; + struct ipe_policy_node *node = NULL; + + node = kzalloc(sizeof(*node), GFP_KERNEL); + if (!node) { + rc = -ENOMEM; + goto out; + } + + node->data_len = len; + node->data = kmemdup(data, len, GFP_KERNEL); + if (!node->data) { + rc = -ENOMEM; + goto out2; + } + + rc = verify_pkcs7_signature(node->content, node->content_size, + node->data, node->data_len, NULL, + VERIFYING_UNSPECIFIED_SIGNATURE, + alloc_callback, node); + if (rc != 0) + goto out2; + + return node; +out2: + ipe_free_policy_node(node); +out: + return ERR_PTR(rc); +} + +/** + * ipe_build_policy_secfs_node: Build a new securityfs node for IPE policies. + * @data: Raw enveloped PKCS#7 data that represents the policy. + * @len: Length of @data. + * + * Return: + * 0 - OK + * -EEXIST - Policy already exists + * -EBADMSG - Invalid policy syntax + * -ENOMEM - Out of memory + */ +int ipe_build_policy_secfs_node(const u8 *data, size_t len) +{ + int rc = 0; + struct dentry *raw = NULL; + struct dentry *root = NULL; + struct inode *root_i = NULL; + struct dentry *content = NULL; + struct crypto_shash *tfm = NULL; + struct ipe_policy_node *node = NULL; + + tfm = crypto_alloc_shash("sha1", 0, 0); + if (IS_ERR(tfm)) + goto out; + + node = ipe_alloc_policy_node(data, len); + if (IS_ERR(node)) { + rc = PTR_ERR(node); + goto out2; + } + + root = securityfs_create_dir(node->parsed->policy_name, + ipe_policies_root); + if (IS_ERR(root)) { + rc = PTR_ERR(root); + goto out3; + } + + root_i = d_inode(root); + + inode_lock(root_i); + root_i->i_private = node; + ipe_audit_policy_load(node->parsed, node->data, node->data_len, tfm); + inode_unlock(root_i); + + raw = securityfs_create_file(IPE_FULL_CONTENT, 0644, root, NULL, + &policy_raw_ops); + if (IS_ERR(raw)) { + rc = PTR_ERR(raw); + goto out4; + } + + content = securityfs_create_file(IPE_INNER_CONTENT, 0444, root, + NULL, &policy_content_ops); + if (IS_ERR(raw)) { + rc = PTR_ERR(raw); + goto out5; + } + + crypto_free_shash(tfm); + return rc; +out5: + securityfs_remove(raw); +out4: + securityfs_remove(root); +out3: + ipe_free_policy_node(node); +out2: + crypto_free_shash(tfm); +out: + return rc; +} + +/** + * ipe_secfs_new_policy: Entry point of the securityfs node, "ipe/new_policy". + * @f: Unused + * @data: Raw enveloped PKCS#7 data that represents the policy. + * @len: Length of @data. + * @offset: Offset for @data. + * + * Return: + * > 0 - OK + * -EEXIST - Policy already exists + * -EBADMSG - Invalid policy syntax + * -ENOMEM - Out of memory + * -EPERM - if a MAC subsystem is enabled, missing CAP_MAC_ADMIN + */ +static ssize_t ipe_secfs_new_policy(struct file *f, const char __user *data, + size_t len, loff_t *offset) +{ + ssize_t rc = 0; + u8 *cpy = NULL; + ssize_t written = 0; + + if (!ns_capable(current_user_ns(), CAP_MAC_ADMIN)) + return -EPERM; + + cpy = kzalloc(len, GFP_KERNEL); + if (!cpy) { + rc = -ENOMEM; + goto err; + } + + written = simple_write_to_buffer(cpy, len, offset, data, len); + if (written < 0) { + rc = written; + goto err; + } + + rc = ipe_build_policy_secfs_node(cpy, written); +err: + kfree(cpy); + return rc < 0 ? rc : written; +} + +/** + * retrieve_backed_dentry: Retrieve a dentry with a backing inode, identified + * by @name, under @parent. + * @name: Name of the dentry under @parent. + * @parent: The parent dentry to search under for @name. + * @size: Length of @name. + * + * This takes a reference to the returned dentry. Caller needs to call dput + * to drop the reference. + * + * Return: + * valid dentry - OK + * ERR_PTR - Error, see lookup_one_len_unlocked + * NULL - No backing inode was found + */ +static struct dentry *retrieve_backed_dentry(const char *name, + struct dentry *parent, + size_t size) +{ + int rc = 0; + struct dentry *tmp = NULL; + + tmp = lookup_one_len_unlocked(name, parent, size); + if (IS_ERR(tmp)) { + rc = PTR_ERR(tmp); + goto out; + } + + if (!d_really_is_positive(tmp)) + goto out1; + + return tmp; +out1: + tmp = NULL; +out: + return rc == 0 ? NULL : ERR_PTR(rc); +} + +/** + * ipe_secfs_del_policy: Delete a policy indicated by the name provided by + * @data + * @f: Unused. + * @data: Buffer containing the policy id to delete. + * @len: Length of @data. + * @offset: Offset into @data. + * + * NOTE: Newlines are treated as part of the name, if using echo to test, + * use -n to prohibit the silent addition of a newline. + * + * Return: + * > 0 - OK + * -ENOMEM - Out of memory + * -EPERM - Policy is active + * -ENOENT - Policy does not exist + * -EPERM - if a MAC subsystem is enabled, missing CAP_MAC_ADMIN + * Other - See retrieve_backed_dentry + */ +static ssize_t ipe_secfs_del_policy(struct file *f, const char __user *data, + size_t len, loff_t *offset) +{ + ssize_t rc = 0; + char *id = NULL; + ssize_t written = 0; + struct dentry *raw = NULL; + struct dentry *content = NULL; + struct inode *policy_i = NULL; + struct dentry *policy_root = NULL; + struct inode *policies_root = NULL; + const struct ipe_policy *target = NULL; + + if (!ns_capable(current_user_ns(), CAP_MAC_ADMIN)) + return -EPERM; + + id = kzalloc(len, GFP_KERNEL); + if (!id) { + rc = -ENOMEM; + goto out; + } + + written = simple_write_to_buffer(id, len, offset, data, len); + if (written < 0) { + rc = written; + goto out; + } + + policies_root = d_inode(ipe_policies_root); + + policy_root = retrieve_backed_dentry(id, ipe_policies_root, written); + if (IS_ERR_OR_NULL(policy_root)) { + rc = IS_ERR(policy_root) ? PTR_ERR(policy_root) : -ENOENT; + goto out; + } + + policy_i = d_inode(policy_root); + + /* if the found dentry matches boot policy, fail */ + if (boot_policy_node == policy_root) { + rc = -EACCES; + goto out1; + } + + target = ((struct ipe_policy_node *)policy_i->i_private)->parsed; + + /* fail if it's the active policy */ + if (ipe_is_active_policy(target)) { + rc = -EPERM; + goto out1; + } + + raw = retrieve_backed_dentry(IPE_FULL_CONTENT, policy_root, + strlen(IPE_FULL_CONTENT)); + if (IS_ERR_OR_NULL(raw)) { + rc = IS_ERR(raw) ? PTR_ERR(raw) : -ENOENT; + goto out1; + } + + content = retrieve_backed_dentry(IPE_INNER_CONTENT, policy_root, + strlen(IPE_INNER_CONTENT)); + if (IS_ERR_OR_NULL(content)) { + rc = IS_ERR(content) ? PTR_ERR(content) : -ENOENT; + goto out2; + } + + inode_lock(policies_root); + ipe_free_policy_node(policy_i->i_private); + policy_i->i_private = NULL; + inode_unlock(policies_root); + + dput(raw); + dput(content); + dput(policy_root); + securityfs_remove(raw); + securityfs_remove(content); + securityfs_remove(policy_root); + + kfree(id); + return written; +out2: + dput(raw); +out1: + dput(policy_root); +out: + kfree(id); + return rc; +} + +/** + * ipe_secfs_rd_policy: Read the raw content (full enveloped PKCS7) data of + * the policy stored within the file's parent inode. + * @f: File representing the securityfs entry. + * @data: User mode buffer to place the raw pkcs7. + * @len: Length of @data. + * @offset: Offset into @data. + * + * Return: + * > 0 - OK + * -ENOMEM - Out of memory + */ +static ssize_t ipe_secfs_rd_policy(struct file *f, char __user *data, + size_t size, loff_t *offset) +{ + ssize_t rc = 0; + size_t avail = 0; + u8 *buffer = NULL; + struct inode *root = NULL; + const struct ipe_policy_node *node = NULL; + + root = d_inode(f->f_path.dentry->d_parent); + + inode_lock_shared(root); + node = (const struct ipe_policy_node *)root->i_private; + + avail = node->data_len; + buffer = kmemdup(node->data, avail, GFP_KERNEL); + if (!buffer) { + rc = -ENOMEM; + goto cleanup; + } + + rc = simple_read_from_buffer(data, size, offset, buffer, avail); +cleanup: + inode_unlock_shared(root); + + return rc; +} + +/** + * ipe_secfs_ud_policy: Update a policy in place with a new PKCS7 policy. + * @f: File representing the securityfs entry. + * @data: Buffer user mode to place the raw pkcs7. + * @len: Length of @data. + * @offset: Offset into @data. + * + * Return: + * 0 - OK + * -EBADMSG - Invalid policy format + * -ENOMEM - Out of memory + * -EPERM - if a MAC subsystem is enabled, missing CAP_MAC_ADMIN + * -EINVAL - Incorrect policy name for this node, or version is < current + */ +static ssize_t ipe_secfs_ud_policy(struct file *f, const char __user *data, + size_t len, loff_t *offset) +{ + ssize_t rc = 0; + u8 *cpy = NULL; + ssize_t written = 0; + struct inode *root = NULL; + struct crypto_shash *tfm = NULL; + struct ipe_policy_node *new = NULL; + struct ipe_policy_node *old = NULL; + + if (!ns_capable(current_user_ns(), CAP_MAC_ADMIN)) + return -EPERM; + + cpy = kzalloc(len, GFP_KERNEL); + if (!cpy) { + rc = -ENOMEM; + goto out; + } + + written = simple_write_to_buffer(cpy, len, offset, data, len); + if (written < 0) { + rc = written; + goto out; + } + + new = ipe_alloc_policy_node(cpy, len); + if (IS_ERR(new)) { + rc = PTR_ERR(new); + goto out; + } + + tfm = crypto_alloc_shash("sha1", 0, 0); + if (IS_ERR(tfm)) + goto out2; + + root = d_inode(f->f_path.dentry->d_parent); + inode_lock(root); + + old = (struct ipe_policy_node *)root->i_private; + + if (strcmp(old->parsed->policy_name, new->parsed->policy_name)) { + rc = -EINVAL; + goto out3; + } + + if (!ipe_is_valid_policy(old->parsed, new->parsed)) { + rc = -EINVAL; + goto out3; + } + + rc = ipe_update_active_policy(old->parsed, new->parsed); + if (rc != 0) + goto out3; + + ipe_audit_policy_load(new->parsed, new->data, new->data_len, tfm); + swap(root->i_private, new); + + inode_unlock(root); + kfree(cpy); + ipe_free_policy_node(new); + crypto_free_shash(tfm); + + return written; +out3: + inode_unlock(root); + ipe_free_policy_node(new); +out2: + crypto_free_shash(tfm); +out: + kfree(cpy); + return rc; +} + +/** + * ipe_secfs_rd_content: Read the inner content of the enveloped PKCS7 data, + * representing the IPE policy. + * @f: File representing the securityfs entry. + * @data: User mode buffer to place the inner content of the pkcs7 data. + * @len: Length of @data. + * @offset: Offset into @data. + * + * Return: + * > 0 - OK + * -ENOMEM - Out of memory + */ +static ssize_t ipe_secfs_rd_content(struct file *f, char __user *data, + size_t size, loff_t *offset) +{ + ssize_t rc = 0; + size_t avail = 0; + u8 *buffer = NULL; + struct inode *root = NULL; + const struct ipe_policy_node *node = NULL; + + root = d_inode(f->f_path.dentry->d_parent); + + inode_lock(root); + node = (const struct ipe_policy_node *)root->i_private; + + avail = node->content_size; + buffer = kmemdup(node->content, avail, GFP_KERNEL); + if (!buffer) { + rc = -ENOMEM; + goto cleanup; + } + + rc = simple_read_from_buffer(data, size, offset, buffer, avail); +cleanup: + inode_unlock(root); + + return rc; +} + +/** + * ipe_build_secfs_root: Build the root of securityfs for IPE. + * + * Return: + * 0 - OK + * !0 - See securityfs_create_dir and securityfs_create_file + */ +int __init ipe_build_secfs_root(void) +{ + int rc = 0; + struct dentry *new = NULL; + struct dentry *del = NULL; + struct dentry *root = NULL; + struct dentry *policies = NULL; + + root = securityfs_create_dir(IPE_ROOT, NULL); + if (IS_ERR(root)) { + rc = PTR_ERR(root); + goto out; + } + + new = securityfs_create_file(IPE_NEW_POLICY, 0644, root, NULL, + &new_policy_ops); + if (IS_ERR(new)) { + rc = PTR_ERR(new); + goto out1; + } + + del = securityfs_create_file(IPE_DELETE_POLICY, 0644, root, NULL, + &del_policy_ops); + if (IS_ERR(del)) { + rc = PTR_ERR(del); + goto out2; + } + + policies = securityfs_create_dir(IPE_POLICIES, root); + if (IS_ERR(policies)) { + rc = PTR_ERR(policies); + goto out3; + } + + ipe_secfs_root = root; + ipe_new_policy = new; + ipe_del_policy = del; + ipe_policies_root = policies; + + return rc; + +out3: + securityfs_remove(del); +out2: + securityfs_remove(new); +out1: + securityfs_remove(root); +out: + return rc; +} + +/** + * ipe_build_secfs_boot_node: Build a policy node for IPE's boot policy. + * + * This differs from the normal policy nodes, as the IPE boot policy is + * read only. + * + * Return: + * 0 - OK + * !0 - See securityfs_create_dir and securityfs_create_file + */ +static int __init ipe_build_secfs_boot_node(void) +{ + int rc = 0; + char *cpy = NULL; + struct dentry *raw = NULL; + struct inode *raw_i = NULL; + struct dentry *root = NULL; + struct dentry *content = NULL; + struct ipe_policy *parsed = NULL; + struct ipe_policy_node *node = NULL; + + if (!ipe_boot_policy) + return 0; + + node = kzalloc(sizeof(*node), GFP_KERNEL); + if (!node) { + rc = -ENOMEM; + goto out; + } + + cpy = kstrdup(ipe_boot_policy, GFP_KERNEL); + if (!cpy) { + rc = -ENOMEM; + goto out; + } + + parsed = ipe_parse_policy(cpy); + if (IS_ERR(parsed)) { + rc = PTR_ERR(parsed); + goto out2; + } + + node->content = ipe_boot_policy; + node->content_size = strlen(cpy); + node->parsed = parsed; + + root = securityfs_create_dir(node->parsed->policy_name, + ipe_policies_root); + if (IS_ERR(root)) { + rc = PTR_ERR(root); + goto out2; + } + + raw_i = d_inode(root); + + inode_lock(raw_i); + raw_i->i_private = node; + inode_unlock(raw_i); + + content = securityfs_create_file(IPE_INNER_CONTENT, 0444, root, NULL, + &policy_content_ops); + if (IS_ERR(raw)) { + rc = PTR_ERR(raw); + goto out3; + } + + boot_policy_node = root; + rc = ipe_activate_policy(node->parsed); + return rc; + +out3: + securityfs_remove(root); +out2: + ipe_free_policy(parsed); +out: + kfree(cpy); + kfree(node); + return rc; +} + +/** + * ipe_set_active_policy: Set the policy identified by @id as the active + * policy. + * @id: Policy id represnting the policy to activate. + * @id_len: Length of @id. + * + * Return: + * 0 - OK + * -ENOENT - Policy identified by @id does not exist + * -EINVAL - Policy that is being activated is lower in version than + * currently running policy. + * Other - See retrieve_backed_dentry + */ +int ipe_set_active_policy(const char *id, size_t id_len) +{ + int rc = 0; + struct dentry *policy_root = NULL; + const struct ipe_policy_node *ref = NULL; + + policy_root = retrieve_backed_dentry(id, ipe_policies_root, id_len); + if (IS_ERR_OR_NULL(policy_root)) + return IS_ERR(policy_root) ? PTR_ERR(policy_root) : -ENOENT; + + inode_lock_shared(d_inode(policy_root)); + + ref = (const struct ipe_policy_node *)d_inode(policy_root)->i_private; + rc = ipe_activate_policy(ref->parsed); + + inode_unlock_shared(d_inode(policy_root)); + dput(policy_root); + + return rc; +} + +/** + * ipe_securityfs_init: Initialize IPE's securityfs entries. + * + * This is called after the lsm initialization. + * + * Return: + * 0 - OK + * !0 - Error + */ +int __init ipe_securityfs_init(void) +{ + int rc = 0; + + rc = ipe_build_secfs_root(); + if (rc != 0) + goto err; + + rc = ipe_build_secfs_boot_node(); + if (rc != 0) + panic("IPE failed to initialize the boot policy: %d", rc); + + return rc; +err: + pr_err("failed to initialize secfs: %d", -rc); + return rc; +} + +core_initcall(ipe_securityfs_init); diff --git a/security/ipe/ipe-secfs.h b/security/ipe/ipe-secfs.h new file mode 100644 index 000000000000..714ae70a4c8e --- /dev/null +++ b/security/ipe/ipe-secfs.h @@ -0,0 +1,25 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ +#include + +#include "ipe-policy.h" + +#ifndef IPE_SECFS_H +#define IPE_SECFS_H + +/** + * ipe_set_active_policy: Set the policy identified by @id as the active + * policy. + * @id: Policy id represnting the policy to activate. + * @id_len: Length of @id. + * + * Return: + * 0 - OK + * -ENOENT - Policy identified by @id does not exist + * Other - See retrieve_backed_dentry + */ +int ipe_set_active_policy(const char *id, size_t id_len); + +#endif /* IPE_SECFS_H */ diff --git a/security/ipe/ipe-sysfs.c b/security/ipe/ipe-sysfs.c index c97685a25b6a..a3c998da69da 100644 --- a/security/ipe/ipe-sysfs.c +++ b/security/ipe/ipe-sysfs.c @@ -5,6 +5,7 @@ #include "ipe.h" #include "ipe-audit.h" +#include "ipe-secfs.h" #include #include @@ -45,6 +46,73 @@ static int ipe_switch_mode(struct ctl_table *table, int write, #endif /* CONFIG_SECURITY_IPE_PERMISSIVE_SWITCH */ +#ifdef CONFIG_SECURITYFS + +/** + * ipe_switch_active_policy: Handler to switch the policy IPE is enforcing. + * @table: Sysctl table entry from the variable, sysctl_table. + * @write: Integer indicating whether this is a write or a read. + * @buffer: Data passed to sysctl. This is the policy id to activate, + * for this function. + * @lenp: Pointer to the size of @buffer. + * @ppos: Offset into @buffer. + * + * This wraps proc_dointvec_minmax, and if there's a change, emits an + * audit event. + * + * Return: + * 0 - OK + * -ENOMEM - Out of memory + * -ENOENT - Policy identified by @id does not exist + * Other - See proc_dostring and retrieve_backed_dentry + */ +static int ipe_switch_active_policy(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int rc = 0; + char *id = NULL; + size_t size = 0; + + if (write) { + id = kzalloc((*lenp) + 1, GFP_KERNEL); + if (!id) + return -ENOMEM; + + table->data = id; + table->maxlen = (*lenp) + 1; + + rc = proc_dostring(table, write, buffer, lenp, ppos); + if (rc != 0) + goto out; + + rc = ipe_set_active_policy(id, strlen(id)); + } else { + rcu_read_lock(); + size = strlen(rcu_dereference(ipe_active_policy)->policy_name); + rcu_read_unlock(); + + id = kzalloc(size + 1, GFP_KERNEL); + if (!id) + return -ENOMEM; + + rcu_read_lock(); + strncpy(id, rcu_dereference(ipe_active_policy)->policy_name, + size); + rcu_read_unlock(); + + table->data = id; + table->maxlen = size; + + rc = proc_dostring(table, write, buffer, lenp, ppos); + } +out: + kfree(id); + return rc; +} + +#endif /* CONFIG_SECURITYFS */ + static struct ctl_table_header *sysctl_header; static const struct ctl_path sysctl_path[] = { @@ -75,6 +143,24 @@ static struct ctl_table sysctl_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, +#ifdef CONFIG_SECURITYFS + { + .procname = "strict_parse", + .data = &strict_parse, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + { + .procname = "active_policy", + .data = NULL, + .maxlen = 0, + .mode = 0644, + .proc_handler = ipe_switch_active_policy, + }, +#endif /* CONFIG_SECURITYFS */ {} /* TODO: Active Policy Selector */ }; diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c index 0c30d7c629c9..4642a0da57e5 100644 --- a/security/ipe/ipe.c +++ b/security/ipe/ipe.c @@ -6,6 +6,7 @@ #include "ipe.h" #include "ipe-policy.h" #include "ipe-hooks.h" +#include "ipe-secfs.h" #include "ipe-sysfs.h" #include @@ -97,3 +98,15 @@ MODULE_PARM_DESC(enforce, "enforce/permissive mode switch"); int success_audit; module_param(success_audit, int, 0644); MODULE_PARM_DESC(success_audit, "audit message on allow"); + +/** + * strict_parse: Kernel command line parameter to enable strict parsing of + * IPE policies - causing unrecognized properties to fail + * parsing. This breaks backwards compatibility of IPE policies, + * when enabled. + * + * This is also controlled by the sysctl, "ipe.strict_parse". + */ +int strict_parse; +module_param(strict_parse, int, 0644); +MODULE_PARM_DESC(strict_parse, "parse using strict semantics"); diff --git a/security/ipe/ipe.h b/security/ipe/ipe.h index 52e5ea0ccaef..c016b57aa70b 100644 --- a/security/ipe/ipe.h +++ b/security/ipe/ipe.h @@ -16,5 +16,6 @@ extern int enforce; extern int success_audit; +extern int strict_parse; #endif /* IPE_H */