| Message ID | 1711657047-10526-3-git-send-email-wufan@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Integrity Policy Enforcement LSM (IPE) | expand |
On Thu Mar 28, 2024 at 10:17 PM EET, Fan Wu wrote: > From: Deven Bowers <deven.desai@linux.microsoft.com> > > IPE's interpretation of the what the user trusts is accomplished through > its policy. IPE's design is to not provide support for a single trust > provider, but to support multiple providers to enable the end-user to > choose the best one to seek their needs. > > This requires the policy to be rather flexible and modular so that > integrity providers, like fs-verity, dm-verity, dm-integrity, or > some other system, can plug into the policy with minimal code changes. > > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com> > > --- > v2: > + Split evaluation loop, access control hooks, > and evaluation loop from policy parser and userspace > interface to pass mailing list character limit > > v3: > + Move policy load and activation audit event to 03/12 > + Fix a potential panic when a policy failed to load. > + use pr_warn for a failure to parse instead of an > audit record > + Remove comments from headers > + Add lockdep assertions to ipe_update_active_policy and > ipe_activate_policy > + Fix up warnings with checkpatch --strict > + Use file_ns_capable for CAP_MAC_ADMIN for securityfs > nodes. > + Use memdup_user instead of kzalloc+simple_write_to_buffer. > + Remove strict_parse command line parameter, as it is added > by the sysctl command line. > + Prefix extern variables with ipe_ > > v4: > + Remove securityfs to reverse-dependency > + Add SHA1 reverse dependency. > + Add versioning scheme for IPE properties, and associated > interface to query the versioning scheme. > + Cause a parser to always return an error on unknown syntax. > + Remove strict_parse option > + Change active_policy interface from sysctl, to securityfs, > and change scheme. > > v5: > + Cause an error if a default action is not defined for each > operation. > + Minor function renames > > v6: > + No changes > > v7: > + Further split parser and userspace interface into two > separate commits, for easier review. > + Refactor policy parser to make code cleaner via introducing a > more modular design, for easier extension of policy, and > easier review. > > v8: > + remove unnecessary pr_info emission on parser loading > + add explicit newline to the pr_err emitted when a parser > fails to load. > > v9: > + switch to match table to parse policy > + remove quote syntax and KERNEL_READ operation > > v10: > + Fix memory leaks in parser > + Fix typos and change code styles > > v11: > + Fix code style issues > > v12: > + Add __always_unused to an unused parameter > + Simplify error case handling > > v13: > + No changes > > v14: > + No changes > > v15: > + No changes > > v16: > + No changes > --- > security/ipe/Makefile | 2 + > security/ipe/policy.c | 101 ++++++++ > security/ipe/policy.h | 83 ++++++ > security/ipe/policy_parser.c | 487 +++++++++++++++++++++++++++++++++++ > security/ipe/policy_parser.h | 11 + > 5 files changed, 684 insertions(+) > create mode 100644 security/ipe/policy.c > create mode 100644 security/ipe/policy.h > create mode 100644 security/ipe/policy_parser.c > create mode 100644 security/ipe/policy_parser.h > > diff --git a/security/ipe/Makefile b/security/ipe/Makefile > index f7a80d0f18f8..c09aec4904f2 100644 > --- a/security/ipe/Makefile > +++ b/security/ipe/Makefile > @@ -7,3 +7,5 @@ > > obj-$(CONFIG_SECURITY_IPE) += \ > ipe.o \ > + policy.o \ > + policy_parser.o \ > diff --git a/security/ipe/policy.c b/security/ipe/policy.c > new file mode 100644 > index 000000000000..f22a576a6d68 > --- /dev/null > +++ b/security/ipe/policy.c > @@ -0,0 +1,101 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > + > +#include <linux/errno.h> > +#include <linux/verification.h> > + > +#include "ipe.h" > +#include "policy.h" > +#include "policy_parser.h" > + > +/** > + * ipe_free_policy - Deallocate a given IPE policy. > + * @p: Supplies the policy to free. > + * > + * Safe to call on IS_ERR/NULL. > + */ > +void ipe_free_policy(struct ipe_policy *p) > +{ > + if (IS_ERR_OR_NULL(p)) > + return; > + > + free_parsed_policy(p->parsed); > + /* > + * p->text is allocated only when p->pkcs7 is not NULL > + * otherwise it points to the plaintext data inside the pkcs7 > + */ > + if (!p->pkcs7) > + kfree(p->text); > + kfree(p->pkcs7); > + kfree(p); > +} > + > +static int set_pkcs7_data(void *ctx, const void *data, size_t len, > + size_t asn1hdrlen __always_unused) > +{ > + struct ipe_policy *p = ctx; > + > + p->text = (const char *)data; > + p->textlen = len; > + > + return 0; > +} > + > +/** > + * ipe_new_policy - Allocate and parse an ipe_policy structure. > + * > + * @text: Supplies a pointer to the plain-text policy to parse. > + * @textlen: Supplies the length of @text. > + * @pkcs7: Supplies a pointer to a pkcs7-signed IPE policy. > + * @pkcs7len: Supplies the length of @pkcs7. > + * > + * @text/@textlen Should be NULL/0 if @pkcs7/@pkcs7len is set. > + * > + * Return: > + * * !IS_ERR - Success s/!IS_ERR/0/ > + * * -EBADMSG - Policy is invalid > + * * -ENOMEM - Out of memory > + */ > +struct ipe_policy *ipe_new_policy(const char *text, size_t textlen, > + const char *pkcs7, size_t pkcs7len) > +{ > + int rc = 0; > + struct ipe_policy *new = NULL; > + > + new = kzalloc(sizeof(*new), GFP_KERNEL); > + if (!new) > + return ERR_PTR(-ENOMEM); > + > + if (!text) { > + new->pkcs7len = pkcs7len; > + new->pkcs7 = kmemdup(pkcs7, pkcs7len, GFP_KERNEL); > + if (!new->pkcs7) { > + rc = -ENOMEM; > + goto err; > + } > + > + rc = verify_pkcs7_signature(NULL, 0, new->pkcs7, pkcs7len, NULL, > + VERIFYING_UNSPECIFIED_SIGNATURE, > + set_pkcs7_data, new); > + if (rc) > + goto err; > + } else { > + new->textlen = textlen; > + new->text = kstrdup(text, GFP_KERNEL); > + if (!new->text) { > + rc = -ENOMEM; > + goto err; > + } > + } > + > + rc = parse_policy(new); > + if (rc) > + goto err; > + > + return new; > +err: > + ipe_free_policy(new); > + return ERR_PTR(rc); > +} > diff --git a/security/ipe/policy.h b/security/ipe/policy.h > new file mode 100644 > index 000000000000..fb906f41522b > --- /dev/null > +++ b/security/ipe/policy.h > @@ -0,0 +1,83 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > +#ifndef _IPE_POLICY_H > +#define _IPE_POLICY_H > + > +#include <linux/list.h> > +#include <linux/types.h> > + > +enum ipe_op_type { > + IPE_OP_EXEC = 0, > + IPE_OP_FIRMWARE, > + IPE_OP_KERNEL_MODULE, > + IPE_OP_KEXEC_IMAGE, > + IPE_OP_KEXEC_INITRAMFS, > + IPE_OP_POLICY, > + IPE_OP_X509, > + __IPE_OP_MAX, > +}; > + > +#define IPE_OP_INVALID __IPE_OP_MAX > + > +enum ipe_action_type { > + IPE_ACTION_ALLOW = 0, > + IPE_ACTION_DENY, > + __IPE_ACTION_MAX > +}; > + > +#define IPE_ACTION_INVALID __IPE_ACTION_MAX > + > +enum ipe_prop_type { > + __IPE_PROP_MAX > +}; > + > +#define IPE_PROP_INVALID __IPE_PROP_MAX > + > +struct ipe_prop { > + struct list_head next; > + enum ipe_prop_type type; > + void *value; > +}; > + > +struct ipe_rule { > + enum ipe_op_type op; > + enum ipe_action_type action; > + struct list_head props; > + struct list_head next; > +}; > + > +struct ipe_op_table { > + struct list_head rules; > + enum ipe_action_type default_action; > +}; > + > +struct ipe_parsed_policy { > + const char *name; > + struct { > + u16 major; > + u16 minor; > + u16 rev; > + } version; > + > + enum ipe_action_type global_default_action; > + > + struct ipe_op_table rules[__IPE_OP_MAX]; > +}; > + > +struct ipe_policy { > + const char *pkcs7; > + size_t pkcs7len; > + > + const char *text; > + size_t textlen; > + > + struct ipe_parsed_policy *parsed; > +}; > + > +struct ipe_policy *ipe_new_policy(const char *text, size_t textlen, > + const char *pkcs7, size_t pkcs7len); > +void ipe_free_policy(struct ipe_policy *pol); > + > +#endif /* _IPE_POLICY_H */ > diff --git a/security/ipe/policy_parser.c b/security/ipe/policy_parser.c > new file mode 100644 > index 000000000000..612839b405f4 > --- /dev/null > +++ b/security/ipe/policy_parser.c > @@ -0,0 +1,487 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > + > +#include <linux/err.h> > +#include <linux/slab.h> > +#include <linux/parser.h> > +#include <linux/types.h> > +#include <linux/ctype.h> > + > +#include "policy.h" > +#include "policy_parser.h" > + > +#define START_COMMENT '#' > +#define IPE_POLICY_DELIM " \t" > +#define IPE_LINE_DELIM "\n\r" > + > +/** > + * new_parsed_policy - Allocate and initialize a parsed policy. > + * > + * Return: > + * * !IS_ERR - OK > + * * -ENOMEM - Out of memory > + */ > +static struct ipe_parsed_policy *new_parsed_policy(void) > +{ > + size_t i = 0; > + struct ipe_parsed_policy *p = NULL; > + struct ipe_op_table *t = NULL; > + > + p = kzalloc(sizeof(*p), GFP_KERNEL); > + if (!p) > + return ERR_PTR(-ENOMEM); > + > + p->global_default_action = IPE_ACTION_INVALID; > + > + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) { > + t = &p->rules[i]; > + > + t->default_action = IPE_ACTION_INVALID; > + INIT_LIST_HEAD(&t->rules); > + } > + > + return p; > +} > + > +/** > + * remove_comment - Truncate all chars following START_COMMENT in a string. > + * > + * @line: Supplies a policy line string for preprocessing. > + */ > +static void remove_comment(char *line) > +{ > + line = strchr(line, START_COMMENT); > + > + if (line) > + *line = '\0'; > +} > + > +/** > + * remove_trailing_spaces - Truncate all trailing spaces in a string. > + * > + * @line: Supplies a policy line string for preprocessing. > + * > + * Return: The length of truncated string. > + */ > +static size_t remove_trailing_spaces(char *line) > +{ > + size_t i = 0; > + > + i = strlen(line); > + while (i > 0 && isspace(line[i - 1])) > + i--; > + > + line[i] = '\0'; > + > + return i; > +} > + > +/** > + * parse_version - Parse policy version. > + * @ver: Supplies a version string to be parsed. > + * @p: Supplies the partial parsed policy. > + * > + * Return: > + * * 0 - OK > + * * !0 - Standard errno > + */ > +static int parse_version(char *ver, struct ipe_parsed_policy *p) > +{ > + int rc = 0; > + size_t sep_count = 0; > + char *token; > + u16 *const cv[] = { &p->version.major, &p->version.minor, &p->version.rev }; > + > + while ((token = strsep(&ver, ".")) != NULL) { > + /* prevent overflow */ > + if (sep_count >= ARRAY_SIZE(cv)) > + return -EBADMSG; > + > + rc = kstrtou16(token, 10, cv[sep_count]); > + if (rc) > + return rc; > + > + ++sep_count; > + } > + > + /* prevent underflow */ > + if (sep_count != ARRAY_SIZE(cv)) > + return -EBADMSG; > + > + return 0; > +} > + > +enum header_opt { > + IPE_HEADER_POLICY_NAME = 0, > + IPE_HEADER_POLICY_VERSION, > + __IPE_HEADER_MAX > +}; > + > +static const match_table_t header_tokens = { > + {IPE_HEADER_POLICY_NAME, "policy_name=%s"}, > + {IPE_HEADER_POLICY_VERSION, "policy_version=%s"}, > + {__IPE_HEADER_MAX, NULL} > +}; > + > +/** > + * parse_header - Parse policy header information. > + * @line: Supplies header line to be parsed. > + * @p: Supplies the partial parsed policy. > + * > + * Return: > + * * 0 - OK > + * * !0 - Standard errno > + */ > +static int parse_header(char *line, struct ipe_parsed_policy *p) > +{ > + int rc = 0; > + char *t, *ver = NULL; > + substring_t args[MAX_OPT_ARGS]; > + size_t idx = 0; > + > + while ((t = strsep(&line, IPE_POLICY_DELIM)) != NULL) { > + int token; > + > + if (*t == '\0') > + continue; > + if (idx >= __IPE_HEADER_MAX) { > + rc = -EBADMSG; > + goto out; > + } > + > + token = match_token(t, header_tokens, args); > + if (token != idx) { > + rc = -EBADMSG; > + goto out; > + } > + > + switch (token) { > + case IPE_HEADER_POLICY_NAME: > + p->name = match_strdup(&args[0]); > + if (!p->name) > + rc = -ENOMEM; > + break; > + case IPE_HEADER_POLICY_VERSION: > + ver = match_strdup(&args[0]); > + if (!ver) { > + rc = -ENOMEM; > + break; > + } > + rc = parse_version(ver, p); > + break; > + default: > + rc = -EBADMSG; > + } > + if (rc) > + goto out; > + ++idx; > + } > + > + if (idx != __IPE_HEADER_MAX) > + rc = -EBADMSG; > + > +out: > + kfree(ver); > + return rc; > +} > + > +/** > + * token_default - Determine if the given token is "DEFAULT". > + * @token: Supplies the token string to be compared. > + * > + * Return: > + * * 0 - The token is not "DEFAULT" > + * * !0 - The token is "DEFAULT" > + */ > +static bool token_default(char *token) > +{ > + return !strcmp(token, "DEFAULT"); > +} > + > +/** > + * free_rule - Free the supplied ipe_rule struct. > + * @r: Supplies the ipe_rule struct to be freed. > + * > + * Free a ipe_rule struct @r. Note @r must be removed from any lists before > + * calling this function. > + */ > +static void free_rule(struct ipe_rule *r) > +{ > + struct ipe_prop *p, *t; > + > + if (IS_ERR_OR_NULL(r)) > + return; > + > + list_for_each_entry_safe(p, t, &r->props, next) { > + list_del(&p->next); > + kfree(p); > + } > + > + kfree(r); > +} > + > +static const match_table_t operation_tokens = { > + {IPE_OP_EXEC, "op=EXECUTE"}, > + {IPE_OP_FIRMWARE, "op=FIRMWARE"}, > + {IPE_OP_KERNEL_MODULE, "op=KMODULE"}, > + {IPE_OP_KEXEC_IMAGE, "op=KEXEC_IMAGE"}, > + {IPE_OP_KEXEC_INITRAMFS, "op=KEXEC_INITRAMFS"}, > + {IPE_OP_POLICY, "op=POLICY"}, > + {IPE_OP_X509, "op=X509_CERT"}, > + {IPE_OP_INVALID, NULL} > +}; > + > +/** > + * parse_operation - Parse the operation type given a token string. > + * @t: Supplies the token string to be parsed. > + * > + * Return: The parsed operation type. > + */ > +static enum ipe_op_type parse_operation(char *t) > +{ > + substring_t args[MAX_OPT_ARGS]; > + > + return match_token(t, operation_tokens, args); > +} > + > +static const match_table_t action_tokens = { > + {IPE_ACTION_ALLOW, "action=ALLOW"}, > + {IPE_ACTION_DENY, "action=DENY"}, > + {IPE_ACTION_INVALID, NULL} > +}; > + > +/** > + * parse_action - Parse the action type given a token string. > + * @t: Supplies the token string to be parsed. > + * > + * Return: The parsed action type. > + */ > +static enum ipe_action_type parse_action(char *t) > +{ > + substring_t args[MAX_OPT_ARGS]; > + > + return match_token(t, action_tokens, args); > +} > + > +/** > + * parse_property - Parse the property type given a token string. > + * @t: Supplies the token string to be parsed. > + * @r: Supplies the ipe_rule the parsed property will be associated with. > + * > + * Return: > + * * !IS_ERR - OK > + * * -ENOMEM - Out of memory > + * * -EBADMSG - The supplied token cannot be parsed > + */ > +static int parse_property(char *t, struct ipe_rule *r) > +{ > + return -EBADMSG; > +} > + > +/** > + * parse_rule - parse a policy rule line. > + * @line: Supplies rule line to be parsed. > + * @p: Supplies the partial parsed policy. > + * > + * Return: > + * * !IS_ERR - OK > + * * -ENOMEM - Out of memory > + * * -EBADMSG - Policy syntax error > + */ > +static int parse_rule(char *line, struct ipe_parsed_policy *p) > +{ > + int rc = 0; > + bool first_token = true, is_default_rule = false; > + bool op_parsed = false; > + enum ipe_op_type op = IPE_OP_INVALID; > + enum ipe_action_type action = IPE_ACTION_INVALID; > + struct ipe_rule *r = NULL; > + char *t; > + > + r = kzalloc(sizeof(*r), GFP_KERNEL); > + if (!r) > + return -ENOMEM; > + > + INIT_LIST_HEAD(&r->next); > + INIT_LIST_HEAD(&r->props); > + > + while (t = strsep(&line, IPE_POLICY_DELIM), line) { > + if (*t == '\0') > + continue; > + if (first_token && token_default(t)) { > + is_default_rule = true; > + } else { > + if (!op_parsed) { > + op = parse_operation(t); > + if (op == IPE_OP_INVALID) > + rc = -EBADMSG; > + else > + op_parsed = true; > + } else { > + rc = parse_property(t, r); > + } > + } > + > + if (rc) > + goto err; > + first_token = false; > + } > + > + action = parse_action(t); > + if (action == IPE_ACTION_INVALID) { > + rc = -EBADMSG; > + goto err; > + } > + > + if (is_default_rule) { > + if (!list_empty(&r->props)) { > + rc = -EBADMSG; > + } else if (op == IPE_OP_INVALID) { > + if (p->global_default_action != IPE_ACTION_INVALID) > + rc = -EBADMSG; > + else > + p->global_default_action = action; > + } else { > + if (p->rules[op].default_action != IPE_ACTION_INVALID) > + rc = -EBADMSG; > + else > + p->rules[op].default_action = action; > + } > + } else if (op != IPE_OP_INVALID && action != IPE_ACTION_INVALID) { > + r->op = op; > + r->action = action; > + } else { > + rc = -EBADMSG; > + } > + > + if (rc) > + goto err; > + if (!is_default_rule) > + list_add_tail(&r->next, &p->rules[op].rules); > + else > + free_rule(r); > + > + return rc; > +err: > + free_rule(r); > + return rc; > +} > + > +/** > + * free_parsed_policy - free a parsed policy structure. > + * @p: Supplies the parsed policy. > + */ > +void free_parsed_policy(struct ipe_parsed_policy *p) > +{ > + size_t i = 0; > + struct ipe_rule *pp, *t; > + > + if (IS_ERR_OR_NULL(p)) > + return; > + > + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) > + list_for_each_entry_safe(pp, t, &p->rules[i].rules, next) { > + list_del(&pp->next); > + free_rule(pp); > + } > + > + kfree(p->name); > + kfree(p); > +} > + > +/** > + * validate_policy - validate a parsed policy. > + * @p: Supplies the fully parsed policy. > + * > + * Given a policy structure that was just parsed, validate that all > + * necessary fields are present, initialized correctly. > + * > + * A parsed policy can be in an invalid state for use (a default was > + * undefined) by just parsing the policy. > + * > + * Return: > + * * 0 - OK > + * * -EBADMSG - Policy is invalid > + */ > +static int validate_policy(const struct ipe_parsed_policy *p) > +{ > + size_t i = 0; > + > + if (p->global_default_action != IPE_ACTION_INVALID) > + return 0; > + > + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) { > + if (p->rules[i].default_action == IPE_ACTION_INVALID) > + return -EBADMSG; > + } > + > + return 0; > +} > + > +/** > + * parse_policy - Given a string, parse the string into an IPE policy. > + * @p: partially filled ipe_policy structure to populate with the result. > + * it must have text and textlen set. > + * > + * Return: > + * * 0 - OK > + * * -EBADMSG - Policy is invalid > + * * -ENOMEM - Out of Memory > + */ > +int parse_policy(struct ipe_policy *p) > +{ > + int rc = 0; > + size_t len; > + char *policy = NULL, *dup = NULL; > + char *line = NULL; > + bool header_parsed = false; > + struct ipe_parsed_policy *pp = NULL; > + > + if (!p->textlen) > + return -EBADMSG; > + > + policy = kmemdup_nul(p->text, p->textlen, GFP_KERNEL); > + if (!policy) > + return -ENOMEM; > + dup = policy; > + > + pp = new_parsed_policy(); > + if (IS_ERR(pp)) { > + rc = PTR_ERR(pp); > + goto out; > + } > + > + while ((line = strsep(&policy, IPE_LINE_DELIM)) != NULL) { > + remove_comment(line); > + len = remove_trailing_spaces(line); > + if (!len) > + continue; > + > + if (!header_parsed) { > + rc = parse_header(line, pp); > + if (rc) > + goto err; > + header_parsed = true; > + } else { > + rc = parse_rule(line, pp); > + if (rc) > + goto err; > + } > + } > + > + if (!header_parsed || validate_policy(pp)) { > + rc = -EBADMSG; > + goto err; > + } > + > + p->parsed = pp; > + > +out: > + kfree(dup); > + return rc; > +err: > + free_parsed_policy(pp); > + goto out; > +} > diff --git a/security/ipe/policy_parser.h b/security/ipe/policy_parser.h > new file mode 100644 > index 000000000000..2b744103d06a > --- /dev/null > +++ b/security/ipe/policy_parser.h > @@ -0,0 +1,11 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > +#ifndef _IPE_POLICY_PARSER_H > +#define _IPE_POLICY_PARSER_H > + > +int parse_policy(struct ipe_policy *p); > +void free_parsed_policy(struct ipe_parsed_policy *p); > + > +#endif /* _IPE_POLICY_PARSER_H */ BR, Jarkko
On Thu Mar 28, 2024 at 10:17 PM EET, Fan Wu wrote: > From: Deven Bowers <deven.desai@linux.microsoft.com> > > IPE's interpretation of the what the user trusts is accomplished through > its policy. IPE's design is to not provide support for a single trust > provider, but to support multiple providers to enable the end-user to > choose the best one to seek their needs. > > This requires the policy to be rather flexible and modular so that > integrity providers, like fs-verity, dm-verity, dm-integrity, or > some other system, can plug into the policy with minimal code changes. > > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com> > > --- > v2: > + Split evaluation loop, access control hooks, > and evaluation loop from policy parser and userspace > interface to pass mailing list character limit > > v3: > + Move policy load and activation audit event to 03/12 > + Fix a potential panic when a policy failed to load. > + use pr_warn for a failure to parse instead of an > audit record > + Remove comments from headers > + Add lockdep assertions to ipe_update_active_policy and > ipe_activate_policy > + Fix up warnings with checkpatch --strict > + Use file_ns_capable for CAP_MAC_ADMIN for securityfs > nodes. > + Use memdup_user instead of kzalloc+simple_write_to_buffer. > + Remove strict_parse command line parameter, as it is added > by the sysctl command line. > + Prefix extern variables with ipe_ > > v4: > + Remove securityfs to reverse-dependency > + Add SHA1 reverse dependency. > + Add versioning scheme for IPE properties, and associated > interface to query the versioning scheme. > + Cause a parser to always return an error on unknown syntax. > + Remove strict_parse option > + Change active_policy interface from sysctl, to securityfs, > and change scheme. > > v5: > + Cause an error if a default action is not defined for each > operation. > + Minor function renames > > v6: > + No changes > > v7: > + Further split parser and userspace interface into two > separate commits, for easier review. > + Refactor policy parser to make code cleaner via introducing a > more modular design, for easier extension of policy, and > easier review. > > v8: > + remove unnecessary pr_info emission on parser loading > + add explicit newline to the pr_err emitted when a parser > fails to load. > > v9: > + switch to match table to parse policy > + remove quote syntax and KERNEL_READ operation > > v10: > + Fix memory leaks in parser > + Fix typos and change code styles > > v11: > + Fix code style issues > > v12: > + Add __always_unused to an unused parameter > + Simplify error case handling > > v13: > + No changes > > v14: > + No changes > > v15: > + No changes > > v16: > + No changes > --- > security/ipe/Makefile | 2 + > security/ipe/policy.c | 101 ++++++++ > security/ipe/policy.h | 83 ++++++ > security/ipe/policy_parser.c | 487 +++++++++++++++++++++++++++++++++++ > security/ipe/policy_parser.h | 11 + > 5 files changed, 684 insertions(+) > create mode 100644 security/ipe/policy.c > create mode 100644 security/ipe/policy.h > create mode 100644 security/ipe/policy_parser.c > create mode 100644 security/ipe/policy_parser.h > > diff --git a/security/ipe/Makefile b/security/ipe/Makefile > index f7a80d0f18f8..c09aec4904f2 100644 > --- a/security/ipe/Makefile > +++ b/security/ipe/Makefile > @@ -7,3 +7,5 @@ > > obj-$(CONFIG_SECURITY_IPE) += \ > ipe.o \ > + policy.o \ > + policy_parser.o \ > diff --git a/security/ipe/policy.c b/security/ipe/policy.c > new file mode 100644 > index 000000000000..f22a576a6d68 > --- /dev/null > +++ b/security/ipe/policy.c > @@ -0,0 +1,101 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > + > +#include <linux/errno.h> > +#include <linux/verification.h> > + > +#include "ipe.h" > +#include "policy.h" > +#include "policy_parser.h" > + > +/** > + * ipe_free_policy - Deallocate a given IPE policy. > + * @p: Supplies the policy to free. > + * > + * Safe to call on IS_ERR/NULL. > + */ > +void ipe_free_policy(struct ipe_policy *p) > +{ > + if (IS_ERR_OR_NULL(p)) > + return; > + > + free_parsed_policy(p->parsed); > + /* > + * p->text is allocated only when p->pkcs7 is not NULL > + * otherwise it points to the plaintext data inside the pkcs7 > + */ > + if (!p->pkcs7) > + kfree(p->text); > + kfree(p->pkcs7); > + kfree(p); > +} > + > +static int set_pkcs7_data(void *ctx, const void *data, size_t len, > + size_t asn1hdrlen __always_unused) > +{ > + struct ipe_policy *p = ctx; > + > + p->text = (const char *)data; > + p->textlen = len; > + > + return 0; > +} > + > +/** > + * ipe_new_policy - Allocate and parse an ipe_policy structure. > + * > + * @text: Supplies a pointer to the plain-text policy to parse. > + * @textlen: Supplies the length of @text. > + * @pkcs7: Supplies a pointer to a pkcs7-signed IPE policy. > + * @pkcs7len: Supplies the length of @pkcs7. > + * > + * @text/@textlen Should be NULL/0 if @pkcs7/@pkcs7len is set. > + * > + * Return: > + * * !IS_ERR - Success > + * * -EBADMSG - Policy is invalid > + * * -ENOMEM - Out of memory > + */ > +struct ipe_policy *ipe_new_policy(const char *text, size_t textlen, > + const char *pkcs7, size_t pkcs7len) > +{ > + int rc = 0; > + struct ipe_policy *new = NULL; In many places: reverse christmas tree would be so much more readable. > + > + new = kzalloc(sizeof(*new), GFP_KERNEL); > + if (!new) > + return ERR_PTR(-ENOMEM); > + > + if (!text) { > + new->pkcs7len = pkcs7len; > + new->pkcs7 = kmemdup(pkcs7, pkcs7len, GFP_KERNEL); > + if (!new->pkcs7) { > + rc = -ENOMEM; > + goto err; > + } > + > + rc = verify_pkcs7_signature(NULL, 0, new->pkcs7, pkcs7len, NULL, > + VERIFYING_UNSPECIFIED_SIGNATURE, > + set_pkcs7_data, new); > + if (rc) > + goto err; > + } else { > + new->textlen = textlen; > + new->text = kstrdup(text, GFP_KERNEL); > + if (!new->text) { > + rc = -ENOMEM; > + goto err; > + } > + } > + > + rc = parse_policy(new); > + if (rc) > + goto err; > + > + return new; > +err: > + ipe_free_policy(new); > + return ERR_PTR(rc); > +} > diff --git a/security/ipe/policy.h b/security/ipe/policy.h > new file mode 100644 > index 000000000000..fb906f41522b > --- /dev/null > +++ b/security/ipe/policy.h > @@ -0,0 +1,83 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > +#ifndef _IPE_POLICY_H > +#define _IPE_POLICY_H > + > +#include <linux/list.h> > +#include <linux/types.h> > + > +enum ipe_op_type { > + IPE_OP_EXEC = 0, > + IPE_OP_FIRMWARE, > + IPE_OP_KERNEL_MODULE, > + IPE_OP_KEXEC_IMAGE, > + IPE_OP_KEXEC_INITRAMFS, > + IPE_OP_POLICY, > + IPE_OP_X509, > + __IPE_OP_MAX, > +}; > + > +#define IPE_OP_INVALID __IPE_OP_MAX > + > +enum ipe_action_type { > + IPE_ACTION_ALLOW = 0, > + IPE_ACTION_DENY, > + __IPE_ACTION_MAX > +}; > + > +#define IPE_ACTION_INVALID __IPE_ACTION_MAX > + > +enum ipe_prop_type { > + __IPE_PROP_MAX > +}; > + > +#define IPE_PROP_INVALID __IPE_PROP_MAX > + > +struct ipe_prop { > + struct list_head next; > + enum ipe_prop_type type; > + void *value; > +}; > + > +struct ipe_rule { > + enum ipe_op_type op; > + enum ipe_action_type action; > + struct list_head props; > + struct list_head next; > +}; > + > +struct ipe_op_table { > + struct list_head rules; > + enum ipe_action_type default_action; > +}; > + > +struct ipe_parsed_policy { > + const char *name; > + struct { > + u16 major; > + u16 minor; > + u16 rev; > + } version; > + > + enum ipe_action_type global_default_action; > + > + struct ipe_op_table rules[__IPE_OP_MAX]; > +}; > + > +struct ipe_policy { > + const char *pkcs7; > + size_t pkcs7len; > + > + const char *text; > + size_t textlen; > + > + struct ipe_parsed_policy *parsed; > +}; > + > +struct ipe_policy *ipe_new_policy(const char *text, size_t textlen, > + const char *pkcs7, size_t pkcs7len); > +void ipe_free_policy(struct ipe_policy *pol); > + > +#endif /* _IPE_POLICY_H */ > diff --git a/security/ipe/policy_parser.c b/security/ipe/policy_parser.c > new file mode 100644 > index 000000000000..612839b405f4 > --- /dev/null > +++ b/security/ipe/policy_parser.c > @@ -0,0 +1,487 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. > + */ > + > +#include <linux/err.h> > +#include <linux/slab.h> > +#include <linux/parser.h> > +#include <linux/types.h> > +#include <linux/ctype.h> > + > +#include "policy.h" > +#include "policy_parser.h" > + > +#define START_COMMENT '#' > +#define IPE_POLICY_DELIM " \t" > +#define IPE_LINE_DELIM "\n\r" > + > +/** > + * new_parsed_policy - Allocate and initialize a parsed policy. > + * > + * Return: > + * * !IS_ERR - OK > + * * -ENOMEM - Out of memory > + */ > +static struct ipe_parsed_policy *new_parsed_policy(void) > +{ > + size_t i = 0; > + struct ipe_parsed_policy *p = NULL; > + struct ipe_op_table *t = NULL; > + > + p = kzalloc(sizeof(*p), GFP_KERNEL); > + if (!p) > + return ERR_PTR(-ENOMEM); > + > + p->global_default_action = IPE_ACTION_INVALID; > + > + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) { > + t = &p->rules[i]; > + > + t->default_action = IPE_ACTION_INVALID; > + INIT_LIST_HEAD(&t->rules); > + } > + > + return p; > +} > + > +/** > + * remove_comment - Truncate all chars following START_COMMENT in a string. > + * > + * @line: Supplies a policy line string for preprocessing. > + */ > +static void remove_comment(char *line) > +{ > + line = strchr(line, START_COMMENT); > + > + if (line) > + *line = '\0'; > +} > + > +/** > + * remove_trailing_spaces - Truncate all trailing spaces in a string. > + * > + * @line: Supplies a policy line string for preprocessing. > + * > + * Return: The length of truncated string. > + */ > +static size_t remove_trailing_spaces(char *line) > +{ > + size_t i = 0; > + > + i = strlen(line); > + while (i > 0 && isspace(line[i - 1])) > + i--; > + > + line[i] = '\0'; > + > + return i; > +} > + > +/** > + * parse_version - Parse policy version. > + * @ver: Supplies a version string to be parsed. > + * @p: Supplies the partial parsed policy. > + * > + * Return: > + * * 0 - OK > + * * !0 - Standard errno > + */ > +static int parse_version(char *ver, struct ipe_parsed_policy *p) > +{ > + int rc = 0; > + size_t sep_count = 0; > + char *token; > + u16 *const cv[] = { &p->version.major, &p->version.minor, &p->version.rev }; > + > + while ((token = strsep(&ver, ".")) != NULL) { > + /* prevent overflow */ > + if (sep_count >= ARRAY_SIZE(cv)) > + return -EBADMSG; > + > + rc = kstrtou16(token, 10, cv[sep_count]); > + if (rc) > + return rc; > + > + ++sep_count; > + } > + > + /* prevent underflow */ > + if (sep_count != ARRAY_SIZE(cv)) > + return -EBADMSG; > + > + return 0; > +} > + > +enum header_opt { > + IPE_HEADER_POLICY_NAME = 0, > + IPE_HEADER_POLICY_VERSION, > + __IPE_HEADER_MAX > +}; > + > +static const match_table_t header_tokens = { > + {IPE_HEADER_POLICY_NAME, "policy_name=%s"}, > + {IPE_HEADER_POLICY_VERSION, "policy_version=%s"}, > + {__IPE_HEADER_MAX, NULL} > +}; > + > +/** > + * parse_header - Parse policy header information. > + * @line: Supplies header line to be parsed. > + * @p: Supplies the partial parsed policy. > + * > + * Return: > + * * 0 - OK > + * * !0 - Standard errno > + */ > +static int parse_header(char *line, struct ipe_parsed_policy *p) > +{ > + int rc = 0; > + char *t, *ver = NULL; > + substring_t args[MAX_OPT_ARGS]; > + size_t idx = 0; > + > + while ((t = strsep(&line, IPE_POLICY_DELIM)) != NULL) { > + int token; > + > + if (*t == '\0') > + continue; > + if (idx >= __IPE_HEADER_MAX) { > + rc = -EBADMSG; > + goto out; > + } > + > + token = match_token(t, header_tokens, args); > + if (token != idx) { > + rc = -EBADMSG; > + goto out; > + } > + > + switch (token) { > + case IPE_HEADER_POLICY_NAME: > + p->name = match_strdup(&args[0]); > + if (!p->name) > + rc = -ENOMEM; > + break; > + case IPE_HEADER_POLICY_VERSION: > + ver = match_strdup(&args[0]); > + if (!ver) { > + rc = -ENOMEM; > + break; > + } > + rc = parse_version(ver, p); > + break; > + default: > + rc = -EBADMSG; > + } > + if (rc) > + goto out; > + ++idx; > + } > + > + if (idx != __IPE_HEADER_MAX) > + rc = -EBADMSG; > + > +out: > + kfree(ver); > + return rc; > +} > + > +/** > + * token_default - Determine if the given token is "DEFAULT". > + * @token: Supplies the token string to be compared. > + * > + * Return: > + * * 0 - The token is not "DEFAULT" > + * * !0 - The token is "DEFAULT" > + */ > +static bool token_default(char *token) > +{ > + return !strcmp(token, "DEFAULT"); > +} > + > +/** > + * free_rule - Free the supplied ipe_rule struct. > + * @r: Supplies the ipe_rule struct to be freed. > + * > + * Free a ipe_rule struct @r. Note @r must be removed from any lists before > + * calling this function. > + */ > +static void free_rule(struct ipe_rule *r) > +{ > + struct ipe_prop *p, *t; > + > + if (IS_ERR_OR_NULL(r)) > + return; > + > + list_for_each_entry_safe(p, t, &r->props, next) { > + list_del(&p->next); > + kfree(p); > + } > + > + kfree(r); > +} > + > +static const match_table_t operation_tokens = { > + {IPE_OP_EXEC, "op=EXECUTE"}, > + {IPE_OP_FIRMWARE, "op=FIRMWARE"}, > + {IPE_OP_KERNEL_MODULE, "op=KMODULE"}, > + {IPE_OP_KEXEC_IMAGE, "op=KEXEC_IMAGE"}, > + {IPE_OP_KEXEC_INITRAMFS, "op=KEXEC_INITRAMFS"}, > + {IPE_OP_POLICY, "op=POLICY"}, > + {IPE_OP_X509, "op=X509_CERT"}, > + {IPE_OP_INVALID, NULL} > +}; > + > +/** > + * parse_operation - Parse the operation type given a token string. > + * @t: Supplies the token string to be parsed. > + * > + * Return: The parsed operation type. > + */ > +static enum ipe_op_type parse_operation(char *t) > +{ > + substring_t args[MAX_OPT_ARGS]; > + > + return match_token(t, operation_tokens, args); > +} > + > +static const match_table_t action_tokens = { > + {IPE_ACTION_ALLOW, "action=ALLOW"}, > + {IPE_ACTION_DENY, "action=DENY"}, > + {IPE_ACTION_INVALID, NULL} > +}; > + > +/** > + * parse_action - Parse the action type given a token string. > + * @t: Supplies the token string to be parsed. > + * > + * Return: The parsed action type. > + */ > +static enum ipe_action_type parse_action(char *t) > +{ > + substring_t args[MAX_OPT_ARGS]; > + > + return match_token(t, action_tokens, args); > +} > + > +/** > + * parse_property - Parse the property type given a token string. > + * @t: Supplies the token string to be parsed. > + * @r: Supplies the ipe_rule the parsed property will be associated with. > + * > + * Return: > + * * !IS_ERR - OK > + * * -ENOMEM - Out of memory > + * * -EBADMSG - The supplied token cannot be parsed > + */ > +static int parse_property(char *t, struct ipe_rule *r) > +{ > + return -EBADMSG; > +} > + > +/** > + * parse_rule - parse a policy rule line. > + * @line: Supplies rule line to be parsed. > + * @p: Supplies the partial parsed policy. > + * > + * Return: > + * * !IS_ERR - OK > + * * -ENOMEM - Out of memory > + * * -EBADMSG - Policy syntax error > + */ > +static int parse_rule(char *line, struct ipe_parsed_policy *p) > +{ > + int rc = 0; > + bool first_token = true, is_default_rule = false; > + bool op_parsed = false; > + enum ipe_op_type op = IPE_OP_INVALID; > + enum ipe_action_type action = IPE_ACTION_INVALID; > + struct ipe_rule *r = NULL; > + char *t; > + > + r = kzalloc(sizeof(*r), GFP_KERNEL); > + if (!r) > + return -ENOMEM; > + > + INIT_LIST_HEAD(&r->next); > + INIT_LIST_HEAD(&r->props); > + > + while (t = strsep(&line, IPE_POLICY_DELIM), line) { > + if (*t == '\0') > + continue; > + if (first_token && token_default(t)) { > + is_default_rule = true; > + } else { > + if (!op_parsed) { > + op = parse_operation(t); > + if (op == IPE_OP_INVALID) > + rc = -EBADMSG; > + else > + op_parsed = true; > + } else { > + rc = parse_property(t, r); > + } > + } > + > + if (rc) > + goto err; > + first_token = false; > + } > + > + action = parse_action(t); > + if (action == IPE_ACTION_INVALID) { > + rc = -EBADMSG; > + goto err; > + } > + > + if (is_default_rule) { > + if (!list_empty(&r->props)) { > + rc = -EBADMSG; > + } else if (op == IPE_OP_INVALID) { > + if (p->global_default_action != IPE_ACTION_INVALID) > + rc = -EBADMSG; > + else > + p->global_default_action = action; > + } else { > + if (p->rules[op].default_action != IPE_ACTION_INVALID) > + rc = -EBADMSG; > + else > + p->rules[op].default_action = action; > + } > + } else if (op != IPE_OP_INVALID && action != IPE_ACTION_INVALID) { > + r->op = op; > + r->action = action; > + } else { > + rc = -EBADMSG; > + } > + > + if (rc) > + goto err; > + if (!is_default_rule) > + list_add_tail(&r->next, &p->rules[op].rules); > + else > + free_rule(r); > + > + return rc; > +err: > + free_rule(r); > + return rc; > +} > + > +/** > + * free_parsed_policy - free a parsed policy structure. > + * @p: Supplies the parsed policy. > + */ > +void free_parsed_policy(struct ipe_parsed_policy *p) > +{ > + size_t i = 0; > + struct ipe_rule *pp, *t; > + > + if (IS_ERR_OR_NULL(p)) > + return; > + > + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) > + list_for_each_entry_safe(pp, t, &p->rules[i].rules, next) { > + list_del(&pp->next); > + free_rule(pp); > + } > + > + kfree(p->name); > + kfree(p); > +} > + > +/** > + * validate_policy - validate a parsed policy. > + * @p: Supplies the fully parsed policy. > + * > + * Given a policy structure that was just parsed, validate that all > + * necessary fields are present, initialized correctly. > + * > + * A parsed policy can be in an invalid state for use (a default was > + * undefined) by just parsing the policy. > + * > + * Return: > + * * 0 - OK > + * * -EBADMSG - Policy is invalid > + */ > +static int validate_policy(const struct ipe_parsed_policy *p) > +{ > + size_t i = 0; > + > + if (p->global_default_action != IPE_ACTION_INVALID) > + return 0; > + > + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) { > + if (p->rules[i].default_action == IPE_ACTION_INVALID) > + return -EBADMSG; > + } > + > + return 0; > +} > + > +/** > + * parse_policy - Given a string, parse the string into an IPE policy. > + * @p: partially filled ipe_policy structure to populate with the result. > + * it must have text and textlen set. > + * > + * Return: > + * * 0 - OK > + * * -EBADMSG - Policy is invalid > + * * -ENOMEM - Out of Memory > + */ > +int parse_policy(struct ipe_policy *p) > +{ > + int rc = 0; > + size_t len; > + char *policy = NULL, *dup = NULL; > + char *line = NULL; > + bool header_parsed = false; > + struct ipe_parsed_policy *pp = NULL; > + > + if (!p->textlen) > + return -EBADMSG; > + > + policy = kmemdup_nul(p->text, p->textlen, GFP_KERNEL); > + if (!policy) > + return -ENOMEM; > + dup = policy; > + > + pp = new_parsed_policy(); > + if (IS_ERR(pp)) { > + rc = PTR_ERR(pp); > + goto out; > + } > + > + while ((line = strsep(&policy, IPE_LINE_DELIM)) != NULL) { > + remove_comment(line); > + len = remove_trailing_spaces(line); > + if (!len) > + continue; > + > + if (!header_parsed) { > + rc = parse_header(line, pp); > + if (rc) > + goto err; > + header_parsed = true; > + } else { > + rc = parse_rule(line, pp); > + if (rc) > + goto err; > + } > + } > + > + if (!header_parsed || validate_policy(pp)) { > + rc = -EBADMSG; > + goto err; > + } > + > + p->parsed = pp; > + > +out: > + kfree(dup); > + return rc; > +err: > + free_parsed_policy(pp); > + goto out; > +} > diff --git a/security/ipe/policy_parser.h b/security/ipe/policy_parser.h > new file mode 100644 > index 000000000000..2b744103d06a > --- /dev/null > +++ b/security/ipe/policy_parser.h > @@ -0,0 +1,11 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) Microsoft Corporation. All rights reserved. The year is missing. > + */ > +#ifndef _IPE_POLICY_PARSER_H > +#define _IPE_POLICY_PARSER_H > + > +int parse_policy(struct ipe_policy *p); > +void free_parsed_policy(struct ipe_parsed_policy *p); > + > +#endif /* _IPE_POLICY_PARSER_H */ BR, Jarkko
diff --git a/security/ipe/Makefile b/security/ipe/Makefile index f7a80d0f18f8..c09aec4904f2 100644 --- a/security/ipe/Makefile +++ b/security/ipe/Makefile @@ -7,3 +7,5 @@ obj-$(CONFIG_SECURITY_IPE) += \ ipe.o \ + policy.o \ + policy_parser.o \ diff --git a/security/ipe/policy.c b/security/ipe/policy.c new file mode 100644 index 000000000000..f22a576a6d68 --- /dev/null +++ b/security/ipe/policy.c @@ -0,0 +1,101 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include <linux/errno.h> +#include <linux/verification.h> + +#include "ipe.h" +#include "policy.h" +#include "policy_parser.h" + +/** + * ipe_free_policy - Deallocate a given IPE policy. + * @p: Supplies the policy to free. + * + * Safe to call on IS_ERR/NULL. + */ +void ipe_free_policy(struct ipe_policy *p) +{ + if (IS_ERR_OR_NULL(p)) + return; + + free_parsed_policy(p->parsed); + /* + * p->text is allocated only when p->pkcs7 is not NULL + * otherwise it points to the plaintext data inside the pkcs7 + */ + if (!p->pkcs7) + kfree(p->text); + kfree(p->pkcs7); + kfree(p); +} + +static int set_pkcs7_data(void *ctx, const void *data, size_t len, + size_t asn1hdrlen __always_unused) +{ + struct ipe_policy *p = ctx; + + p->text = (const char *)data; + p->textlen = len; + + return 0; +} + +/** + * ipe_new_policy - Allocate and parse an ipe_policy structure. + * + * @text: Supplies a pointer to the plain-text policy to parse. + * @textlen: Supplies the length of @text. + * @pkcs7: Supplies a pointer to a pkcs7-signed IPE policy. + * @pkcs7len: Supplies the length of @pkcs7. + * + * @text/@textlen Should be NULL/0 if @pkcs7/@pkcs7len is set. + * + * Return: + * * !IS_ERR - Success + * * -EBADMSG - Policy is invalid + * * -ENOMEM - Out of memory + */ +struct ipe_policy *ipe_new_policy(const char *text, size_t textlen, + const char *pkcs7, size_t pkcs7len) +{ + int rc = 0; + struct ipe_policy *new = NULL; + + new = kzalloc(sizeof(*new), GFP_KERNEL); + if (!new) + return ERR_PTR(-ENOMEM); + + if (!text) { + new->pkcs7len = pkcs7len; + new->pkcs7 = kmemdup(pkcs7, pkcs7len, GFP_KERNEL); + if (!new->pkcs7) { + rc = -ENOMEM; + goto err; + } + + rc = verify_pkcs7_signature(NULL, 0, new->pkcs7, pkcs7len, NULL, + VERIFYING_UNSPECIFIED_SIGNATURE, + set_pkcs7_data, new); + if (rc) + goto err; + } else { + new->textlen = textlen; + new->text = kstrdup(text, GFP_KERNEL); + if (!new->text) { + rc = -ENOMEM; + goto err; + } + } + + rc = parse_policy(new); + if (rc) + goto err; + + return new; +err: + ipe_free_policy(new); + return ERR_PTR(rc); +} diff --git a/security/ipe/policy.h b/security/ipe/policy.h new file mode 100644 index 000000000000..fb906f41522b --- /dev/null +++ b/security/ipe/policy.h @@ -0,0 +1,83 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ +#ifndef _IPE_POLICY_H +#define _IPE_POLICY_H + +#include <linux/list.h> +#include <linux/types.h> + +enum ipe_op_type { + IPE_OP_EXEC = 0, + IPE_OP_FIRMWARE, + IPE_OP_KERNEL_MODULE, + IPE_OP_KEXEC_IMAGE, + IPE_OP_KEXEC_INITRAMFS, + IPE_OP_POLICY, + IPE_OP_X509, + __IPE_OP_MAX, +}; + +#define IPE_OP_INVALID __IPE_OP_MAX + +enum ipe_action_type { + IPE_ACTION_ALLOW = 0, + IPE_ACTION_DENY, + __IPE_ACTION_MAX +}; + +#define IPE_ACTION_INVALID __IPE_ACTION_MAX + +enum ipe_prop_type { + __IPE_PROP_MAX +}; + +#define IPE_PROP_INVALID __IPE_PROP_MAX + +struct ipe_prop { + struct list_head next; + enum ipe_prop_type type; + void *value; +}; + +struct ipe_rule { + enum ipe_op_type op; + enum ipe_action_type action; + struct list_head props; + struct list_head next; +}; + +struct ipe_op_table { + struct list_head rules; + enum ipe_action_type default_action; +}; + +struct ipe_parsed_policy { + const char *name; + struct { + u16 major; + u16 minor; + u16 rev; + } version; + + enum ipe_action_type global_default_action; + + struct ipe_op_table rules[__IPE_OP_MAX]; +}; + +struct ipe_policy { + const char *pkcs7; + size_t pkcs7len; + + const char *text; + size_t textlen; + + struct ipe_parsed_policy *parsed; +}; + +struct ipe_policy *ipe_new_policy(const char *text, size_t textlen, + const char *pkcs7, size_t pkcs7len); +void ipe_free_policy(struct ipe_policy *pol); + +#endif /* _IPE_POLICY_H */ diff --git a/security/ipe/policy_parser.c b/security/ipe/policy_parser.c new file mode 100644 index 000000000000..612839b405f4 --- /dev/null +++ b/security/ipe/policy_parser.c @@ -0,0 +1,487 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/parser.h> +#include <linux/types.h> +#include <linux/ctype.h> + +#include "policy.h" +#include "policy_parser.h" + +#define START_COMMENT '#' +#define IPE_POLICY_DELIM " \t" +#define IPE_LINE_DELIM "\n\r" + +/** + * new_parsed_policy - Allocate and initialize a parsed policy. + * + * Return: + * * !IS_ERR - OK + * * -ENOMEM - Out of memory + */ +static struct ipe_parsed_policy *new_parsed_policy(void) +{ + size_t i = 0; + struct ipe_parsed_policy *p = NULL; + struct ipe_op_table *t = NULL; + + p = kzalloc(sizeof(*p), GFP_KERNEL); + if (!p) + return ERR_PTR(-ENOMEM); + + p->global_default_action = IPE_ACTION_INVALID; + + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) { + t = &p->rules[i]; + + t->default_action = IPE_ACTION_INVALID; + INIT_LIST_HEAD(&t->rules); + } + + return p; +} + +/** + * remove_comment - Truncate all chars following START_COMMENT in a string. + * + * @line: Supplies a policy line string for preprocessing. + */ +static void remove_comment(char *line) +{ + line = strchr(line, START_COMMENT); + + if (line) + *line = '\0'; +} + +/** + * remove_trailing_spaces - Truncate all trailing spaces in a string. + * + * @line: Supplies a policy line string for preprocessing. + * + * Return: The length of truncated string. + */ +static size_t remove_trailing_spaces(char *line) +{ + size_t i = 0; + + i = strlen(line); + while (i > 0 && isspace(line[i - 1])) + i--; + + line[i] = '\0'; + + return i; +} + +/** + * parse_version - Parse policy version. + * @ver: Supplies a version string to be parsed. + * @p: Supplies the partial parsed policy. + * + * Return: + * * 0 - OK + * * !0 - Standard errno + */ +static int parse_version(char *ver, struct ipe_parsed_policy *p) +{ + int rc = 0; + size_t sep_count = 0; + char *token; + u16 *const cv[] = { &p->version.major, &p->version.minor, &p->version.rev }; + + while ((token = strsep(&ver, ".")) != NULL) { + /* prevent overflow */ + if (sep_count >= ARRAY_SIZE(cv)) + return -EBADMSG; + + rc = kstrtou16(token, 10, cv[sep_count]); + if (rc) + return rc; + + ++sep_count; + } + + /* prevent underflow */ + if (sep_count != ARRAY_SIZE(cv)) + return -EBADMSG; + + return 0; +} + +enum header_opt { + IPE_HEADER_POLICY_NAME = 0, + IPE_HEADER_POLICY_VERSION, + __IPE_HEADER_MAX +}; + +static const match_table_t header_tokens = { + {IPE_HEADER_POLICY_NAME, "policy_name=%s"}, + {IPE_HEADER_POLICY_VERSION, "policy_version=%s"}, + {__IPE_HEADER_MAX, NULL} +}; + +/** + * parse_header - Parse policy header information. + * @line: Supplies header line to be parsed. + * @p: Supplies the partial parsed policy. + * + * Return: + * * 0 - OK + * * !0 - Standard errno + */ +static int parse_header(char *line, struct ipe_parsed_policy *p) +{ + int rc = 0; + char *t, *ver = NULL; + substring_t args[MAX_OPT_ARGS]; + size_t idx = 0; + + while ((t = strsep(&line, IPE_POLICY_DELIM)) != NULL) { + int token; + + if (*t == '\0') + continue; + if (idx >= __IPE_HEADER_MAX) { + rc = -EBADMSG; + goto out; + } + + token = match_token(t, header_tokens, args); + if (token != idx) { + rc = -EBADMSG; + goto out; + } + + switch (token) { + case IPE_HEADER_POLICY_NAME: + p->name = match_strdup(&args[0]); + if (!p->name) + rc = -ENOMEM; + break; + case IPE_HEADER_POLICY_VERSION: + ver = match_strdup(&args[0]); + if (!ver) { + rc = -ENOMEM; + break; + } + rc = parse_version(ver, p); + break; + default: + rc = -EBADMSG; + } + if (rc) + goto out; + ++idx; + } + + if (idx != __IPE_HEADER_MAX) + rc = -EBADMSG; + +out: + kfree(ver); + return rc; +} + +/** + * token_default - Determine if the given token is "DEFAULT". + * @token: Supplies the token string to be compared. + * + * Return: + * * 0 - The token is not "DEFAULT" + * * !0 - The token is "DEFAULT" + */ +static bool token_default(char *token) +{ + return !strcmp(token, "DEFAULT"); +} + +/** + * free_rule - Free the supplied ipe_rule struct. + * @r: Supplies the ipe_rule struct to be freed. + * + * Free a ipe_rule struct @r. Note @r must be removed from any lists before + * calling this function. + */ +static void free_rule(struct ipe_rule *r) +{ + struct ipe_prop *p, *t; + + if (IS_ERR_OR_NULL(r)) + return; + + list_for_each_entry_safe(p, t, &r->props, next) { + list_del(&p->next); + kfree(p); + } + + kfree(r); +} + +static const match_table_t operation_tokens = { + {IPE_OP_EXEC, "op=EXECUTE"}, + {IPE_OP_FIRMWARE, "op=FIRMWARE"}, + {IPE_OP_KERNEL_MODULE, "op=KMODULE"}, + {IPE_OP_KEXEC_IMAGE, "op=KEXEC_IMAGE"}, + {IPE_OP_KEXEC_INITRAMFS, "op=KEXEC_INITRAMFS"}, + {IPE_OP_POLICY, "op=POLICY"}, + {IPE_OP_X509, "op=X509_CERT"}, + {IPE_OP_INVALID, NULL} +}; + +/** + * parse_operation - Parse the operation type given a token string. + * @t: Supplies the token string to be parsed. + * + * Return: The parsed operation type. + */ +static enum ipe_op_type parse_operation(char *t) +{ + substring_t args[MAX_OPT_ARGS]; + + return match_token(t, operation_tokens, args); +} + +static const match_table_t action_tokens = { + {IPE_ACTION_ALLOW, "action=ALLOW"}, + {IPE_ACTION_DENY, "action=DENY"}, + {IPE_ACTION_INVALID, NULL} +}; + +/** + * parse_action - Parse the action type given a token string. + * @t: Supplies the token string to be parsed. + * + * Return: The parsed action type. + */ +static enum ipe_action_type parse_action(char *t) +{ + substring_t args[MAX_OPT_ARGS]; + + return match_token(t, action_tokens, args); +} + +/** + * parse_property - Parse the property type given a token string. + * @t: Supplies the token string to be parsed. + * @r: Supplies the ipe_rule the parsed property will be associated with. + * + * Return: + * * !IS_ERR - OK + * * -ENOMEM - Out of memory + * * -EBADMSG - The supplied token cannot be parsed + */ +static int parse_property(char *t, struct ipe_rule *r) +{ + return -EBADMSG; +} + +/** + * parse_rule - parse a policy rule line. + * @line: Supplies rule line to be parsed. + * @p: Supplies the partial parsed policy. + * + * Return: + * * !IS_ERR - OK + * * -ENOMEM - Out of memory + * * -EBADMSG - Policy syntax error + */ +static int parse_rule(char *line, struct ipe_parsed_policy *p) +{ + int rc = 0; + bool first_token = true, is_default_rule = false; + bool op_parsed = false; + enum ipe_op_type op = IPE_OP_INVALID; + enum ipe_action_type action = IPE_ACTION_INVALID; + struct ipe_rule *r = NULL; + char *t; + + r = kzalloc(sizeof(*r), GFP_KERNEL); + if (!r) + return -ENOMEM; + + INIT_LIST_HEAD(&r->next); + INIT_LIST_HEAD(&r->props); + + while (t = strsep(&line, IPE_POLICY_DELIM), line) { + if (*t == '\0') + continue; + if (first_token && token_default(t)) { + is_default_rule = true; + } else { + if (!op_parsed) { + op = parse_operation(t); + if (op == IPE_OP_INVALID) + rc = -EBADMSG; + else + op_parsed = true; + } else { + rc = parse_property(t, r); + } + } + + if (rc) + goto err; + first_token = false; + } + + action = parse_action(t); + if (action == IPE_ACTION_INVALID) { + rc = -EBADMSG; + goto err; + } + + if (is_default_rule) { + if (!list_empty(&r->props)) { + rc = -EBADMSG; + } else if (op == IPE_OP_INVALID) { + if (p->global_default_action != IPE_ACTION_INVALID) + rc = -EBADMSG; + else + p->global_default_action = action; + } else { + if (p->rules[op].default_action != IPE_ACTION_INVALID) + rc = -EBADMSG; + else + p->rules[op].default_action = action; + } + } else if (op != IPE_OP_INVALID && action != IPE_ACTION_INVALID) { + r->op = op; + r->action = action; + } else { + rc = -EBADMSG; + } + + if (rc) + goto err; + if (!is_default_rule) + list_add_tail(&r->next, &p->rules[op].rules); + else + free_rule(r); + + return rc; +err: + free_rule(r); + return rc; +} + +/** + * free_parsed_policy - free a parsed policy structure. + * @p: Supplies the parsed policy. + */ +void free_parsed_policy(struct ipe_parsed_policy *p) +{ + size_t i = 0; + struct ipe_rule *pp, *t; + + if (IS_ERR_OR_NULL(p)) + return; + + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) + list_for_each_entry_safe(pp, t, &p->rules[i].rules, next) { + list_del(&pp->next); + free_rule(pp); + } + + kfree(p->name); + kfree(p); +} + +/** + * validate_policy - validate a parsed policy. + * @p: Supplies the fully parsed policy. + * + * Given a policy structure that was just parsed, validate that all + * necessary fields are present, initialized correctly. + * + * A parsed policy can be in an invalid state for use (a default was + * undefined) by just parsing the policy. + * + * Return: + * * 0 - OK + * * -EBADMSG - Policy is invalid + */ +static int validate_policy(const struct ipe_parsed_policy *p) +{ + size_t i = 0; + + if (p->global_default_action != IPE_ACTION_INVALID) + return 0; + + for (i = 0; i < ARRAY_SIZE(p->rules); ++i) { + if (p->rules[i].default_action == IPE_ACTION_INVALID) + return -EBADMSG; + } + + return 0; +} + +/** + * parse_policy - Given a string, parse the string into an IPE policy. + * @p: partially filled ipe_policy structure to populate with the result. + * it must have text and textlen set. + * + * Return: + * * 0 - OK + * * -EBADMSG - Policy is invalid + * * -ENOMEM - Out of Memory + */ +int parse_policy(struct ipe_policy *p) +{ + int rc = 0; + size_t len; + char *policy = NULL, *dup = NULL; + char *line = NULL; + bool header_parsed = false; + struct ipe_parsed_policy *pp = NULL; + + if (!p->textlen) + return -EBADMSG; + + policy = kmemdup_nul(p->text, p->textlen, GFP_KERNEL); + if (!policy) + return -ENOMEM; + dup = policy; + + pp = new_parsed_policy(); + if (IS_ERR(pp)) { + rc = PTR_ERR(pp); + goto out; + } + + while ((line = strsep(&policy, IPE_LINE_DELIM)) != NULL) { + remove_comment(line); + len = remove_trailing_spaces(line); + if (!len) + continue; + + if (!header_parsed) { + rc = parse_header(line, pp); + if (rc) + goto err; + header_parsed = true; + } else { + rc = parse_rule(line, pp); + if (rc) + goto err; + } + } + + if (!header_parsed || validate_policy(pp)) { + rc = -EBADMSG; + goto err; + } + + p->parsed = pp; + +out: + kfree(dup); + return rc; +err: + free_parsed_policy(pp); + goto out; +} diff --git a/security/ipe/policy_parser.h b/security/ipe/policy_parser.h new file mode 100644 index 000000000000..2b744103d06a --- /dev/null +++ b/security/ipe/policy_parser.h @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ +#ifndef _IPE_POLICY_PARSER_H +#define _IPE_POLICY_PARSER_H + +int parse_policy(struct ipe_policy *p); +void free_parsed_policy(struct ipe_parsed_policy *p); + +#endif /* _IPE_POLICY_PARSER_H */