On 4/18/22 07:59, Casey Schaufler wrote: > Integrity measurement may filter on security module information > and needs to be clear in the case of multiple active security > modules which applies. Provide a boot option ima_rules_lsm= to > allow the user to specify an active security module to apply > filters to. If not specified, use the first registered module > that supports the audit_rule_match() LSM hook. Allow the user > to specify in the IMA policy an lsm= option to specify the > security module to use for a particular rule. > > Signed-off-by: Casey Schaufler <[email protected]>
Reviewed-by: John Johansen <[email protected]> > To: Mimi Zohar <[email protected]> > To: [email protected] > --- > Documentation/ABI/testing/ima_policy | 8 ++++- > include/linux/security.h | 14 ++++---- > security/integrity/ima/ima_policy.c | 51 ++++++++++++++++++++++++---- > security/security.c | 35 +++++++++++++++---- > 4 files changed, 89 insertions(+), 19 deletions(-) > > diff --git a/Documentation/ABI/testing/ima_policy > b/Documentation/ABI/testing/ima_policy > index 839fab811b18..64863e9d87ea 100644 > --- a/Documentation/ABI/testing/ima_policy > +++ b/Documentation/ABI/testing/ima_policy > @@ -26,7 +26,7 @@ Description: > [uid=] [euid=] [gid=] [egid=] > [fowner=] [fgroup=]] > lsm: [[subj_user=] [subj_role=] [subj_type=] > - [obj_user=] [obj_role=] [obj_type=]] > + [obj_user=] [obj_role=] [obj_type=]] [lsm=] > option: [[appraise_type=]] [template=] [permit_directio] > [appraise_flag=] [appraise_algos=] [keyrings=] > base: > @@ -126,6 +126,12 @@ Description: > > measure subj_user=_ func=FILE_CHECK mask=MAY_READ > > + It is possible to explicitly specify which security > + module a rule applies to using lsm=. If the security > + module specified is not active on the system the rule > + will be rejected. If lsm= is not specified the first > + security module registered on the system will be assumed. > + > Example of measure rules using alternate PCRs:: > > measure func=KEXEC_KERNEL_CHECK pcr=4 > diff --git a/include/linux/security.h b/include/linux/security.h > index d00870d2b416..3666eddad59a 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1985,25 +1985,27 @@ static inline void security_audit_rule_free(struct > audit_lsm_rules *lsmrules) > #endif /* CONFIG_AUDIT */ > > #if defined(CONFIG_IMA_LSM_RULES) && defined(CONFIG_SECURITY) > -int ima_filter_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule); > -int ima_filter_rule_match(u32 secid, u32 field, u32 op, void *lsmrule); > -void ima_filter_rule_free(void *lsmrule); > +int ima_filter_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule, > + int lsmslot); > +int ima_filter_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, > + int lsmslot); > +void ima_filter_rule_free(void *lsmrule, int lsmslot); > > #else > > static inline int ima_filter_rule_init(u32 field, u32 op, char *rulestr, > - void **lsmrule) > + void **lsmrule, int lsmslot) > { > return 0; > } > > static inline int ima_filter_rule_match(u32 secid, u32 field, u32 op, > - void *lsmrule) > + void *lsmrule, int lsmslot) > { > return 0; > } > > -static inline void ima_filter_rule_free(void *lsmrule) > +static inline void ima_filter_rule_free(void *lsmrule, int lsmslot) > { } > > #endif /* defined(CONFIG_IMA_LSM_RULES) && defined(CONFIG_SECURITY) */ > diff --git a/security/integrity/ima/ima_policy.c > b/security/integrity/ima/ima_policy.c > index eea6e92500b8..97470354c8ae 100644 > --- a/security/integrity/ima/ima_policy.c > +++ b/security/integrity/ima/ima_policy.c > @@ -89,6 +89,7 @@ struct ima_rule_entry { > bool (*fgroup_op)(kgid_t cred_gid, kgid_t rule_gid); /* gid_eq(), > gid_gt(), gid_lt() */ > int pcr; > unsigned int allowed_algos; /* bitfield of allowed hash algorithms */ > + int which; /* which LSM rule applies to */ > struct { > void *rule; /* LSM file metadata specific */ > char *args_p; /* audit value */ > @@ -285,6 +286,20 @@ static int __init default_appraise_policy_setup(char > *str) > } > __setup("ima_appraise_tcb", default_appraise_policy_setup); > > +static int ima_rules_lsm __ro_after_init; > + > +static int __init ima_rules_lsm_init(char *str) > +{ > + ima_rules_lsm = lsm_name_to_slot(str); > + if (ima_rules_lsm < 0) { > + ima_rules_lsm = 0; > + pr_err("rule lsm \"%s\" not registered", str); > + } > + > + return 1; > +} > +__setup("ima_rules_lsm=", ima_rules_lsm_init); > + > static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t > *src) > { > struct ima_rule_opt_list *opt_list; > @@ -356,7 +371,7 @@ static void ima_lsm_free_rule(struct ima_rule_entry > *entry) > int i; > > for (i = 0; i < MAX_LSM_RULES; i++) { > - ima_filter_rule_free(entry->lsm[i].rule); > + ima_filter_rule_free(entry->lsm[i].rule, entry->which); > kfree(entry->lsm[i].args_p); > } > } > @@ -407,7 +422,8 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct > ima_rule_entry *entry) > > ima_filter_rule_init(nentry->lsm[i].type, Audit_equal, > nentry->lsm[i].args_p, > - &nentry->lsm[i].rule); > + &nentry->lsm[i].rule, > + entry->which); > if (!nentry->lsm[i].rule) > pr_warn("rule for LSM \'%s\' is undefined\n", > nentry->lsm[i].args_p); > @@ -623,14 +639,16 @@ static bool ima_match_rules(struct ima_rule_entry *rule, > security_inode_getsecid(inode, &osid); > rc = ima_filter_rule_match(osid, rule->lsm[i].type, > Audit_equal, > - rule->lsm[i].rule); > + rule->lsm[i].rule, > + rule->which); > break; > case LSM_SUBJ_USER: > case LSM_SUBJ_ROLE: > case LSM_SUBJ_TYPE: > rc = ima_filter_rule_match(secid, rule->lsm[i].type, > Audit_equal, > - rule->lsm[i].rule); > + rule->lsm[i].rule, > + rule->which); > break; > default: > break; > @@ -1025,7 +1043,7 @@ enum policy_opt { > Opt_fowner_lt, Opt_fgroup_lt, > Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos, > Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, > - Opt_label, Opt_err > + Opt_lsm, Opt_label, Opt_err > }; > > static const match_table_t policy_tokens = { > @@ -1073,6 +1091,7 @@ static const match_table_t policy_tokens = { > {Opt_template, "template=%s"}, > {Opt_keyrings, "keyrings=%s"}, > {Opt_label, "label=%s"}, > + {Opt_lsm, "lsm=%s"}, > {Opt_err, NULL} > }; > > @@ -1091,7 +1110,8 @@ static int ima_lsm_rule_init(struct ima_rule_entry > *entry, > entry->lsm[lsm_rule].type = audit_type; > result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal, > entry->lsm[lsm_rule].args_p, > - &entry->lsm[lsm_rule].rule); > + &entry->lsm[lsm_rule].rule, > + entry->which); > if (!entry->lsm[lsm_rule].rule) { > pr_warn("rule for LSM \'%s\' is undefined\n", > entry->lsm[lsm_rule].args_p); > @@ -1780,6 +1800,19 @@ static int ima_parse_rule(char *rule, struct > ima_rule_entry *entry) > &(template_desc->num_fields)); > entry->template = template_desc; > break; > + case Opt_lsm: > + result = lsm_name_to_slot(args[0].from); > + if (result == LSMBLOB_INVALID) { > + int i; > + > + for (i = 0; i < MAX_LSM_RULES; i++) > + entry->lsm[i].args_p = NULL; > + result = -EINVAL; > + break; > + } > + entry->which = result; > + result = 0; > + break; > case Opt_err: > ima_log_string(ab, "UNKNOWN", p); > result = -EINVAL; > @@ -1816,6 +1849,7 @@ ssize_t ima_parse_add_rule(char *rule) > struct ima_rule_entry *entry; > ssize_t result, len; > int audit_info = 0; > + int i; > > p = strsep(&rule, "\n"); > len = strlen(p) + 1; > @@ -1833,6 +1867,9 @@ ssize_t ima_parse_add_rule(char *rule) > > INIT_LIST_HEAD(&entry->list); > > + for (i = 0; i < MAX_LSM_RULES; i++) > + entry->which = ima_rules_lsm; > + > result = ima_parse_rule(p, entry); > if (result) { > ima_free_rule(entry); > @@ -2158,6 +2195,8 @@ int ima_policy_show(struct seq_file *m, void *v) > seq_puts(m, "appraise_flag=check_blacklist "); > if (entry->flags & IMA_PERMIT_DIRECTIO) > seq_puts(m, "permit_directio "); > + if (entry->which >= 0) > + seq_printf(m, pt(Opt_lsm), lsm_slot_to_name(entry->which)); > rcu_read_unlock(); > seq_puts(m, "\n"); > return 0; > diff --git a/security/security.c b/security/security.c > index d1ddbb857af1..9e0139b0d346 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -2728,19 +2728,42 @@ int security_audit_rule_match(u32 secid, u32 field, > u32 op, > * The integrity subsystem uses the same hooks as > * the audit subsystem. > */ > -int ima_filter_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule) > +int ima_filter_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule, > + int lsmslot) > { > - return call_int_hook(audit_rule_init, 0, field, op, rulestr, lsmrule); > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.audit_rule_init, list) > + if (hp->lsmid->slot == lsmslot) > + return hp->hook.audit_rule_init(field, op, rulestr, > + lsmrule); > + > + return 0; > } > > -void ima_filter_rule_free(void *lsmrule) > +void ima_filter_rule_free(void *lsmrule, int lsmslot) > { > - call_void_hook(audit_rule_free, lsmrule); > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.audit_rule_free, list) { > + if (hp->lsmid->slot == lsmslot) { > + hp->hook.audit_rule_free(lsmrule); > + return; > + } > + } > } > > -int ima_filter_rule_match(u32 secid, u32 field, u32 op, void *lsmrule) > +int ima_filter_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, > + int lsmslot) > { > - return call_int_hook(audit_rule_match, 0, secid, field, op, lsmrule); > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.audit_rule_match, list) > + if (hp->lsmid->slot == lsmslot) > + return hp->hook.audit_rule_match(secid, field, op, > + lsmrule); > + > + return 0; > } > #endif /* CONFIG_IMA_LSM_RULES */ > -- Linux-audit mailing list [email protected] https://listman.redhat.com/mailman/listinfo/linux-audit
