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MuVx8U3ZU3LiZmN0PV3yxuPoilIB0hlEbjTBjDjAjNbp_YI.hL8dL8xaTMcKxAQt1fw8uEWvxbSR AfL6lfWH11sLfYVtNT_.0oN7vWqmAVA1HOSXpBepZ2NlR3IfHtOlcwfIa_oZr527FdPn0cbPyBVQ HzB9HIxHMHpTDqx3GE5LDcFJ5ta.fGgd.Hq.PeL7Sy9kv9O8Bidk.72KPFKfYZVC3qPbNmxvXeXI tcq2cMLUlJlgbMs6WMy03FE_JEcsKwTRyD8b6a8e5cJ7FTaxxKEEBY6vDbo2xJu_LwhYl2TGHtFE VMpHatpWjT0Injf5qLivku8U6p80zxC3vPWLCtYX6MeUPG0Y.NGA_fXSEbbxuazjCvo59UftOH_U 8.rjv_T.6dNFFhhqilC7pugbJ5b55_pebevxW.lNOnGKAX_.IN7nnPv1gDjPyXkPXBUfCW8ECyah DYCTLfOjvDaLesVvD_ObIT_o4hyVvsVwSPAJ87jIKDDhBGKL01p8S97pR4ffl.Goj3vc3X32IaVE IxQNoWtcb0Tm.FzWwiSAXLiHygqB6JCXf.Fdkhxd50YboPBeTR62z8Ahkwleap3NwSzB_RHnIsm0 j6SkBXAaGCHGHCoRWw70lz8ErVw5ZEs_rMWdj_Tn5znr76Ay38PWhWSx8v2.bTt.DHrjxxuhnvzT iV57SkV5dz.jzER7gf_q9tCl244Evjn7jZQCCb1OwQyB3VXhz5qSwUj2CCEiO7jx3GckTX0OfgIM MFFAh6CrmMUFCt2XT5tZIhcyyMSy7h7qrZz6iSFHDbk88EDWPvJ7Z2JBqkpssVdLZI0mw2jtUiCa 43pXv0yzR0dBIp7MxsIamNpYpv.W4l8mZUiXV_lPMoB5vtqXcC4bH1GZYndkavKWHWMc5cvroLIL NDD0xlnuhSFDyvuDDVsZ5P7m7vogVPLk- Received: from sonic.gate.mail.ne1.yahoo.com by sonic314.consmr.mail.ne1.yahoo.com with HTTP; Tue, 26 Jan 2021 16:55:47 +0000 Received: by smtp425.mail.gq1.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID e895881efdbbf41af31f9904897acf15; Tue, 26 Jan 2021 16:45:42 +0000 (UTC) From: Casey Schaufler To: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: casey@schaufler-ca.com, linux-audit@redhat.com, keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov, linux-kernel@vger.kernel.org Subject: [PATCH v24 04/25] IMA: avoid label collisions with stacked LSMs Date: Tue, 26 Jan 2021 08:40:47 -0800 Message-Id: <20210126164108.1958-5-casey@schaufler-ca.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20210126164108.1958-1-casey@schaufler-ca.com> References: <20210126164108.1958-1-casey@schaufler-ca.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: 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 securty 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 To: Mimi Zohar To: linux-integrity@vger.kernel.org --- Documentation/ABI/testing/ima_policy | 8 +++- security/integrity/ima/ima_policy.c | 64 ++++++++++++++++++++++------ 2 files changed, 57 insertions(+), 15 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index e35263f97fc1..a7943d40466f 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -25,7 +25,7 @@ Description: base: [[func=] [mask=] [fsmagic=] [fsuuid=] [uid=] [euid=] [fowner=] [fsname=]] 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=] [keyrings=] base: @@ -114,6 +114,12 @@ 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 + modules 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/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 8002683003e6..de72b719c90c 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -82,6 +82,7 @@ struct ima_rule_entry { void *rules[LSMBLOB_ENTRIES]; /* LSM file metadata specific */ char *args_p; /* audit value */ int type; /* audit type */ + int which_lsm; /* which of the rules to use */ } lsm[MAX_LSM_RULES]; char *fsname; struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */ @@ -90,17 +91,15 @@ struct ima_rule_entry { /** * ima_lsm_isset - Is a rule set for any of the active security modules - * @rules: The set of IMA rules to check + * @entry: the rule entry to examine + * @lsm_rule: the specific rule type in question * - * If a rule is set for any LSM return true, otherwise return false. + * If a rule is set return true, otherwise return false. */ -static inline bool ima_lsm_isset(void *rules[]) +static inline bool ima_lsm_isset(struct ima_rule_entry *entry, int lsm_rule) { - int i; - - for (i = 0; i < LSMBLOB_ENTRIES; i++) - if (rules[i]) - return true; + if (entry->lsm[lsm_rule].rules[entry->lsm[lsm_rule].which_lsm]) + return true; return false; } @@ -273,6 +272,20 @@ static int __init default_appraise_policy_setup(char *str) } __setup("ima_appraise_tcb", default_appraise_policy_setup); +static int ima_rule_lsm __ro_after_init; + +static int __init ima_rule_lsm_init(char *str) +{ + ima_rule_lsm = lsm_name_to_slot(str); + if (ima_rule_lsm < 0) { + ima_rule_lsm = 0; + pr_err("rule lsm \"%s\" not registered", str); + } + + return 1; +} +__setup("ima_rule_lsm=", ima_rule_lsm_init); + static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src) { struct ima_rule_opt_list *opt_list; @@ -346,7 +359,8 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry) for (i = 0; i < MAX_LSM_RULES; i++) { for (r = 0; r < LSMBLOB_ENTRIES; r++) - ima_filter_rule_free(entry->lsm[i].rules[r]); + if (entry->lsm[i].rules[r]) + ima_filter_rule_free(entry->lsm[i].rules[r]); kfree(entry->lsm[i].args_p); } } @@ -398,7 +412,7 @@ 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].rules[0]); - if (!ima_lsm_isset(nentry->lsm[i].rules)) + if (!ima_lsm_isset(nentry, i)) pr_warn("rule for LSM \'%s\' is undefined\n", nentry->lsm[i].args_p); } @@ -563,7 +577,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, int rc = 0; u32 osid; - if (!ima_lsm_isset(rule->lsm[i].rules)) { + if (!ima_lsm_isset(rule, i)) { if (!rule->lsm[i].args_p) continue; else @@ -925,6 +939,7 @@ enum { Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, Opt_appraise_type, Opt_appraise_flag, Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, + Opt_lsm, Opt_err }; @@ -962,6 +977,7 @@ static const match_table_t policy_tokens = { {Opt_pcr, "pcr=%s"}, {Opt_template, "template=%s"}, {Opt_keyrings, "keyrings=%s"}, + {Opt_lsm, "lsm=%s"}, {Opt_err, NULL} }; @@ -970,7 +986,7 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry, { int result; - if (ima_lsm_isset(entry->lsm[lsm_rule].rules)) + if (ima_lsm_isset(entry, lsm_rule)) return -EINVAL; entry->lsm[lsm_rule].args_p = match_strdup(args); @@ -981,7 +997,7 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry, result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal, entry->lsm[lsm_rule].args_p, &entry->lsm[lsm_rule].rules[0]); - if (!ima_lsm_isset(entry->lsm[lsm_rule].rules)) { + if (!ima_lsm_isset(entry, lsm_rule)) { pr_warn("rule for LSM \'%s\' is undefined\n", entry->lsm[lsm_rule].args_p); @@ -1488,6 +1504,19 @@ 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->lsm->which_lsm = result; + result = 0; + break; case Opt_err: ima_log_string(ab, "UNKNOWN", p); result = -EINVAL; @@ -1524,6 +1553,7 @@ 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; @@ -1541,6 +1571,9 @@ ssize_t ima_parse_add_rule(char *rule) INIT_LIST_HEAD(&entry->list); + for (i = 0; i < MAX_LSM_RULES; i++) + entry->lsm[i].which_lsm = ima_rule_lsm; + result = ima_parse_rule(p, entry); if (result) { ima_free_rule(entry); @@ -1751,7 +1784,7 @@ int ima_policy_show(struct seq_file *m, void *v) } for (i = 0; i < MAX_LSM_RULES; i++) { - if (ima_lsm_isset(entry->lsm[i].rules)) { + if (ima_lsm_isset(entry, i)) { switch (i) { case LSM_OBJ_USER: seq_printf(m, pt(Opt_obj_user), @@ -1793,6 +1826,9 @@ 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->lsm->which_lsm >= 0) + seq_printf(m, pt(Opt_lsm), + lsm_slot_to_name(entry->lsm->which_lsm)); rcu_read_unlock(); seq_puts(m, "\n"); return 0; -- 2.25.4