Re: [PATCH 6/9] LSM/Audit: Introduce generic Audit LSM hooks

Introduce a generic Audit interface for security modules by adding the following new LSM hooks: audit_rule_init(field, op, rulestr, lsmrule) audit_rule_known(krule) audit_rule_match(secid, field, op, rule, actx) audit_rule_free(rule) Those hooks are only available if CONFIG_AUDIT is enabled. Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; Signed-off-by: Ahmed S. Darwish <darwish.07(a)gmail.com&gt;

--- include/linux/security.h | 72 +++++++++++++++++++++++++++++++++++++++++++++++ security/dummy.c | 31 +++++++++++++++++++- security/security.c | 25 ++++++++++++++++ 3 files changed, 127 insertions(+), 1 deletion(-) diff --git a/include/linux/security.h b/include/linux/security.h index b5d1ad7..eb663e5 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -43,6 +43,7 @@ extern unsigned securebits; struct ctl_table; +struct audit_krule; /* * These functions are in security/capability.c and are used @@ -1227,6 +1228,37 @@ struct request_sock; * @secdata contains the security context. * @seclen contains the length of the security context. * + * Security hooks for Audit + * + * @audit_rule_init: + * Allocate and initialize an LSM audit rule structure. + * @field contains the required Audit action. Fields flags are defined in include/linux/audit.h + * @op contains the operator the rule uses. + * @rulestr contains the context where the rule will be applied to. + * @lsmrule contains a pointer to receive the result. + * Return 0 if @lsmrule has been successfully set, + * -EINVAL in case of an invalid rule. + * + * @audit_rule_known: + * Specifies whether given @rule contains any fields related to current LSM. + * @rule contains the audit rule of interest. + * Return 1 in case of relation found, 0 otherwise. + * + * @audit_rule_match: + * Determine if given @secid matches a rule previously approved + * by @audit_rule_known. + * @secid contains the security id in question. + * @field contains the field which relates to current LSM. + * @op contains the operator that will be used for matching. + * @rule points to the audit rule that will be checked against. + * @actx points to the audit context associated with the check. + * Return 1 if secid matches the rule, 0 if it does not, -ERRNO on failure. + * + * @audit_rule_free: + * Deallocate the LSM audit rule structure previously allocated by + * audit_rule_init. + * @rule contains the allocated rule + * * This is the main security structure. */ struct security_operations { @@ -1487,6 +1519,13 @@ struct security_operations { int (*key_getsecurity)(struct key *key, char **_buffer); #endif /* CONFIG_KEYS */ +#ifdef CONFIG_AUDIT + int (*audit_rule_init)(u32 field, u32 op, char *rulestr, void **lsmrule); + int (*audit_rule_known)(struct audit_krule *krule); + int (*audit_rule_match)(u32 secid, u32 field, u32 op, void *lsmrule, + struct audit_context *actx); + void (*audit_rule_free)(void *lsmrule); +#endif /* CONFIG_AUDIT */ }; /* prototypes */ @@ -2670,5 +2709,38 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer) #endif #endif /* CONFIG_KEYS */ +#ifdef CONFIG_AUDIT +#ifdef CONFIG_SECURITY +int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule); +int security_audit_rule_known(struct audit_krule *krule); +int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, + struct audit_context *actx); +void security_audit_rule_free(void *lsmrule); + +#else + +static inline int security_audit_rule_init(u32 field, u32 op, char *rulestr, + void **lsmrule) +{ + return 0; +} + +static inline int security_audit_rule_known(struct audit_krule *krule) +{ + return 0; +} + +static inline int security_audit_rule_match(u32 secid, u32 field, u32 op, + void *lsmrule, struct audit_context *actx) +{ + return 0; +} + +static inline void security_audit_rule_free(void *lsmrule) +{ } + +#endif /* CONFIG_SECURITY */ +#endif /* CONFIG_AUDIT */ + #endif /* ! __LINUX_SECURITY_H */ diff --git a/security/dummy.c b/security/dummy.c index b4967f4..241ab20 100644 --- a/security/dummy.c +++ b/security/dummy.c @@ -998,6 +998,30 @@ static int dummy_key_getsecurity(struct key *key, char **_buffer) #endif /* CONFIG_KEYS */ +#ifdef CONFIG_AUDIT +static inline int dummy_audit_rule_init(u32 field, u32 op, char *rulestr, + void **lsmrule) +{ + return 0; +} + +static inline int dummy_audit_rule_known(struct audit_krule *krule) +{ + return 0; +} + +static inline int dummy_audit_rule_match(u32 secid, u32 field, u32 op, + void *lsmrule, + struct audit_context *actx) +{ + return 0; +} + +static inline void dummy_audit_rule_free(void *lsmrule) +{ } + +#endif /* CONFIG_AUDIT */ + struct security_operations dummy_security_ops; #define set_to_dummy_if_null(ops, function) \ @@ -1187,6 +1211,11 @@ void security_fixup_ops (struct security_operations *ops) set_to_dummy_if_null(ops, key_permission); set_to_dummy_if_null(ops, key_getsecurity); #endif /* CONFIG_KEYS */ - +#ifdef CONFIG_AUDIT + set_to_dummy_if_null(ops, audit_rule_init); + set_to_dummy_if_null(ops, audit_rule_known); + set_to_dummy_if_null(ops, audit_rule_match); + set_to_dummy_if_null(ops, audit_rule_free); +#endif } diff --git a/security/security.c b/security/security.c index 1748329..1bf2ee4 100644 --- a/security/security.c +++ b/security/security.c @@ -1118,3 +1118,28 @@ int security_key_getsecurity(struct key *key, char **_buffer) } #endif /* CONFIG_KEYS */ + +#ifdef CONFIG_AUDIT + +int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule) +{ + return security_ops->audit_rule_init(field, op, rulestr, lsmrule); +} + +int security_audit_rule_known(struct audit_krule *krule) +{ + return security_ops->audit_rule_known(krule); +} + +void security_audit_rule_free(void *lsmrule) +{ + security_ops->audit_rule_free(lsmrule); +} + +int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, + struct audit_context *actx) +{ + return security_ops->audit_rule_match(secid, field, op, lsmrule, actx); +} + +#endif /* CONFIG_AUDIT */