Re: [PATCH v35 06/29] LSM: Use lsmblob in security_audit_rule_match

John Johansen
2022-04-21T16:50:04Z

On 4/18/22 07:59, Casey Schaufler wrote:
> Change the secid parameter of security_audit_rule_match
> to a lsmblob structure pointer. Pass the entry from the
> lsmblob structure for the approprite slot to the LSM hook.
>
> Change the users of security_audit_rule_match to use the
> lsmblob instead of a u32. The scaffolding function lsmblob_init()
> fills the blob with the value of the old secid, ensuring that
> it is available to the appropriate module hook. The sources of
> the secid, security_task_getsecid() and security_inode_getsecid(),
> will be converted to use the blob structure later in the series.
> At the point the use of lsmblob_init() is dropped.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> Acked-by: Paul Moore <paul@paul-moore.com>

Reviewed-by: John Johansen <john.johansen@canonical.com>

> Cc: linux-audit@redhat.com
> ---
> include/linux/security.h | 5 +++--
> kernel/auditfilter.c | 6 ++++--
> kernel/auditsc.c | 16 +++++++++++-----
> security/security.c | 5 +++--
> 4 files changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 3666eddad59a..ee5d14dac65f 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -1955,7 +1955,7 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer)
> int security_audit_rule_init(u32 field, u32 op, char *rulestr,
> struct audit_lsm_rules *lsmrules);
> int security_audit_rule_known(struct audit_krule *krule);
> -int security_audit_rule_match(u32 secid, u32 field, u32 op,
> +int security_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
> struct audit_lsm_rules *lsmrules);
> void security_audit_rule_free(struct audit_lsm_rules *lsmrules);
>
> @@ -1972,7 +1972,8 @@ 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,
> +static inline int security_audit_rule_match(struct lsmblob *blob,
> + u32 field, u32 op,
> struct audit_lsm_rules *lsmrules)
> {
> return 0;
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index de75bd6ad866..15cd4fe35e9c 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -1337,6 +1337,7 @@ int audit_filter(int msgtype, unsigned int listtype)
>
> for (i = 0; i < e->rule.field_count; i++) {
> struct audit_field *f = &e->rule.fields[i];
> + struct lsmblob blob;
> pid_t pid;
> u32 sid;
>
> @@ -1369,8 +1370,9 @@ int audit_filter(int msgtype, unsigned int listtype)
> case AUDIT_SUBJ_CLR:
> if (f->lsm_str) {
> security_current_getsecid_subj(&sid);
> - result = security_audit_rule_match(sid,
> - f->type, f->op,
> + lsmblob_init(&blob, sid);
> + result = security_audit_rule_match(
> + &blob, f->type, f->op,
> &f->lsm_rules);
> }
> break;
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index d272b5cf18a8..a9d5bfa37cb3 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -468,6 +468,7 @@ static int audit_filter_rules(struct task_struct *tsk,
> const struct cred *cred;
> int i, need_sid = 1;
> u32 sid;
> + struct lsmblob blob;
> unsigned int sessionid;
>
> if (ctx && rule->prio <= ctx->prio)
> @@ -678,8 +679,10 @@ static int audit_filter_rules(struct task_struct *tsk,
> security_current_getsecid_subj(&sid);
> need_sid = 0;
> }
> - result = security_audit_rule_match(sid, f->type,
> - f->op, &f->lsm_rules);
> + lsmblob_init(&blob, sid);
> + result = security_audit_rule_match(&blob,
> + f->type, f->op,
> + &f->lsm_rules);
> }
> break;
> case AUDIT_OBJ_USER:
> @@ -692,15 +695,17 @@ static int audit_filter_rules(struct task_struct *tsk,
> if (f->lsm_str) {
> /* Find files that match */
> if (name) {
> + lsmblob_init(&blob, name->osid);
> result = security_audit_rule_match(
> - name->osid,
> + &blob,
> f->type,
> f->op,
> &f->lsm_rules);
> } else if (ctx) {
> list_for_each_entry(n, &ctx->names_list, list) {
> + lsmblob_init(&blob, n->osid);
> if (security_audit_rule_match(
> - n->osid, f->type, f->op,
> + &blob, f->type, f->op,
> &f->lsm_rules)) {
> ++result;
> break;
> @@ -710,7 +715,8 @@ static int audit_filter_rules(struct task_struct *tsk,
> /* Find ipc objects that match */
> if (!ctx || ctx->type != AUDIT_IPC)
> break;
> - if (security_audit_rule_match(ctx->ipc.osid,
> + lsmblob_init(&blob, ctx->ipc.osid);
> + if (security_audit_rule_match(&blob,
> f->type, f->op,
> &f->lsm_rules))
> ++result;
> diff --git a/security/security.c b/security/security.c
> index 9e0139b0d346..ced1c76a380f 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2703,7 +2703,7 @@ void security_audit_rule_free(struct audit_lsm_rules *lsmrules)
> }
> }
>
> -int security_audit_rule_match(u32 secid, u32 field, u32 op,
> +int security_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
> struct audit_lsm_rules *lsmrules)
> {
> struct security_hook_list *hp;
> @@ -2714,7 +2714,8 @@ int security_audit_rule_match(u32 secid, u32 field, u32 op,
> continue;
> if (lsmrules->rule[hp->lsmid->slot] == NULL)
> continue;
> - rc = hp->hook.audit_rule_match(secid, field, op,
> + rc = hp->hook.audit_rule_match(blob->secid[hp->lsmid->slot],
> + field, op,
> &lsmrules->rule[hp->lsmid->slot]);
> if (rc)
> return rc;