[PATCH v16 20/23] Audit: Add a new record for multiple subject LSM attributes
Kees Cook
keescook at chromium.org
Tue Apr 7 18:43:16 UTC 2020
On Mon, Apr 06, 2020 at 05:01:56PM -0700, Casey Schaufler wrote:
> Create a new audit record type to contain the subject information
> when there are multiple security modules that require such data.
> This record is emitted before the other records for the event, but
> is linked with the same timestamp and serial number.
>
> Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
Reviewed-by: Kees Cook <keescook at chromium.org>
-Kees
> Cc: linux-audit at redhat.com
> ---
> drivers/android/binder.c | 2 +-
> include/linux/security.h | 9 +++-
> include/net/scm.h | 3 +-
> include/uapi/linux/audit.h | 1 +
> kernel/audit.c | 56 +++++++++++++++++++------
> kernel/auditsc.c | 7 ++--
> net/ipv4/ip_sockglue.c | 2 +-
> net/netfilter/nf_conntrack_netlink.c | 4 +-
> net/netfilter/nf_conntrack_standalone.c | 2 +-
> net/netfilter/nfnetlink_queue.c | 2 +-
> net/netlabel/netlabel_unlabeled.c | 11 +++--
> net/netlabel/netlabel_user.c | 2 +-
> security/security.c | 51 ++++++++++++++++++++--
> 13 files changed, 118 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index c76fc2abd091..e79c4948ab12 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -3109,7 +3109,7 @@ static void binder_transaction(struct binder_proc *proc,
> size_t added_size;
>
> security_task_getsecid(proc->tsk, &blob);
> - ret = security_secid_to_secctx(&blob, &lsmctx);
> + ret = security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_DISPLAY);
> if (ret) {
> return_error = BR_FAILED_REPLY;
> return_error_param = ret;
> diff --git a/include/linux/security.h b/include/linux/security.h
> index fac5547dd89e..896b939f5d62 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -178,6 +178,8 @@ struct lsmblob {
> #define LSMBLOB_INVALID -1 /* Not a valid LSM slot number */
> #define LSMBLOB_NEEDED -2 /* Slot requested on initialization */
> #define LSMBLOB_NOT_NEEDED -3 /* Slot not requested */
> +#define LSMBLOB_DISPLAY -4 /* Use the "display" slot */
> +#define LSMBLOB_FIRST -5 /* Use the default "display" slot */
>
> /**
> * lsmblob_init - initialize an lsmblob structure.
> @@ -240,6 +242,8 @@ static inline u32 lsmblob_value(const struct lsmblob *blob)
> return 0;
> }
>
> +const char *security_lsm_slot_name(int slot);
> +
> /* These functions are in security/commoncap.c */
> extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
> int cap, unsigned int opts);
> @@ -549,7 +553,8 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
> size_t size);
> int security_netlink_send(struct sock *sk, struct sk_buff *skb);
> int security_ismaclabel(const char *name);
> -int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp);
> +int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp,
> + int display);
> int security_secctx_to_secid(const char *secdata, u32 seclen,
> struct lsmblob *blob);
> void security_release_secctx(struct lsmcontext *cp);
> @@ -1354,7 +1359,7 @@ static inline int security_ismaclabel(const char *name)
> }
>
> static inline int security_secid_to_secctx(struct lsmblob *blob,
> - struct lsmcontext *cp)
> + struct lsmcontext *cp, int display)
> {
> return -EOPNOTSUPP;
> }
> diff --git a/include/net/scm.h b/include/net/scm.h
> index 4a6ad8caf423..8b5a4737e1b8 100644
> --- a/include/net/scm.h
> +++ b/include/net/scm.h
> @@ -96,7 +96,8 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
> int err;
>
> if (test_bit(SOCK_PASSSEC, &sock->flags)) {
> - err = security_secid_to_secctx(&scm->lsmblob, &context);
> + err = security_secid_to_secctx(&scm->lsmblob, &context,
> + LSMBLOB_DISPLAY);
>
> if (!err) {
> put_cmsg(msg, SOL_SOCKET, SCM_SECURITY,
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index a534d71e689a..2e6dbf907ee3 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -138,6 +138,7 @@
> #define AUDIT_MAC_UNLBL_STCDEL 1417 /* NetLabel: del a static label */
> #define AUDIT_MAC_CALIPSO_ADD 1418 /* NetLabel: add CALIPSO DOI entry */
> #define AUDIT_MAC_CALIPSO_DEL 1419 /* NetLabel: del CALIPSO DOI entry */
> +#define AUDIT_MAC_TASK_CONTEXTS 1420 /* Multiple LSM contexts */
>
> #define AUDIT_FIRST_KERN_ANOM_MSG 1700
> #define AUDIT_LAST_KERN_ANOM_MSG 1799
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 013a90dd2bd5..00a4fbecfdf7 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -1419,7 +1419,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
> case AUDIT_SIGNAL_INFO:
> if (lsmblob_is_set(&audit_sig_lsm)) {
> err = security_secid_to_secctx(&audit_sig_lsm,
> - &context);
> + &context, LSMBLOB_FIRST);
> if (err)
> return err;
> }
> @@ -2058,28 +2058,58 @@ void audit_log_key(struct audit_buffer *ab, char *key)
>
> int audit_log_task_context(struct audit_buffer *ab)
> {
> + int i;
> int error;
> + bool sep = false;
> struct lsmblob blob;
> - struct lsmcontext context;
> + struct lsmcontext lsmdata;
> + struct audit_buffer *lsmab = NULL;
> + struct audit_context *context = NULL;
>
> security_task_getsecid(current, &blob);
> if (!lsmblob_is_set(&blob))
> return 0;
>
> - error = security_secid_to_secctx(&blob, &context);
> - if (error) {
> - if (error != -EINVAL)
> - goto error_path;
> - return 0;
> + /*
> + * If there is more than one security module that has a
> + * subject "context" it's necessary to put the subject data
> + * into a separate record to maintain compatibility.
> + */
> + if (security_lsm_slot_name(1) != NULL) {
> + audit_log_format(ab, " subj=?");
> + context = ab->ctx;
> + if (context)
> + lsmab = audit_log_start(context, GFP_KERNEL,
> + AUDIT_MAC_TASK_CONTEXTS);
> }
>
> - audit_log_format(ab, " subj=%s", context.context);
> - security_release_secctx(&context);
> - return 0;
> + for (i = 0; i < LSMBLOB_ENTRIES; i++) {
> + if (blob.secid[i] == 0)
> + continue;
> + error = security_secid_to_secctx(&blob, &lsmdata, i);
> + if (error && error != -EINVAL) {
> + audit_panic("error in audit_log_task_context");
> + return error;
> + }
> +
> + if (context) {
> + audit_log_format(lsmab, "%ssubj_%s=%s",
> + sep ? " " : "",
> + security_lsm_slot_name(i),
> + lsmdata.context);
> + sep = true;
> + } else
> + audit_log_format(ab, " subj=%s", lsmdata.context);
> +
> + security_release_secctx(&lsmdata);
> + if (!context)
> + break;
> + }
> +
> + if (context)
> + audit_log_end(lsmab);
>
> -error_path:
> - audit_panic("error in audit_log_task_context");
> - return error;
> + return 0;
> }
> EXPORT_SYMBOL(audit_log_task_context);
>
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index b7275860ba5f..4df540c32581 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -980,7 +980,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
> from_kuid(&init_user_ns, auid),
> from_kuid(&init_user_ns, uid), sessionid);
> if (lsmblob_is_set(blob)) {
> - if (security_secid_to_secctx(blob, &lsmctx)) {
> + if (security_secid_to_secctx(blob, &lsmctx, LSMBLOB_FIRST)) {
> audit_log_format(ab, " obj=(none)");
> rc = 1;
> } else {
> @@ -1225,7 +1225,8 @@ static void show_special(struct audit_context *context, int *call_panic)
> struct lsmblob blob;
>
> lsmblob_init(&blob, osid);
> - if (security_secid_to_secctx(&blob, &lsmcxt)) {
> + if (security_secid_to_secctx(&blob, &lsmcxt,
> + LSMBLOB_FIRST)) {
> audit_log_format(ab, " osid=%u", osid);
> *call_panic = 1;
> } else {
> @@ -1377,7 +1378,7 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
> struct lsmcontext lsmctx;
>
> lsmblob_init(&blob, n->osid);
> - if (security_secid_to_secctx(&blob, &lsmctx)) {
> + if (security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_FIRST)) {
> audit_log_format(ab, " osid=%u", n->osid);
> if (call_panic)
> *call_panic = 2;
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index 27af7a6b8780..10b418029cdd 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -138,7 +138,7 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
> if (err)
> return;
>
> - err = security_secid_to_secctx(&lb, &context);
> + err = security_secid_to_secctx(&lb, &context, LSMBLOB_DISPLAY);
> if (err)
> return;
>
> diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> index 2fa1e5bd781d..cd559fada596 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -337,7 +337,7 @@ static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
> * security_secid_to_secctx() will know which security module
> * to use to create the secctx. */
> lsmblob_init(&blob, ct->secmark);
> - ret = security_secid_to_secctx(&blob, &context);
> + ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
> if (ret)
> return 0;
>
> @@ -651,7 +651,7 @@ static inline int ctnetlink_secctx_size(const struct nf_conn *ct)
> struct lsmblob blob;
> struct lsmcontext context;
>
> - ret = security_secid_to_secctx(&blob, &context);
> + ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
> if (ret)
> return 0;
>
> diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
> index 383a4f44be63..9551e8be6ca4 100644
> --- a/net/netfilter/nf_conntrack_standalone.c
> +++ b/net/netfilter/nf_conntrack_standalone.c
> @@ -177,7 +177,7 @@ static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
> struct lsmcontext context;
>
> lsmblob_init(&blob, ct->secmark);
> - ret = security_secid_to_secctx(&blob, &context);
> + ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
> if (ret)
> return;
>
> diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
> index d07900c317fd..dc8902f8cea2 100644
> --- a/net/netfilter/nfnetlink_queue.c
> +++ b/net/netfilter/nfnetlink_queue.c
> @@ -316,7 +316,7 @@ static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, struct lsmcontext *context)
> * blob. security_secid_to_secctx() will know which security
> * module to use to create the secctx. */
> lsmblob_init(&blob, skb->secmark);
> - security_secid_to_secctx(&blob, context);
> + security_secid_to_secctx(&blob, context, LSMBLOB_DISPLAY);
> }
>
> read_unlock_bh(&skb->sk->sk_callback_lock);
> diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
> index c14a485ff045..d816909866cc 100644
> --- a/net/netlabel/netlabel_unlabeled.c
> +++ b/net/netlabel/netlabel_unlabeled.c
> @@ -437,7 +437,8 @@ int netlbl_unlhsh_add(struct net *net,
> unlhsh_add_return:
> rcu_read_unlock();
> if (audit_buf != NULL) {
> - if (security_secid_to_secctx(lsmblob, &context) == 0) {
> + if (security_secid_to_secctx(lsmblob, &context,
> + LSMBLOB_FIRST) == 0) {
> audit_log_format(audit_buf, " sec_obj=%s",
> context.context);
> security_release_secctx(&context);
> @@ -492,7 +493,8 @@ static int netlbl_unlhsh_remove_addr4(struct net *net,
> if (dev != NULL)
> dev_put(dev);
> if (entry != NULL &&
> - security_secid_to_secctx(&entry->lsmblob, &context) == 0) {
> + security_secid_to_secctx(&entry->lsmblob, &context,
> + LSMBLOB_FIRST) == 0) {
> audit_log_format(audit_buf, " sec_obj=%s",
> context.context);
> security_release_secctx(&context);
> @@ -552,7 +554,8 @@ static int netlbl_unlhsh_remove_addr6(struct net *net,
> if (dev != NULL)
> dev_put(dev);
> if (entry != NULL &&
> - security_secid_to_secctx(&entry->lsmblob, &context) == 0) {
> + security_secid_to_secctx(&entry->lsmblob, &context,
> + LSMBLOB_FIRST) == 0) {
> audit_log_format(audit_buf, " sec_obj=%s",
> context.context);
> security_release_secctx(&context);
> @@ -1122,7 +1125,7 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd,
> lsmb = (struct lsmblob *)&addr6->lsmblob;
> }
>
> - ret_val = security_secid_to_secctx(lsmb, &context);
> + ret_val = security_secid_to_secctx(lsmb, &context, LSMBLOB_FIRST);
> if (ret_val != 0)
> goto list_cb_failure;
> ret_val = nla_put(cb_arg->skb,
> diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
> index 951ba0639d20..1941877fd16f 100644
> --- a/net/netlabel/netlabel_user.c
> +++ b/net/netlabel/netlabel_user.c
> @@ -100,7 +100,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
>
> lsmblob_init(&blob, audit_info->secid);
> if (audit_info->secid != 0 &&
> - security_secid_to_secctx(&blob, &context) == 0) {
> + security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST) == 0) {
> audit_log_format(audit_buf, " subj=%s", context.context);
> security_release_secctx(&context);
> }
> diff --git a/security/security.c b/security/security.c
> index b7c2ed1eee42..d3bf71d66724 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -480,7 +480,31 @@ static int lsm_append(const char *new, char **result)
> * Pointers to the LSM id structures for local use.
> */
> static int lsm_slot __lsm_ro_after_init;
> -static struct lsm_id *lsm_slotlist[LSMBLOB_ENTRIES];
> +static struct lsm_id *lsm_slotlist[LSMBLOB_ENTRIES] __lsm_ro_after_init;
> +
> +/**
> + * security_lsm_slot_name - Get the name of the security module in a slot
> + * @slot: index into the "display" slot list.
> + *
> + * Provide the name of the security module associated with
> + * a display slot.
> + *
> + * If @slot is LSMBLOB_INVALID return the value
> + * for slot 0 if it has been set, otherwise NULL.
> + *
> + * Returns a pointer to the name string or NULL.
> + */
> +const char *security_lsm_slot_name(int slot)
> +{
> + if (slot == LSMBLOB_INVALID)
> + slot = 0;
> + else if (slot >= LSMBLOB_ENTRIES || slot < 0)
> + return NULL;
> +
> + if (lsm_slotlist[slot] == NULL)
> + return NULL;
> + return lsm_slotlist[slot]->lsm;
> +}
>
> /**
> * security_add_hooks - Add a modules hooks to the hook lists.
> @@ -2169,13 +2193,32 @@ int security_ismaclabel(const char *name)
> }
> EXPORT_SYMBOL(security_ismaclabel);
>
> -int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
> +int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp,
> + int display)
> {
> struct security_hook_list *hp;
> - int display = lsm_task_display(current);
>
> memset(cp, 0, sizeof(*cp));
>
> + /*
> + * display either is the slot number use for formatting
> + * or an instruction on which relative slot to use.
> + */
> + if (display == LSMBLOB_DISPLAY)
> + display = lsm_task_display(current);
> + else if (display == LSMBLOB_FIRST)
> + display = LSMBLOB_INVALID;
> + else if (display < 0) {
> + WARN_ONCE(true,
> + "LSM: %s unknown display\n", __func__);
> + display = LSMBLOB_INVALID;
> + } else if (display >= lsm_slot) {
> + WARN_ONCE(true,
> + "LSM: %s invalid display\n", __func__);
> + display = LSMBLOB_INVALID;
> + }
> +
> +
> hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) {
> if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
> continue;
> @@ -2186,7 +2229,7 @@ int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
> &cp->context, &cp->len);
> }
> }
> - return 0;
> + return -EOPNOTSUPP;
> }
> EXPORT_SYMBOL(security_secid_to_secctx);
>
> --
> 2.24.1
>
--
Kees Cook
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