[PATCH v18 06/23] LSM: Use lsmblob in security_secctx_to_secid
Casey Schaufler
casey at schaufler-ca.com
Thu Jul 9 00:12:17 UTC 2020
Change security_secctx_to_secid() to fill in a lsmblob instead
of a u32 secid. Multiple LSMs may be able to interpret the
string, and this allows for setting whichever secid is
appropriate. Change security_secmark_relabel_packet() to use a
lsmblob instead of a u32 secid. In some other cases there is
scaffolding where interfaces have yet to be converted.
Reviewed-by: Kees Cook <keescook at chromium.org>
Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
Cc: netdev at vger.kernel.org
---
include/linux/security.h | 30 +++++++++++++++++++++++----
include/net/scm.h | 7 +++++--
kernel/cred.c | 4 +---
net/ipv4/ip_sockglue.c | 6 ++++--
net/netfilter/nft_meta.c | 18 +++++++++-------
net/netfilter/xt_SECMARK.c | 9 ++++++--
net/netlabel/netlabel_unlabeled.c | 23 +++++++++++++--------
security/security.c | 34 ++++++++++++++++++++++++++-----
8 files changed, 98 insertions(+), 33 deletions(-)
diff --git a/include/linux/security.h b/include/linux/security.h
index d81e8886d799..98176faaaba5 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -189,6 +189,27 @@ static inline bool lsmblob_equal(struct lsmblob *bloba, struct lsmblob *blobb)
return !memcmp(bloba, blobb, sizeof(*bloba));
}
+/**
+ * lsmblob_value - find the first non-zero value in an lsmblob structure.
+ * @blob: Pointer to the data
+ *
+ * This needs to be used with extreme caution, as the cases where
+ * it is appropriate are rare.
+ *
+ * Return the first secid value set in the lsmblob.
+ * There should only be one.
+ */
+static inline u32 lsmblob_value(const struct lsmblob *blob)
+{
+ int i;
+
+ for (i = 0; i < LSMBLOB_ENTRIES; i++)
+ if (blob->secid[i])
+ return blob->secid[i];
+
+ return 0;
+}
+
/* These functions are in security/commoncap.c */
extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
int cap, unsigned int opts);
@@ -502,7 +523,8 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
int security_netlink_send(struct sock *sk, struct sk_buff *skb);
int security_ismaclabel(const char *name);
int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
-int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
+int security_secctx_to_secid(const char *secdata, u32 seclen,
+ struct lsmblob *blob);
void security_release_secctx(char *secdata, u32 seclen);
void security_inode_invalidate_secctx(struct inode *inode);
int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
@@ -1321,7 +1343,7 @@ static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *secle
static inline int security_secctx_to_secid(const char *secdata,
u32 seclen,
- u32 *secid)
+ struct lsmblob *blob)
{
return -EOPNOTSUPP;
}
@@ -1411,7 +1433,7 @@ void security_inet_csk_clone(struct sock *newsk,
const struct request_sock *req);
void security_inet_conn_established(struct sock *sk,
struct sk_buff *skb);
-int security_secmark_relabel_packet(u32 secid);
+int security_secmark_relabel_packet(struct lsmblob *blob);
void security_secmark_refcount_inc(void);
void security_secmark_refcount_dec(void);
int security_tun_dev_alloc_security(void **security);
@@ -1584,7 +1606,7 @@ static inline void security_inet_conn_established(struct sock *sk,
{
}
-static inline int security_secmark_relabel_packet(u32 secid)
+static inline int security_secmark_relabel_packet(struct lsmblob *blob)
{
return 0;
}
diff --git a/include/net/scm.h b/include/net/scm.h
index e2e71c4bf9d0..c09f2dfeec88 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -97,8 +97,11 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
int err;
if (test_bit(SOCK_PASSSEC, &sock->flags)) {
- /* Scaffolding - it has to be element 0 for now */
- err = security_secid_to_secctx(scm->lsmblob.secid[0],
+ /* There can currently be only one value in the lsmblob,
+ * so getting it from lsmblob_value is appropriate until
+ * security_secid_to_secctx() is converted to taking a
+ * lsmblob directly. */
+ err = security_secid_to_secctx(lsmblob_value(&scm->lsmblob),
&secdata, &seclen);
if (!err) {
diff --git a/kernel/cred.c b/kernel/cred.c
index 22e0e7cbefde..848306c7d823 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -757,14 +757,12 @@ EXPORT_SYMBOL(set_security_override);
int set_security_override_from_ctx(struct cred *new, const char *secctx)
{
struct lsmblob blob;
- u32 secid;
int ret;
- ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
+ ret = security_secctx_to_secid(secctx, strlen(secctx), &blob);
if (ret < 0)
return ret;
- lsmblob_init(&blob, secid);
return set_security_override(new, &blob);
}
EXPORT_SYMBOL(set_security_override_from_ctx);
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 3ea1103b4c29..6bdac5f87a1e 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -139,8 +139,10 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
if (err)
return;
- /* Scaffolding - it has to be element 0 */
- err = security_secid_to_secctx(lb.secid[0], &secdata, &seclen);
+ /* There can only be one secid in the lsmblob at this point,
+ * so getting it using lsmblob_value() is sufficient until
+ * security_secid_to_secctx() is changed to use a lsmblob */
+ err = security_secid_to_secctx(lsmblob_value(&lb), &secdata, &seclen);
if (err)
return;
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index 951b6e87ed5d..5875222aeac5 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -801,7 +801,7 @@ struct nft_expr_type nft_meta_type __read_mostly = {
#ifdef CONFIG_NETWORK_SECMARK
struct nft_secmark {
- u32 secid;
+ struct lsmblob lsmdata;
char *ctx;
};
@@ -811,21 +811,21 @@ static const struct nla_policy nft_secmark_policy[NFTA_SECMARK_MAX + 1] = {
static int nft_secmark_compute_secid(struct nft_secmark *priv)
{
- u32 tmp_secid = 0;
+ struct lsmblob blob;
int err;
- err = security_secctx_to_secid(priv->ctx, strlen(priv->ctx), &tmp_secid);
+ err = security_secctx_to_secid(priv->ctx, strlen(priv->ctx), &blob);
if (err)
return err;
- if (!tmp_secid)
+ if (!lsmblob_is_set(&blob))
return -ENOENT;
- err = security_secmark_relabel_packet(tmp_secid);
+ err = security_secmark_relabel_packet(&blob);
if (err)
return err;
- priv->secid = tmp_secid;
+ priv->lsmdata = blob;
return 0;
}
@@ -835,7 +835,11 @@ static void nft_secmark_obj_eval(struct nft_object *obj, struct nft_regs *regs,
const struct nft_secmark *priv = nft_obj_data(obj);
struct sk_buff *skb = pkt->skb;
- skb->secmark = priv->secid;
+ /* It is not possible for more than one secid to be set in
+ * the lsmblob structure because it is set using
+ * security_secctx_to_secid(). Any secid that is set must therefore
+ * be the one that should go in the secmark. */
+ skb->secmark = lsmblob_value(&priv->lsmdata);
}
static int nft_secmark_obj_init(const struct nft_ctx *ctx,
diff --git a/net/netfilter/xt_SECMARK.c b/net/netfilter/xt_SECMARK.c
index 75625d13e976..5a268707eeda 100644
--- a/net/netfilter/xt_SECMARK.c
+++ b/net/netfilter/xt_SECMARK.c
@@ -43,13 +43,14 @@ secmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
static int checkentry_lsm(struct xt_secmark_target_info *info)
{
+ struct lsmblob blob;
int err;
info->secctx[SECMARK_SECCTX_MAX - 1] = '\0';
info->secid = 0;
err = security_secctx_to_secid(info->secctx, strlen(info->secctx),
- &info->secid);
+ &blob);
if (err) {
if (err == -EINVAL)
pr_info_ratelimited("invalid security context \'%s\'\n",
@@ -57,13 +58,17 @@ static int checkentry_lsm(struct xt_secmark_target_info *info)
return err;
}
+ /* xt_secmark_target_info can't be changed to use lsmblobs because
+ * it is exposed as an API. Use lsmblob_value() to get the one
+ * value that got set by security_secctx_to_secid(). */
+ info->secid = lsmblob_value(&blob);
if (!info->secid) {
pr_info_ratelimited("unable to map security context \'%s\'\n",
info->secctx);
return -ENOENT;
}
- err = security_secmark_relabel_packet(info->secid);
+ err = security_secmark_relabel_packet(&blob);
if (err) {
pr_info_ratelimited("unable to obtain relabeling permission\n");
return err;
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 77bb1bb22c3b..8948557eaebb 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -882,7 +882,7 @@ static int netlbl_unlabel_staticadd(struct sk_buff *skb,
void *addr;
void *mask;
u32 addr_len;
- u32 secid;
+ struct lsmblob blob;
struct netlbl_audit audit_info;
/* Don't allow users to add both IPv4 and IPv6 addresses for a
@@ -906,13 +906,18 @@ static int netlbl_unlabel_staticadd(struct sk_buff *skb,
ret_val = security_secctx_to_secid(
nla_data(info->attrs[NLBL_UNLABEL_A_SECCTX]),
nla_len(info->attrs[NLBL_UNLABEL_A_SECCTX]),
- &secid);
+ &blob);
if (ret_val != 0)
return ret_val;
+ /* netlbl_unlhsh_add will be changed to pass a struct lsmblob *
+ * instead of a u32 later in this patch set. security_secctx_to_secid()
+ * will only be setting one entry in the lsmblob struct, so it is
+ * safe to use lsmblob_value() to get that one value. */
+
return netlbl_unlhsh_add(&init_net,
- dev_name, addr, mask, addr_len, secid,
- &audit_info);
+ dev_name, addr, mask, addr_len,
+ lsmblob_value(&blob), &audit_info);
}
/**
@@ -933,7 +938,7 @@ static int netlbl_unlabel_staticadddef(struct sk_buff *skb,
void *addr;
void *mask;
u32 addr_len;
- u32 secid;
+ struct lsmblob blob;
struct netlbl_audit audit_info;
/* Don't allow users to add both IPv4 and IPv6 addresses for a
@@ -955,13 +960,15 @@ static int netlbl_unlabel_staticadddef(struct sk_buff *skb,
ret_val = security_secctx_to_secid(
nla_data(info->attrs[NLBL_UNLABEL_A_SECCTX]),
nla_len(info->attrs[NLBL_UNLABEL_A_SECCTX]),
- &secid);
+ &blob);
if (ret_val != 0)
return ret_val;
+ /* security_secctx_to_secid() will only put one secid into the lsmblob
+ * so it's safe to use lsmblob_value() to get the secid. */
return netlbl_unlhsh_add(&init_net,
- NULL, addr, mask, addr_len, secid,
- &audit_info);
+ NULL, addr, mask, addr_len,
+ lsmblob_value(&blob), &audit_info);
}
/**
diff --git a/security/security.c b/security/security.c
index 2122ed9df058..d6c2905bf496 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2050,10 +2050,22 @@ int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
}
EXPORT_SYMBOL(security_secid_to_secctx);
-int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
+int security_secctx_to_secid(const char *secdata, u32 seclen,
+ struct lsmblob *blob)
{
- *secid = 0;
- return call_int_hook(secctx_to_secid, 0, secdata, seclen, secid);
+ struct security_hook_list *hp;
+ int rc;
+
+ lsmblob_init(blob, 0);
+ hlist_for_each_entry(hp, &security_hook_heads.secctx_to_secid, list) {
+ if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+ continue;
+ rc = hp->hook.secctx_to_secid(secdata, seclen,
+ &blob->secid[hp->lsmid->slot]);
+ if (rc != 0)
+ return rc;
+ }
+ return 0;
}
EXPORT_SYMBOL(security_secctx_to_secid);
@@ -2286,9 +2298,21 @@ void security_inet_conn_established(struct sock *sk,
}
EXPORT_SYMBOL(security_inet_conn_established);
-int security_secmark_relabel_packet(u32 secid)
+int security_secmark_relabel_packet(struct lsmblob *blob)
{
- return call_int_hook(secmark_relabel_packet, 0, secid);
+ struct security_hook_list *hp;
+ int rc = 0;
+
+ hlist_for_each_entry(hp, &security_hook_heads.secmark_relabel_packet,
+ list) {
+ if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+ continue;
+ rc = hp->hook.secmark_relabel_packet(
+ blob->secid[hp->lsmid->slot]);
+ if (rc != 0)
+ break;
+ }
+ return rc;
}
EXPORT_SYMBOL(security_secmark_relabel_packet);
--
2.24.1
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