Re: [PATCH v19 06/23] LSM: Use lsmblob in security_secctx_to_secid

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(a)chromium.org&gt; Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; Cc: netdev(a)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 c42873876954..5c2ed1db0658 100644 --- a/security/security.c +++ b/security/security.c @@ -2065,10 +2065,22 @@ 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); @@ -2301,9 +2313,21 @@ 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);