Re: [PATCH v35 08/29] LSM: Use lsmblob in security_secctx_to_secid

Change the security_secctx_to_secid interface to use a lsmblob structure in place of the single u32 secid in support of module stacking. Change its callers to do the same. The security module hook is unchanged, still passing back a secid. The infrastructure passes the correct entry from the lsmblob. Acked-by: Paul Moore <paul(a)paul-moore.com&gt; 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 Cc: netfilter-devel(a)vger.kernel.org To: Pablo Neira Ayuso <pablo(a)netfilter.org&gt;

--- include/linux/security.h | 26 ++++++++++++++++++-- kernel/cred.c | 4 +--- net/netfilter/nft_meta.c | 10 ++++---- net/netfilter/xt_SECMARK.c | 7 +++++- net/netlabel/netlabel_unlabeled.c | 23 +++++++++++------- security/security.c | 40 ++++++++++++++++++++++++++----- 6 files changed, 85 insertions(+), 25 deletions(-) diff --git a/include/linux/security.h b/include/linux/security.h index 68ab0add23d3..57879f0b9f89 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -199,6 +199,27 @@ static inline bool lsmblob_equal(const struct lsmblob *bloba, extern int lsm_name_to_slot(char *name); extern const char *lsm_slot_to_name(int slot); +/** + * 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); @@ -529,7 +550,8 @@ 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); @@ -1384,7 +1406,7 @@ 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; } diff --git a/kernel/cred.c b/kernel/cred.c index 3925d38f49f4..adea727744f4 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -791,14 +791,12 @@ 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/netfilter/nft_meta.c b/net/netfilter/nft_meta.c index ac4859241e17..fc0028c9e33d 100644 --- a/net/netfilter/nft_meta.c +++ b/net/netfilter/nft_meta.c @@ -860,21 +860,21 @@ 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(lsmblob_value(&blob)); if (err) return err; - priv->secid = tmp_secid; + priv->secid = lsmblob_value(&blob); return 0; } diff --git a/net/netfilter/xt_SECMARK.c b/net/netfilter/xt_SECMARK.c index 498a0bf6f044..87ca3a537d1c 100644 --- a/net/netfilter/xt_SECMARK.c +++ b/net/netfilter/xt_SECMARK.c @@ -42,13 +42,14 @@ secmark_tg(struct sk_buff *skb, const struct xt_secmark_target_info_v1 *info) static int checkentry_lsm(struct xt_secmark_target_info_v1 *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", @@ -56,6 +57,10 @@ static int checkentry_lsm(struct xt_secmark_target_info_v1 *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); diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c index 8490e46359ae..f3e2cde76919 100644 --- a/net/netlabel/netlabel_unlabeled.c +++ b/net/netlabel/netlabel_unlabeled.c @@ -880,7 +880,7 @@ 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 @@ -904,13 +904,18 @@ 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); } /** @@ -931,7 +936,7 @@ 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 @@ -953,13 +958,15 @@ 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 e9f1487af0e5..f814a41c5d9f 100644 --- a/security/security.c +++ b/security/security.c @@ -2211,10 +2211,22 @@ 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); @@ -2365,10 +2377,26 @@ int security_socket_getpeersec_stream(struct socket *sock, char __user *optval, optval, optlen, len); } -int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid) +int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, + u32 *secid) { - return call_int_hook(socket_getpeersec_dgram, -ENOPROTOOPT, sock, - skb, secid); + struct security_hook_list *hp; + int rc = -ENOPROTOOPT; + + /* + * Only one security module should provide a real hook for + * this. A stub or bypass like is used in BPF should either + * (somehow) leave rc unaltered or return -ENOPROTOOPT. + */ + hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_dgram, + list) { + if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot)) + continue; + rc = hp->hook.socket_getpeersec_dgram(sock, skb, secid); + if (rc != -ENOPROTOOPT) + break; + } + return rc; } EXPORT_SYMBOL(security_socket_getpeersec_dgram);