On 4/18/22 07:59, Casey Schaufler wrote: > 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 <[email protected]> > Reviewed-by: Kees Cook <[email protected]> > Signed-off-by: Casey Schaufler <[email protected]> > Cc: [email protected] > Cc: [email protected] > To: Pablo Neira Ayuso <[email protected]>
Reviewed-by: John Johansen <[email protected]> > --- > 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); > -- Linux-audit mailing list [email protected] https://listman.redhat.com/mailman/listinfo/linux-audit
