[PATCH v2 07/25] net: Prepare UDS for secuirty module stacking
Kees Cook
keescook at chromium.org
Wed Jun 19 04:59:52 UTC 2019
typo in Subject -> "secuirty" -> "security"
On Tue, Jun 18, 2019 at 04:05:33PM -0700, Casey Schaufler wrote:
> Change the data used in UDS SO_PEERSEC processing from a
> secid to a more general struct lsmblob. Update the
> security_socket_getpeersec_dgram() interface to use the
> lsmblob. There is a small amount of scaffolding code
> that will come out when the security_secid_to_secctx()
> code is brought in line with the lsmblob.
Can you spell this out a little more, "scaffolding code passes slot 1
unconditionally while the following patches will fix this up when they
are made aware of lsmblob" etc. (Also, why slot 1 and not slot 0?)
-Kees
>
> Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
> ---
> include/linux/security.h | 7 +++++--
> include/net/af_unix.h | 2 +-
> include/net/scm.h | 8 +++++---
> net/ipv4/ip_sockglue.c | 8 +++++---
> net/unix/af_unix.c | 6 +++---
> security/security.c | 16 +++++++++++++---
> 6 files changed, 32 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 89a5391f2441..64f5cc2dd249 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -1276,7 +1276,8 @@ int security_socket_shutdown(struct socket *sock, int how);
> int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb);
> int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
> int __user *optlen, unsigned 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,
> + struct lsmblob *l);
> int security_sk_alloc(struct sock *sk, int family, gfp_t priority);
> void security_sk_free(struct sock *sk);
> void security_sk_clone(const struct sock *sk, struct sock *newsk);
> @@ -1414,7 +1415,9 @@ static inline int security_socket_getpeersec_stream(struct socket *sock, char __
> return -ENOPROTOOPT;
> }
>
> -static inline int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)
> +static inline int security_socket_getpeersec_dgram(struct socket *sock,
> + struct sk_buff *skb,
> + struct lsmblob *l)
> {
> return -ENOPROTOOPT;
> }
> diff --git a/include/net/af_unix.h b/include/net/af_unix.h
> index 3426d6dacc45..933492c08b8c 100644
> --- a/include/net/af_unix.h
> +++ b/include/net/af_unix.h
> @@ -36,7 +36,7 @@ struct unix_skb_parms {
> kgid_t gid;
> struct scm_fp_list *fp; /* Passed files */
> #ifdef CONFIG_SECURITY_NETWORK
> - u32 secid; /* Security ID */
> + struct lsmblob lsmblob; /* Security LSM data */
> #endif
> u32 consumed;
> } __randomize_layout;
> diff --git a/include/net/scm.h b/include/net/scm.h
> index 1ce365f4c256..c87a17101c86 100644
> --- a/include/net/scm.h
> +++ b/include/net/scm.h
> @@ -33,7 +33,7 @@ struct scm_cookie {
> struct scm_fp_list *fp; /* Passed files */
> struct scm_creds creds; /* Skb credentials */
> #ifdef CONFIG_SECURITY_NETWORK
> - u32 secid; /* Passed security ID */
> + struct lsmblob lsmblob; /* Passed LSM data */
> #endif
> };
>
> @@ -46,7 +46,7 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl);
> #ifdef CONFIG_SECURITY_NETWORK
> static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
> {
> - security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
> + security_socket_getpeersec_dgram(sock, NULL, &scm->lsmblob);
> }
> #else
> static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
> @@ -97,7 +97,9 @@ 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->secid, &secdata, &seclen);
> + /* Scaffolding - it has to be element 1 for now */
> + err = security_secid_to_secctx(scm->lsmblob.secid[1],
> + &secdata, &seclen);
>
> if (!err) {
> put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index 82f341e84fae..fbe2147ee595 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -130,15 +130,17 @@ static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
>
> static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
> {
> + struct lsmblob lb;
> char *secdata;
> - u32 seclen, secid;
> + u32 seclen;
> int err;
>
> - err = security_socket_getpeersec_dgram(NULL, skb, &secid);
> + err = security_socket_getpeersec_dgram(NULL, skb, &lb);
> if (err)
> return;
>
> - err = security_secid_to_secctx(secid, &secdata, &seclen);
> + /* Scaffolding - it has to be element 1 */
> + err = security_secid_to_secctx(lb.secid[1], &secdata, &seclen);
> if (err)
> return;
>
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index ddb838a1b74c..c50a004a1389 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -143,17 +143,17 @@ static struct hlist_head *unix_sockets_unbound(void *addr)
> #ifdef CONFIG_SECURITY_NETWORK
> static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
> {
> - UNIXCB(skb).secid = scm->secid;
> + UNIXCB(skb).lsmblob = scm->lsmblob;
> }
>
> static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
> {
> - scm->secid = UNIXCB(skb).secid;
> + scm->lsmblob = UNIXCB(skb).lsmblob;
> }
>
> static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
> {
> - return (scm->secid == UNIXCB(skb).secid);
> + return lsmblob_equal(&scm->lsmblob, &(UNIXCB(skb).lsmblob));
> }
> #else
> static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
> diff --git a/security/security.c b/security/security.c
> index 4296cd2ca508..5ed818699e15 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2132,10 +2132,20 @@ 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,
> + struct lsmblob *l)
> {
> - return call_int_hook(socket_getpeersec_dgram, -ENOPROTOOPT, sock,
> - skb, secid);
> + struct security_hook_list *hp;
> + int rc = -ENOPROTOOPT;
> +
> + hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_dgram,
> + list) {
> + rc = hp->hook.socket_getpeersec_dgram(sock, skb,
> + &l->secid[hp->slot]);
> + if (rc != 0)
> + break;
> + }
> + return rc;
> }
> EXPORT_SYMBOL(security_socket_getpeersec_dgram);
>
> --
> 2.20.1
>
--
Kees Cook
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