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Date: Tue, 18 Jan 2011 21:45:38 -0800
From: ebiederm@...ssion.com (Eric W. Biederman)
To: Casey Schaufler <casey@...aufler-ca.com>
Cc: LKLM <linux-kernel@...r.kernel.org>, xemul@...nvz.org,
David Miller <davem@...emloft.net>,
"Sakkinen Jarkko.2 \(EXT-Tieto\/Tampere\)"
<ext-jarkko.2.sakkinen@...ia.com>,
Janne Karhunen <Janne.Karhunen@...ia.com>,
"Reshetova Elena \(Nokia-D\/Helsinki\)" <elena.reshetova@...ia.com>
Subject: Re: [PATCH] scm: provide full privilege set via SCM_PRIVILEGE
Casey Schaufler <casey@...aufler-ca.com> writes:
> Subject: [PATCH] scm: provide full privilege set via SCM_PRIVILEGE
>
> The SCM mechanism currently provides interfaces for delivering
> the uid/gid and the "security context" (LSM information) of the
> peer on a UDS socket. All of the security credential information
> is available, but there is no interface available to obtain it.
> Further, the existing interfaces require that the user chose
> between the uid/gid and the context as the existing interfaces
> are exclusive.
>
> This patch introduces an additional interface that provides
> a complete set of security information from the peer credential.
> No additional work is required to provide the information
> internally, it is all being passed, just not exposed.
In ascii text?
A bitmap in hex?
Maybe it is just me, but this seems harder to deal with than
if the data had been transferred in binary.
Eric
>
> Signed-off-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
>
> include/asm-generic/socket.h | 1 +
> include/linux/net.h | 1 +
> include/linux/socket.h | 1 +
> include/net/scm.h | 80 +++++++++++++++++++++++++++++++++++++++++-
> net/core/sock.c | 11 ++++++
> 5 files changed, 93 insertions(+), 1 deletions(-)
> diff --git a/include/asm-generic/socket.h b/include/asm-generic/socket.h
> index 9a6115e..7aa8e84 100644
> --- a/include/asm-generic/socket.h
> +++ b/include/asm-generic/socket.h
> @@ -64,4 +64,5 @@
> #define SO_DOMAIN 39
>
> #define SO_RXQ_OVFL 40
> +#define SO_PASSPRIV 41
> #endif /* __ASM_GENERIC_SOCKET_H */
> diff --git a/include/linux/net.h b/include/linux/net.h
> index 16faa13..159a929 100644
> --- a/include/linux/net.h
> +++ b/include/linux/net.h
> @@ -71,6 +71,7 @@ struct net;
> #define SOCK_NOSPACE 2
> #define SOCK_PASSCRED 3
> #define SOCK_PASSSEC 4
> +#define SOCK_PASSPRIV 5
>
> #ifndef ARCH_HAS_SOCKET_TYPES
> /**
> diff --git a/include/linux/socket.h b/include/linux/socket.h
> index 86b652f..e9cfd68 100644
> --- a/include/linux/socket.h
> +++ b/include/linux/socket.h
> @@ -147,6 +147,7 @@ static inline struct cmsghdr * cmsg_nxthdr (struct msghdr *__msg, struct cmsghdr
> #define SCM_RIGHTS 0x01 /* rw: access rights (array of int) */
> #define SCM_CREDENTIALS 0x02 /* rw: struct ucred */
> #define SCM_SECURITY 0x03 /* rw: security label */
> +#define SCM_PRIVILEGES 0x04 /* rw: privilege set */
>
> struct ucred {
> __u32 pid;
> diff --git a/include/net/scm.h b/include/net/scm.h
> index 3165650..4b8db21 100644
> --- a/include/net/scm.h
> +++ b/include/net/scm.h
> @@ -101,6 +101,83 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
> { }
> #endif /* CONFIG_SECURITY_NETWORK */
>
> +static __inline__ void scm_passpriv(struct socket *sock, struct msghdr *msg,
> + struct scm_cookie *scm)
> +{
> + const struct cred *credp = scm->cred;
> + const struct group_info *gip;
> + char *result;
> + char *cp;
> + int i;
> +#ifdef CONFIG_SECURITY_NETWORK
> + char *secdata;
> + u32 seclen;
> + int err;
> +#endif /* CONFIG_SECURITY_NETWORK */
> +
> + if (!test_bit(SOCK_PASSPRIV, &sock->flags))
> + return;
> +
> + gip = credp->group_info;
> +
> + /*
> + * uid + euid + gid + egid + group-list + capabilities
> + * + "uid=" + "euid=" + "gid=" + "egid=" + "grps="
> + * + "cap-e=" + "cap-p=" + "cap-i="
> + * 10 + 10 + 10 + 10 + (ngrps * 10) + ecap + pcap + icap
> + * + 4 + 5 + 4 + 5 + 5 + 6 + 6 + 6
> + */
> + i = ((4 + gip->ngroups) * 11) + (3 * (_KERNEL_CAPABILITY_U32S * 8 + 1))
> + + 41;
> +
> +#ifdef CONFIG_SECURITY_NETWORK
> + err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
> + if (!err)
> + /*
> + * " context="
> + */
> + i += seclen + 10;
> +#endif /* CONFIG_SECURITY_NETWORK */
> +
> + result = kzalloc(i, GFP_KERNEL);
> + if (result == NULL)
> + return;
> +
> + cp = result + sprintf(result, "euid=%d uid=%d egid=%d gid=%d",
> + credp->euid, credp->uid,
> + credp->egid, credp->gid);
> +
> + if (gip != NULL && gip->ngroups > 0) {
> + cp += sprintf(cp, " grps=%d", GROUP_AT(gip, 0));
> + for (i = 1 ; i < gip->ngroups; i++)
> + cp += sprintf(cp, ",%d", GROUP_AT(gip, i));
> + }
> +
> + cp += sprintf(cp, " cap-e=");
> + CAP_FOR_EACH_U32(i)
> + cp += sprintf(cp, "%08x", credp->cap_effective.cap[i]);
> + cp += sprintf(cp, " cap-p=");
> + CAP_FOR_EACH_U32(i)
> + cp += sprintf(cp, "%08x", credp->cap_permitted.cap[i]);
> + cp += sprintf(cp, " cap-i=");
> + CAP_FOR_EACH_U32(i)
> + cp += sprintf(cp, "%08x", credp->cap_inheritable.cap[i]);
> +
> +#ifdef CONFIG_SECURITY_NETWORK
> + cp += sprintf(cp, " context=");
> + strncpy(cp, secdata, seclen);
> + cp += seclen;
> + *cp = '\0';
> +
> + security_release_secctx(secdata, seclen);
> +#endif /* CONFIG_SECURITY_NETWORK */
> +
> + put_cmsg(msg, SOL_SOCKET, SCM_PRIVILEGES, strlen(result)+1, result);
> +
> + kfree(result);
> +}
> +
> +
> static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
> struct scm_cookie *scm, int flags)
> {
> @@ -114,6 +191,8 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
> if (test_bit(SOCK_PASSCRED, &sock->flags))
> put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds);
>
> + scm_passpriv(sock, msg, scm);
> +
> scm_destroy_cred(scm);
>
> scm_passec(sock, msg, scm);
> @@ -124,6 +203,5 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
> scm_detach_fds(msg, scm);
> }
>
> -
> #endif /* __LINUX_NET_SCM_H */
>
> diff --git a/net/core/sock.c b/net/core/sock.c
> index fb60801..f134126 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -725,6 +725,13 @@ set_rcvbuf:
> else
> clear_bit(SOCK_PASSSEC, &sock->flags);
> break;
> +
> + case SO_PASSPRIV:
> + if (valbool)
> + set_bit(SOCK_PASSPRIV, &sock->flags);
> + else
> + clear_bit(SOCK_PASSPRIV, &sock->flags);
> + break;
> case SO_MARK:
> if (!capable(CAP_NET_ADMIN))
> ret = -EPERM;
> @@ -950,6 +957,10 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
> v.val = test_bit(SOCK_PASSSEC, &sock->flags) ? 1 : 0;
> break;
>
> + case SO_PASSPRIV:
> + v.val = test_bit(SOCK_PASSPRIV, &sock->flags) ? 1 : 0;
> + break;
> +
> case SO_PEERSEC:
> return security_socket_getpeersec_stream(sock, optval, optlen, len);
>
--
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