[3/3] selinux: Add SELinux GTP support

Message ID	20200930094934.32144-4-richard_c_haines@btinternet.com (mailing list archive)
State	Changes Requested
Delegated to:	Paul Moore
Headers	show Return-Path: <SRS0=YCxb=DH=vger.kernel.org=selinux-owner@kernel.org> From: Richard Haines <richard_c_haines@btinternet.com> To: selinux@vger.kernel.org, linux-security-module@vger.kernel.org, osmocom-net-gprs@lists.osmocom.org, netdev@vger.kernel.org Cc: stephen.smalley.work@gmail.com, paul@paul-moore.com, pablo@netfilter.org, laforge@gnumonks.org, jmorris@namei.org, Richard Haines <richard_c_haines@btinternet.com> Subject: [PATCH 3/3] selinux: Add SELinux GTP support Date: Wed, 30 Sep 2020 10:49:34 +0100 Message-Id: <20200930094934.32144-4-richard_c_haines@btinternet.com> In-Reply-To: <20200930094934.32144-1-richard_c_haines@btinternet.com> References: <20200930094934.32144-1-richard_c_haines@btinternet.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Add LSM/SELinux support for GPRS Tunneling Protocol (GTP) \| expand [0/3] Add LSM/SELinux support for GPRS Tunneling Protocol (GTP) [1/3] security: Add GPRS Tunneling Protocol (GTP) security hooks [2/3] gtp: Add LSM hooks to GPRS Tunneling Protocol (GTP) [3/3] selinux: Add SELinux GTP support

diff --git a/Documentation/security/GTP.rst b/Documentation/security/GTP.rst index c748587ec..433fcb688 100644 --- a/Documentation/security/GTP.rst +++ b/Documentation/security/GTP.rst @@ -15,6 +15,9 @@ For security module support, three GTP specific hooks have been implemented:: security_gtp_dev_free() security_gtp_dev_cmd() +The usage of these hooks are described below with the SELinux implementation +described in the `GTP SELinux Support`_ chapter. + security_gtp_dev_alloc() ~~~~~~~~~~~~~~~~~~~~~~ @@ -37,3 +40,61 @@ zero on success, negative values on failure. The commands are based on values from ``include/uapi/linux/gtp.h`` as follows:: ``enum gtp_genl_cmds { GTP_CMD_NEWPDP, GTP_CMD_DELPDP, GTP_CMD_GETPDP };`` + + +GTP SELinux Support +=================== + +Policy Statements +----------------- +The following class and permissions to support GTP are available within the +kernel:: + + class gtp { add del get } + +The permissions are described in the sections that follow. + + +Security Hooks +-------------- + +The `GTP LSM Support`_ chapter above describes the following GTP security +hooks with the SELinux specifics expanded below:: + + security_gtp_dev_alloc -> selinux_gtp_dev_alloc_security(gtp) + security_gtp_dev_free -> selinux_gtp_dev_free_security(gtp) + security_gtp_dev_cmd -> selinux_gtp_dev_cmd(gtp, cmd) + + +selinux_gtp_dev_alloc_security() +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Allocates a security structure for a GTP device provided the caller has the +``gtp { add }`` permission. Can return errors ``-ENOMEM`` or ``-EACCES``. +Returns zero if the security structure has been allocated. + + +selinux_gtp_dev_free_security() +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Frees a security structure for a GTP device provided the caller has the +``gtp { del }`` permission. Can return error ``-EACCES``. Returns zero if the +security structure has been freed. + + +selinux_gtp_dev_cmd() +~~~~~~~~~~~~~~~~~~~~~ +Validate if the caller (current SID) and the GTP device SID have the required +permission to perform the operation. The GTP/SELinux permission map is +as follow:: + + GTP_CMD_NEWPDP = gtp { add } + GTP_CMD_DELPDP = gtp { del } + GTP_CMD_GETPDP = gtp { get } + +Returns ``-EACCES`` if denied or zero if allowed. + +NOTES:: + 1) If the GTP device has the ``{ add }`` permission it can add device and + also add PDP's (packet data protocol). + + 2) If the GTP device has the ``{ del }`` permission it can delete a device + and also delete PDP's. diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index d6b182c11..5229a4f20 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -91,6 +91,7 @@ #include <uapi/linux/mount.h> #include <linux/fsnotify.h> #include <linux/fanotify.h> +#include <net/gtp.h> #include "avc.h" #include "objsec.h" @@ -5520,6 +5521,68 @@ static int selinux_tun_dev_open(void *security) return 0; } +static int selinux_gtp_dev_alloc_security(struct gtp_dev *gtp) +{ + struct gtp_security_struct *gtpsec; + u32 sid = current_sid(); + int err; + + err = avc_has_perm(&selinux_state, sid, sid, + SECCLASS_GTP, GTP__ADD, NULL); + if (err < 0) + return err; + + gtpsec = kzalloc(sizeof(*gtpsec), GFP_KERNEL); + if (!gtpsec) + return -ENOMEM; + + gtpsec->sid = sid; + gtp->security = gtpsec; + + return 0; +} + +static int selinux_gtp_dev_free_security(struct gtp_dev *gtp) +{ + struct gtp_security_struct *gtpsec = gtp->security; + u32 sid = current_sid(); + int err; + + err = avc_has_perm(&selinux_state, sid, gtpsec->sid, + SECCLASS_GTP, GTP__DEL, NULL); + if (err < 0) + return err; + + gtp->security = NULL; + kfree(gtpsec); + + return 0; +} + +static int selinux_gtp_dev_cmd(struct gtp_dev *gtp, enum gtp_genl_cmds cmd) +{ + struct gtp_security_struct *gtpsec = gtp->security; + u32 perm, sid = current_sid(); + + switch (cmd) { + case GTP_CMD_NEWPDP: + perm = GTP__ADD; + break; + case GTP_CMD_DELPDP: + perm = GTP__DEL; + break; + case GTP_CMD_GETPDP: + perm = GTP__GET; + break; + default: + WARN_ON(1); + return -EPERM; + } + + return avc_has_perm(&selinux_state, sid, gtpsec->sid, + SECCLASS_GTP, perm, NULL); +} + #ifdef CONFIG_NETFILTER static unsigned int selinux_ip_forward(struct sk_buff *skb, @@ -7130,6 +7193,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(tun_dev_attach_queue, selinux_tun_dev_attach_queue), LSM_HOOK_INIT(tun_dev_attach, selinux_tun_dev_attach), LSM_HOOK_INIT(tun_dev_open, selinux_tun_dev_open), + LSM_HOOK_INIT(gtp_dev_free_security, selinux_gtp_dev_free_security), + LSM_HOOK_INIT(gtp_dev_cmd, selinux_gtp_dev_cmd), #ifdef CONFIG_SECURITY_INFINIBAND LSM_HOOK_INIT(ib_pkey_access, selinux_ib_pkey_access), LSM_HOOK_INIT(ib_endport_manage_subnet, @@ -7204,6 +7269,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_getsecctx, selinux_inode_getsecctx), LSM_HOOK_INIT(sk_alloc_security, selinux_sk_alloc_security), LSM_HOOK_INIT(tun_dev_alloc_security, selinux_tun_dev_alloc_security), + LSM_HOOK_INIT(gtp_dev_alloc_security, selinux_gtp_dev_alloc_security), #ifdef CONFIG_SECURITY_INFINIBAND LSM_HOOK_INIT(ib_alloc_security, selinux_ib_alloc_security), #endif diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 40cebde62..3865a4549 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -249,6 +249,8 @@ struct security_class_mapping secclass_map[] = { {"open", "cpu", "kernel", "tracepoint", "read", "write"} }, { "lockdown", { "integrity", "confidentiality", NULL } }, + { "gtp", + { "add", "del", "get", NULL } }, { NULL } }; diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h index 330b7b6d4..311ffb6ea 100644 --- a/security/selinux/include/objsec.h +++ b/security/selinux/include/objsec.h @@ -148,6 +148,10 @@ struct perf_event_security_struct { u32 sid; /* SID of perf_event obj creator */ }; +struct gtp_security_struct { + u32 sid; /* SID of gtp obj creator */ +}; + extern struct lsm_blob_sizes selinux_blob_sizes; static inline struct task_security_struct *selinux_cred(const struct cred *cred) {

[3/3] selinux: Add SELinux GTP support

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