From patchwork Wed Nov 27 21:37:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 11264953 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AC07E112B for ; Wed, 27 Nov 2019 21:38:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7764221555 for ; Wed, 27 Nov 2019 21:38:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="uBXhPTGa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728463AbfK0ViI (ORCPT ); Wed, 27 Nov 2019 16:38:08 -0500 Received: from sonic306-28.consmr.mail.ne1.yahoo.com ([66.163.189.90]:42384 "EHLO sonic306-28.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728295AbfK0ViH (ORCPT ); Wed, 27 Nov 2019 16:38:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1574890685; bh=T+7vkOglemjDcJCtI0jsgL0AaHeYGYB4YiqPLcOqBMY=; h=From:To:Subject:Date:In-Reply-To:References:From:Subject; b=uBXhPTGa2XYAneMY4uLbH1LJbz0NhhthxnxNtkbvedN3WiCvhtkZNcrU8+y2HGA06YSeDRTEQ3EQsGPJmERcAb3MqNth5SGB+vIS+yBvvj7Lvsi5C8HQ0zNEmDi/HMmvCrUXsi1cEhAuE8QQO/ReC5ot7w3SkiuTuWf60sSUxmVqs4rY+qHGX549giKUrRA6t+xEHNlMJVRU4OXr/p1AaXHt2lnC0lo9RolACYmBuhjSoiaXcQbjb6oWdN1cG1yKhmY3pbZdiy1pgn70lkuX76DCHJ4SY9qz52I8c+Y9rcypknijC+79jH2yWKVSUjzRR3h9BZm5+LJc7BZ1mjZmgQ== X-YMail-OSG: hjQKjJIVM1nlTTerEVJtmLooIB7y.xsJQv9zlpGgYI39o7zpDzp.dddLKLUsVRV s7Xmo4aaXIPhaoqjBzaX_zW9XSKIIGRZ_4HqIJegZ.AunVLo5mA4pqgaQV4XqGgBhFacafeKg73J 2iO.JQwcDgJfCyBJ65f083z6fWbx07ypcpEJisa95dWxT5MDjpAxtjsdHRr6mXmBgFgwLk9W0Uii QDIv8g1KKwOK_7.5_.380keS9BxIyXfXdr_UCLinAUwhUVjpp0dZaM3SsLRKOzNKJGLWwSIngLB9 R1OWNFTkTbvkQd327IXICtZzET_cKpN6ElPnRz555YFNmdwSLTogfr51vZ85z88UI_CYuxEtR6El 9vfT6wxbiccyn9dFbPtj.zsCYvvdVSh3FsDSMtfI.qribEv901PSZq3KIH92sKF_zXh73jsxzWbu QQ3v70.CktWMG1Cuulf4ZXgYlnDY4J_sX0MbcW5CoriZzOiLYceXVxrMxcy4UhiDQcs38dycLFfe JjUcAasKGWjLGj_DGhA5vKrZUrjz3PPxm14LK7faRrR5e8JBWbejMZKHEcY26hY6fTOpgrdoOs2e HYM1omCie7_rnZbOSc1uEh2t.LECFrfVUgqXM7N0XpxkxDAFsTxEB90ekjPLAh73uUTV7Ot5tAyI QgViAOEQWUTglKHCN0jSV_ATEHxHKyY9gvdd5JHCPBi0zwAq4veq5xGai18Igm1ZUIXoaFlKw1PB kcvFCepf9V4ujDc5syuhHMYTEdqsszDIf5VCiBuuxY.Nj8TRZicE5hY4mP.YWJqh0Zv0Ocs1u..c YWiCZ5hPV8Irh_n5VoDtbd1KHWOBF5a_Ud2mYb8sW2gjC_Tw8bJhr6rzugx7vKWcXHEst._fnshZ MlJmf7OGBZDO6GH26_3XB9TVksQ9kNyLoiloevvgttd.q4rTzVPcGeBfgQcpSJc1G.sD6WUZ_qya .95eVP.LmuxJXr_Z4GIzRU56yk_kyVs72buCTsogSwVSfJR0bA8.gls_v7KXtxBLMYVmBVlIyHv0 Eb1fTt5zst_F4ZtjcjVVHPAYuMGcKFnLAHsyo9M96ZyVJvN7qzlzv.3qGzSAPni5TITk1cNdE4hI z5p2GbWYjEpRBdiNXqmaVh9x9QRWwNwxClqXeNO.1PvoaeUV52fLPhhVtLAAmKTdzhJabtwzlj.i Xv4FPHuITLcItPBOA4oqUdoeJiKhkL2uTkT5AXrTPPWzYYTiSHedDtc2lS6bn4UtmY1n6BB_X97W qPvs8i67mPmo33uJNYtddBqq3Rbc6yzaKG3DhLCk.BA7FnY_bLDeSJ.4d5yCHWIA6Hjl757NmqqK ve99ZgzBURMGeyNxPOvJepYDAyNRzi5c7MHMgN0RePpGr4NqtDK.2KLIXobvAtIerY9507WQjok7 nudii32S0P_ZHCnMzUHVe9QUOK9HvxFwGF459gPIP13AqQItp7RT7 Received: from sonic.gate.mail.ne1.yahoo.com by sonic306.consmr.mail.ne1.yahoo.com with HTTP; Wed, 27 Nov 2019 21:38:05 +0000 Received: by smtp406.mail.bf1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID 2c2d0f9121a87dc46718f3aa46e4610a; Wed, 27 Nov 2019 21:38:00 +0000 (UTC) From: Casey Schaufler To: linux-integrity@vger.kernel.org, zohar@linux.ibm.com Subject: [v11-ima PATCH 13/25] LSM: Specify which LSM to display Date: Wed, 27 Nov 2019 13:37:06 -0800 Message-Id: <20191127213718.18267-14-casey@schaufler-ca.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191127213718.18267-1-casey@schaufler-ca.com> References: <20191127213718.18267-1-casey@schaufler-ca.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Create a new entry "display" in the procfs attr directory for controlling which LSM security information is displayed for a process. A process can only read or write its own display value. The name of an active LSM that supplies hooks for human readable data may be written to "display" to set the value. The name of the LSM currently in use can be read from "display". At this point there can only be one LSM capable of display active. A helper function lsm_task_display() is provided to get the display slot for a task_struct. Setting the "display" requires that all security modules using setprocattr hooks allow the action. Each security module is responsible for defining its policy. AppArmor hook provided by John Johansen SELinux hook provided by Stephen Smalley Signed-off-by: Casey Schaufler --- fs/proc/base.c | 1 + include/linux/lsm_hooks.h | 15 +++ security/apparmor/include/apparmor.h | 3 +- security/apparmor/lsm.c | 32 +++++ security/security.c | 169 ++++++++++++++++++++++++--- security/selinux/hooks.c | 11 ++ security/selinux/include/classmap.h | 2 +- security/smack/smack_lsm.c | 7 ++ 8 files changed, 221 insertions(+), 19 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index ebea9501afb8..950c200cb9ad 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2652,6 +2652,7 @@ static const struct pid_entry attr_dir_stuff[] = { ATTR(NULL, "fscreate", 0666), ATTR(NULL, "keycreate", 0666), ATTR(NULL, "sockcreate", 0666), + ATTR(NULL, "display", 0666), #ifdef CONFIG_SECURITY_SMACK DIR("smack", 0555, proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops), diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index cfe5393840c7..b2ec81fcd1e2 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -2171,4 +2171,19 @@ static inline void security_delete_hooks(struct security_hook_list *hooks, extern int lsm_inode_alloc(struct inode *inode); +/** + * lsm_task_display - the "display" LSM for this task + * @task: The task to report on + * + * Returns the task's display LSM slot. + */ +static inline int lsm_task_display(struct task_struct *task) +{ + int *display = task->security; + + if (display) + return *display; + return LSMBLOB_INVALID; +} + #endif /* ! __LINUX_LSM_HOOKS_H */ diff --git a/security/apparmor/include/apparmor.h b/security/apparmor/include/apparmor.h index 6b7e6e13176e..e4b43e5bb8f9 100644 --- a/security/apparmor/include/apparmor.h +++ b/security/apparmor/include/apparmor.h @@ -28,8 +28,9 @@ #define AA_CLASS_SIGNAL 10 #define AA_CLASS_NET 14 #define AA_CLASS_LABEL 16 +#define AA_CLASS_DISPLAY_LSM 17 -#define AA_CLASS_LAST AA_CLASS_LABEL +#define AA_CLASS_LAST AA_CLASS_DISPLAY_LSM /* Control parameters settable through module/boot flags */ extern enum audit_mode aa_g_audit; diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 11845348eefb..fefccd559541 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -599,6 +599,25 @@ static int apparmor_getprocattr(struct task_struct *task, char *name, return error; } + +static int profile_display_lsm(struct aa_profile *profile, + struct common_audit_data *sa) +{ + struct aa_perms perms = { }; + unsigned int state; + + state = PROFILE_MEDIATES(profile, AA_CLASS_DISPLAY_LSM); + if (state) { + aa_compute_perms(profile->policy.dfa, state, &perms); + aa_apply_modes_to_perms(profile, &perms); + aad(sa)->label = &profile->label; + + return aa_check_perms(profile, &perms, AA_MAY_WRITE, sa, NULL); + } + + return 0; +} + static int apparmor_setprocattr(const char *name, void *value, size_t size) { @@ -610,6 +629,19 @@ static int apparmor_setprocattr(const char *name, void *value, if (size == 0) return -EINVAL; + /* LSM infrastructure does actual setting of display if allowed */ + if (!strcmp(name, "display")) { + struct aa_profile *profile; + struct aa_label *label; + + aad(&sa)->info = "set display lsm"; + label = begin_current_label_crit_section(); + error = fn_for_each_confined(label, profile, + profile_display_lsm(profile, &sa)); + end_current_label_crit_section(label); + return error; + } + /* AppArmor requires that the buffer must be null terminated atm */ if (args[size - 1] != '\0') { /* null terminate */ diff --git a/security/security.c b/security/security.c index 3aba440624f9..c2874f6587d2 100644 --- a/security/security.c +++ b/security/security.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include @@ -43,7 +44,14 @@ static struct kmem_cache *lsm_file_cache; static struct kmem_cache *lsm_inode_cache; char *lsm_names; -static struct lsm_blob_sizes blob_sizes __lsm_ro_after_init; + +/* + * The task blob includes the "display" slot used for + * chosing which module presents contexts. + */ +static struct lsm_blob_sizes blob_sizes __lsm_ro_after_init = { + .lbs_task = sizeof(int), +}; /* Boot-time LSM user choice */ static __initdata const char *chosen_lsm_order; @@ -438,8 +446,10 @@ static int lsm_append(const char *new, char **result) /* * Current index to use while initializing the lsmblob secid list. + * Pointers to the LSM id structures for local use. */ static int lsm_slot __lsm_ro_after_init; +static struct lsm_id *lsm_slotlist[LSMBLOB_ENTRIES]; /** * security_add_hooks - Add a modules hooks to the hook lists. @@ -459,6 +469,7 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count, if (lsmid->slot == LSMBLOB_NEEDED) { if (lsm_slot >= LSMBLOB_ENTRIES) panic("%s Too many LSMs registered.\n", __func__); + lsm_slotlist[lsm_slot] = lsmid; lsmid->slot = lsm_slot++; init_debug("%s assigned lsmblob slot %d\n", lsmid->lsm, lsmid->slot); @@ -588,6 +599,8 @@ int lsm_inode_alloc(struct inode *inode) */ static int lsm_task_alloc(struct task_struct *task) { + int *display; + if (blob_sizes.lbs_task == 0) { task->security = NULL; return 0; @@ -596,6 +609,15 @@ static int lsm_task_alloc(struct task_struct *task) task->security = kzalloc(blob_sizes.lbs_task, GFP_KERNEL); if (task->security == NULL) return -ENOMEM; + + /* + * The start of the task blob contains the "display" LSM slot number. + * Start with it set to the invalid slot number, indicating that the + * default first registered LSM be displayed. + */ + display = task->security; + *display = LSMBLOB_INVALID; + return 0; } @@ -1551,14 +1573,26 @@ int security_file_open(struct file *file) int security_task_alloc(struct task_struct *task, unsigned long clone_flags) { + int *odisplay = current->security; + int *ndisplay; int rc = lsm_task_alloc(task); - if (rc) + if (unlikely(rc)) return rc; + rc = call_int_hook(task_alloc, 0, task, clone_flags); - if (unlikely(rc)) + if (unlikely(rc)) { security_task_free(task); - return rc; + return rc; + } + + if (odisplay) { + ndisplay = task->security; + if (ndisplay) + *ndisplay = *odisplay; + } + + return 0; } void security_task_free(struct task_struct *task) @@ -1955,23 +1989,110 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name, char **value) { struct security_hook_list *hp; + int display = lsm_task_display(current); + int slot = 0; + + if (!strcmp(name, "display")) { + /* + * lsm_slot will be 0 if there are no displaying modules. + */ + if (lsm_slot == 0) + return -EINVAL; + + /* + * Only allow getting the current process' display. + * There are too few reasons to get another process' + * display and too many LSM policy issues. + */ + if (current != p) + return -EINVAL; + + display = lsm_task_display(p); + if (display != LSMBLOB_INVALID) + slot = display; + *value = kstrdup(lsm_slotlist[slot]->lsm, GFP_KERNEL); + if (*value) + return strlen(*value); + return -ENOMEM; + } hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) { if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm)) continue; + if (lsm == NULL && display != LSMBLOB_INVALID && + display != hp->lsmid->slot) + continue; return hp->hook.getprocattr(p, name, value); } return -EINVAL; } +/** + * security_setprocattr - Set process attributes via /proc + * @lsm: name of module involved, or NULL + * @name: name of the attribute + * @value: value to set the attribute to + * @size: size of the value + * + * Set the process attribute for the specified security module + * to the specified value. Note that this can only be used to set + * the process attributes for the current, or "self" process. + * The /proc code has already done this check. + * + * Returns 0 on success, an appropriate code otherwise. + */ int security_setprocattr(const char *lsm, const char *name, void *value, size_t size) { struct security_hook_list *hp; + char *term; + char *cp; + int *display = current->security; + int rc = -EINVAL; + int slot = 0; + + if (!strcmp(name, "display")) { + /* + * Change the "display" value only if all the security + * modules that support setting a procattr allow it. + * It is assumed that all such security modules will be + * cooperative. + */ + if (size == 0) + return -EINVAL; + + hlist_for_each_entry(hp, &security_hook_heads.setprocattr, + list) { + rc = hp->hook.setprocattr(name, value, size); + if (rc < 0) + return rc; + } + + rc = -EINVAL; + + term = kmemdup_nul(value, size, GFP_KERNEL); + if (term == NULL) + return -ENOMEM; + + cp = strsep(&term, " \n"); + + for (slot = 0; slot < lsm_slot; slot++) + if (!strcmp(cp, lsm_slotlist[slot]->lsm)) { + *display = lsm_slotlist[slot]->slot; + rc = size; + break; + } + + kfree(cp); + return rc; + } hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) { if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm)) continue; + if (lsm == NULL && *display != LSMBLOB_INVALID && + *display != hp->lsmid->slot) + continue; return hp->hook.setprocattr(name, value, size); } return -EINVAL; @@ -1991,15 +2112,15 @@ EXPORT_SYMBOL(security_ismaclabel); int security_secid_to_secctx(struct lsmblob *blob, char **secdata, u32 *seclen) { struct security_hook_list *hp; - int rc; + int display = lsm_task_display(current); hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) { if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot)) continue; - rc = hp->hook.secid_to_secctx(blob->secid[hp->lsmid->slot], - secdata, seclen); - if (rc != 0) - return rc; + if (display == LSMBLOB_INVALID || display == hp->lsmid->slot) + return hp->hook.secid_to_secctx( + blob->secid[hp->lsmid->slot], + secdata, seclen); } return 0; } @@ -2009,16 +2130,15 @@ int security_secctx_to_secid(const char *secdata, u32 seclen, struct lsmblob *blob) { struct security_hook_list *hp; - int rc; + int display = lsm_task_display(current); 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; + if (display == LSMBLOB_INVALID || display == hp->lsmid->slot) + return hp->hook.secctx_to_secid(secdata, seclen, + &blob->secid[hp->lsmid->slot]); } return 0; } @@ -2026,7 +2146,15 @@ EXPORT_SYMBOL(security_secctx_to_secid); void security_release_secctx(char *secdata, u32 seclen) { - call_void_hook(release_secctx, secdata, seclen); + struct security_hook_list *hp; + int *display = current->security; + + hlist_for_each_entry(hp, &security_hook_heads.release_secctx, list) + if (display == NULL || *display == LSMBLOB_INVALID || + *display == hp->lsmid->slot) { + hp->hook.release_secctx(secdata, seclen); + return; + } } EXPORT_SYMBOL(security_release_secctx); @@ -2151,8 +2279,15 @@ EXPORT_SYMBOL(security_sock_rcv_skb); int security_socket_getpeersec_stream(struct socket *sock, char __user *optval, int __user *optlen, unsigned len) { - return call_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock, - optval, optlen, len); + int display = lsm_task_display(current); + struct security_hook_list *hp; + + hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_stream, + list) + if (display == LSMBLOB_INVALID || display == hp->lsmid->slot) + return hp->hook.socket_getpeersec_stream(sock, optval, + optlen, len); + return -ENOPROTOOPT; } int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 5570a6ed49d5..5f50dae7c107 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6315,6 +6315,17 @@ static int selinux_setprocattr(const char *name, void *value, size_t size) /* * Basic control over ability to set these attributes at all. */ + + /* + * For setting display, we only perform a permission check; + * the actual update to the display value is handled by the + * LSM framework. + */ + if (!strcmp(name, "display")) + return avc_has_perm(&selinux_state, + mysid, mysid, SECCLASS_PROCESS2, + PROCESS2__SETDISPLAY, NULL); + if (!strcmp(name, "exec")) error = avc_has_perm(&selinux_state, mysid, mysid, SECCLASS_PROCESS, diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 32e9b03be3dd..ab68612d0885 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -52,7 +52,7 @@ struct security_class_mapping secclass_map[] = { "execmem", "execstack", "execheap", "setkeycreate", "setsockcreate", "getrlimit", NULL } }, { "process2", - { "nnp_transition", "nosuid_transition", NULL } }, + { "nnp_transition", "nosuid_transition", "setdisplay", NULL } }, { "system", { "ipc_info", "syslog_read", "syslog_mod", "syslog_console", "module_request", "module_load", NULL } }, diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index e42336328446..aac8cb0de733 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3519,6 +3519,13 @@ static int smack_setprocattr(const char *name, void *value, size_t size) struct smack_known_list_elem *sklep; int rc; + /* + * Allow the /proc/.../attr/current and SO_PEERSEC "display" + * to be reset at will. + */ + if (strcmp(name, "display") == 0) + return 0; + if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel)) return -EPERM;