From patchwork Wed Nov 13 00:09:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 11240533 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 012EF13BD for ; Wed, 13 Nov 2019 00:10:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C429C21D7F for ; Wed, 13 Nov 2019 00:10:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="BuM0yZpY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727233AbfKMAKJ (ORCPT ); Tue, 12 Nov 2019 19:10:09 -0500 Received: from sonic306-28.consmr.mail.ne1.yahoo.com ([66.163.189.90]:40705 "EHLO sonic306-28.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727208AbfKMAKJ (ORCPT ); Tue, 12 Nov 2019 19:10:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1573603807; bh=T+7vkOglemjDcJCtI0jsgL0AaHeYGYB4YiqPLcOqBMY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject; b=BuM0yZpYF8rarAlhhmXna60LcZZh+R+kUEGIBIKqAaYkHavw240Kgj2uTippjYGgFzTPZ2MvIbj+ZgHCsdE5nPlLmU7wfi/oqujXRJi44wQwjzMrvtHl1d9z+43suoCQnsnF8wgy3zTz9dNyYpu+1oOnXL78Zehn2OUZKEp1U69MLWrxhuTbaeO2hFgHh/oJ9uY9BTXrnrM3oNgX6CqVSRRNrEGPo+N6AXCEWdHdjDjKpTj/OWAbZD/c7h0TRypBMvMuX/XEn7Z8EnHccWHT7AjRw8oLLDujkcb62wCD/rImFsa4LWft2pQn+mm9p0aX22WTUH/zC+1VdoWBGzI8Bw== X-YMail-OSG: YTAhPScVM1lX89mWhRT1xUS4q8VX8gltH2Vvept_r7aHxccNi3DzUQfTjk5hpPg DrE9vFRHZ3.z014S8hVrNBv3yHctIWWjeJHjyaHAm_98Dz4vWdx2xStVi5XyGXrAWqTcMP.mv3Vq HrNU6bVNsiSzFVfaTHUwzEW1r7q8wcmS1YKp4Td3SUdnWCyuByYHHIf_Crgf22F_64qB7LLzZf5l Hj.cB2RKQufYpvgv7p1BdfuVEQG8a_Xnz4885XZhj83N30uRzgL_3Z.6aYdvX1M8Ra3GpIVHcRaj FaKArtDDAQ1KnWCUHFHV9cc3B63cpA14X.07MamK0K3tPZ_rOpwUn2xyHaKDIICTpGHXi49m04PO kxym4QI.V.a7Xl5OxjMBGdRWDGATVH5HCTP5pd68RkrYWl_LqOAqfveTPOJ7tzoXVv9af6WsC6OI V9s3hk0rO47ko.kIq.0Fz9khTRSx7ISC44mEm4DQWfwQLfz86yTb42rIqxr_tlqOt8koPZ8iALKG _A_dQvJ8qdtjhO0X2dXZ5GO_wiN6OnHuOFP2SE8FR28Dax.x7mL5lUu0Bx4PXkBhipI6gtTfC_s2 _4Ip27hfd3P9ghud8xFYIgd4pilf9h1miifKL3FQtuNfBKP35gthaBh6ZY7GKnTPB06zokQRTQ1k fE7ZjYdNMkfZp8fI0LpztNCWE23VaxpdouV4xSRaTBIwvzad4N0YTpKQ5tvW67_M3Aldu.8l0nb3 09fLhCChmPcEn_ztBWw9hti.1Yo1QH0.TLdq0StTXUNBzquCy_RvlwKj.TOwC5rcRMOPaO3FaiC5 cdRttkeY.e5xXirSpCd7WkKH1t4Z3EkQs7eQ.pGVuS2dKlDkt6DeFGVnTrs18XqY9NBdTqHPfDlt ayfNR0ShwNB_s2scctzG_r0oyfGSLGeeKM6ZVIxH_vL9kJhapL8EY46zUth31y2LJalPSkn1gaa3 BfrMb958MnNSY98z5dihbENZzsVtKJVaVlVYlC5ttiq7iTm_6jssAB5sGSXkhxEaKp2UqFp9uLiu hIxBJbWJC9Isii6oIKYLFKVJWmyZbeucPOIAOnxy.d1amkNCSwN_I_GYMq00TtvMp91RRalWcGtL L6U8SuOeQIDQc63iyxc_NGe1fFTEDixHjfqNyJI4T9F0XQ1ApG4f1_mi5e__SCqOAN6OisJVGA5_ qTt8BMMundYjNIrwwPydfgzUVz07CUc2Y1LwOxZuRWnINVNphCCHTD6Oy0l4nrq_jbMMeLnIO90t BsuBbWaiA_E5PSU.ujYfI42bG.a8KijM0_McMbXJ1.flnTkl.G57GVG9P0bXAjrjmokLjtkTGKGw 4Qnf.yrzUUyIPL2vC9w8vGvwH52BdXelQTxoOvu.NvrU.HgNp4CXEvDqLxJpykscYLEeGizUaebf RRg4hxuLerez2btftsrokVD5ZIW6ELv48fF1ozgr1RfG6OZse31Zg8tedv3t1Po92CA-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic306.consmr.mail.ne1.yahoo.com with HTTP; Wed, 13 Nov 2019 00:10:07 +0000 Received: by smtp428.mail.ne1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID 93aa6347d771200c823c70ba6657789f; Wed, 13 Nov 2019 00:10:05 +0000 (UTC) From: Casey Schaufler To: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: casey@schaufler-ca.com, keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov Subject: [PATCH 13/25] LSM: Specify which LSM to display Date: Tue, 12 Nov 2019 16:09:01 -0800 Message-Id: <20191113000913.5414-14-casey@schaufler-ca.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191113000913.5414-1-casey@schaufler-ca.com> References: <20191113000913.5414-1-casey@schaufler-ca.com> MIME-Version: 1.0 Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@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;