From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A2D6C35240 for ; Fri, 24 Jan 2020 00:25:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF260214AF for ; Fri, 24 Jan 2020 00:25:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="gj3lL5Tr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729927AbgAXAZN (ORCPT ); Thu, 23 Jan 2020 19:25:13 -0500 Received: from sonic316-27.consmr.mail.ne1.yahoo.com ([66.163.187.153]:42616 "EHLO sonic316-27.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729893AbgAXAZN (ORCPT ); Thu, 23 Jan 2020 19:25:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1579825511; bh=pFBdkoTTn2iNs67+Pwg1C4/gV1dQ8/C6DKJQQw4XeY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject; b=gj3lL5Tr1FoSNvU1JEwYq+z5hdS3fFQ+0GR/+H5iAhZ3PHbXBPTC1kVG156NjyhLzZfxL3+P9STF9/dOhvmmAvUS48YKBwN1hte734SAs6gWF1XF5fc9miTj4jBFc9+AelF1fHwMxkVF1RvLB96OXRulKwNhzWddEbw1Ao1xUmcIM8YDtrpsGT1sGF4x9jkdQtH2YuD+IRm7v/8Q4LadIgVLD5EExuJt5F90IO1qbqM61ejn55zYb2a4kfNs8Qb6c6GmePyEgjE4gL8pIMBU0Z4ASYZehfSIYvgpXTKKksL+x1+BStQK/qhGp2bKxDTv4lQGCDqfX91Q7RIpVFM75g== X-YMail-OSG: 03V4izYVM1kCiOZJsb8rLUg9Nenjr1phUckvyfk0SsPhtEoAxqBJrHTk16SvJeC xqqJ7sDWRBk_I.DzUSfmi7h6Uu9r9Ntv0dtw5gwowYeSEAPX74un9PsbWJDr9a0s1eNPG.0eX_yX xRrKNJ4gr3wT7S4U9FhAlY7cxRu2XADw0GJA762vsbOBBg0K8cO9zEM8WDrqCV_iFzXEiexbBiDd qVulVV8TGEomdf9uRwSZDdqoPhW8wHAfaB_H7ZvN7niPLFdUlf5FgbpFkaoMOVC3OOlQlaiVHk9K jLHscNdr.12IPNG345FbF2TI.Q41sWGjN4NibawI1qLLVK9zTf1tRG2opqn7HDcJWloyKn6m20HE NwMt0B.Tsgw4Px5junTzzexcjtyci8UFjMAQQAwSuIGG3KvoSuJJeO0fSQbe4MelTT1OftXQZp1l oMTbvBH0ZWf5Ob.54wnp_vpAm.ah.Qt9hbzLlk3zkuOpS9.lJJu1QL9IuXvVTqWeVWs_1GgSnDmI NquLPLQ9L0rv0gYkekhHPZ_2xl7D.INUQ2lxrNaAW_Quri0BXWPHo1TRl5JWwunXRUFTK_g8Hx.x cv_S.NvsP4VzGG4FH__VajmrMAnoOsj0r5mJj_p61osn3vX5NiIupMH6UPt90TGC9FQyNHckbuXm _E1i7qZEmklat.PecmO620qfN6PDMBotwT67vhCDpRvhmswnxMSVYJi3ForcxvyMg536KLJZ50z9 gk5tNIlHdiaiuJNHN7pkBMvT7YjqzCFKOVLrAaezRlD64GoA9IXjrCjqtJxvJRaOmSv3R2w6BRsZ p3XbufUyaPEIkfcFFS9gzok70ErKkMWTr2svvcHPVI3BC.6qiUKyVnjZj5Cl56_s1X7ZDR54sMdD On6oP6PGFpTBc6OXZIASa4I_5IUiBoz0o1J.rfuWEUrqdGUfs1AzQg2A_FShkHMkUKDGv0Ud8iEQ 19mlLNJh_zjn7_JvUqZxHSK4W8Cs9n2V_8kQRQzSMO8EJVAvoH4qDqy9beG51Am_fMVzjeMhCscA PBeX9aPCWwEX9DXbR7q76n.88Yi5oM4vcyBQlI9u_3sDOlRWm8zmG.Q8dnErX05m2.iHqKxG15z2 je..IK0jNHfVhcTK5WZinpjcpyYVQX9AaTs2x9lKWmENflED93R2gDFQtVaWjtHzsT2ygDzOLq1Z rzhgChJzqWhikEXqX0z8qfVtKQpUh0VjOduU6tatV2li5sDD8gyCNMXSc7mprTg28dtB7..OIn0P HLGmHz1HqN.XymH2EOrL5Co_W6yxykkgv0EhqCB5x3Z_df_l7mXQEyQlM4lBRyMboujmCqrYmWuU FgYTAsWW5C0LZwT_ocQgB3X08ikMh9yqlHSseaBsJ7PCDpJkaz795UkEQVJFiD_bPJl0UyXTpaZG NLQh86P_kEUrtlnLKpnbhm4clX.37UDfigoFBNPiAhrw6ThhxLrpsNYUVaGBm4yNXUudnhMpRe0g - Received: from sonic.gate.mail.ne1.yahoo.com by sonic316.consmr.mail.ne1.yahoo.com with HTTP; Fri, 24 Jan 2020 00:25:11 +0000 Received: by smtp423.mail.bf1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID fa03a9a6bb2ee60ca432da5cd71a54a0; Fri, 24 Jan 2020 00:25:10 +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 v14 13/23] LSM: Specify which LSM to display Date: Thu, 23 Jan 2020 16:22:56 -0800 Message-Id: <20200124002306.3552-14-casey@schaufler-ca.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200124002306.3552-1-casey@schaufler-ca.com> References: <20200124002306.3552-1-casey@schaufler-ca.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: 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 Acked-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 | 167 ++++++++++++++++++++++++--- security/selinux/hooks.c | 11 ++ security/selinux/include/classmap.h | 2 +- security/smack/smack_lsm.c | 7 ++ 8 files changed, 219 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 7eb808cde051..2bf82e1cf347 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -2186,4 +2186,19 @@ 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 1fbabdb565a8..b1622fcb4394 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 146d75e5e021..16b992235c11 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -612,6 +612,25 @@ 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) { @@ -623,6 +642,19 @@ 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 100e55777426..80ff19ba62e5 100644 --- a/security/security.c +++ b/security/security.c @@ -43,7 +43,14 @@ 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 +445,10 @@ 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 +468,7 @@ 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 +598,8 @@ 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 +608,15 @@ 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 +1572,26 @@ 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 +1988,110 @@ 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 *termed; + char *copy; + 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; + + copy = kmemdup_nul(value, size, GFP_KERNEL); + if (copy == NULL) + return -ENOMEM; + + termed = strsep(©, " \n"); + + for (slot = 0; slot < lsm_slot; slot++) + if (!strcmp(termed, lsm_slotlist[slot]->lsm)) { + *display = lsm_slotlist[slot]->slot; + rc = size; + break; + } + + kfree(copy); + 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 +2111,15 @@ 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 +2129,15 @@ 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 +2145,14 @@ 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 = lsm_task_display(current); + + hlist_for_each_entry(hp, &security_hook_heads.release_secctx, list) + if (display == LSMBLOB_INVALID || display == hp->lsmid->slot) { + hp->hook.release_secctx(secdata, seclen); + return; + } } EXPORT_SYMBOL(security_release_secctx); @@ -2151,8 +2277,15 @@ 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 97f2ee6e4080..b8501ca3c8f3 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6323,6 +6323,17 @@ 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 7db24855e12d..323da8a38c43 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 82cbb3eeec76..9737ead06b39 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3518,6 +3518,13 @@ 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; -- 2.24.1