From patchwork Fri Feb 14 23:41:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 11383591 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 3C47117F0 for ; Fri, 14 Feb 2020 23:44:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A4CE24649 for ; Fri, 14 Feb 2020 23:44:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="bhBnXW6P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728176AbgBNXoS (ORCPT ); Fri, 14 Feb 2020 18:44:18 -0500 Received: from sonic314-27.consmr.mail.ne1.yahoo.com ([66.163.189.153]:44575 "EHLO sonic314-27.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728234AbgBNXoS (ORCPT ); Fri, 14 Feb 2020 18:44:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1581723855; bh=Yognqs0uaU0CcJGK22af100kJpc21EI8ynuOxYSuPbg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject; b=bhBnXW6PRxY/+zriqWEM9tsvz1kaGY/yU1qDOkVLKlkUO8gZ+ty2KvhB0ebuzUeskuha7ZbQzK4tXwgILiUTz5jy13nVCBqeYtHXToxIzJfcl2pdr1OBPOvHmA/0RpiLW2pVzZTIn+JSxsFc2rgGklz4Xf9yxBvThvu1D9lgAGTssnm0frc9Vt1DW5/2xeocM/EWxLI3EvLuCLNA/YhGfdPINJxr9F8i6PxvigF2/jE+8TRG/ucVAUliWcBq4BfIEDV6HJ5gN9PIc+vtL4qt7EsIHUVy1zChMDaY6CIWNxAwLMFMqYKM7RoNR9Xu7q4k4burKMgiB1l0YHEeV4AmBg== X-YMail-OSG: 46W63oEVM1lU5VPxt_QsbkB4D3qwl10Hd1h2ad09dsM9Z35oNhs3.A53EZVLx3T gRS7YCesHNl02deHo9iVfI71vtoRmAfllVjHlVpu4g2E5w5o4wPY683OCnwwGbyiFidsv.QPsbC2 LmvkJ7zGfbjHs80nMfIjc0c.9zc2x8UH0w_Hc7RcerXpJ.wCRpVuGk3DHRhrbVCsWv6OzFY8e.i5 9GH4khbQRSMTtWVYyJQW8ftHQbhGBt5WoMTjtkNcuaq9ffW3gwD2SCQz_4G2qYqYoW_xiTgqSZm7 62esS2OLSeOPpDL3BBBkvFZ1Nuoc2pinto9k7Q.z7HZZWTz9PCAQ8qbvahdYc60oG0CrTjXCvePi hVodafO3xq.qWs7kwIvmqjwfSDEkVHfYfARjEt8sZqQzC37GlEcrZbCuL6UiWx06lqURnims6dj2 ah8CSg3MSRGs.thUjB3Ia2Q.ghW5Z.Z4PLlGbdDda6KRfmYn1V6SlKkthAXMGLguZGG1yUB7IRfA iam5DyKoI95UUFIeIzmvpEu1U.HFL9QAK.sqlPIX.uAMOam7GGySxgG2HCQMRFMu212ZvtDFktCP A41Ja2fZ7MUktcgaxSXhByzXruPbDYL7wZ_P4ktb.TCTzI46cjUENwO.wHZnd65mERnMJpd3BXuD 1ODLb3QB6z_6fWVa5AySboMdm2HJu_7evPJ3MXtpide3LxLG13JoMlkhtG3eom.0kf1YvZYCLi0A DL0DPshDEb0sXyozWRN52j8BJtnqBBxi02a0KcAhZaEL80ENAegOz_LdxrXYO_yk.kFDl2PdBbuW UDeHTg.vU7lyMzCNOLMB5eIH5w2.UBy02LFKnfgqX9n.YsG1hmqO4S9scnrl9RKsPnuHqz8BdA.c Z8Kh9uXIrYzw2j78wKkHO4u1oR4xRfIN9cFnOaG3FO9dttD_xaD7KLMSG08xvQGCI00McwWcjuG5 Xkno7Ytazk1q1O4Xeh7oa3uFTOtz3h3iz5wv1.h10LfDRWCMSpAO66kED8XGR04IHNVskCK4WVxT c1K4tRH4D4w5NuPWOckduryarm2.6JtRANKlwkMqCp6ceNKj59K1Co4XFoBmfclOWJ59Bi5lA3TM 0em3pfI6_JghdwGz8EEcSaxNUyLnnpTNdu6bvhUhL6Lybq4K1zum1nYpDBr_zZOXYYubJ6TxObdI VN0fGD4A5ClaboDy8fBEsX6zr_.BP7cEb53k.4CVuKPpoAHBzwG8ZX3SwOSjWIZq7m3sYGoH36WH QwYfF9NDTgskB7LwH0oZ7Mtmy6r3yLmdGyRmuAg8KbE.5baXVL4aP1_wdfkp.dvDrs28Rye8ZKpV vjjOT6X5PWwnWJY5utjrKyVlLpNkincSBAutNErvIHAmCxJNlpH8tRNwMDaQNlyGoWLUyecU.Ezi 2EUM59Ftk_MVFyWo.ZYjC1095Tob1VKBAwY6XvIu3jpTufsPGeJLK4njEGGeTYabDzAGVNPlX6O0 - Received: from sonic.gate.mail.ne1.yahoo.com by sonic314.consmr.mail.ne1.yahoo.com with HTTP; Fri, 14 Feb 2020 23:44:15 +0000 Received: by smtp427.mail.ne1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID cb3a62f0a1530c83edfb2fd8c399384b; Fri, 14 Feb 2020 23:44:11 +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 v15 13/23] LSM: Specify which LSM to display Date: Fri, 14 Feb 2020 15:41:53 -0800 Message-Id: <20200214234203.7086-14-casey@schaufler-ca.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200214234203.7086-1-casey@schaufler-ca.com> References: <20200214234203.7086-1-casey@schaufler-ca.com> MIME-Version: 1.0 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 Acked-by: Paul Moore --- 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 c7c64272b0fa..505331ab7a14 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2743,6 +2743,7 @@ 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 2218abab789a..475929e3e1e4 100644 --- a/security/security.c +++ b/security/security.c @@ -75,7 +75,14 @@ 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; @@ -470,8 +477,10 @@ 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. @@ -491,6 +500,7 @@ 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); @@ -620,6 +630,8 @@ 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; @@ -628,6 +640,15 @@ 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; } @@ -1583,14 +1604,26 @@ 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) @@ -1987,23 +2020,110 @@ 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; @@ -2023,15 +2143,15 @@ 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; } @@ -2041,16 +2161,15 @@ 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; } @@ -2058,7 +2177,14 @@ 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); @@ -2183,8 +2309,15 @@ 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 22b882867dd2..a12cc8959f6c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6299,6 +6299,17 @@ 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 986f3ac14282..ba36a55b5ea4 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 12e01d450dd4..00a304861657 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3510,6 +3510,13 @@ 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;