From patchwork Mon Dec 16 22:24:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 11295533 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 1CB84138D for ; Mon, 16 Dec 2019 22:25:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E977024683 for ; Mon, 16 Dec 2019 22:25:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="IQowWTXq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726833AbfLPWZk (ORCPT ); Mon, 16 Dec 2019 17:25:40 -0500 Received: from sonic313-15.consmr.mail.ne1.yahoo.com ([66.163.185.38]:44517 "EHLO sonic313-15.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727438AbfLPWZk (ORCPT ); Mon, 16 Dec 2019 17:25:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1576535136; bh=g8TWN1eoe+uy+sZe5wVWXpzABF5M7+tcGA3nRh7X6XE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject; b=IQowWTXqOa9OqgGQ9DSDsDwiLPM87UJuu6TRIOMe1lp13BcJJAp6XTr82eay1GnfJdvEYdGDJiOlAyt6dC4QBmje9p8sxg1xoTYuZhwwF5znTuyB858ZSrhBZm4dTjtPQb3gwTCIJmIb8erabBufHe3AWEsVxU3DTKl0K18Kjfn0sQ0+X0tUWAavRrOeM4iEcePyMIXNq7obwl7J3LD4rsXvnXE2CweUU27/5UL+D4oasl9N5IExtvZSbOlHmB5xt52Tm1GU0pr4Ub37fyRtvZd0TeqQh5wv5hg4E2Zkqk0+X7p5JeiJlKwTEyXibzlLaRoouBYiPyqAUhrHJvg4PQ== X-YMail-OSG: mBT_YnEVM1lPxE99xEh_QtOJotmAAmnzbJPRqXM7_6i8MN69AUh8Vbq9rWP4iKw dbleWGU22D4Z.RF288Z8nJDcLRMaQ5KjglLCx.w.GfAnPHEPUTNf02CZA7bOX5D8N0Lyfdyly3Pl B4qRblWgX.bz1b5l5w_VSq54tmoO3Fa57u_RodL25E0jzJpgm2HzCJ010ulwGjow6dSmho1QQjzT yuqX_3LULI8nlUAoGm186xU6CC2i_abKcX6vo5EHfveeeYu4o6e6uJ89ihASl.q1u5m6ZeERmGZs NqValZ.N0fntnXcpCwgktVVulX8s7fVEBqxvCRf4lmSxckofXLF9dbrrOLkj.lJpZ0UA7dToJAly zPuypNYU0kgRnuUtN3Iqb0RmYkacJsTdLkuVBrg00U0Ic88znCd_CIBBOo2MTfnqqL1al5uGQB5b lNxmE4t8quYqX2HgP1dir0IgdwT9mCDlB_yw8Zd3F.iKs_G1FTM9pyJmhStaNt0cQITrMzbbPuUU mMn9QXO5U7Wt88Nee2_NbRXUNOZyZk7q8UaJM7fYJowlZqZKpUe4alrKKlll.w2Iz6D0L.osbsUu FAzlONGzhncFmw3AAA3fp34zZA__FaYszLJp94kH0YufIbyCu5DRxgcHsBClKSTmWqMVxENPXJxo 8Z5gon6tHwTnwU7F8IhyxWUNN6w0W0vgT26XIiwBzsQhJnkqzVtLK9Ps.8avf7DzNJI0dqLY_5O1 2kqRY5kB5ixKwlS77SjWJN2xrD25f596w0grzwhk3PFq89zs8_SMWgj1qJrsDN1N6YshEgbX8Ccs .06.SDvOw0CSqHDVhEE.7PU4CAiYi4AsugqrLGQSrqL4dVkYad1TR0_Tge4xqjHRTjhauZ6wNf.E MMrnK14ay8UM9wD.1GoOW8i_YVAHf0FEAetsZq4eMxOWy2ONOJ6xig8yOhk4fM_Wq83gCX3IRSQh 9estI5YAJnYA47KuL46Of_.qYTtVq1h55fmuIuP1PDlO3qnHEefOichFLnHRTdBzcdi7VD1Cg0CZ vf5Jq9wrIc5eqUG23_V6.jZVdM1HZ6xSxdLlOEcXh6tCpoDn9YeGsKIR1GVKP3UpbQyn5duAQPhr r.DQ3.Ygz4cBVvJtJ46bsotZeCZL6wy7Urg_Ze1QhW5_i1pTcVsq5s5gQrtnJDT0tRf4g2Pt1UQR 3AFbZpYzY3.h18yNwZr2cNQKDWq2JKbxS04RnhQk1LRtBFVKbbuVK9kbwmQDKTIyQ6JmYd99dP73 PFSEmUh3ULQmrdVSWdLr36qw6.kWGA.IdCOYkUlfGKzjtXNP8uwxctd44a.YsCFlq1Gn1JuKpYRP SLuQlaPP_ApLvSjSeMdMGHg6Kh0ubgHjhlqIhqWaXsPr5LpRoEO1ttSXmDsQ2oHrRymJutjuyG8Z qjrzDPIlOFPygKlhGZY36KuMwPTin4Y2zOaqXi4PMSZdL9c4R7smnqK.PbWRKvsQKZW_g7A-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic313.consmr.mail.ne1.yahoo.com with HTTP; Mon, 16 Dec 2019 22:25:36 +0000 Received: by smtp405.mail.ne1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID 92ff60b9e77fc5dff8e9e81027c191c6; Mon, 16 Dec 2019 22:25:31 +0000 (UTC) From: Casey Schaufler To: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov Subject: [PATCH v12 13/25] LSM: Specify which LSM to display Date: Mon, 16 Dec 2019 14:24:19 -0800 Message-Id: <20191216222431.4956-14-casey@schaufler-ca.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191216222431.4956-1-casey@schaufler-ca.com> References: <20191216222431.4956-1-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 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 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 32354942b7e8..aaac748e4d83 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 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;