From patchwork Thu Mar 8 01:52:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 10265801 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 60DBF6055B for ; Thu, 8 Mar 2018 01:52:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 50ED329097 for ; Thu, 8 Mar 2018 01:52:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 44DBD290BB; Thu, 8 Mar 2018 01:52:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4DBE629097 for ; Thu, 8 Mar 2018 01:52:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934465AbeCHBwd (ORCPT ); Wed, 7 Mar 2018 20:52:33 -0500 Received: from sonic317-41.consmr.mail.ne1.yahoo.com ([66.163.184.52]:39846 "EHLO sonic317-41.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933351AbeCHBwb (ORCPT ); Wed, 7 Mar 2018 20:52:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1520473950; bh=bhHwCImYvZXhwXIPTwLV7DHZ7c2WB6BAUYx4rz50fkc=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From:Subject; b=dbhDLMgwHbtrD1GAaL8h6FiCqrsSldWi4IG4XOBBlaN5Saa08AyvN6ETDLP+pHOoD0ky15gB5qaSKM+IRwGyNAl3VG4FjpMbsEB1hHMS1VJVk64NK0kejuIyS35O661fg1z6TgnSYz0OmuX0VHpD9CpBEnrkf2vjqmq/cJII+PU7d3oQ+Pb5dk3Oy1KzasI1lFYdLtbwLb7kr2ZRibEOo0UPsN2ibFvo2JLGX8zxtAzUk/BrmHd8k/Nf7s5C2X5Cvq0LeQRYr9D3FfYXIhS4VS2s6XhVQqROvVPovwUKnKDykbrnRzxEGxRQPw24wKp9pj4VAtAxa+T3pB1IPEJbhw== X-YMail-OSG: vzJLqP0VM1kVijyzu9NisOifEKYFoyA9rXqb_ERlVtC8D_OKawveOYBWmZanQKV IIS52dWnz_8XrmwvGmXXyLXBD__qyrTZt2plB0o1rdxFu0OFhjIGEU8Zg4yFE2uoStiKokh5ihuE He86u9RAM7rNLU0Po3p5imkGvCuk4m.chDEk5Ee6CM9qnAYcnVFrBU4_RI_oCzPwRVWM5fBpRm6e cieHlgtQPcuZ3cOHHm820gX2hsyu0eP7l5rolLWL9__zg1IW3SfxSOA07nyumvgZ3WWgX72IU4oU QeYDZE3nW.b.Of8lsd2oATfGFCVXrD5iiFDSV2cJMEEdv_EJdCiLwZl.GNjQ3stYsd6glfQznmVn h7hPPg420jxXvcUDuhJRJjo0ZIk70HBhm9cbFujfdYTqpJYLYbYbOTELHVzDQkPg1DLWKN2AUQJD igyVfqx_F7yRd82mVa_T2Yr0DoPPr_fHViktvT03PESHzUPSykt0DVlQegk0tDZzjWesLDZv8zoK Wm2y6jlqUgaGNGH.dJERYZ4grEdKbYoIudHd9H6dziqs8v3fcmg-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic317.consmr.mail.ne1.yahoo.com with HTTP; Thu, 8 Mar 2018 01:52:30 +0000 Received: from smtp226.mail.ne1.yahoo.com (EHLO [192.168.0.104]) ([10.218.253.215]) by smtp412.mail.ne1.yahoo.com (JAMES SMTP Server ) with ESMTPA ID 1f0eeccf7611445fb07abe0252cb8a9a; Thu, 08 Mar 2018 01:52:29 +0000 (UTC) Subject: [PATCH 1/8] procfs: add smack subdir to attrs To: LSM , James Morris Cc: John Johansen , Tetsuo Handa , Paul Moore , Kees Cook , Stephen Smalley , SE Linux , SMACK-announce@lists.01.org, Casey Schaufler References: From: Casey Schaufler Message-ID: <3a0a4089-f95b-bb6b-5716-92f767a66e5c@schaufler-ca.com> Date: Wed, 7 Mar 2018 17:52:27 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Subject: [PATCH 1/8] procfs: add smack subdir to attrs Back in 2007 I made what turned out to be a rather serious mistake in the implementation of the Smack security module. The SELinux module used an interface in /proc to manipulate the security context on processes. Rather than use a similar interface, I used the same interface. The AppArmor team did likewise. Now /proc/.../attr/current will tell you the security "context" of the process, but it will be different depending on the security module you're using. This patch provides a subdirectory in /proc/.../attr for Smack. Smack user space can use the "current" file in this subdirectory and never have to worry about getting SELinux attributes by mistake. Programs that use the old interface will continue to work (or fail, as the case may be) as before. The original implementation is by Kees Cook. Signed-off-by: Casey Schaufler --- --- Documentation/admin-guide/LSM/index.rst | 13 +++++-- fs/proc/base.c | 63 ++++++++++++++++++++++++++++----- fs/proc/internal.h | 1 + include/linux/security.h | 15 +++++--- security/security.c | 24 ++++++++++--- 5 files changed, 95 insertions(+), 21 deletions(-) diff --git a/Documentation/admin-guide/LSM/index.rst b/Documentation/admin-guide/LSM/index.rst index c980dfe9abf1..9842e21afd4a 100644 --- a/Documentation/admin-guide/LSM/index.rst +++ b/Documentation/admin-guide/LSM/index.rst @@ -17,9 +17,8 @@ MAC extensions, other extensions can be built using the LSM to provide specific changes to system operation when these tweaks are not available in the core functionality of Linux itself. -Without a specific LSM built into the kernel, the default LSM will be the -Linux capabilities system. Most LSMs choose to extend the capabilities -system, building their checks on top of the defined capability hooks. +The Linux capabilities modules will always be included. This may be +followed by any number of "minor" modules and at most one "major" module. For more details on capabilities, see ``capabilities(7)`` in the Linux man-pages project. @@ -30,6 +29,14 @@ order in which checks are made. The capability module will always be first, followed by any "minor" modules (e.g. Yama) and then the one "major" module (e.g. SELinux) if there is one configured. +Process attributes associated with "major" security modules should +be accessed and maintained using the special files in ``/proc/.../attr``. +A security module may maintain a module specific subdirectory there, +named after the module. ``/proc/.../attr/smack`` is provided by the Smack +security module and contains all its special files. The files directly +in ``/proc/.../attr`` remain as legacy interfaces for modules that provide +subdirectories. + .. toctree:: :maxdepth: 1 diff --git a/fs/proc/base.c b/fs/proc/base.c index 9298324325ed..3c89d3442cd2 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -143,9 +143,13 @@ struct pid_entry { #define REG(NAME, MODE, fops) \ NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {}) #define ONE(NAME, MODE, show) \ - NOD(NAME, (S_IFREG|(MODE)), \ + NOD(NAME, (S_IFREG|(MODE)), \ NULL, &proc_single_file_operations, \ { .proc_show = show } ) +#define ATTR(LSM, NAME, MODE) \ + NOD(NAME, (S_IFREG|(MODE)), \ + NULL, &proc_pid_attr_operations, \ + { .lsm = LSM }) /* * Count the number of hardlinks for the pid_entry table, excluding the . @@ -2526,7 +2530,7 @@ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf, if (!task) return -ESRCH; - length = security_getprocattr(task, + length = security_getprocattr(task, PROC_I(inode)->op.lsm, (char*)file->f_path.dentry->d_name.name, &p); put_task_struct(task); @@ -2572,7 +2576,8 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, if (length < 0) goto out_free; - length = security_setprocattr(file->f_path.dentry->d_name.name, + length = security_setprocattr(PROC_I(inode)->op.lsm, + file->f_path.dentry->d_name.name, page, count); mutex_unlock(¤t->signal->cred_guard_mutex); out_free: @@ -2589,13 +2594,53 @@ static const struct file_operations proc_pid_attr_operations = { .llseek = generic_file_llseek, }; +#define LSM_DIR_OPS(LSM) \ +static int proc_##LSM##_attr_dir_iterate(struct file *filp, \ + struct dir_context *ctx) \ +{ \ + return proc_pident_readdir(filp, ctx, \ + LSM##_attr_dir_stuff, \ + ARRAY_SIZE(LSM##_attr_dir_stuff)); \ +} \ +\ +static const struct file_operations proc_##LSM##_attr_dir_ops = { \ + .read = generic_read_dir, \ + .iterate = proc_##LSM##_attr_dir_iterate, \ + .llseek = default_llseek, \ +}; \ +\ +static struct dentry *proc_##LSM##_attr_dir_lookup(struct inode *dir, \ + struct dentry *dentry, unsigned int flags) \ +{ \ + return proc_pident_lookup(dir, dentry, \ + LSM##_attr_dir_stuff, \ + ARRAY_SIZE(LSM##_attr_dir_stuff)); \ +} \ +\ +static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \ + .lookup = proc_##LSM##_attr_dir_lookup, \ + .getattr = pid_getattr, \ + .setattr = proc_setattr, \ +} + +#ifdef CONFIG_SECURITY_SMACK +static const struct pid_entry smack_attr_dir_stuff[] = { + ATTR("smack", "current", 0666), +}; +LSM_DIR_OPS(smack); +#endif + static const struct pid_entry attr_dir_stuff[] = { - REG("current", S_IRUGO|S_IWUGO, proc_pid_attr_operations), - REG("prev", S_IRUGO, proc_pid_attr_operations), - REG("exec", S_IRUGO|S_IWUGO, proc_pid_attr_operations), - REG("fscreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations), - REG("keycreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations), - REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations), + ATTR(NULL, "current", 0666), + ATTR(NULL, "prev", 0444), + ATTR(NULL, "exec", 0666), + ATTR(NULL, "fscreate", 0666), + ATTR(NULL, "keycreate", 0666), + ATTR(NULL, "sockcreate", 0666), +#ifdef CONFIG_SECURITY_SMACK + DIR("smack", 0555, + proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops), +#endif }; static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx) diff --git a/fs/proc/internal.h b/fs/proc/internal.h index d697c8ab0a14..86efb9842c8b 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -62,6 +62,7 @@ union proc_op { int (*proc_show)(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task); + const char *lsm; }; struct proc_inode { diff --git a/include/linux/security.h b/include/linux/security.h index 3f5fd988ee87..6a31a3dba040 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -375,8 +375,10 @@ int security_sem_semctl(struct sem_array *sma, int cmd); int security_sem_semop(struct sem_array *sma, struct sembuf *sops, unsigned nsops, int alter); void security_d_instantiate(struct dentry *dentry, struct inode *inode); -int security_getprocattr(struct task_struct *p, char *name, char **value); -int security_setprocattr(const char *name, void *value, size_t size); +int security_getprocattr(struct task_struct *p, const char *lsm, char *name, + char **value); +int security_setprocattr(const char *lsm, const char *name, void *value, + size_t size); int security_netlink_send(struct sock *sk, struct sk_buff *skb); int security_ismaclabel(const char *name); int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen); @@ -1128,15 +1130,18 @@ static inline int security_sem_semop(struct sem_array *sma, return 0; } -static inline void security_d_instantiate(struct dentry *dentry, struct inode *inode) +static inline void security_d_instantiate(struct dentry *dentry, + struct inode *inode) { } -static inline int security_getprocattr(struct task_struct *p, char *name, char **value) +static inline int security_getprocattr(struct task_struct *p, const char *lsm, + char *name, char **value) { return -EINVAL; } -static inline int security_setprocattr(char *name, void *value, size_t size) +static inline int security_setprocattr(const char *lsm, char *name, + void *value, size_t size) { return -EINVAL; } diff --git a/security/security.c b/security/security.c index 14c291910d25..459977ed5dec 100644 --- a/security/security.c +++ b/security/security.c @@ -1254,14 +1254,30 @@ void security_d_instantiate(struct dentry *dentry, struct inode *inode) } EXPORT_SYMBOL(security_d_instantiate); -int security_getprocattr(struct task_struct *p, char *name, char **value) +int security_getprocattr(struct task_struct *p, const char *lsm, char *name, + char **value) { - return call_int_hook(getprocattr, -EINVAL, p, name, value); + struct security_hook_list *hp; + + list_for_each_entry(hp, &security_hook_heads.getprocattr, list) { + if (lsm != NULL && strcmp(lsm, hp->lsm)) + continue; + return hp->hook.getprocattr(p, name, value); + } + return -EINVAL; } -int security_setprocattr(const char *name, void *value, size_t size) +int security_setprocattr(const char *lsm, const char *name, void *value, + size_t size) { - return call_int_hook(setprocattr, -EINVAL, name, value, size); + struct security_hook_list *hp; + + list_for_each_entry(hp, &security_hook_heads.setprocattr, list) { + if (lsm != NULL && strcmp(lsm, hp->lsm)) + continue; + return hp->hook.setprocattr(name, value, size); + } + return -EINVAL; } int security_netlink_send(struct sock *sk, struct sk_buff *skb)