diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/Kconfig | 1 | ||||
| -rw-r--r-- | security/Makefile | 2 | ||||
| -rw-r--r-- | security/integrity/ima/ima_appraise.c | 7 | ||||
| -rw-r--r-- | security/integrity/ima/ima_main.c | 25 | ||||
| -rw-r--r-- | security/integrity/integrity.h | 1 | ||||
| -rw-r--r-- | security/loadpin/Kconfig | 10 | ||||
| -rw-r--r-- | security/loadpin/Makefile | 1 | ||||
| -rw-r--r-- | security/loadpin/loadpin.c | 190 | ||||
| -rw-r--r-- | security/security.c | 1 | ||||
| -rw-r--r-- | security/yama/yama_lsm.c | 31 |
10 files changed, 257 insertions, 12 deletions
diff --git a/security/Kconfig b/security/Kconfig index e45237897b43..176758cdfa57 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -122,6 +122,7 @@ source security/selinux/Kconfig source security/smack/Kconfig source security/tomoyo/Kconfig source security/apparmor/Kconfig +source security/loadpin/Kconfig source security/yama/Kconfig source security/integrity/Kconfig diff --git a/security/Makefile b/security/Makefile index c9bfbc84ff50..f2d71cdb8e19 100644 --- a/security/Makefile +++ b/security/Makefile @@ -8,6 +8,7 @@ subdir-$(CONFIG_SECURITY_SMACK) += smack subdir-$(CONFIG_SECURITY_TOMOYO) += tomoyo subdir-$(CONFIG_SECURITY_APPARMOR) += apparmor subdir-$(CONFIG_SECURITY_YAMA) += yama +subdir-$(CONFIG_SECURITY_LOADPIN) += loadpin # always enable default capabilities obj-y += commoncap.o @@ -22,6 +23,7 @@ obj-$(CONFIG_AUDIT) += lsm_audit.o obj-$(CONFIG_SECURITY_TOMOYO) += tomoyo/ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/ obj-$(CONFIG_SECURITY_YAMA) += yama/ +obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/ obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o # Object integrity file lists diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 6b4694aedae8..1bcbc12e03d9 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -275,6 +275,11 @@ out: xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { if (!ima_fix_xattr(dentry, iint)) status = INTEGRITY_PASS; + } else if ((inode->i_size == 0) && + (iint->flags & IMA_NEW_FILE) && + (xattr_value && + xattr_value->type == EVM_IMA_XATTR_DIGSIG)) { + status = INTEGRITY_PASS; } integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, op, cause, rc, 0); @@ -328,7 +333,7 @@ void ima_inode_post_setattr(struct dentry *dentry) if (iint) { iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED | IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK | - IMA_ACTION_FLAGS); + IMA_ACTION_RULE_FLAGS); if (must_appraise) iint->flags |= IMA_APPRAISE; } diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 391f41751021..68b26c340acd 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -246,7 +246,8 @@ static int process_measurement(struct file *file, char *buf, loff_t size, ima_audit_measurement(iint, pathname); out_digsig: - if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG)) + if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) && + !(iint->flags & IMA_NEW_FILE)) rc = -EACCES; kfree(xattr_value); out_free: @@ -316,6 +317,28 @@ int ima_file_check(struct file *file, int mask, int opened) EXPORT_SYMBOL_GPL(ima_file_check); /** + * ima_post_path_mknod - mark as a new inode + * @dentry: newly created dentry + * + * Mark files created via the mknodat syscall as new, so that the + * file data can be written later. + */ +void ima_post_path_mknod(struct dentry *dentry) +{ + struct integrity_iint_cache *iint; + struct inode *inode = dentry->d_inode; + int must_appraise; + + must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK); + if (!must_appraise) + return; + + iint = integrity_inode_get(inode); + if (iint) + iint->flags |= IMA_NEW_FILE; +} + +/** * ima_read_file - pre-measure/appraise hook decision based on policy * @file: pointer to the file to be measured/appraised/audit * @read_id: caller identifier diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index e08935cf343f..90bc57d796ec 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -28,6 +28,7 @@ /* iint cache flags */ #define IMA_ACTION_FLAGS 0xff000000 +#define IMA_ACTION_RULE_FLAGS 0x06000000 #define IMA_DIGSIG 0x01000000 #define IMA_DIGSIG_REQUIRED 0x02000000 #define IMA_PERMIT_DIRECTIO 0x04000000 diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig new file mode 100644 index 000000000000..c668ac4eda65 --- /dev/null +++ b/security/loadpin/Kconfig @@ -0,0 +1,10 @@ +config SECURITY_LOADPIN + bool "Pin load of kernel files (modules, fw, etc) to one filesystem" + depends on SECURITY && BLOCK + help + Any files read through the kernel file reading interface + (kernel modules, firmware, kexec images, security policy) will + be pinned to the first filesystem used for loading. Any files + that come from other filesystems will be rejected. This is best + used on systems without an initrd that have a root filesystem + backed by a read-only device such as dm-verity or a CDROM. diff --git a/security/loadpin/Makefile b/security/loadpin/Makefile new file mode 100644 index 000000000000..c2d77f83037b --- /dev/null +++ b/security/loadpin/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_SECURITY_LOADPIN) += loadpin.o diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c new file mode 100644 index 000000000000..e4debae3c4d6 --- /dev/null +++ b/security/loadpin/loadpin.c @@ -0,0 +1,190 @@ +/* + * Module and Firmware Pinning Security Module + * + * Copyright 2011-2016 Google Inc. + * + * Author: Kees Cook <keescook@chromium.org> + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#define pr_fmt(fmt) "LoadPin: " fmt + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/fs_struct.h> +#include <linux/lsm_hooks.h> +#include <linux/mount.h> +#include <linux/path.h> +#include <linux/sched.h> /* current */ +#include <linux/string_helpers.h> + +static void report_load(const char *origin, struct file *file, char *operation) +{ + char *cmdline, *pathname; + + pathname = kstrdup_quotable_file(file, GFP_KERNEL); + cmdline = kstrdup_quotable_cmdline(current, GFP_KERNEL); + + pr_notice("%s %s obj=%s%s%s pid=%d cmdline=%s%s%s\n", + origin, operation, + (pathname && pathname[0] != '<') ? "\"" : "", + pathname, + (pathname && pathname[0] != '<') ? "\"" : "", + task_pid_nr(current), + cmdline ? "\"" : "", cmdline, cmdline ? "\"" : ""); + + kfree(cmdline); + kfree(pathname); +} + +static int enabled = 1; +static struct super_block *pinned_root; +static DEFINE_SPINLOCK(pinned_root_spinlock); + +#ifdef CONFIG_SYSCTL +static int zero; +static int one = 1; + +static struct ctl_path loadpin_sysctl_path[] = { + { .procname = "kernel", }, + { .procname = "loadpin", }, + { } +}; + +static struct ctl_table loadpin_sysctl_table[] = { + { + .procname = "enabled", + .data = &enabled, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &one, + }, + { } +}; + +/* + * This must be called after early kernel init, since then the rootdev + * is available. + */ +static void check_pinning_enforcement(struct super_block *mnt_sb) +{ + bool ro = false; + + /* + * If load pinning is not enforced via a read-only block + * device, allow sysctl to change modes for testing. + */ + if (mnt_sb->s_bdev) { + ro = bdev_read_only(mnt_sb->s_bdev); + pr_info("dev(%u,%u): %s\n", + MAJOR(mnt_sb->s_bdev->bd_dev), + MINOR(mnt_sb->s_bdev->bd_dev), + ro ? "read-only" : "writable"); + } else + pr_info("mnt_sb lacks block device, treating as: writable\n"); + + if (!ro) { + if (!register_sysctl_paths(loadpin_sysctl_path, + loadpin_sysctl_table)) + pr_notice("sysctl registration failed!\n"); + else + pr_info("load pinning can be disabled.\n"); + } else + pr_info("load pinning engaged.\n"); +} +#else +static void check_pinning_enforcement(struct super_block *mnt_sb) +{ + pr_info("load pinning engaged.\n"); +} +#endif + +static void loadpin_sb_free_security(struct super_block *mnt_sb) +{ + /* + * When unmounting the filesystem we were using for load + * pinning, we acknowledge the superblock release, but make sure + * no other modules or firmware can be loaded. + */ + if (!IS_ERR_OR_NULL(pinned_root) && mnt_sb == pinned_root) { + pinned_root = ERR_PTR(-EIO); + pr_info("umount pinned fs: refusing further loads\n"); + } +} + +static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) +{ + struct super_block *load_root; + const char *origin = kernel_read_file_id_str(id); + + /* This handles the older init_module API that has a NULL file. */ + if (!file) { + if (!enabled) { + report_load(origin, NULL, "old-api-pinning-ignored"); + return 0; + } + + report_load(origin, NULL, "old-api-denied"); + return -EPERM; + } + + load_root = file->f_path.mnt->mnt_sb; + + /* First loaded module/firmware defines the root for all others. */ + spin_lock(&pinned_root_spinlock); + /* + * pinned_root is only NULL at startup. Otherwise, it is either + * a valid reference, or an ERR_PTR. + */ + if (!pinned_root) { + pinned_root = load_root; + /* + * Unlock now since it's only pinned_root we care about. + * In the worst case, we will (correctly) report pinning + * failures before we have announced that pinning is + * enabled. This would be purely cosmetic. + */ + spin_unlock(&pinned_root_spinlock); + check_pinning_enforcement(pinned_root); + report_load(origin, file, "pinned"); + } else { + spin_unlock(&pinned_root_spinlock); + } + + if (IS_ERR_OR_NULL(pinned_root) || load_root != pinned_root) { + if (unlikely(!enabled)) { + report_load(origin, file, "pinning-ignored"); + return 0; + } + + report_load(origin, file, "denied"); + return -EPERM; + } + + return 0; +} + +static struct security_hook_list loadpin_hooks[] = { + LSM_HOOK_INIT(sb_free_security, loadpin_sb_free_security), + LSM_HOOK_INIT(kernel_read_file, loadpin_read_file), +}; + +void __init loadpin_add_hooks(void) +{ + pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis"); + security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks)); +} + +/* Should not be mutable after boot, so not listed in sysfs (perm == 0). */ +module_param(enabled, int, 0); +MODULE_PARM_DESC(enabled, "Pin module/firmware loading (default: true)"); diff --git a/security/security.c b/security/security.c index 554c3fb7d4a5..e42860899f23 100644 --- a/security/security.c +++ b/security/security.c @@ -60,6 +60,7 @@ int __init security_init(void) */ capability_add_hooks(); yama_add_hooks(); + loadpin_add_hooks(); /* * Load all the remaining security modules. diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index cb6ed10816d4..9b756b1f3dc5 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -18,6 +18,7 @@ #include <linux/prctl.h> #include <linux/ratelimit.h> #include <linux/workqueue.h> +#include <linux/string_helpers.h> #define YAMA_SCOPE_DISABLED 0 #define YAMA_SCOPE_RELATIONAL 1 @@ -41,6 +42,22 @@ static DEFINE_SPINLOCK(ptracer_relations_lock); static void yama_relation_cleanup(struct work_struct *work); static DECLARE_WORK(yama_relation_work, yama_relation_cleanup); +static void report_access(const char *access, struct task_struct *target, + struct task_struct *agent) +{ + char *target_cmd, *agent_cmd; + + target_cmd = kstrdup_quotable_cmdline(target, GFP_ATOMIC); + agent_cmd = kstrdup_quotable_cmdline(agent, GFP_ATOMIC); + + pr_notice_ratelimited( + "ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n", + access, target_cmd, target->pid, agent_cmd, agent->pid); + + kfree(agent_cmd); + kfree(target_cmd); +} + /** * yama_relation_cleanup - remove invalid entries from the relation list * @@ -307,11 +324,8 @@ static int yama_ptrace_access_check(struct task_struct *child, } } - if (rc && (mode & PTRACE_MODE_NOAUDIT) == 0) { - printk_ratelimited(KERN_NOTICE - "ptrace of pid %d was attempted by: %s (pid %d)\n", - child->pid, current->comm, current->pid); - } + if (rc && (mode & PTRACE_MODE_NOAUDIT) == 0) + report_access("attach", child, current); return rc; } @@ -337,11 +351,8 @@ int yama_ptrace_traceme(struct task_struct *parent) break; } - if (rc) { - printk_ratelimited(KERN_NOTICE - "ptraceme of pid %d was attempted by: %s (pid %d)\n", - current->pid, parent->comm, parent->pid); - } + if (rc) + report_access("traceme", current, parent); return rc; } |