14 files changed, 97 insertions, 24 deletions

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index e29d4c62a3c8..1aa63335de9e 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -630,10 +630,19 @@
  *	Check permission before getting the ioprio value of @p.
  *	@p contains the task_struct of process.
  *	Return 0 if permission is granted.
+ * @task_prlimit:
+ *	Check permission before getting and/or setting the resource limits of
+ *	another task.
+ *	@cred points to the cred structure for the current task.
+ *	@tcred points to the cred structure for the target task.
+ *	@flags contains the LSM_PRLIMIT_* flag bits indicating whether the
+ *	resource limits are being read, modified, or both.
+ *	Return 0 if permission is granted.
  * @task_setrlimit:
- *	Check permission before setting the resource limits of the current
- *	process for @resource to @new_rlim.  The old resource limit values can
- *	be examined by dereferencing (current->signal->rlim + resource).
+ *	Check permission before setting the resource limits of process @p
+ *	for @resource to @new_rlim.  The old resource limit values can
+ *	be examined by dereferencing (p->signal->rlim + resource).
+ *	@p points to the task_struct for the target task's group leader.
  *	@resource contains the resource whose limit is being set.
  *	@new_rlim contains the new limits for @resource.
  *	Return 0 if permission is granted.
@@ -1494,6 +1503,8 @@ union security_list_options {
 	int (*task_setnice)(struct task_struct *p, int nice);
 	int (*task_setioprio)(struct task_struct *p, int ioprio);
 	int (*task_getioprio)(struct task_struct *p);
+	int (*task_prlimit)(const struct cred *cred, const struct cred *tcred,
+			    unsigned int flags);
 	int (*task_setrlimit)(struct task_struct *p, unsigned int resource,
 				struct rlimit *new_rlim);
 	int (*task_setscheduler)(struct task_struct *p);
@@ -1755,6 +1766,7 @@ struct security_hook_heads {
 	struct list_head task_setnice;
 	struct list_head task_setioprio;
 	struct list_head task_getioprio;
+	struct list_head task_prlimit;
 	struct list_head task_setrlimit;
 	struct list_head task_setscheduler;
 	struct list_head task_getscheduler;
@@ -1908,6 +1920,13 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
 }
 #endif /* CONFIG_SECURITY_SELINUX_DISABLE */
 
+/* Currently required to handle SELinux runtime hook disable. */
+#ifdef CONFIG_SECURITY_WRITABLE_HOOKS
+#define __lsm_ro_after_init
+#else
+#define __lsm_ro_after_init	__ro_after_init
+#endif /* CONFIG_SECURITY_WRITABLE_HOOKS */
+
 extern int __init security_module_enable(const char *module);
 extern void __init capability_add_hooks(void);
 #ifdef CONFIG_SECURITY_YAMA
diff --git a/include/linux/security.h b/include/linux/security.h
index 96899fad7016..97df7bac5b48 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -133,6 +133,10 @@ extern unsigned long dac_mmap_min_addr;
 /* setfsuid or setfsgid, id0 == fsuid or fsgid */
 #define LSM_SETID_FS	8
 
+/* Flags for security_task_prlimit(). */
+#define LSM_PRLIMIT_READ  1
+#define LSM_PRLIMIT_WRITE 2
+
 /* forward declares to avoid warnings */
 struct sched_param;
 struct request_sock;
@@ -324,6 +328,8 @@ void security_task_getsecid(struct task_struct *p, u32 *secid);
 int security_task_setnice(struct task_struct *p, int nice);
 int security_task_setioprio(struct task_struct *p, int ioprio);
 int security_task_getioprio(struct task_struct *p);
+int security_task_prlimit(const struct cred *cred, const struct cred *tcred,
+			  unsigned int flags);
 int security_task_setrlimit(struct task_struct *p, unsigned int resource,
 		struct rlimit *new_rlim);
 int security_task_setscheduler(struct task_struct *p);
@@ -949,6 +955,13 @@ static inline int security_task_getioprio(struct task_struct *p)
 	return 0;
 }
 
+static inline int security_task_prlimit(const struct cred *cred,
+					const struct cred *tcred,
+					unsigned int flags)
+{
+	return 0;
+}
+
 static inline int security_task_setrlimit(struct task_struct *p,
 					  unsigned int resource,
 					  struct rlimit *new_rlim)
diff --git a/kernel/sys.c b/kernel/sys.c
index 7ff6d1b10cec..196c7134bee6 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1432,25 +1432,26 @@ out:
 }
 
 /* rcu lock must be held */
-static int check_prlimit_permission(struct task_struct *task)
+static int check_prlimit_permission(struct task_struct *task,
+				    unsigned int flags)
 {
 	const struct cred *cred = current_cred(), *tcred;
+	bool id_match;
 
 	if (current == task)
 		return 0;
 
 	tcred = __task_cred(task);
-	if (uid_eq(cred->uid, tcred->euid) &&
-	    uid_eq(cred->uid, tcred->suid) &&
-	    uid_eq(cred->uid, tcred->uid)  &&
-	    gid_eq(cred->gid, tcred->egid) &&
-	    gid_eq(cred->gid, tcred->sgid) &&
-	    gid_eq(cred->gid, tcred->gid))
-		return 0;
-	if (ns_capable(tcred->user_ns, CAP_SYS_RESOURCE))
-		return 0;
+	id_match = (uid_eq(cred->uid, tcred->euid) &&
+		    uid_eq(cred->uid, tcred->suid) &&
+		    uid_eq(cred->uid, tcred->uid)  &&
+		    gid_eq(cred->gid, tcred->egid) &&
+		    gid_eq(cred->gid, tcred->sgid) &&
+		    gid_eq(cred->gid, tcred->gid));
+	if (!id_match && !ns_capable(tcred->user_ns, CAP_SYS_RESOURCE))
+		return -EPERM;
 
-	return -EPERM;
+	return security_task_prlimit(cred, tcred, flags);
 }
 
 SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
@@ -1460,12 +1461,17 @@ SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
 	struct rlimit64 old64, new64;
 	struct rlimit old, new;
 	struct task_struct *tsk;
+	unsigned int checkflags = 0;
 	int ret;
 
+	if (old_rlim)
+		checkflags |= LSM_PRLIMIT_READ;
+
 	if (new_rlim) {
 		if (copy_from_user(&new64, new_rlim, sizeof(new64)))
 			return -EFAULT;
 		rlim64_to_rlim(&new64, &new);
+		checkflags |= LSM_PRLIMIT_WRITE;
 	}
 
 	rcu_read_lock();
@@ -1474,7 +1480,7 @@ SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
 		rcu_read_unlock();
 		return -ESRCH;
 	}
-	ret = check_prlimit_permission(tsk);
+	ret = check_prlimit_permission(tsk, checkflags);
 	if (ret) {
 		rcu_read_unlock();
 		return ret;
diff --git a/security/Kconfig b/security/Kconfig
index d5c8cb01b145..4619cee79c3e 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -31,6 +31,11 @@ config SECURITY
 
 	  If you are unsure how to answer this question, answer N.
 
+config SECURITY_WRITABLE_HOOKS
+	depends on SECURITY
+	bool
+	default n
+
 config SECURITYFS
 	bool "Enable the securityfs filesystem"
 	help
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 709eacd23909..e287b691a30e 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -587,7 +587,7 @@ static int apparmor_task_setrlimit(struct task_struct *task,
 	return error;
 }
 
-static struct security_hook_list apparmor_hooks[] = {
+static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(ptrace_access_check, apparmor_ptrace_access_check),
 	LSM_HOOK_INIT(ptrace_traceme, apparmor_ptrace_traceme),
 	LSM_HOOK_INIT(capget, apparmor_capget),
diff --git a/security/commoncap.c b/security/commoncap.c
index 78b37838a2d3..7abebd782d5e 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -1071,7 +1071,7 @@ int cap_mmap_file(struct file *file, unsigned long reqprot,
 
 #ifdef CONFIG_SECURITY
 
-struct security_hook_list capability_hooks[] = {
+struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(capable, cap_capable),
 	LSM_HOOK_INIT(settime, cap_settime),
 	LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index 1d82eae3a5b8..dbe6efde77a0 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -174,7 +174,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
 	return 0;
 }
 
-static struct security_hook_list loadpin_hooks[] = {
+static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_free_security, loadpin_sb_free_security),
 	LSM_HOOK_INIT(kernel_read_file, loadpin_read_file),
 };
diff --git a/security/security.c b/security/security.c
index d0e07f269b2d..d6d18a3721aa 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1036,6 +1036,12 @@ int security_task_getioprio(struct task_struct *p)
 	return call_int_hook(task_getioprio, 0, p);
 }
 
+int security_task_prlimit(const struct cred *cred, const struct cred *tcred,
+			  unsigned int flags)
+{
+	return call_int_hook(task_prlimit, 0, cred, tcred, flags);
+}
+
 int security_task_setrlimit(struct task_struct *p, unsigned int resource,
 		struct rlimit *new_rlim)
 {
@@ -1622,7 +1628,7 @@ int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule,
 }
 #endif /* CONFIG_AUDIT */
 
-struct security_hook_heads security_hook_heads = {
+struct security_hook_heads security_hook_heads __lsm_ro_after_init = {
 	.binder_set_context_mgr =
 		LIST_HEAD_INIT(security_hook_heads.binder_set_context_mgr),
 	.binder_transaction =
@@ -1793,6 +1799,8 @@ struct security_hook_heads security_hook_heads = {
 		LIST_HEAD_INIT(security_hook_heads.task_setioprio),
 	.task_getioprio =
 		LIST_HEAD_INIT(security_hook_heads.task_getioprio),
+	.task_prlimit =
+		LIST_HEAD_INIT(security_hook_heads.task_prlimit),
 	.task_setrlimit =
 		LIST_HEAD_INIT(security_hook_heads.task_setrlimit),
 	.task_setscheduler =
diff --git a/security/selinux/Kconfig b/security/selinux/Kconfig
index ea7e3efbe0f7..8af7a690eb40 100644
--- a/security/selinux/Kconfig
+++ b/security/selinux/Kconfig
@@ -40,6 +40,7 @@ config SECURITY_SELINUX_BOOTPARAM_VALUE
 config SECURITY_SELINUX_DISABLE
 	bool "NSA SELinux runtime disable"
 	depends on SECURITY_SELINUX
+	select SECURITY_WRITABLE_HOOKS
 	default n
 	help
 	  This option enables writing to a selinuxfs node 'disable', which
@@ -50,6 +51,11 @@ config SECURITY_SELINUX_DISABLE
 	  portability across platforms where boot parameters are difficult
 	  to employ.
 
+	  NOTE: selecting this option will disable the '__ro_after_init'
+	  kernel hardening feature for security hooks.   Please consider
+	  using the selinux=0 boot parameter instead of enabling this
+	  option.
+
 	  If you are unsure how to answer this question, answer N.
 
 config SECURITY_SELINUX_DEVELOP
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0c2ac318aa7f..d37a72316e9d 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3920,6 +3920,21 @@ static int selinux_task_getioprio(struct task_struct *p)
 			    PROCESS__GETSCHED, NULL);
 }
 
+int selinux_task_prlimit(const struct cred *cred, const struct cred *tcred,
+			 unsigned int flags)
+{
+	u32 av = 0;
+
+	if (!flags)
+		return 0;
+	if (flags & LSM_PRLIMIT_WRITE)
+		av |= PROCESS__SETRLIMIT;
+	if (flags & LSM_PRLIMIT_READ)
+		av |= PROCESS__GETRLIMIT;
+	return avc_has_perm(cred_sid(cred), cred_sid(tcred),
+			    SECCLASS_PROCESS, av, NULL);
+}
+
 static int selinux_task_setrlimit(struct task_struct *p, unsigned int resource,
 		struct rlimit *new_rlim)
 {
@@ -6108,7 +6123,7 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
 
 #endif
 
-static struct security_hook_list selinux_hooks[] = {
+static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(binder_set_context_mgr, selinux_binder_set_context_mgr),
 	LSM_HOOK_INIT(binder_transaction, selinux_binder_transaction),
 	LSM_HOOK_INIT(binder_transfer_binder, selinux_binder_transfer_binder),
@@ -6206,6 +6221,7 @@ static struct security_hook_list selinux_hooks[] = {
 	LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
 	LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
 	LSM_HOOK_INIT(task_getioprio, selinux_task_getioprio),
+	LSM_HOOK_INIT(task_prlimit, selinux_task_prlimit),
 	LSM_HOOK_INIT(task_setrlimit, selinux_task_setrlimit),
 	LSM_HOOK_INIT(task_setscheduler, selinux_task_setscheduler),
 	LSM_HOOK_INIT(task_getscheduler, selinux_task_getscheduler),
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index d429c4a1c551..1e0cc9b5de20 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -47,7 +47,7 @@ struct security_class_mapping secclass_map[] = {
 	    "getattr", "setexec", "setfscreate", "noatsecure", "siginh",
 	    "setrlimit", "rlimitinh", "dyntransition", "setcurrent",
 	    "execmem", "execstack", "execheap", "setkeycreate",
-	    "setsockcreate", NULL } },
+	    "setsockcreate", "getrlimit", 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 fc8fb31fc24f..927e60e622d1 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4633,7 +4633,7 @@ static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
 	return 0;
 }
 
-static struct security_hook_list smack_hooks[] = {
+static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(ptrace_access_check, smack_ptrace_access_check),
 	LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme),
 	LSM_HOOK_INIT(syslog, smack_syslog),
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index edc52d620f29..b5fb930349a9 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -496,7 +496,7 @@ static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
  * tomoyo_security_ops is a "struct security_operations" which is used for
  * registering TOMOYO.
  */
-static struct security_hook_list tomoyo_hooks[] = {
+static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(cred_alloc_blank, tomoyo_cred_alloc_blank),
 	LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
 	LSM_HOOK_INIT(cred_transfer, tomoyo_cred_transfer),
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 88271a3bf37f..8298e094f4f7 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -428,7 +428,7 @@ int yama_ptrace_traceme(struct task_struct *parent)
 	return rc;
 }
 
-static struct security_hook_list yama_hooks[] = {
+static struct security_hook_list yama_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(ptrace_access_check, yama_ptrace_access_check),
 	LSM_HOOK_INIT(ptrace_traceme, yama_ptrace_traceme),
 	LSM_HOOK_INIT(task_prctl, yama_task_prctl),