LSM: Add all of the new security/* files for basic task control

This includes the security_* functions, and the default and capability
modules.

1 files changed, 471 insertions, 0 deletions

diff --git a/security/capability.c b/security/capability.c
new file mode 100644
index 000000000000..d5b7c5c066c4
--- /dev/null
+++ b/security/capability.c
@@ -0,0 +1,471 @@
+/*
+ *  Capabilities Linux Security Module
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License as published by
+ *	the Free Software Foundation; either version 2 of the License, or
+ *	(at your option) any later version.
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/security.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/smp_lock.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+
+/* flag to keep track of how we were registered */
+static int secondary;
+
+static int cap_capable (struct task_struct *tsk, int cap)
+{
+	/* Derived from include/linux/sched.h:capable. */
+	if (cap_raised (tsk->cap_effective, cap))
+		return 0;
+	else
+		return -EPERM;
+}
+
+static int cap_sys_security (unsigned int id, unsigned int call,
+			     unsigned long *args)
+{
+	return -ENOSYS;
+}
+
+static int cap_ptrace (struct task_struct *parent, struct task_struct *child)
+{
+	/* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
+	if (!cap_issubset (child->cap_permitted, current->cap_permitted) &&
+	    !capable (CAP_SYS_PTRACE))
+		return -EPERM;
+	else
+		return 0;
+}
+
+static int cap_capget (struct task_struct *target, kernel_cap_t * effective,
+		       kernel_cap_t * inheritable, kernel_cap_t * permitted)
+{
+	/* Derived from kernel/capability.c:sys_capget. */
+	*effective = cap_t (target->cap_effective);
+	*inheritable = cap_t (target->cap_inheritable);
+	*permitted = cap_t (target->cap_permitted);
+	return 0;
+}
+
+static int cap_capset_check (struct task_struct *target,
+			     kernel_cap_t * effective,
+			     kernel_cap_t * inheritable,
+			     kernel_cap_t * permitted)
+{
+	/* Derived from kernel/capability.c:sys_capset. */
+	/* verify restrictions on target's new Inheritable set */
+	if (!cap_issubset (*inheritable,
+			   cap_combine (target->cap_inheritable,
+					current->cap_permitted))) {
+		return -EPERM;
+	}
+
+	/* verify restrictions on target's new Permitted set */
+	if (!cap_issubset (*permitted,
+			   cap_combine (target->cap_permitted,
+					current->cap_permitted))) {
+		return -EPERM;
+	}
+
+	/* verify the _new_Effective_ is a subset of the _new_Permitted_ */
+	if (!cap_issubset (*effective, *permitted)) {
+		return -EPERM;
+	}
+
+	return 0;
+}
+
+static void cap_capset_set (struct task_struct *target,
+			    kernel_cap_t * effective,
+			    kernel_cap_t * inheritable,
+			    kernel_cap_t * permitted)
+{
+	target->cap_effective = *effective;
+	target->cap_inheritable = *inheritable;
+	target->cap_permitted = *permitted;
+}
+
+static int cap_bprm_alloc_security (struct linux_binprm *bprm)
+{
+	return 0;
+}
+
+static int cap_bprm_set_security (struct linux_binprm *bprm)
+{
+	/* Copied from fs/exec.c:prepare_binprm. */
+
+	/* We don't have VFS support for capabilities yet */
+	cap_clear (bprm->cap_inheritable);
+	cap_clear (bprm->cap_permitted);
+	cap_clear (bprm->cap_effective);
+
+	/*  To support inheritance of root-permissions and suid-root
+	 *  executables under compatibility mode, we raise all three
+	 *  capability sets for the file.
+	 *
+	 *  If only the real uid is 0, we only raise the inheritable
+	 *  and permitted sets of the executable file.
+	 */
+
+	if (!issecure (SECURE_NOROOT)) {
+		if (bprm->e_uid == 0 || current->uid == 0) {
+			cap_set_full (bprm->cap_inheritable);
+			cap_set_full (bprm->cap_permitted);
+		}
+		if (bprm->e_uid == 0)
+			cap_set_full (bprm->cap_effective);
+	}
+	return 0;
+}
+
+static int cap_bprm_check_security (struct linux_binprm *bprm)
+{
+	return 0;
+}
+
+static void cap_bprm_free_security (struct linux_binprm *bprm)
+{
+	return;
+}
+
+/* Copied from fs/exec.c */
+static inline int must_not_trace_exec (struct task_struct *p)
+{
+	return (p->ptrace & PT_PTRACED) && !(p->ptrace & PT_PTRACE_CAP);
+}
+
+static void cap_bprm_compute_creds (struct linux_binprm *bprm)
+{
+	/* Derived from fs/exec.c:compute_creds. */
+	kernel_cap_t new_permitted, working;
+	int do_unlock = 0;
+
+	new_permitted = cap_intersect (bprm->cap_permitted, cap_bset);
+	working = cap_intersect (bprm->cap_inheritable,
+				 current->cap_inheritable);
+	new_permitted = cap_combine (new_permitted, working);
+
+	if (!cap_issubset (new_permitted, current->cap_permitted)) {
+		current->mm->dumpable = 0;
+
+		lock_kernel ();
+		if (must_not_trace_exec (current)
+		    || atomic_read (&current->fs->count) > 1
+		    || atomic_read (&current->files->count) > 1
+		    || atomic_read (&current->sig->count) > 1) {
+			if (!capable (CAP_SETPCAP)) {
+				new_permitted = cap_intersect (new_permitted,
+							       current->
+							       cap_permitted);
+			}
+		}
+		do_unlock = 1;
+	}
+
+	/* For init, we want to retain the capabilities set
+	 * in the init_task struct. Thus we skip the usual
+	 * capability rules */
+	if (current->pid != 1) {
+		current->cap_permitted = new_permitted;
+		current->cap_effective =
+		    cap_intersect (new_permitted, bprm->cap_effective);
+	}
+
+	/* AUD: Audit candidate if current->cap_effective is set */
+
+	if (do_unlock)
+		unlock_kernel ();
+
+	current->keep_capabilities = 0;
+}
+
+static int cap_task_create (unsigned long clone_flags)
+{
+	return 0;
+}
+
+static int cap_task_alloc_security (struct task_struct *p)
+{
+	return 0;
+}
+
+static void cap_task_free_security (struct task_struct *p)
+{
+	return;
+}
+
+static int cap_task_setuid (uid_t id0, uid_t id1, uid_t id2, int flags)
+{
+	return 0;
+}
+
+/* moved from kernel/sys.c. */
+/* 
+ * cap_emulate_setxuid() fixes the effective / permitted capabilities of
+ * a process after a call to setuid, setreuid, or setresuid.
+ *
+ *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
+ *  {r,e,s}uid != 0, the permitted and effective capabilities are
+ *  cleared.
+ *
+ *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
+ *  capabilities of the process are cleared.
+ *
+ *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
+ *  capabilities are set to the permitted capabilities.
+ *
+ *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should 
+ *  never happen.
+ *
+ *  -astor 
+ *
+ * cevans - New behaviour, Oct '99
+ * A process may, via prctl(), elect to keep its capabilities when it
+ * calls setuid() and switches away from uid==0. Both permitted and
+ * effective sets will be retained.
+ * Without this change, it was impossible for a daemon to drop only some
+ * of its privilege. The call to setuid(!=0) would drop all privileges!
+ * Keeping uid 0 is not an option because uid 0 owns too many vital
+ * files..
+ * Thanks to Olaf Kirch and Peter Benie for spotting this.
+ */
+static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
+					int old_suid)
+{
+	if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
+	    (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
+	    !current->keep_capabilities) {
+		cap_clear (current->cap_permitted);
+		cap_clear (current->cap_effective);
+	}
+	if (old_euid == 0 && current->euid != 0) {
+		cap_clear (current->cap_effective);
+	}
+	if (old_euid != 0 && current->euid == 0) {
+		current->cap_effective = current->cap_permitted;
+	}
+}
+
+static int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
+				 int flags)
+{
+	switch (flags) {
+	case LSM_SETID_RE:
+	case LSM_SETID_ID:
+	case LSM_SETID_RES:
+		/* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
+		if (!issecure (SECURE_NO_SETUID_FIXUP)) {
+			cap_emulate_setxuid (old_ruid, old_euid, old_suid);
+		}
+		break;
+	case LSM_SETID_FS:
+		{
+			uid_t old_fsuid = old_ruid;
+
+			/* Copied from kernel/sys.c:setfsuid. */
+
+			/*
+			 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
+			 *          if not, we might be a bit too harsh here.
+			 */
+
+			if (!issecure (SECURE_NO_SETUID_FIXUP)) {
+				if (old_fsuid == 0 && current->fsuid != 0) {
+					cap_t (current->cap_effective) &=
+					    ~CAP_FS_MASK;
+				}
+				if (old_fsuid != 0 && current->fsuid == 0) {
+					cap_t (current->cap_effective) |=
+					    (cap_t (current->cap_permitted) &
+					     CAP_FS_MASK);
+				}
+			}
+			break;
+		}
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int cap_task_setgid (gid_t id0, gid_t id1, gid_t id2, int flags)
+{
+	return 0;
+}
+
+static int cap_task_setpgid (struct task_struct *p, pid_t pgid)
+{
+	return 0;
+}
+
+static int cap_task_getpgid (struct task_struct *p)
+{
+	return 0;
+}
+
+static int cap_task_getsid (struct task_struct *p)
+{
+	return 0;
+}
+
+static int cap_task_setgroups (int gidsetsize, gid_t * grouplist)
+{
+	return 0;
+}
+
+static int cap_task_setnice (struct task_struct *p, int nice)
+{
+	return 0;
+}
+
+static int cap_task_setrlimit (unsigned int resource, struct rlimit *new_rlim)
+{
+	return 0;
+}
+
+static int cap_task_setscheduler (struct task_struct *p, int policy,
+				  struct sched_param *lp)
+{
+	return 0;
+}
+
+static int cap_task_getscheduler (struct task_struct *p)
+{
+	return 0;
+}
+
+static int cap_task_wait (struct task_struct *p)
+{
+	return 0;
+}
+
+static int cap_task_kill (struct task_struct *p, struct siginfo *info, int sig)
+{
+	return 0;
+}
+
+static int cap_task_prctl (int option, unsigned long arg2, unsigned long arg3,
+			   unsigned long arg4, unsigned long arg5)
+{
+	return 0;
+}
+
+static void cap_task_kmod_set_label (void)
+{
+	cap_set_full (current->cap_effective);
+	return;
+}
+
+static void cap_task_reparent_to_init (struct task_struct *p)
+{
+	p->cap_effective = CAP_INIT_EFF_SET;
+	p->cap_inheritable = CAP_INIT_INH_SET;
+	p->cap_permitted = CAP_FULL_SET;
+	p->keep_capabilities = 0;
+	return;
+}
+
+static int cap_register (const char *name, struct security_operations *ops)
+{
+	return -EINVAL;
+}
+
+static int cap_unregister (const char *name, struct security_operations *ops)
+{
+	return -EINVAL;
+}
+
+static struct security_operations capability_ops = {
+	ptrace:				cap_ptrace,
+	capget:				cap_capget,
+	capset_check:			cap_capset_check,
+	capset_set:			cap_capset_set,
+	capable:			cap_capable,
+	sys_security:			cap_sys_security,
+	
+	bprm_alloc_security:		cap_bprm_alloc_security,
+	bprm_free_security:		cap_bprm_free_security,
+	bprm_compute_creds:		cap_bprm_compute_creds,
+	bprm_set_security:		cap_bprm_set_security,
+	bprm_check_security:		cap_bprm_check_security,
+	
+	task_create:			cap_task_create,
+	task_alloc_security:		cap_task_alloc_security,
+	task_free_security:		cap_task_free_security,
+	task_setuid:			cap_task_setuid,
+	task_post_setuid:		cap_task_post_setuid,
+	task_setgid:			cap_task_setgid,
+	task_setpgid:			cap_task_setpgid,
+	task_getpgid:			cap_task_getpgid,
+	task_getsid:			cap_task_getsid,
+	task_setgroups:			cap_task_setgroups,
+	task_setnice:			cap_task_setnice,
+	task_setrlimit:			cap_task_setrlimit,
+	task_setscheduler:		cap_task_setscheduler,
+	task_getscheduler:		cap_task_getscheduler,
+	task_wait:			cap_task_wait,
+	task_kill:			cap_task_kill,
+	task_prctl:			cap_task_prctl,
+	task_kmod_set_label:		cap_task_kmod_set_label,
+	task_reparent_to_init:		cap_task_reparent_to_init,
+	
+	register_security:		cap_register,
+	unregister_security:		cap_unregister,
+};
+
+#if defined(CONFIG_SECURITY_CAPABILITIES_MODULE)
+#define MY_NAME THIS_MODULE->name
+#else
+#define MY_NAME "capability"
+#endif
+
+static int __init capability_init (void)
+{
+	/* register ourselves with the security framework */
+	if (register_security (&capability_ops)) {
+		printk (KERN_INFO
+			"Failure registering capabilities with the kernel\n");
+		/* try registering with primary module */
+		if (mod_reg_security (MY_NAME, &capability_ops)) {
+			printk (KERN_INFO "Failure registering capabilities "
+				"with primary security module.\n");
+			return -EINVAL;
+		}
+		secondary = 1;
+	}
+	printk (KERN_INFO "Capability LSM initialized\n");
+	return 0;
+}
+
+static void __exit capability_exit (void)
+{
+	/* remove ourselves from the security framework */
+	if (secondary) {
+		if (mod_unreg_security (MY_NAME, &capability_ops))
+			printk (KERN_INFO "Failure unregistering capabilities "
+				"with primary module.\n");
+		return;
+	}
+
+	if (unregister_security (&capability_ops)) {
+		printk (KERN_INFO
+			"Failure unregistering capabilities with the kernel\n");
+	}
+}
+
+module_init (capability_init);
+module_exit (capability_exit);
+
+MODULE_DESCRIPTION("Standard Linux Capabilities Security Module");
+MODULE_LICENSE("GPL");