Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 983 insertions, 0 deletions

diff --git a/kernel/security/commoncap.c b/kernel/security/commoncap.c
new file mode 100644
index 000000000..f2875cd9f
--- /dev/null
+++ b/kernel/security/commoncap.c
@@ -0,0 +1,983 @@
+/* Common capabilities, needed by capability.o.
+ *
+ *	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/capability.h>
+#include <linux/audit.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/mman.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+#include <linux/ptrace.h>
+#include <linux/xattr.h>
+#include <linux/hugetlb.h>
+#include <linux/mount.h>
+#include <linux/sched.h>
+#include <linux/prctl.h>
+#include <linux/securebits.h>
+#include <linux/user_namespace.h>
+#include <linux/binfmts.h>
+#include <linux/personality.h>
+
+/*
+ * If a non-root user executes a setuid-root binary in
+ * !secure(SECURE_NOROOT) mode, then we raise capabilities.
+ * However if fE is also set, then the intent is for only
+ * the file capabilities to be applied, and the setuid-root
+ * bit is left on either to change the uid (plausible) or
+ * to get full privilege on a kernel without file capabilities
+ * support.  So in that case we do not raise capabilities.
+ *
+ * Warn if that happens, once per boot.
+ */
+static void warn_setuid_and_fcaps_mixed(const char *fname)
+{
+	static int warned;
+	if (!warned) {
+		printk(KERN_INFO "warning: `%s' has both setuid-root and"
+			" effective capabilities. Therefore not raising all"
+			" capabilities.\n", fname);
+		warned = 1;
+	}
+}
+
+int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
+{
+	return 0;
+}
+
+/**
+ * cap_capable - Determine whether a task has a particular effective capability
+ * @cred: The credentials to use
+ * @ns:  The user namespace in which we need the capability
+ * @cap: The capability to check for
+ * @audit: Whether to write an audit message or not
+ *
+ * Determine whether the nominated task has the specified capability amongst
+ * its effective set, returning 0 if it does, -ve if it does not.
+ *
+ * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
+ * and has_capability() functions.  That is, it has the reverse semantics:
+ * cap_has_capability() returns 0 when a task has a capability, but the
+ * kernel's capable() and has_capability() returns 1 for this case.
+ */
+int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
+		int cap, int audit)
+{
+	struct user_namespace *ns = targ_ns;
+
+	/* See if cred has the capability in the target user namespace
+	 * by examining the target user namespace and all of the target
+	 * user namespace's parents.
+	 */
+	for (;;) {
+		/* Do we have the necessary capabilities? */
+		if (ns == cred->user_ns)
+			return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+
+		/* Have we tried all of the parent namespaces? */
+		if (ns == &init_user_ns)
+			return -EPERM;
+
+		/* 
+		 * The owner of the user namespace in the parent of the
+		 * user namespace has all caps.
+		 */
+		if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
+			return 0;
+
+		/*
+		 * If you have a capability in a parent user ns, then you have
+		 * it over all children user namespaces as well.
+		 */
+		ns = ns->parent;
+	}
+
+	/* We never get here */
+}
+
+/**
+ * cap_settime - Determine whether the current process may set the system clock
+ * @ts: The time to set
+ * @tz: The timezone to set
+ *
+ * Determine whether the current process may set the system clock and timezone
+ * information, returning 0 if permission granted, -ve if denied.
+ */
+int cap_settime(const struct timespec *ts, const struct timezone *tz)
+{
+	if (!capable(CAP_SYS_TIME))
+		return -EPERM;
+	return 0;
+}
+
+/**
+ * cap_ptrace_access_check - Determine whether the current process may access
+ *			   another
+ * @child: The process to be accessed
+ * @mode: The mode of attachment.
+ *
+ * If we are in the same or an ancestor user_ns and have all the target
+ * task's capabilities, then ptrace access is allowed.
+ * If we have the ptrace capability to the target user_ns, then ptrace
+ * access is allowed.
+ * Else denied.
+ *
+ * Determine whether a process may access another, returning 0 if permission
+ * granted, -ve if denied.
+ */
+int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
+{
+	int ret = 0;
+	const struct cred *cred, *child_cred;
+
+	rcu_read_lock();
+	cred = current_cred();
+	child_cred = __task_cred(child);
+	if (cred->user_ns == child_cred->user_ns &&
+	    cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
+		goto out;
+	if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
+		goto out;
+	ret = -EPERM;
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+/**
+ * cap_ptrace_traceme - Determine whether another process may trace the current
+ * @parent: The task proposed to be the tracer
+ *
+ * If parent is in the same or an ancestor user_ns and has all current's
+ * capabilities, then ptrace access is allowed.
+ * If parent has the ptrace capability to current's user_ns, then ptrace
+ * access is allowed.
+ * Else denied.
+ *
+ * Determine whether the nominated task is permitted to trace the current
+ * process, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_ptrace_traceme(struct task_struct *parent)
+{
+	int ret = 0;
+	const struct cred *cred, *child_cred;
+
+	rcu_read_lock();
+	cred = __task_cred(parent);
+	child_cred = current_cred();
+	if (cred->user_ns == child_cred->user_ns &&
+	    cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
+		goto out;
+	if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
+		goto out;
+	ret = -EPERM;
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+/**
+ * cap_capget - Retrieve a task's capability sets
+ * @target: The task from which to retrieve the capability sets
+ * @effective: The place to record the effective set
+ * @inheritable: The place to record the inheritable set
+ * @permitted: The place to record the permitted set
+ *
+ * This function retrieves the capabilities of the nominated task and returns
+ * them to the caller.
+ */
+int cap_capget(struct task_struct *target, kernel_cap_t *effective,
+	       kernel_cap_t *inheritable, kernel_cap_t *permitted)
+{
+	const struct cred *cred;
+
+	/* Derived from kernel/capability.c:sys_capget. */
+	rcu_read_lock();
+	cred = __task_cred(target);
+	*effective   = cred->cap_effective;
+	*inheritable = cred->cap_inheritable;
+	*permitted   = cred->cap_permitted;
+	rcu_read_unlock();
+	return 0;
+}
+
+/*
+ * Determine whether the inheritable capabilities are limited to the old
+ * permitted set.  Returns 1 if they are limited, 0 if they are not.
+ */
+static inline int cap_inh_is_capped(void)
+{
+
+	/* they are so limited unless the current task has the CAP_SETPCAP
+	 * capability
+	 */
+	if (cap_capable(current_cred(), current_cred()->user_ns,
+			CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
+		return 0;
+	return 1;
+}
+
+/**
+ * cap_capset - Validate and apply proposed changes to current's capabilities
+ * @new: The proposed new credentials; alterations should be made here
+ * @old: The current task's current credentials
+ * @effective: A pointer to the proposed new effective capabilities set
+ * @inheritable: A pointer to the proposed new inheritable capabilities set
+ * @permitted: A pointer to the proposed new permitted capabilities set
+ *
+ * This function validates and applies a proposed mass change to the current
+ * process's capability sets.  The changes are made to the proposed new
+ * credentials, and assuming no error, will be committed by the caller of LSM.
+ */
+int cap_capset(struct cred *new,
+	       const struct cred *old,
+	       const kernel_cap_t *effective,
+	       const kernel_cap_t *inheritable,
+	       const kernel_cap_t *permitted)
+{
+	if (cap_inh_is_capped() &&
+	    !cap_issubset(*inheritable,
+			  cap_combine(old->cap_inheritable,
+				      old->cap_permitted)))
+		/* incapable of using this inheritable set */
+		return -EPERM;
+
+	if (!cap_issubset(*inheritable,
+			  cap_combine(old->cap_inheritable,
+				      old->cap_bset)))
+		/* no new pI capabilities outside bounding set */
+		return -EPERM;
+
+	/* verify restrictions on target's new Permitted set */
+	if (!cap_issubset(*permitted, old->cap_permitted))
+		return -EPERM;
+
+	/* verify the _new_Effective_ is a subset of the _new_Permitted_ */
+	if (!cap_issubset(*effective, *permitted))
+		return -EPERM;
+
+	new->cap_effective   = *effective;
+	new->cap_inheritable = *inheritable;
+	new->cap_permitted   = *permitted;
+	return 0;
+}
+
+/*
+ * Clear proposed capability sets for execve().
+ */
+static inline void bprm_clear_caps(struct linux_binprm *bprm)
+{
+	cap_clear(bprm->cred->cap_permitted);
+	bprm->cap_effective = false;
+}
+
+/**
+ * cap_inode_need_killpriv - Determine if inode change affects privileges
+ * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
+ *
+ * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
+ * affects the security markings on that inode, and if it is, should
+ * inode_killpriv() be invoked or the change rejected?
+ *
+ * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
+ * -ve to deny the change.
+ */
+int cap_inode_need_killpriv(struct dentry *dentry)
+{
+	struct inode *inode = d_backing_inode(dentry);
+	int error;
+
+	if (!inode->i_op->getxattr)
+	       return 0;
+
+	error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
+	if (error <= 0)
+		return 0;
+	return 1;
+}
+
+/**
+ * cap_inode_killpriv - Erase the security markings on an inode
+ * @dentry: The inode/dentry to alter
+ *
+ * Erase the privilege-enhancing security markings on an inode.
+ *
+ * Returns 0 if successful, -ve on error.
+ */
+int cap_inode_killpriv(struct dentry *dentry)
+{
+	struct inode *inode = d_backing_inode(dentry);
+
+	if (!inode->i_op->removexattr)
+	       return 0;
+
+	return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
+}
+
+/*
+ * Calculate the new process capability sets from the capability sets attached
+ * to a file.
+ */
+static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
+					  struct linux_binprm *bprm,
+					  bool *effective,
+					  bool *has_cap)
+{
+	struct cred *new = bprm->cred;
+	unsigned i;
+	int ret = 0;
+
+	if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
+		*effective = true;
+
+	if (caps->magic_etc & VFS_CAP_REVISION_MASK)
+		*has_cap = true;
+
+	CAP_FOR_EACH_U32(i) {
+		__u32 permitted = caps->permitted.cap[i];
+		__u32 inheritable = caps->inheritable.cap[i];
+
+		/*
+		 * pP' = (X & fP) | (pI & fI)
+		 */
+		new->cap_permitted.cap[i] =
+			(new->cap_bset.cap[i] & permitted) |
+			(new->cap_inheritable.cap[i] & inheritable);
+
+		if (permitted & ~new->cap_permitted.cap[i])
+			/* insufficient to execute correctly */
+			ret = -EPERM;
+	}
+
+	/*
+	 * For legacy apps, with no internal support for recognizing they
+	 * do not have enough capabilities, we return an error if they are
+	 * missing some "forced" (aka file-permitted) capabilities.
+	 */
+	return *effective ? ret : 0;
+}
+
+/*
+ * Extract the on-exec-apply capability sets for an executable file.
+ */
+int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
+{
+	struct inode *inode = d_backing_inode(dentry);
+	__u32 magic_etc;
+	unsigned tocopy, i;
+	int size;
+	struct vfs_cap_data caps;
+
+	memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
+
+	if (!inode || !inode->i_op->getxattr)
+		return -ENODATA;
+
+	size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
+				   XATTR_CAPS_SZ);
+	if (size == -ENODATA || size == -EOPNOTSUPP)
+		/* no data, that's ok */
+		return -ENODATA;
+	if (size < 0)
+		return size;
+
+	if (size < sizeof(magic_etc))
+		return -EINVAL;
+
+	cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
+
+	switch (magic_etc & VFS_CAP_REVISION_MASK) {
+	case VFS_CAP_REVISION_1:
+		if (size != XATTR_CAPS_SZ_1)
+			return -EINVAL;
+		tocopy = VFS_CAP_U32_1;
+		break;
+	case VFS_CAP_REVISION_2:
+		if (size != XATTR_CAPS_SZ_2)
+			return -EINVAL;
+		tocopy = VFS_CAP_U32_2;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	CAP_FOR_EACH_U32(i) {
+		if (i >= tocopy)
+			break;
+		cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
+		cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
+	}
+
+	cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
+	cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
+
+	return 0;
+}
+
+/*
+ * Attempt to get the on-exec apply capability sets for an executable file from
+ * its xattrs and, if present, apply them to the proposed credentials being
+ * constructed by execve().
+ */
+static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap)
+{
+	int rc = 0;
+	struct cpu_vfs_cap_data vcaps;
+
+	bprm_clear_caps(bprm);
+
+	if (!file_caps_enabled)
+		return 0;
+
+	if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
+		return 0;
+
+	rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
+	if (rc < 0) {
+		if (rc == -EINVAL)
+			printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
+				__func__, rc, bprm->filename);
+		else if (rc == -ENODATA)
+			rc = 0;
+		goto out;
+	}
+
+	rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap);
+	if (rc == -EINVAL)
+		printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
+		       __func__, rc, bprm->filename);
+
+out:
+	if (rc)
+		bprm_clear_caps(bprm);
+
+	return rc;
+}
+
+/**
+ * cap_bprm_set_creds - Set up the proposed credentials for execve().
+ * @bprm: The execution parameters, including the proposed creds
+ *
+ * Set up the proposed credentials for a new execution context being
+ * constructed by execve().  The proposed creds in @bprm->cred is altered,
+ * which won't take effect immediately.  Returns 0 if successful, -ve on error.
+ */
+int cap_bprm_set_creds(struct linux_binprm *bprm)
+{
+	const struct cred *old = current_cred();
+	struct cred *new = bprm->cred;
+	bool effective, has_cap = false;
+	int ret;
+	kuid_t root_uid;
+
+	effective = false;
+	ret = get_file_caps(bprm, &effective, &has_cap);
+	if (ret < 0)
+		return ret;
+
+	root_uid = make_kuid(new->user_ns, 0);
+
+	if (!issecure(SECURE_NOROOT)) {
+		/*
+		 * If the legacy file capability is set, then don't set privs
+		 * for a setuid root binary run by a non-root user.  Do set it
+		 * for a root user just to cause least surprise to an admin.
+		 */
+		if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) {
+			warn_setuid_and_fcaps_mixed(bprm->filename);
+			goto skip;
+		}
+		/*
+		 * To support inheritance of root-permissions and suid-root
+		 * executables under compatibility mode, we override the
+		 * capability sets for the file.
+		 *
+		 * If only the real uid is 0, we do not set the effective bit.
+		 */
+		if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) {
+			/* pP' = (cap_bset & ~0) | (pI & ~0) */
+			new->cap_permitted = cap_combine(old->cap_bset,
+							 old->cap_inheritable);
+		}
+		if (uid_eq(new->euid, root_uid))
+			effective = true;
+	}
+skip:
+
+	/* if we have fs caps, clear dangerous personality flags */
+	if (!cap_issubset(new->cap_permitted, old->cap_permitted))
+		bprm->per_clear |= PER_CLEAR_ON_SETID;
+
+
+	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
+	 * credentials unless they have the appropriate permit.
+	 *
+	 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
+	 */
+	if ((!uid_eq(new->euid, old->uid) ||
+	     !gid_eq(new->egid, old->gid) ||
+	     !cap_issubset(new->cap_permitted, old->cap_permitted)) &&
+	    bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
+		/* downgrade; they get no more than they had, and maybe less */
+		if (!capable(CAP_SETUID) ||
+		    (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
+			new->euid = new->uid;
+			new->egid = new->gid;
+		}
+		new->cap_permitted = cap_intersect(new->cap_permitted,
+						   old->cap_permitted);
+	}
+
+	new->suid = new->fsuid = new->euid;
+	new->sgid = new->fsgid = new->egid;
+
+	if (effective)
+		new->cap_effective = new->cap_permitted;
+	else
+		cap_clear(new->cap_effective);
+	bprm->cap_effective = effective;
+
+	/*
+	 * Audit candidate if current->cap_effective is set
+	 *
+	 * We do not bother to audit if 3 things are true:
+	 *   1) cap_effective has all caps
+	 *   2) we are root
+	 *   3) root is supposed to have all caps (SECURE_NOROOT)
+	 * Since this is just a normal root execing a process.
+	 *
+	 * Number 1 above might fail if you don't have a full bset, but I think
+	 * that is interesting information to audit.
+	 */
+	if (!cap_isclear(new->cap_effective)) {
+		if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
+		    !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
+		    issecure(SECURE_NOROOT)) {
+			ret = audit_log_bprm_fcaps(bprm, new, old);
+			if (ret < 0)
+				return ret;
+		}
+	}
+
+	new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
+	return 0;
+}
+
+/**
+ * cap_bprm_secureexec - Determine whether a secure execution is required
+ * @bprm: The execution parameters
+ *
+ * Determine whether a secure execution is required, return 1 if it is, and 0
+ * if it is not.
+ *
+ * The credentials have been committed by this point, and so are no longer
+ * available through @bprm->cred.
+ */
+int cap_bprm_secureexec(struct linux_binprm *bprm)
+{
+	const struct cred *cred = current_cred();
+	kuid_t root_uid = make_kuid(cred->user_ns, 0);
+
+	if (!uid_eq(cred->uid, root_uid)) {
+		if (bprm->cap_effective)
+			return 1;
+		if (!cap_isclear(cred->cap_permitted))
+			return 1;
+	}
+
+	return (!uid_eq(cred->euid, cred->uid) ||
+		!gid_eq(cred->egid, cred->gid));
+}
+
+/**
+ * cap_inode_setxattr - Determine whether an xattr may be altered
+ * @dentry: The inode/dentry being altered
+ * @name: The name of the xattr to be changed
+ * @value: The value that the xattr will be changed to
+ * @size: The size of value
+ * @flags: The replacement flag
+ *
+ * Determine whether an xattr may be altered or set on an inode, returning 0 if
+ * permission is granted, -ve if denied.
+ *
+ * This is used to make sure security xattrs don't get updated or set by those
+ * who aren't privileged to do so.
+ */
+int cap_inode_setxattr(struct dentry *dentry, const char *name,
+		       const void *value, size_t size, int flags)
+{
+	if (!strcmp(name, XATTR_NAME_CAPS)) {
+		if (!capable(CAP_SETFCAP))
+			return -EPERM;
+		return 0;
+	}
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX,
+		     sizeof(XATTR_SECURITY_PREFIX) - 1) &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	return 0;
+}
+
+/**
+ * cap_inode_removexattr - Determine whether an xattr may be removed
+ * @dentry: The inode/dentry being altered
+ * @name: The name of the xattr to be changed
+ *
+ * Determine whether an xattr may be removed from an inode, returning 0 if
+ * permission is granted, -ve if denied.
+ *
+ * This is used to make sure security xattrs don't get removed by those who
+ * aren't privileged to remove them.
+ */
+int cap_inode_removexattr(struct dentry *dentry, const char *name)
+{
+	if (!strcmp(name, XATTR_NAME_CAPS)) {
+		if (!capable(CAP_SETFCAP))
+			return -EPERM;
+		return 0;
+	}
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX,
+		     sizeof(XATTR_SECURITY_PREFIX) - 1) &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	return 0;
+}
+
+/*
+ * 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(struct cred *new, const struct cred *old)
+{
+	kuid_t root_uid = make_kuid(old->user_ns, 0);
+
+	if ((uid_eq(old->uid, root_uid) ||
+	     uid_eq(old->euid, root_uid) ||
+	     uid_eq(old->suid, root_uid)) &&
+	    (!uid_eq(new->uid, root_uid) &&
+	     !uid_eq(new->euid, root_uid) &&
+	     !uid_eq(new->suid, root_uid)) &&
+	    !issecure(SECURE_KEEP_CAPS)) {
+		cap_clear(new->cap_permitted);
+		cap_clear(new->cap_effective);
+	}
+	if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
+		cap_clear(new->cap_effective);
+	if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
+		new->cap_effective = new->cap_permitted;
+}
+
+/**
+ * cap_task_fix_setuid - Fix up the results of setuid() call
+ * @new: The proposed credentials
+ * @old: The current task's current credentials
+ * @flags: Indications of what has changed
+ *
+ * Fix up the results of setuid() call before the credential changes are
+ * actually applied, returning 0 to grant the changes, -ve to deny them.
+ */
+int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
+{
+	switch (flags) {
+	case LSM_SETID_RE:
+	case LSM_SETID_ID:
+	case LSM_SETID_RES:
+		/* juggle the capabilities to follow [RES]UID changes unless
+		 * otherwise suppressed */
+		if (!issecure(SECURE_NO_SETUID_FIXUP))
+			cap_emulate_setxuid(new, old);
+		break;
+
+	case LSM_SETID_FS:
+		/* juggle the capabilties to follow FSUID changes, unless
+		 * otherwise suppressed
+		 *
+		 * 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)) {
+			kuid_t root_uid = make_kuid(old->user_ns, 0);
+			if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
+				new->cap_effective =
+					cap_drop_fs_set(new->cap_effective);
+
+			if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
+				new->cap_effective =
+					cap_raise_fs_set(new->cap_effective,
+							 new->cap_permitted);
+		}
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Rationale: code calling task_setscheduler, task_setioprio, and
+ * task_setnice, assumes that
+ *   . if capable(cap_sys_nice), then those actions should be allowed
+ *   . if not capable(cap_sys_nice), but acting on your own processes,
+ *   	then those actions should be allowed
+ * This is insufficient now since you can call code without suid, but
+ * yet with increased caps.
+ * So we check for increased caps on the target process.
+ */
+static int cap_safe_nice(struct task_struct *p)
+{
+	int is_subset, ret = 0;
+
+	rcu_read_lock();
+	is_subset = cap_issubset(__task_cred(p)->cap_permitted,
+				 current_cred()->cap_permitted);
+	if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
+		ret = -EPERM;
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/**
+ * cap_task_setscheduler - Detemine if scheduler policy change is permitted
+ * @p: The task to affect
+ *
+ * Detemine if the requested scheduler policy change is permitted for the
+ * specified task, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_task_setscheduler(struct task_struct *p)
+{
+	return cap_safe_nice(p);
+}
+
+/**
+ * cap_task_ioprio - Detemine if I/O priority change is permitted
+ * @p: The task to affect
+ * @ioprio: The I/O priority to set
+ *
+ * Detemine if the requested I/O priority change is permitted for the specified
+ * task, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_task_setioprio(struct task_struct *p, int ioprio)
+{
+	return cap_safe_nice(p);
+}
+
+/**
+ * cap_task_ioprio - Detemine if task priority change is permitted
+ * @p: The task to affect
+ * @nice: The nice value to set
+ *
+ * Detemine if the requested task priority change is permitted for the
+ * specified task, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_task_setnice(struct task_struct *p, int nice)
+{
+	return cap_safe_nice(p);
+}
+
+/*
+ * Implement PR_CAPBSET_DROP.  Attempt to remove the specified capability from
+ * the current task's bounding set.  Returns 0 on success, -ve on error.
+ */
+static int cap_prctl_drop(unsigned long cap)
+{
+	struct cred *new;
+
+	if (!ns_capable(current_user_ns(), CAP_SETPCAP))
+		return -EPERM;
+	if (!cap_valid(cap))
+		return -EINVAL;
+
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+	cap_lower(new->cap_bset, cap);
+	return commit_creds(new);
+}
+
+/**
+ * cap_task_prctl - Implement process control functions for this security module
+ * @option: The process control function requested
+ * @arg2, @arg3, @arg4, @arg5: The argument data for this function
+ *
+ * Allow process control functions (sys_prctl()) to alter capabilities; may
+ * also deny access to other functions not otherwise implemented here.
+ *
+ * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
+ * here, other -ve on error.  If -ENOSYS is returned, sys_prctl() and other LSM
+ * modules will consider performing the function.
+ */
+int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
+		   unsigned long arg4, unsigned long arg5)
+{
+	const struct cred *old = current_cred();
+	struct cred *new;
+
+	switch (option) {
+	case PR_CAPBSET_READ:
+		if (!cap_valid(arg2))
+			return -EINVAL;
+		return !!cap_raised(old->cap_bset, arg2);
+
+	case PR_CAPBSET_DROP:
+		return cap_prctl_drop(arg2);
+
+	/*
+	 * The next four prctl's remain to assist with transitioning a
+	 * system from legacy UID=0 based privilege (when filesystem
+	 * capabilities are not in use) to a system using filesystem
+	 * capabilities only - as the POSIX.1e draft intended.
+	 *
+	 * Note:
+	 *
+	 *  PR_SET_SECUREBITS =
+	 *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
+	 *    | issecure_mask(SECURE_NOROOT)
+	 *    | issecure_mask(SECURE_NOROOT_LOCKED)
+	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
+	 *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
+	 *
+	 * will ensure that the current process and all of its
+	 * children will be locked into a pure
+	 * capability-based-privilege environment.
+	 */
+	case PR_SET_SECUREBITS:
+		if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
+		     & (old->securebits ^ arg2))			/*[1]*/
+		    || ((old->securebits & SECURE_ALL_LOCKS & ~arg2))	/*[2]*/
+		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))	/*[3]*/
+		    || (cap_capable(current_cred(),
+				    current_cred()->user_ns, CAP_SETPCAP,
+				    SECURITY_CAP_AUDIT) != 0)		/*[4]*/
+			/*
+			 * [1] no changing of bits that are locked
+			 * [2] no unlocking of locks
+			 * [3] no setting of unsupported bits
+			 * [4] doing anything requires privilege (go read about
+			 *     the "sendmail capabilities bug")
+			 */
+		    )
+			/* cannot change a locked bit */
+			return -EPERM;
+
+		new = prepare_creds();
+		if (!new)
+			return -ENOMEM;
+		new->securebits = arg2;
+		return commit_creds(new);
+
+	case PR_GET_SECUREBITS:
+		return old->securebits;
+
+	case PR_GET_KEEPCAPS:
+		return !!issecure(SECURE_KEEP_CAPS);
+
+	case PR_SET_KEEPCAPS:
+		if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
+			return -EINVAL;
+		if (issecure(SECURE_KEEP_CAPS_LOCKED))
+			return -EPERM;
+
+		new = prepare_creds();
+		if (!new)
+			return -ENOMEM;
+		if (arg2)
+			new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
+		else
+			new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
+		return commit_creds(new);
+
+	default:
+		/* No functionality available - continue with default */
+		return -ENOSYS;
+	}
+}
+
+/**
+ * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
+ * @mm: The VM space in which the new mapping is to be made
+ * @pages: The size of the mapping
+ *
+ * Determine whether the allocation of a new virtual mapping by the current
+ * task is permitted, returning 0 if permission is granted, -ve if not.
+ */
+int cap_vm_enough_memory(struct mm_struct *mm, long pages)
+{
+	int cap_sys_admin = 0;
+
+	if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
+			SECURITY_CAP_NOAUDIT) == 0)
+		cap_sys_admin = 1;
+	return __vm_enough_memory(mm, pages, cap_sys_admin);
+}
+
+/*
+ * cap_mmap_addr - check if able to map given addr
+ * @addr: address attempting to be mapped
+ *
+ * If the process is attempting to map memory below dac_mmap_min_addr they need
+ * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
+ * capability security module.  Returns 0 if this mapping should be allowed
+ * -EPERM if not.
+ */
+int cap_mmap_addr(unsigned long addr)
+{
+	int ret = 0;
+
+	if (addr < dac_mmap_min_addr) {
+		ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
+				  SECURITY_CAP_AUDIT);
+		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
+		if (ret == 0)
+			current->flags |= PF_SUPERPRIV;
+	}
+	return ret;
+}
+
+int cap_mmap_file(struct file *file, unsigned long reqprot,
+		  unsigned long prot, unsigned long flags)
+{
+	return 0;
+}