/* Common capabilities, needed by capability.o and root_plug.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/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>

  int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
  {
  	NETLINK_CB(skb).eff_cap = current->cap_effective;
  	return 0;
  }

  int cap_netlink_recv(struct sk_buff *skb, int cap)

  {

  	if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))

  		return -EPERM;
  	return 0;
  }
  
  EXPORT_SYMBOL(cap_netlink_recv);

  /*
   * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
   * function.  That is, it has the reverse semantics: cap_capable()
   * returns 0 when a task has a capability, but the kernel's capable()
   * returns 1 for this case.
   */

  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;
  	return -EPERM;
  }
  
  int cap_settime(struct timespec *ts, struct timezone *tz)
  {
  	if (!capable(CAP_SYS_TIME))
  		return -EPERM;
  	return 0;
  }
  
  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, parent->cap_permitted) &&
  	    !__capable(parent, CAP_SYS_PTRACE))

  		return -EPERM;
  	return 0;
  }
  
  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 = target->cap_effective;
  	*inheritable = target->cap_inheritable;
  	*permitted = target->cap_permitted;

  	return 0;
  }

  #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
  
  static inline int cap_block_setpcap(struct task_struct *target)
  {
  	/*
  	 * No support for remote process capability manipulation with
  	 * filesystem capability support.
  	 */
  	return (target != current);
  }
  
  static inline int cap_inh_is_capped(void)
  {
  	/*

  	 * Return 1 if changes to the inheritable set are limited
  	 * to the old permitted set. That is, if the current task
  	 * does *not* possess the CAP_SETPCAP capability.

  	 */

  	return (cap_capable(current, CAP_SETPCAP) != 0);

  }

  static inline int cap_limit_ptraced_target(void) { return 1; }

  #else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
  
  static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
  static inline int cap_inh_is_capped(void) { return 1; }

  static inline int cap_limit_ptraced_target(void)
  {
  	return !capable(CAP_SETPCAP);
  }

  
  #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */

  int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
  		      kernel_cap_t *inheritable, kernel_cap_t *permitted)
  {

  	if (cap_block_setpcap(target)) {
  		return -EPERM;
  	}
  	if (cap_inh_is_capped()
  	    && !cap_issubset(*inheritable,
  			     cap_combine(target->cap_inheritable,
  					 current->cap_permitted))) {
  		/* incapable of using this inheritable set */

  		return -EPERM;
  	}

  	if (!cap_issubset(*inheritable,
  			   cap_combine(target->cap_inheritable,
  				       current->cap_bset))) {
  		/* no new pI capabilities outside bounding set */
  		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;
  }
  
  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 inline void bprm_clear_caps(struct linux_binprm *bprm)
  {
  	cap_clear(bprm->cap_inheritable);
  	cap_clear(bprm->cap_permitted);
  	bprm->cap_effective = false;
  }
  
  #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
  
  int cap_inode_need_killpriv(struct dentry *dentry)
  {
  	struct inode *inode = dentry->d_inode;
  	int error;
  
  	if (!inode->i_op || !inode->i_op->getxattr)
  	       return 0;
  
  	error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
  	if (error <= 0)
  		return 0;
  	return 1;
  }
  
  int cap_inode_killpriv(struct dentry *dentry)
  {
  	struct inode *inode = dentry->d_inode;
  
  	if (!inode->i_op || !inode->i_op->removexattr)
  	       return 0;
  
  	return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
  }

  static inline int cap_from_disk(struct vfs_cap_data *caps,
  				struct linux_binprm *bprm, unsigned size)

  {
  	__u32 magic_etc;

  	unsigned tocopy, i;

  	if (size < sizeof(magic_etc))

  		return -EINVAL;

  	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;
  	}

  
  	if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) {
  		bprm->cap_effective = true;
  	} else {
  		bprm->cap_effective = false;
  	}
  
  	for (i = 0; i < tocopy; ++i) {
  		bprm->cap_permitted.cap[i] =
  			le32_to_cpu(caps->data[i].permitted);
  		bprm->cap_inheritable.cap[i] =
  			le32_to_cpu(caps->data[i].inheritable);
  	}
  	while (i < VFS_CAP_U32) {
  		bprm->cap_permitted.cap[i] = 0;
  		bprm->cap_inheritable.cap[i] = 0;
  		i++;
  	}
  
  	return 0;

  }
  
  /* Locate any VFS capabilities: */
  static int get_file_caps(struct linux_binprm *bprm)
  {
  	struct dentry *dentry;
  	int rc = 0;

  	struct vfs_cap_data vcaps;

  	struct inode *inode;
  
  	if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
  		bprm_clear_caps(bprm);
  		return 0;
  	}
  
  	dentry = dget(bprm->file->f_dentry);
  	inode = dentry->d_inode;
  	if (!inode->i_op || !inode->i_op->getxattr)
  		goto out;

  	rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps,
  				   XATTR_CAPS_SZ);

  	if (rc == -ENODATA || rc == -EOPNOTSUPP) {
  		/* no data, that's ok */
  		rc = 0;
  		goto out;
  	}
  	if (rc < 0)
  		goto out;

  	rc = cap_from_disk(&vcaps, bprm, rc);

  	if (rc)
  		printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s
  ",

  			__func__, rc, bprm->filename);

  
  out:
  	dput(dentry);
  	if (rc)
  		bprm_clear_caps(bprm);
  
  	return rc;
  }
  
  #else
  int cap_inode_need_killpriv(struct dentry *dentry)
  {
  	return 0;
  }
  
  int cap_inode_killpriv(struct dentry *dentry)
  {
  	return 0;
  }
  
  static inline int get_file_caps(struct linux_binprm *bprm)
  {
  	bprm_clear_caps(bprm);
  	return 0;
  }
  #endif

  int cap_bprm_set_security (struct linux_binprm *bprm)
  {

  	int ret;

  	ret = get_file_caps(bprm);
  	if (ret)
  		printk(KERN_NOTICE "%s: get_file_caps returned %d for %s
  ",

  			__func__, ret, bprm->filename);

  
  	/*  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)

  			bprm->cap_effective = true;

  	}

  
  	return ret;

  }
  
  void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
  {
  	/* Derived from fs/exec.c:compute_creds. */
  	kernel_cap_t new_permitted, working;

  	new_permitted = cap_intersect(bprm->cap_permitted,
  				 current->cap_bset);
  	working = cap_intersect(bprm->cap_inheritable,

  				 current->cap_inheritable);

  	new_permitted = cap_combine(new_permitted, working);

  
  	if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
  	    !cap_issubset (new_permitted, current->cap_permitted)) {

  		set_dumpable(current->mm, suid_dumpable);

  		current->pdeath_signal = 0;

  
  		if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
  			if (!capable(CAP_SETUID)) {
  				bprm->e_uid = current->uid;
  				bprm->e_gid = current->gid;
  			}

  			if (cap_limit_ptraced_target()) {
  				new_permitted =
  					cap_intersect(new_permitted,
  						      current->cap_permitted);

  			}
  		}
  	}
  
  	current->suid = current->euid = current->fsuid = bprm->e_uid;
  	current->sgid = current->egid = current->fsgid = bprm->e_gid;
  
  	/* For init, we want to retain the capabilities set
  	 * in the init_task struct. Thus we skip the usual
  	 * capability rules */

  	if (!is_global_init(current)) {

  		current->cap_permitted = new_permitted;

  		if (bprm->cap_effective)
  			current->cap_effective = new_permitted;
  		else
  			cap_clear(current->cap_effective);

  	}
  
  	/* AUD: Audit candidate if current->cap_effective is set */

  	current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);

  }
  
  int cap_bprm_secureexec (struct linux_binprm *bprm)
  {

  	if (current->uid != 0) {
  		if (bprm->cap_effective)
  			return 1;
  		if (!cap_isclear(bprm->cap_permitted))
  			return 1;
  		if (!cap_isclear(bprm->cap_inheritable))
  			return 1;
  	}

  	return (current->euid != current->uid ||
  		current->egid != current->gid);
  }

  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;
  	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,

  		     sizeof(XATTR_SECURITY_PREFIX) - 1)  &&
  	    !capable(CAP_SYS_ADMIN))
  		return -EPERM;
  	return 0;
  }

  int cap_inode_removexattr(struct dentry *dentry, const char *name)

  {

  	if (!strcmp(name, XATTR_NAME_CAPS)) {
  		if (!capable(CAP_SETFCAP))
  			return -EPERM;
  		return 0;
  	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,

  		     sizeof(XATTR_SECURITY_PREFIX) - 1)  &&
  	    !capable(CAP_SYS_ADMIN))
  		return -EPERM;
  	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) &&

  	    !issecure(SECURE_KEEP_CAPS)) {

  		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;
  	}
  }
  
  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) {

  					current->cap_effective =
  						cap_drop_fs_set(
  						    current->cap_effective);

  				}
  				if (old_fsuid != 0 && current->fsuid == 0) {

  					current->cap_effective =
  						cap_raise_fs_set(
  						    current->cap_effective,
  						    current->cap_permitted);

  				}
  			}
  			break;
  		}
  	default:
  		return -EINVAL;
  	}
  
  	return 0;
  }

  #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
  /*
   * 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 inline int cap_safe_nice(struct task_struct *p)
  {
  	if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
  	    !__capable(current, CAP_SYS_NICE))
  		return -EPERM;
  	return 0;
  }
  
  int cap_task_setscheduler (struct task_struct *p, int policy,
  			   struct sched_param *lp)
  {
  	return cap_safe_nice(p);
  }
  
  int cap_task_setioprio (struct task_struct *p, int ioprio)
  {
  	return cap_safe_nice(p);
  }
  
  int cap_task_setnice (struct task_struct *p, int nice)
  {
  	return cap_safe_nice(p);
  }

  /*
   * called from kernel/sys.c for prctl(PR_CABSET_DROP)
   * done without task_capability_lock() because it introduces
   * no new races - i.e. only another task doing capget() on
   * this task could get inconsistent info.  There can be no
   * racing writer bc a task can only change its own caps.
   */

  static long cap_prctl_drop(unsigned long cap)

  {
  	if (!capable(CAP_SETPCAP))
  		return -EPERM;
  	if (!cap_valid(cap))
  		return -EINVAL;
  	cap_lower(current->cap_bset, cap);
  	return 0;
  }

  #else
  int cap_task_setscheduler (struct task_struct *p, int policy,
  			   struct sched_param *lp)
  {
  	return 0;
  }
  int cap_task_setioprio (struct task_struct *p, int ioprio)
  {
  	return 0;
  }
  int cap_task_setnice (struct task_struct *p, int nice)
  {
  	return 0;
  }

  #endif

  int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
  		   unsigned long arg4, unsigned long arg5, long *rc_p)
  {
  	long error = 0;
  
  	switch (option) {
  	case PR_CAPBSET_READ:
  		if (!cap_valid(arg2))
  			error = -EINVAL;
  		else
  			error = !!cap_raised(current->cap_bset, arg2);
  		break;
  #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
  	case PR_CAPBSET_DROP:
  		error = cap_prctl_drop(arg2);
  		break;
  
  	/*
  	 * 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 ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
  		     & (current->securebits ^ arg2))                  /*[1]*/
  		    || ((current->securebits & SECURE_ALL_LOCKS
  			 & ~arg2))                                    /*[2]*/
  		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
  		    || (cap_capable(current, CAP_SETPCAP) != 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")
  			 */
  			error = -EPERM;  /* cannot change a locked bit */
  		} else {
  			current->securebits = arg2;
  		}
  		break;
  	case PR_GET_SECUREBITS:
  		error = current->securebits;
  		break;
  
  #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
  
  	case PR_GET_KEEPCAPS:
  		if (issecure(SECURE_KEEP_CAPS))
  			error = 1;
  		break;
  	case PR_SET_KEEPCAPS:
  		if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
  			error = -EINVAL;
  		else if (issecure(SECURE_KEEP_CAPS_LOCKED))
  			error = -EPERM;
  		else if (arg2)
  			current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
  		else
  			current->securebits &=
  				~issecure_mask(SECURE_KEEP_CAPS);
  		break;
  
  	default:
  		/* No functionality available - continue with default */
  		return 0;
  	}
  
  	/* Functionality provided */
  	*rc_p = error;
  	return 1;
  }

  void cap_task_reparent_to_init (struct task_struct *p)
  {

  	cap_set_init_eff(p->cap_effective);
  	cap_clear(p->cap_inheritable);
  	cap_set_full(p->cap_permitted);

  	p->securebits = SECUREBITS_DEFAULT;

  	return;
  }
  
  int cap_syslog (int type)
  {
  	if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
  		return -EPERM;
  	return 0;
  }

  int cap_vm_enough_memory(struct mm_struct *mm, long pages)

  {
  	int cap_sys_admin = 0;
  
  	if (cap_capable(current, CAP_SYS_ADMIN) == 0)
  		cap_sys_admin = 1;

  	return __vm_enough_memory(mm, pages, cap_sys_admin);

  }