/* 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/smp_lock.h>
  #include <linux/skbuff.h>
  #include <linux/netlink.h>
  #include <linux/ptrace.h>
  #include <linux/xattr.h>
  #include <linux/hugetlb.h>
  
  int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
  {
  	NETLINK_CB(skb).eff_cap = current->cap_effective;
  	return 0;
  }
  
  EXPORT_SYMBOL(cap_netlink_send);

  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);
  
  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 = cap_t (target->cap_effective);
  	*inheritable = cap_t (target->cap_inheritable);
  	*permitted = cap_t (target->cap_permitted);
  	return 0;
  }
  
  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;
  }
  
  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;
  }
  
  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;
  }
  
  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, 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)) {

  		current->mm->dumpable = suid_dumpable;

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

  		current->cap_permitted = new_permitted;
  		current->cap_effective =
  		    cap_intersect (new_permitted, bprm->cap_effective);
  	}
  
  	/* AUD: Audit candidate if current->cap_effective is set */
  
  	current->keep_capabilities = 0;
  }
  
  int cap_bprm_secureexec (struct linux_binprm *bprm)
  {
  	/* If/when this module is enhanced to incorporate capability
  	   bits on files, the test below should be extended to also perform a 
  	   test between the old and new capability sets.  For now,
  	   it simply preserves the legacy decision algorithm used by
  	   the old userland. */
  	return (current->euid != current->uid ||
  		current->egid != current->gid);
  }
  
  int cap_inode_setxattr(struct dentry *dentry, char *name, void *value,
  		       size_t size, int flags)
  {
  	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, char *name)
  {
  	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) &&
  	    !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;
  	}
  }
  
  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;
  }
  
  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;
  }
  
  int cap_syslog (int type)
  {
  	if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
  		return -EPERM;
  	return 0;
  }
  
  int cap_vm_enough_memory(long pages)
  {
  	int cap_sys_admin = 0;
  
  	if (cap_capable(current, CAP_SYS_ADMIN) == 0)
  		cap_sys_admin = 1;
  	return __vm_enough_memory(pages, cap_sys_admin);
  }
  
  EXPORT_SYMBOL(cap_capable);
  EXPORT_SYMBOL(cap_settime);
  EXPORT_SYMBOL(cap_ptrace);
  EXPORT_SYMBOL(cap_capget);
  EXPORT_SYMBOL(cap_capset_check);
  EXPORT_SYMBOL(cap_capset_set);
  EXPORT_SYMBOL(cap_bprm_set_security);
  EXPORT_SYMBOL(cap_bprm_apply_creds);
  EXPORT_SYMBOL(cap_bprm_secureexec);
  EXPORT_SYMBOL(cap_inode_setxattr);
  EXPORT_SYMBOL(cap_inode_removexattr);
  EXPORT_SYMBOL(cap_task_post_setuid);
  EXPORT_SYMBOL(cap_task_reparent_to_init);
  EXPORT_SYMBOL(cap_syslog);
  EXPORT_SYMBOL(cap_vm_enough_memory);
  
  MODULE_DESCRIPTION("Standard Linux Common Capabilities Security Module");
  MODULE_LICENSE("GPL");