smack.h

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/*
 * Copyright (C) 2007 Casey Schaufler <[email protected]>
 *
 *      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, version 2.
 *
 * Author:
 *      Casey Schaufler <[email protected]>
 *
 */

#ifndef _SECURITY_SMACK_H
#define _SECURITY_SMACK_H

#include <linux/capability.h>
#include <linux/spinlock.h>
#include <linux/security.h>
#include <linux/in.h>
#include <net/netlabel.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/lsm_audit.h>

/*
 * Smack labels were limited to 23 characters for a long time.
 */
#define SMK_LABELLEN    24
#define SMK_LONGLABEL   256

/*
 * Maximum number of bytes for the levels in a CIPSO IP option.
 * Why 23? CIPSO is constrained to 30, so a 32 byte buffer is
 * bigger than can be used, and 24 is the next lower multiple
 * of 8, and there are too many issues if there isn't space set
 * aside for the terminating null byte.
 */
#define SMK_CIPSOLEN    24

struct superblock_smack {
    char        *smk_root;
    char        *smk_floor;
    char        *smk_hat;
    char        *smk_default;
    int     smk_initialized;
};

struct socket_smack {
    char        *smk_out;   /* outbound label */
    char        *smk_in;    /* inbound label */
    char        *smk_packet;    /* TCP peer label */
};

/*
 * Inode smack data
 */
struct inode_smack {
    char        *smk_inode; /* label of the fso */
    char        *smk_task;  /* label of the task */
    char        *smk_mmap;  /* label of the mmap domain */
    struct mutex    smk_lock;   /* initialization lock */
    int     smk_flags;  /* smack inode flags */
};

struct task_smack {
    char            *smk_task;  /* label for access control */
    char            *smk_forked;    /* label when forked */
    struct list_head    smk_rules;  /* per task access rules */
    struct mutex        smk_rules_lock; /* lock for the rules */
};

#define SMK_INODE_INSTANT   0x01    /* inode is instantiated */
#define SMK_INODE_TRANSMUTE 0x02    /* directory is transmuting */
#define SMK_INODE_CHANGED   0x04    /* smack was transmuted */

/*
 * A label access rule.
 */
struct smack_rule {
    struct list_head    list;
    char            *smk_subject;
    char            *smk_object;
    int         smk_access;
};

/*
 * An entry in the table identifying hosts.
 */
struct smk_netlbladdr {
    struct list_head    list;
    struct sockaddr_in  smk_host;   /* network address */
    struct in_addr      smk_mask;   /* network mask */
    char            *smk_label; /* label */
};

/*
 * This is the repository for labels seen so that it is
 * not necessary to keep allocating tiny chuncks of memory
 * and so that they can be shared.
 *
 * Labels are never modified in place. Anytime a label
 * is imported (e.g. xattrset on a file) the list is checked
 * for it and it is added if it doesn't exist. The address
 * is passed out in either case. Entries are added, but
 * never deleted.
 *
 * Since labels are hanging around anyway it doesn't
 * hurt to maintain a secid for those awkward situations
 * where kernel components that ought to use LSM independent
 * interfaces don't. The secid should go away when all of
 * these components have been repaired.
 *
 * The cipso value associated with the label gets stored here, too.
 *
 * Keep the access rules for this subject label here so that
 * the entire set of rules does not need to be examined every
 * time.
 */
struct smack_known {
    struct list_head        list;
    char                *smk_known;
    u32             smk_secid;
    struct netlbl_lsm_secattr   smk_netlabel;   /* on wire labels */
    struct list_head        smk_rules;  /* access rules */
    struct mutex            smk_rules_lock; /* lock for rules */
};

/*
 * Mount options
 */
#define SMK_FSDEFAULT   "smackfsdef="
#define SMK_FSFLOOR "smackfsfloor="
#define SMK_FSHAT   "smackfshat="
#define SMK_FSROOT  "smackfsroot="

#define SMACK_CIPSO_OPTION  "-CIPSO"

/*
 * How communications on this socket are treated.
 * Usually it's determined by the underlying netlabel code
 * but there are certain cases, including single label hosts
 * and potentially single label interfaces for which the
 * treatment can not be known in advance.
 *
 * The possibility of additional labeling schemes being
 * introduced in the future exists as well.
 */
#define SMACK_UNLABELED_SOCKET  0
#define SMACK_CIPSO_SOCKET  1

/*
 * smackfs magic number
 */
#define SMACK_MAGIC 0x43415d53 /* "SMAC" */

/*
 * CIPSO defaults.
 */
#define SMACK_CIPSO_DOI_DEFAULT     3   /* Historical */
#define SMACK_CIPSO_DOI_INVALID     -1  /* Not a DOI */
#define SMACK_CIPSO_DIRECT_DEFAULT  250 /* Arbitrary */
#define SMACK_CIPSO_MAPPED_DEFAULT  251 /* Also arbitrary */
#define SMACK_CIPSO_MAXCATVAL       63  /* Bigger gets harder */
#define SMACK_CIPSO_MAXLEVEL            255     /* CIPSO 2.2 standard */
#define SMACK_CIPSO_MAXCATNUM           239     /* CIPSO 2.2 standard */

/*
 * Flag for transmute access
 */
#define MAY_TRANSMUTE   64
/*
 * Just to make the common cases easier to deal with
 */
#define MAY_ANYREAD (MAY_READ | MAY_EXEC)
#define MAY_READWRITE   (MAY_READ | MAY_WRITE)
#define MAY_NOT     0

/*
 * Number of access types used by Smack (rwxat)
 */
#define SMK_NUM_ACCESS_TYPE 5

/* SMACK data */
struct smack_audit_data {
    const char *function;
    char *subject;
    char *object;
    char *request;
    int result;
};

/*
 * Smack audit data; is empty if CONFIG_AUDIT not set
 * to save some stack
 */
struct smk_audit_info {
#ifdef CONFIG_AUDIT
    struct common_audit_data a;
    struct smack_audit_data sad;
#endif
};
/*
 * These functions are in smack_lsm.c
 */
struct inode_smack *new_inode_smack(char *);

/*
 * These functions are in smack_access.c
 */
int smk_access_entry(char *, char *, struct list_head *);
int smk_access(char *, char *, int, struct smk_audit_info *);
int smk_curacc(char *, u32, struct smk_audit_info *);
char *smack_from_secid(const u32);
char *smk_parse_smack(const char *string, int len);
int smk_netlbl_mls(int, char *, struct netlbl_lsm_secattr *, int);
char *smk_import(const char *, int);
struct smack_known *smk_import_entry(const char *, int);
struct smack_known *smk_find_entry(const char *);
u32 smack_to_secid(const char *);

/*
 * Shared data.
 */
extern int smack_cipso_direct;
extern int smack_cipso_mapped;
extern char *smack_net_ambient;
extern char *smack_onlycap;
extern const char *smack_cipso_option;

extern struct smack_known smack_known_floor;
extern struct smack_known smack_known_hat;
extern struct smack_known smack_known_huh;
extern struct smack_known smack_known_invalid;
extern struct smack_known smack_known_star;
extern struct smack_known smack_known_web;

extern struct mutex smack_known_lock;
extern struct list_head smack_known_list;
extern struct list_head smk_netlbladdr_list;

extern struct security_operations smack_ops;

/*
 * Is the directory transmuting?
 */
static inline int smk_inode_transmutable(const struct inode *isp)
{
    struct inode_smack *sip = isp->i_security;
    return (sip->smk_flags & SMK_INODE_TRANSMUTE) != 0;
}

/*
 * Present a pointer to the smack label in an inode blob.
 */
static inline char *smk_of_inode(const struct inode *isp)
{
    struct inode_smack *sip = isp->i_security;
    return sip->smk_inode;
}

/*
 * Present a pointer to the smack label in an task blob.
 */
static inline char *smk_of_task(const struct task_smack *tsp)
{
    return tsp->smk_task;
}

/*
 * Present a pointer to the forked smack label in an task blob.
 */
static inline char *smk_of_forked(const struct task_smack *tsp)
{
    return tsp->smk_forked;
}

/*
 * Present a pointer to the smack label in the current task blob.
 */
static inline char *smk_of_current(void)
{
    return smk_of_task(current_security());
}

/*
 * Is the task privileged and allowed to be privileged
 * by the onlycap rule.
 */
static inline int smack_privileged(int cap)
{
    if (!capable(cap))
        return 0;
    if (smack_onlycap == NULL || smack_onlycap == smk_of_current())
        return 1;
    return 0;
}

/*
 * logging functions
 */
#define SMACK_AUDIT_DENIED 0x1
#define SMACK_AUDIT_ACCEPT 0x2
extern int log_policy;

void smack_log(char *subject_label, char *object_label,
        int request,
        int result, struct smk_audit_info *auditdata);

#ifdef CONFIG_AUDIT

/*
 * some inline functions to set up audit data
 * they do nothing if CONFIG_AUDIT is not set
 *
 */
static inline void smk_ad_init(struct smk_audit_info *a, const char *func,
                   char type)
{
    memset(&a->sad, 0, sizeof(a->sad));
    a->a.type = type;
    a->a.smack_audit_data = &a->sad;
    a->a.smack_audit_data->function = func;
}

static inline void smk_ad_init_net(struct smk_audit_info *a, const char *func,
                   char type, struct lsm_network_audit *net)
{
    smk_ad_init(a, func, type);
    memset(net, 0, sizeof(*net));
    a->a.u.net = net;
}

static inline void smk_ad_setfield_u_tsk(struct smk_audit_info *a,
                     struct task_struct *t)
{
    a->a.u.tsk = t;
}
static inline void smk_ad_setfield_u_fs_path_dentry(struct smk_audit_info *a,
                            struct dentry *d)
{
    a->a.u.dentry = d;
}
static inline void smk_ad_setfield_u_fs_inode(struct smk_audit_info *a,
                          struct inode *i)
{
    a->a.u.inode = i;
}
static inline void smk_ad_setfield_u_fs_path(struct smk_audit_info *a,
                         struct path p)
{
    a->a.u.path = p;
}
static inline void smk_ad_setfield_u_net_sk(struct smk_audit_info *a,
                        struct sock *sk)
{
    a->a.u.net->sk = sk;
}

#else /* no AUDIT */

static inline void smk_ad_init(struct smk_audit_info *a, const char *func,
                   char type)
{
}
static inline void smk_ad_setfield_u_tsk(struct smk_audit_info *a,
                     struct task_struct *t)
{
}
static inline void smk_ad_setfield_u_fs_path_dentry(struct smk_audit_info *a,
                            struct dentry *d)
{
}
static inline void smk_ad_setfield_u_fs_path_mnt(struct smk_audit_info *a,
                         struct vfsmount *m)
{
}
static inline void smk_ad_setfield_u_fs_inode(struct smk_audit_info *a,
                          struct inode *i)
{
}
static inline void smk_ad_setfield_u_fs_path(struct smk_audit_info *a,
                         struct path p)
{
}
static inline void smk_ad_setfield_u_net_sk(struct smk_audit_info *a,
                        struct sock *sk)
{
}
#endif

#endif  /* _SECURITY_SMACK_H */