8b964eae20
If the xindex value stored in the accept tables is 0, the extraction of that value will result in an underflow (0 - 4). In properly compiled policy this should not happen for file rules but it may be possible for other rule types in the future. To exploit this underflow a user would have to be able to load a corrupt policy, which requires CAP_MAC_ADMIN, overwrite system policy in kernel memory or know of a compiler error resulting in the flaw being present for loaded policy (no such flaw is known at this time). Signed-off-by: John Johansen <john.johansen@canonical.com> Acked-by: Kees Cook <kees@ubuntu.com>
216 lines
6.5 KiB
C
216 lines
6.5 KiB
C
/*
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* AppArmor security module
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*
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* This file contains AppArmor file mediation function definitions.
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*
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* Copyright (C) 1998-2008 Novell/SUSE
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* Copyright 2009-2010 Canonical Ltd.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#ifndef __AA_FILE_H
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#define __AA_FILE_H
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#include "domain.h"
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#include "match.h"
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struct aa_profile;
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struct path;
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/*
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* We use MAY_EXEC, MAY_WRITE, MAY_READ, MAY_APPEND and the following flags
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* for profile permissions
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*/
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#define AA_MAY_CREATE 0x0010
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#define AA_MAY_DELETE 0x0020
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#define AA_MAY_META_WRITE 0x0040
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#define AA_MAY_META_READ 0x0080
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#define AA_MAY_CHMOD 0x0100
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#define AA_MAY_CHOWN 0x0200
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#define AA_MAY_LOCK 0x0400
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#define AA_EXEC_MMAP 0x0800
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#define AA_MAY_LINK 0x1000
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#define AA_LINK_SUBSET AA_MAY_LOCK /* overlaid */
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#define AA_MAY_ONEXEC 0x40000000 /* exec allows onexec */
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#define AA_MAY_CHANGE_PROFILE 0x80000000
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#define AA_MAY_CHANGEHAT 0x80000000 /* ctrl auditing only */
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#define AA_AUDIT_FILE_MASK (MAY_READ | MAY_WRITE | MAY_EXEC | MAY_APPEND |\
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AA_MAY_CREATE | AA_MAY_DELETE | \
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AA_MAY_META_READ | AA_MAY_META_WRITE | \
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AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_LOCK | \
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AA_EXEC_MMAP | AA_MAY_LINK)
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/*
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* The xindex is broken into 3 parts
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* - index - an index into either the exec name table or the variable table
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* - exec type - which determines how the executable name and index are used
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* - flags - which modify how the destination name is applied
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*/
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#define AA_X_INDEX_MASK 0x03ff
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#define AA_X_TYPE_MASK 0x0c00
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#define AA_X_TYPE_SHIFT 10
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#define AA_X_NONE 0x0000
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#define AA_X_NAME 0x0400 /* use executable name px */
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#define AA_X_TABLE 0x0800 /* use a specified name ->n# */
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#define AA_X_UNSAFE 0x1000
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#define AA_X_CHILD 0x2000 /* make >AA_X_NONE apply to children */
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#define AA_X_INHERIT 0x4000
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#define AA_X_UNCONFINED 0x8000
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/* AA_SECURE_X_NEEDED - is passed in the bprm->unsafe field */
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#define AA_SECURE_X_NEEDED 0x8000
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/* need to make conditional which ones are being set */
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struct path_cond {
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uid_t uid;
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umode_t mode;
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};
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/* struct file_perms - file permission
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* @allow: mask of permissions that are allowed
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* @audit: mask of permissions to force an audit message for
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* @quiet: mask of permissions to quiet audit messages for
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* @kill: mask of permissions that when matched will kill the task
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* @xindex: exec transition index if @allow contains MAY_EXEC
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*
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* The @audit and @queit mask should be mutually exclusive.
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*/
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struct file_perms {
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u32 allow;
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u32 audit;
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u32 quiet;
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u32 kill;
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u16 xindex;
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};
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extern struct file_perms nullperms;
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#define COMBINED_PERM_MASK(X) ((X).allow | (X).audit | (X).quiet | (X).kill)
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/* FIXME: split perms from dfa and match this to description
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* also add delegation info.
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*/
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static inline u16 dfa_map_xindex(u16 mask)
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{
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u16 old_index = (mask >> 10) & 0xf;
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u16 index = 0;
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if (mask & 0x100)
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index |= AA_X_UNSAFE;
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if (mask & 0x200)
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index |= AA_X_INHERIT;
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if (mask & 0x80)
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index |= AA_X_UNCONFINED;
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if (old_index == 1) {
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index |= AA_X_UNCONFINED;
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} else if (old_index == 2) {
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index |= AA_X_NAME;
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} else if (old_index == 3) {
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index |= AA_X_NAME | AA_X_CHILD;
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} else if (old_index) {
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index |= AA_X_TABLE;
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index |= old_index - 4;
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}
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return index;
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}
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/*
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* map old dfa inline permissions to new format
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*/
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#define dfa_user_allow(dfa, state) (((ACCEPT_TABLE(dfa)[state]) & 0x7f) | \
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((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
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#define dfa_user_audit(dfa, state) ((ACCEPT_TABLE2(dfa)[state]) & 0x7f)
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#define dfa_user_quiet(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 7) & 0x7f)
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#define dfa_user_xindex(dfa, state) \
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(dfa_map_xindex(ACCEPT_TABLE(dfa)[state] & 0x3fff))
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#define dfa_other_allow(dfa, state) ((((ACCEPT_TABLE(dfa)[state]) >> 14) & \
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0x7f) | \
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((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
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#define dfa_other_audit(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 14) & 0x7f)
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#define dfa_other_quiet(dfa, state) \
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((((ACCEPT_TABLE2(dfa)[state]) >> 7) >> 14) & 0x7f)
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#define dfa_other_xindex(dfa, state) \
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dfa_map_xindex((ACCEPT_TABLE(dfa)[state] >> 14) & 0x3fff)
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int aa_audit_file(struct aa_profile *profile, struct file_perms *perms,
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gfp_t gfp, int op, u32 request, const char *name,
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const char *target, uid_t ouid, const char *info, int error);
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/**
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* struct aa_file_rules - components used for file rule permissions
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* @dfa: dfa to match path names and conditionals against
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* @perms: permission table indexed by the matched state accept entry of @dfa
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* @trans: transition table for indexed by named x transitions
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*
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* File permission are determined by matching a path against @dfa and then
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* then using the value of the accept entry for the matching state as
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* an index into @perms. If a named exec transition is required it is
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* looked up in the transition table.
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*/
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struct aa_file_rules {
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unsigned int start;
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struct aa_dfa *dfa;
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/* struct perms perms; */
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struct aa_domain trans;
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/* TODO: add delegate table */
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};
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unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
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const char *name, struct path_cond *cond,
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struct file_perms *perms);
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int aa_path_perm(int op, struct aa_profile *profile, struct path *path,
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int flags, u32 request, struct path_cond *cond);
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int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
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struct path *new_dir, struct dentry *new_dentry);
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int aa_file_perm(int op, struct aa_profile *profile, struct file *file,
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u32 request);
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static inline void aa_free_file_rules(struct aa_file_rules *rules)
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{
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aa_put_dfa(rules->dfa);
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aa_free_domain_entries(&rules->trans);
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}
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#define ACC_FMODE(x) (("\000\004\002\006"[(x)&O_ACCMODE]) | (((x) << 1) & 0x40))
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/* from namei.c */
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#define MAP_OPEN_FLAGS(x) ((((x) + 1) & O_ACCMODE) ? (x) + 1 : (x))
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/**
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* aa_map_file_perms - map file flags to AppArmor permissions
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* @file: open file to map flags to AppArmor permissions
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*
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* Returns: apparmor permission set for the file
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*/
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static inline u32 aa_map_file_to_perms(struct file *file)
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{
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int flags = MAP_OPEN_FLAGS(file->f_flags);
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u32 perms = ACC_FMODE(file->f_mode);
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if ((flags & O_APPEND) && (perms & MAY_WRITE))
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perms = (perms & ~MAY_WRITE) | MAY_APPEND;
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/* trunc implies write permission */
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if (flags & O_TRUNC)
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perms |= MAY_WRITE;
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if (flags & O_CREAT)
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perms |= AA_MAY_CREATE;
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return perms;
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}
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#endif /* __AA_FILE_H */
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