AppArmor: misc. base functions and defines

Miscellaneous functions and defines needed by AppArmor, including
the base path resolution routines.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
John Johansen 2010-07-29 14:47:57 -07:00 committed by James Morris
parent e6f6a4cc95
commit cdff264264
4 changed files with 491 additions and 0 deletions

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/*
* AppArmor security module
*
* This file contains AppArmor basic global and lib definitions
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*
* 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 of the
* License.
*/
#ifndef __APPARMOR_H
#define __APPARMOR_H
#include <linux/fs.h>
#include "match.h"
/* Control parameters settable through module/boot flags */
extern enum audit_mode aa_g_audit;
extern int aa_g_audit_header;
extern int aa_g_debug;
extern int aa_g_lock_policy;
extern int aa_g_logsyscall;
extern int aa_g_paranoid_load;
extern unsigned int aa_g_path_max;
/*
* DEBUG remains global (no per profile flag) since it is mostly used in sysctl
* which is not related to profile accesses.
*/
#define AA_DEBUG(fmt, args...) \
do { \
if (aa_g_debug && printk_ratelimit()) \
printk(KERN_DEBUG "AppArmor: " fmt, ##args); \
} while (0)
#define AA_ERROR(fmt, args...) \
do { \
if (printk_ratelimit()) \
printk(KERN_ERR "AppArmor: " fmt, ##args); \
} while (0)
/* Flag indicating whether initialization completed */
extern int apparmor_initialized __initdata;
/* fn's in lib */
char *aa_split_fqname(char *args, char **ns_name);
void aa_info_message(const char *str);
void *kvmalloc(size_t size);
void kvfree(void *buffer);
/**
* aa_strneq - compare null terminated @str to a non null terminated substring
* @str: a null terminated string
* @sub: a substring, not necessarily null terminated
* @len: length of @sub to compare
*
* The @str string must be full consumed for this to be considered a match
*/
static inline bool aa_strneq(const char *str, const char *sub, int len)
{
return !strncmp(str, sub, len) && !str[len];
}
/**
* aa_dfa_null_transition - step to next state after null character
* @dfa: the dfa to match against
* @start: the state of the dfa to start matching in
*
* aa_dfa_null_transition transitions to the next state after a null
* character which is not used in standard matching and is only
* used to separate pairs.
*/
static inline unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
unsigned int start)
{
/* the null transition only needs the string's null terminator byte */
return aa_dfa_match_len(dfa, start, "", 1);
}
static inline bool mediated_filesystem(struct inode *inode)
{
return !(inode->i_sb->s_flags & MS_NOUSER);
}
#endif /* __APPARMOR_H */

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/*
* AppArmor security module
*
* This file contains AppArmor basic path manipulation function definitions.
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*
* 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 of the
* License.
*/
#ifndef __AA_PATH_H
#define __AA_PATH_H
enum path_flags {
PATH_IS_DIR = 0x1, /* path is a directory */
PATH_CONNECT_PATH = 0x4, /* connect disconnected paths to / */
PATH_CHROOT_REL = 0x8, /* do path lookup relative to chroot */
PATH_CHROOT_NSCONNECT = 0x10, /* connect paths that are at ns root */
PATH_DELEGATE_DELETED = 0x08000, /* delegate deleted files */
PATH_MEDIATE_DELETED = 0x10000, /* mediate deleted paths */
};
int aa_get_name(struct path *path, int flags, char **buffer, const char **name);
#endif /* __AA_PATH_H */

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security/apparmor/lib.c Normal file
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/*
* AppArmor security module
*
* This file contains basic common functions used in AppArmor
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*
* 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 of the
* License.
*/
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include "include/audit.h"
/**
* aa_split_fqname - split a fqname into a profile and namespace name
* @fqname: a full qualified name in namespace profile format (NOT NULL)
* @ns_name: pointer to portion of the string containing the ns name (NOT NULL)
*
* Returns: profile name or NULL if one is not specified
*
* Split a namespace name from a profile name (see policy.c for naming
* description). If a portion of the name is missing it returns NULL for
* that portion.
*
* NOTE: may modify the @fqname string. The pointers returned point
* into the @fqname string.
*/
char *aa_split_fqname(char *fqname, char **ns_name)
{
char *name = strim(fqname);
*ns_name = NULL;
if (name[0] == ':') {
char *split = strchr(&name[1], ':');
if (split) {
/* overwrite ':' with \0 */
*split = 0;
name = skip_spaces(split + 1);
} else
/* a ns name without a following profile is allowed */
name = NULL;
*ns_name = &name[1];
}
if (name && *name == 0)
name = NULL;
return name;
}
/**
* aa_info_message - log a none profile related status message
* @str: message to log
*/
void aa_info_message(const char *str)
{
if (audit_enabled) {
struct common_audit_data sa;
COMMON_AUDIT_DATA_INIT(&sa, NONE);
sa.aad.info = str;
aa_audit_msg(AUDIT_APPARMOR_STATUS, &sa, NULL);
}
printk(KERN_INFO "AppArmor: %s\n", str);
}
/**
* kvmalloc - do allocation preferring kmalloc but falling back to vmalloc
* @size: size of allocation
*
* Return: allocated buffer or NULL if failed
*
* It is possible that policy being loaded from the user is larger than
* what can be allocated by kmalloc, in those cases fall back to vmalloc.
*/
void *kvmalloc(size_t size)
{
void *buffer = NULL;
if (size == 0)
return NULL;
/* do not attempt kmalloc if we need more than 16 pages at once */
if (size <= (16*PAGE_SIZE))
buffer = kmalloc(size, GFP_NOIO | __GFP_NOWARN);
if (!buffer) {
/* see kvfree for why size must be at least work_struct size
* when allocated via vmalloc
*/
if (size < sizeof(struct work_struct))
size = sizeof(struct work_struct);
buffer = vmalloc(size);
}
return buffer;
}
/**
* do_vfree - workqueue routine for freeing vmalloced memory
* @work: data to be freed
*
* The work_struct is overlaid to the data being freed, as at the point
* the work is scheduled the data is no longer valid, be its freeing
* needs to be delayed until safe.
*/
static void do_vfree(struct work_struct *work)
{
vfree(work);
}
/**
* kvfree - free an allocation do by kvmalloc
* @buffer: buffer to free (MAYBE_NULL)
*
* Free a buffer allocated by kvmalloc
*/
void kvfree(void *buffer)
{
if (is_vmalloc_addr(buffer)) {
/* Data is no longer valid so just use the allocated space
* as the work_struct
*/
struct work_struct *work = (struct work_struct *) buffer;
INIT_WORK(work, do_vfree);
schedule_work(work);
} else
kfree(buffer);
}

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security/apparmor/path.c Normal file
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/*
* AppArmor security module
*
* This file contains AppArmor function for pathnames
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*
* 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 of the
* License.
*/
#include <linux/magic.h>
#include <linux/mnt_namespace.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/nsproxy.h>
#include <linux/path.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs_struct.h>
#include "include/apparmor.h"
#include "include/path.h"
#include "include/policy.h"
/* modified from dcache.c */
static int prepend(char **buffer, int buflen, const char *str, int namelen)
{
buflen -= namelen;
if (buflen < 0)
return -ENAMETOOLONG;
*buffer -= namelen;
memcpy(*buffer, str, namelen);
return 0;
}
#define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT)
/**
* d_namespace_path - lookup a name associated with a given path
* @path: path to lookup (NOT NULL)
* @buf: buffer to store path to (NOT NULL)
* @buflen: length of @buf
* @name: Returns - pointer for start of path name with in @buf (NOT NULL)
* @flags: flags controlling path lookup
*
* Handle path name lookup.
*
* Returns: %0 else error code if path lookup fails
* When no error the path name is returned in @name which points to
* to a position in @buf
*/
static int d_namespace_path(struct path *path, char *buf, int buflen,
char **name, int flags)
{
struct path root, tmp;
char *res;
int deleted, connected;
int error = 0;
/* Get the root we want to resolve too */
if (flags & PATH_CHROOT_REL) {
/* resolve paths relative to chroot */
read_lock(&current->fs->lock);
root = current->fs->root;
/* released below */
path_get(&root);
read_unlock(&current->fs->lock);
} else {
/* resolve paths relative to namespace */
root.mnt = current->nsproxy->mnt_ns->root;
root.dentry = root.mnt->mnt_root;
/* released below */
path_get(&root);
}
spin_lock(&dcache_lock);
/* There is a race window between path lookup here and the
* need to strip the " (deleted) string that __d_path applies
* Detect the race and relookup the path
*
* The stripping of (deleted) is a hack that could be removed
* with an updated __d_path
*/
do {
tmp = root;
deleted = d_unlinked(path->dentry);
res = __d_path(path, &tmp, buf, buflen);
} while (deleted != d_unlinked(path->dentry));
spin_unlock(&dcache_lock);
*name = res;
/* handle error conditions - and still allow a partial path to
* be returned.
*/
if (IS_ERR(res)) {
error = PTR_ERR(res);
*name = buf;
goto out;
}
if (deleted) {
/* On some filesystems, newly allocated dentries appear to the
* security_path hooks as a deleted dentry except without an
* inode allocated.
*
* Remove the appended deleted text and return as string for
* normal mediation, or auditing. The (deleted) string is
* guaranteed to be added in this case, so just strip it.
*/
buf[buflen - 11] = 0; /* - (len(" (deleted)") +\0) */
if (path->dentry->d_inode && !(flags & PATH_MEDIATE_DELETED)) {
error = -ENOENT;
goto out;
}
}
/* Determine if the path is connected to the expected root */
connected = tmp.dentry == root.dentry && tmp.mnt == root.mnt;
/* If the path is not connected,
* check if it is a sysctl and handle specially else remove any
* leading / that __d_path may have returned.
* Unless
* specifically directed to connect the path,
* OR
* if in a chroot and doing chroot relative paths and the path
* resolves to the namespace root (would be connected outside
* of chroot) and specifically directed to connect paths to
* namespace root.
*/
if (!connected) {
/* is the disconnect path a sysctl? */
if (tmp.dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
strncmp(*name, "/sys/", 5) == 0) {
/* TODO: convert over to using a per namespace
* control instead of hard coded /proc
*/
error = prepend(name, *name - buf, "/proc", 5);
} else if (!(flags & PATH_CONNECT_PATH) &&
!(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
(tmp.mnt == current->nsproxy->mnt_ns->root &&
tmp.dentry == tmp.mnt->mnt_root))) {
/* disconnected path, don't return pathname starting
* with '/'
*/
error = -ESTALE;
if (*res == '/')
*name = res + 1;
}
}
out:
path_put(&root);
return error;
}
/**
* get_name_to_buffer - get the pathname to a buffer ensure dir / is appended
* @path: path to get name for (NOT NULL)
* @flags: flags controlling path lookup
* @buffer: buffer to put name in (NOT NULL)
* @size: size of buffer
* @name: Returns - contains position of path name in @buffer (NOT NULL)
*
* Returns: %0 else error on failure
*/
static int get_name_to_buffer(struct path *path, int flags, char *buffer,
int size, char **name)
{
int adjust = (flags & PATH_IS_DIR) ? 1 : 0;
int error = d_namespace_path(path, buffer, size - adjust, name, flags);
if (!error && (flags & PATH_IS_DIR) && (*name)[1] != '\0')
/*
* Append "/" to the pathname. The root directory is a special
* case; it already ends in slash.
*/
strcpy(&buffer[size - 2], "/");
return error;
}
/**
* aa_get_name - compute the pathname of a file
* @path: path the file (NOT NULL)
* @flags: flags controlling path name generation
* @buffer: buffer that aa_get_name() allocated (NOT NULL)
* @name: Returns - the generated path name if !error (NOT NULL)
*
* @name is a pointer to the beginning of the pathname (which usually differs
* from the beginning of the buffer), or NULL. If there is an error @name
* may contain a partial or invalid name that can be used for audit purposes,
* but it can not be used for mediation.
*
* We need PATH_IS_DIR to indicate whether the file is a directory or not
* because the file may not yet exist, and so we cannot check the inode's
* file type.
*
* Returns: %0 else error code if could retrieve name
*/
int aa_get_name(struct path *path, int flags, char **buffer, const char **name)
{
char *buf, *str = NULL;
int size = 256;
int error;
*name = NULL;
*buffer = NULL;
for (;;) {
/* freed by caller */
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
return -ENOMEM;
error = get_name_to_buffer(path, flags, buf, size, &str);
if (error != -ENAMETOOLONG)
break;
kfree(buf);
size <<= 1;
if (size > aa_g_path_max)
return -ENAMETOOLONG;
}
*buffer = buf;
*name = str;
return error;
}