Message-Id: <1266572188-26529-2-git-send-email-john.johansen@canonical.com>
Date:	Fri, 19 Feb 2010 01:36:17 -0800
From:	john.johansen@...onical.com
To:	linux-kernel@...r.kernel.org
Cc:	linux-security-module@...r.kernel.org,
	John Johansen <john.johansen@...onical.com>
Subject: [PATCH 01/12] Miscellaneous functions and defines needed by AppArmor, including the base path resolution routines.

From: John Johansen <john.johansen@...onical.com>

Signed-off-by: John Johansen <john.johansen@...onical.com>
---
 security/apparmor/include/apparmor.h |   82 +++++++++++++
 security/apparmor/include/path.h     |   31 +++++
 security/apparmor/lib.c              |   85 +++++++++++++
 security/apparmor/path.c             |  215 ++++++++++++++++++++++++++++++++++
 4 files changed, 413 insertions(+), 0 deletions(-)
 create mode 100644 security/apparmor/include/apparmor.h
 create mode 100644 security/apparmor/include/path.h
 create mode 100644 security/apparmor/lib.c
 create mode 100644 security/apparmor/path.c

diff --git a/security/apparmor/include/apparmor.h b/security/apparmor/include/apparmor.h
new file mode 100644
index 0000000..25c1647
--- /dev/null
+++ b/security/apparmor/include/apparmor.h
@@ -0,0 +1,82 @@
+/*
+ * 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 thru module/boot flags or
+ * via /sys/kernel/security/apparmor/control */
+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;
+void apparmor_disable(void);
+
+/* fn's in lib */
+char *aa_split_fqname(char *args, char **ns_name);
+bool aa_strneq(const char *str, const char *sub, int len);
+void aa_info_message(const char *str);
+
+/**
+ * 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
+ * @old: true if using // as the null transition
+ *
+ * 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 seperate pairs.
+ */
+static inline unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
+						  unsigned int start, bool old)
+{
+	if (unlikely(old))
+		return aa_dfa_match_len(dfa, start, "//", 2);
+	else
+		return aa_dfa_match_len(dfa, start, "\0", 1);
+}
+
+static inline bool mediated_filesystem(struct inode *inode)
+{
+	return !(inode->i_sb->s_flags & MS_NOUSER);
+}
+
+#endif /* __APPARMOR_H */
diff --git a/security/apparmor/include/path.h b/security/apparmor/include/path.h
new file mode 100644
index 0000000..6933d64
--- /dev/null
+++ b/security/apparmor/include/path.h
@@ -0,0 +1,31 @@
+/*
+ * 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_MEDIATE_DELETED = 0x10000,	/* mediate deleted paths */
+};
+
+int aa_get_name(struct path *path, int flags, char **buffer, char **name);
+char *sysctl_pathname(struct ctl_table *table, char *buffer, int buflen);
+
+#endif /* __AA_PATH_H */
diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
new file mode 100644
index 0000000..896f8d2
--- /dev/null
+++ b/security/apparmor/lib.c
@@ -0,0 +1,85 @@
+/*
+ * 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 "include/audit.h"
+
+
+/**
+ * aa_split_fqname - split a fqname into a profile and namespace name
+ * @fqname: a full qualified name in namespace profile format
+ * @ns_name: pointer to portion of the string containing the ns name
+ *
+ * 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 modifiy the @fqname string.  The pointers returned point
+ *       into the @fqname string.
+ */
+char *aa_split_fqname(char *fqname, char **ns_name)
+{
+	char *name = strstrip(fqname);
+
+	*ns_name = NULL;
+	if (fqname[0] == ':') {
+		char *split = strchr(&fqname[1], ':');
+		if (split) {
+			/* overwrite ':' with \0 */
+			*split = 0;
+			name = strstrip(split + 1);
+		} else
+			/* a ns name without a following profile is allowed */
+			name = NULL;
+		*ns_name = &fqname[1];
+	}
+	if (name && *name == 0)
+		name = NULL;
+
+	return name;
+}
+
+/**
+ * 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
+ */
+bool aa_strneq(const char *str, const char *sub, int len)
+{
+	int res = strncmp(str, sub, len);
+	if (res)
+		return 0;
+	if (str[len] == 0)
+		return 1;
+	return 0;
+}
+
+void aa_info_message(const char *str)
+{
+	struct aa_audit sa = {
+		.gfp_mask = GFP_KERNEL,
+		.info = str,
+	};
+	printk(KERN_INFO "AppArmor: %s\n", str);
+	if (audit_enabled)
+		aa_audit(AUDIT_APPARMOR_STATUS, NULL, &sa, NULL);
+}
+
diff --git a/security/apparmor/path.c b/security/apparmor/path.c
new file mode 100644
index 0000000..a589d9d
--- /dev/null
+++ b/security/apparmor/path.c
@@ -0,0 +1,215 @@
+/*
+ * 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/mnt_namespace.h>
+#include <linux/mount.h>
+#include <linux/namei.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"
+
+/**
+ * d_namespace_path - lookup a name associated with a given path
+ * @path: path to lookup
+ * @buf:  buffer to store path to
+ * @buflen: length of @buf
+ * @name: returns pointer for start of path name with in @buf
+ * @flags: flags controling path lookup
+ *
+ */
+static int d_namespace_path(struct path *path, char *buf, int buflen,
+			    char **name, int flags)
+{
+	struct path root, tmp, ns_root = { };
+	char *res;
+	int deleted, connected;
+	int error = 0;
+
+	read_lock(&current->fs->lock);
+	root = current->fs->root;
+	/* released below */
+	path_get(&root);
+	read_unlock(&current->fs->lock);
+
+	spin_lock(&vfsmount_lock);
+	if (root.mnt && root.mnt->mnt_ns)
+		/* released below */
+		ns_root.mnt = mntget(root.mnt->mnt_ns->root);
+	if (ns_root.mnt)
+		/* released below */
+		ns_root.dentry = dget(ns_root.mnt->mnt_root);
+	spin_unlock(&vfsmount_lock);
+
+	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 {
+		if (flags & PATH_CHROOT_REL)
+			tmp = root;
+		else
+			tmp = ns_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
+		 * guarenteed 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;
+		}
+	}
+
+	if (flags & PATH_CHROOT_REL)
+		connected = tmp.dentry == root.dentry && tmp.mnt == root.mnt;
+	else
+		connected = tmp.dentry == ns_root.dentry &&
+			tmp.mnt == ns_root.mnt;
+
+	if (!connected && 
+	    !(flags & PATH_CONNECT_PATH) &&
+	    !((flags & PATH_CHROOT_REL) && (flags & PATH_CHROOT_NSCONNECT) &&
+	      (tmp.dentry == ns_root.dentry && tmp.mnt == ns_root.mnt))) {
+		/* disconnected path, don't return pathname starting with '/' */
+		error = -ESTALE;
+		if (*res == '/')
+			*name = res + 1;
+	}
+
+out:
+	path_put(&root);
+	path_put(&ns_root);
+
+	return error;
+}
+
+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
+ * @flags: flags controling path name generation
+ * @buffer: buffer that aa_get_name() allocated
+ * @name: the generated path name if there is an error
+ *
+ * Returns an error code if the there was a failure in obtaining the
+ * name.
+ *
+ * @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 (in the case of a deleted file), 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.
+ */
+int aa_get_name(struct path *path, int flags, char **buffer, 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 || (error == -ENOENT) || (error == -ESTALE))
+			break;
+
+		kfree(buf);
+		size <<= 1;
+		if (size > aa_g_path_max)
+			return -ENAMETOOLONG;
+	}
+	*buffer = buf;
+	*name = str;
+
+	return error;
+}
+
+char *sysctl_pathname(struct ctl_table *table, char *buffer, int buflen)
+{
+	if (buflen < 1)
+		return NULL;
+	buffer += --buflen;
+	*buffer = '\0';
+
+	while (table) {
+		int namelen = strlen(table->procname);
+
+		if (buflen < namelen + 1)
+			return NULL;
+		buflen -= namelen + 1;
+		buffer -= namelen;
+		memcpy(buffer, table->procname, namelen);
+		*--buffer = '/';
+		table = table->parent;
+	}
+	if (buflen < 4)
+		return NULL;
+	buffer -= 4;
+	memcpy(buffer, "/sys", 4);
+
+	return buffer;
+}
-- 
1.6.6.1

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