Commit message: AppArmor: fix oops in apparmor_setprocattr

When invalid parameters are passed to apparmor_setprocattr a NULL deref
oops occurs when it tries to record an audit message. This is because
it is passing NULL for the profile parameter for aa_audit. But aa_audit
now requires that the profile passed is not NULL.

Fix this by passing the current profile on the task that is trying to
setprocattr.

Signed-off-by: Kees Cook <kees@ubuntu.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Cc: stable@kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
CVE: CVE-2011-3619
CWE: CWE-20
Vulnerability description: The apparmor_setprocattr function in security/apparmor/lsm.c in the Linux kernel before 3.0 does not properly handle invalid parameters, which allows local users to cause a denial of service (NULL pointer dereference and OOPS) or possibly have unspecified other impact by writing to a /proc/#####/attr/current file.

Project: linux
File: lsm.c

static int apparmor_capable(struct task_struct *task, const struct cred *cred,
			    struct user_namespace *ns, int cap, int audit)
{
	struct aa_profile *profile;
	/* cap_capable returns 0 on success, else -EPERM */
	int error = cap_capable(task, cred, ns, cap, audit);
	if (!error) {
		profile = aa_cred_profile(cred);
		if (!unconfined(profile))
			error = aa_capable(task, profile, cap, audit);
	}
	return error;
}

Project: linux
File: lsm.c

static int apparmor_capget(struct task_struct *target, kernel_cap_t *effective,
			   kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
	struct aa_profile *profile;
	const struct cred *cred;

	rcu_read_lock();
	cred = __task_cred(target);
	profile = aa_cred_profile(cred);

	*effective = cred->cap_effective;
	*inheritable = cred->cap_inheritable;
	*permitted = cred->cap_permitted;

	if (!unconfined(profile)) {
		*effective = cap_intersect(*effective, profile->caps.allow);
		*permitted = cap_intersect(*permitted, profile->caps.allow);
	}
	rcu_read_unlock();

	return 0;
}

Project: linux
File: lsm.c

static void apparmor_cred_free(struct cred *cred)
{
	aa_free_task_context(cred->security);
	cred->security = NULL;
}

Project: linux
File: lsm.c

static int apparmor_cred_prepare(struct cred *new, const struct cred *old,
				 gfp_t gfp)
{
	/* freed by apparmor_cred_free */
	struct aa_task_cxt *cxt = aa_alloc_task_context(gfp);
	if (!cxt)
		return -ENOMEM;

	aa_dup_task_context(cxt, old->security);
	new->security = cxt;
	return 0;
}

Project: linux
File: lsm.c

static void apparmor_cred_transfer(struct cred *new, const struct cred *old)
{
	const struct aa_task_cxt *old_cxt = old->security;
	struct aa_task_cxt *new_cxt = new->security;

	aa_dup_task_context(new_cxt, old_cxt);
}

Project: linux
File: lsm.c

static int apparmor_dentry_open(struct file *file, const struct cred *cred)
{
	struct aa_file_cxt *fcxt = file->f_security;
	struct aa_profile *profile;
	int error = 0;

	if (!mediated_filesystem(file->f_path.dentry->d_inode))
		return 0;

	/* If in exec, permission is handled by bprm hooks.
	 * Cache permissions granted by the previous exec check, with
	 * implicit read and executable mmap which are required to
	 * actually execute the image.
	 */
	if (current->in_execve) {
		fcxt->allow = MAY_EXEC | MAY_READ | AA_EXEC_MMAP;
		return 0;
	}

	profile = aa_cred_profile(cred);
	if (!unconfined(profile)) {
		struct inode *inode = file->f_path.dentry->d_inode;
		struct path_cond cond = { inode->i_uid, inode->i_mode };

		error = aa_path_perm(OP_OPEN, profile, &file->f_path, 0,
				     aa_map_file_to_perms(file), &cond);
		/* todo cache full allowed permissions set and state */
		fcxt->allow = aa_map_file_to_perms(file);
	}

	return error;
}

Project: linux
File: lsm.c

static int __init apparmor_enabled_setup(char *str)
{
	unsigned long enabled;
	int error = strict_strtoul(str, 0, &enabled);
	if (!error)
		apparmor_enabled = enabled ? 1 : 0;
	return 1;
}

Project: linux
File: lsm.c

static void apparmor_file_free_security(struct file *file)
{
	struct aa_file_cxt *cxt = file->f_security;

	aa_free_file_context(cxt);
}

Project: linux
File: lsm.c

static int apparmor_file_lock(struct file *file, unsigned int cmd)
{
	u32 mask = AA_MAY_LOCK;

	if (cmd == F_WRLCK)
		mask |= MAY_WRITE;

	return common_file_perm(OP_FLOCK, file, mask);
}

Project: linux
File: lsm.c

static int apparmor_file_mprotect(struct vm_area_struct *vma,
				  unsigned long reqprot, unsigned long prot)
{
	return common_mmap(OP_FMPROT, vma->vm_file, prot,
			   !(vma->vm_flags & VM_SHARED) ? MAP_PRIVATE : 0);
}

Project: linux
File: lsm.c

static int apparmor_file_permission(struct file *file, int mask)
{
	return common_file_perm(OP_FPERM, file, mask);
}

Project: linux
File: lsm.c

static int apparmor_getprocattr(struct task_struct *task, char *name,
				char **value)
{
	int error = -ENOENT;
	struct aa_profile *profile;
	/* released below */
	const struct cred *cred = get_task_cred(task);
	struct aa_task_cxt *cxt = cred->security;
	profile = aa_cred_profile(cred);

	if (strcmp(name, "current") == 0)
		error = aa_getprocattr(aa_newest_version(cxt->profile),
				       value);
	else if (strcmp(name, "prev") == 0  && cxt->previous)
		error = aa_getprocattr(aa_newest_version(cxt->previous),
				       value);
	else if (strcmp(name, "exec") == 0 && cxt->onexec)
		error = aa_getprocattr(aa_newest_version(cxt->onexec),
				       value);
	else
		error = -EINVAL;

	put_cred(cred);

	return error;
}

Project: linux
File: lsm.c

static int __init apparmor_init(void)
{
	int error;

	if (!apparmor_enabled || !security_module_enable(&apparmor_ops)) {
		aa_info_message("AppArmor disabled by boot time parameter");
		apparmor_enabled = 0;
		return 0;
	}

	error = aa_alloc_root_ns();
	if (error) {
		AA_ERROR("Unable to allocate default profile namespace\n");
		goto alloc_out;
	}

	error = set_init_cxt();
	if (error) {
		AA_ERROR("Failed to set context on init task\n");
		goto register_security_out;
	}

	error = register_security(&apparmor_ops);
	if (error) {
		AA_ERROR("Unable to register AppArmor\n");
		goto set_init_cxt_out;
	}

	/* Report that AppArmor successfully initialized */
	apparmor_initialized = 1;
	if (aa_g_profile_mode == APPARMOR_COMPLAIN)
		aa_info_message("AppArmor initialized: complain mode enabled");
	else if (aa_g_profile_mode == APPARMOR_KILL)
		aa_info_message("AppArmor initialized: kill mode enabled");
	else
		aa_info_message("AppArmor initialized");

	return error;

set_init_cxt_out:
	aa_free_task_context(current->real_cred->security);

register_security_out:
	aa_free_root_ns();

alloc_out:
	aa_destroy_aafs();

	apparmor_enabled = 0;
	return error;
}

Project: linux
File: lsm.c

static int apparmor_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
{
	if (!mediated_filesystem(dentry->d_inode))
		return 0;

	return common_perm_mnt_dentry(OP_GETATTR, mnt, dentry,
				      AA_MAY_META_READ);
}

Project: linux
File: lsm.c

static int apparmor_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
			       mode_t mode)
{
	if (!mediated_filesystem(dentry->d_inode))
		return 0;

	return common_perm_mnt_dentry(OP_CHMOD, mnt, dentry, AA_MAY_CHMOD);
}

Project: linux
File: lsm.c

static int apparmor_path_chown(struct path *path, uid_t uid, gid_t gid)
{
	struct path_cond cond =  { path->dentry->d_inode->i_uid,
				   path->dentry->d_inode->i_mode
	};

	if (!mediated_filesystem(path->dentry->d_inode))
		return 0;

	return common_perm(OP_CHOWN, path, AA_MAY_CHOWN, &cond);
}

Project: linux
File: lsm.c

static int apparmor_path_mkdir(struct path *dir, struct dentry *dentry,
			       int mode)
{
	return common_perm_create(OP_MKDIR, dir, dentry, AA_MAY_CREATE,
				  S_IFDIR);
}

Project: linux
File: lsm.c

static int apparmor_path_mknod(struct path *dir, struct dentry *dentry,
			       int mode, unsigned int dev)
{
	return common_perm_create(OP_MKNOD, dir, dentry, AA_MAY_CREATE, mode);
}

Project: linux
File: lsm.c

static int apparmor_path_rename(struct path *old_dir, struct dentry *old_dentry,
				struct path *new_dir, struct dentry *new_dentry)
{
	struct aa_profile *profile;
	int error = 0;

	if (!mediated_filesystem(old_dentry->d_inode))
		return 0;

	profile = aa_current_profile();
	if (!unconfined(profile)) {
		struct path old_path = { old_dir->mnt, old_dentry };
		struct path new_path = { new_dir->mnt, new_dentry };
		struct path_cond cond = { old_dentry->d_inode->i_uid,
					  old_dentry->d_inode->i_mode
		};

		error = aa_path_perm(OP_RENAME_SRC, profile, &old_path, 0,
				     MAY_READ | AA_MAY_META_READ | MAY_WRITE |
				     AA_MAY_META_WRITE | AA_MAY_DELETE,
				     &cond);
		if (!error)
			error = aa_path_perm(OP_RENAME_DEST, profile, &new_path,
					     0, MAY_WRITE | AA_MAY_META_WRITE |
					     AA_MAY_CREATE, &cond);

	}
	return error;
}

Project: linux
File: lsm.c

static int apparmor_path_rmdir(struct path *dir, struct dentry *dentry)
{
	return common_perm_rm(OP_RMDIR, dir, dentry, AA_MAY_DELETE);
}

Project: linux
File: lsm.c

static int apparmor_path_symlink(struct path *dir, struct dentry *dentry,
				 const char *old_name)
{
	return common_perm_create(OP_SYMLINK, dir, dentry, AA_MAY_CREATE,
				  S_IFLNK);
}

Project: linux
File: lsm.c

static int apparmor_ptrace_traceme(struct task_struct *parent)
{
	int error = cap_ptrace_traceme(parent);
	if (error)
		return error;

	return aa_ptrace(parent, current, PTRACE_MODE_ATTACH);
}

Project: linux
File: lsm.c

static int common_file_perm(int op, struct file *file, u32 mask)
{
	struct aa_file_cxt *fcxt = file->f_security;
	struct aa_profile *profile, *fprofile = aa_cred_profile(file->f_cred);
	int error = 0;

	BUG_ON(!fprofile);

	if (!file->f_path.mnt ||
	    !mediated_filesystem(file->f_path.dentry->d_inode))
		return 0;

	profile = __aa_current_profile();

	/* revalidate access, if task is unconfined, or the cached cred
	 * doesn't match or if the request is for more permissions than
	 * was granted.
	 *
	 * Note: the test for !unconfined(fprofile) is to handle file
	 *       delegation from unconfined tasks
	 */
	if (!unconfined(profile) && !unconfined(fprofile) &&
	    ((fprofile != profile) || (mask & ~fcxt->allow)))
		error = aa_file_perm(op, profile, file, mask);

	return error;
}

Project: linux
File: lsm.c

static int common_mmap(int op, struct file *file, unsigned long prot,
		       unsigned long flags)
{
	struct dentry *dentry;
	int mask = 0;

	if (!file || !file->f_security)
		return 0;

	if (prot & PROT_READ)
		mask |= MAY_READ;
	/*
	 * Private mappings don't require write perms since they don't
	 * write back to the files
	 */
	if ((prot & PROT_WRITE) && !(flags & MAP_PRIVATE))
		mask |= MAY_WRITE;
	if (prot & PROT_EXEC)
		mask |= AA_EXEC_MMAP;

	dentry = file->f_path.dentry;
	return common_file_perm(op, file, mask);
}

Project: linux
File: lsm.c

static int common_perm(int op, struct path *path, u32 mask,
		       struct path_cond *cond)
{
	struct aa_profile *profile;
	int error = 0;

	profile = __aa_current_profile();
	if (!unconfined(profile))
		error = aa_path_perm(op, profile, path, 0, mask, cond);

	return error;
}

Project: linux
File: lsm.c

static int common_perm_create(int op, struct path *dir, struct dentry *dentry,
			      u32 mask, umode_t mode)
{
	struct path_cond cond = { current_fsuid(), mode };

	if (!dir->mnt || !mediated_filesystem(dir->dentry->d_inode))
		return 0;

	return common_perm_dir_dentry(op, dir, dentry, mask, &cond);
}

Project: linux
File: lsm.c

static int common_perm_dir_dentry(int op, struct path *dir,
				  struct dentry *dentry, u32 mask,
				  struct path_cond *cond)
{
	struct path path = { dir->mnt, dentry };

	return common_perm(op, &path, mask, cond);
}

Project: linux
File: lsm.c

static int common_perm_mnt_dentry(int op, struct vfsmount *mnt,
				  struct dentry *dentry, u32 mask)
{
	struct path path = { mnt, dentry };
	struct path_cond cond = { dentry->d_inode->i_uid,
				  dentry->d_inode->i_mode
	};

	return common_perm(op, &path, mask, &cond);
}

Project: linux
File: lsm.c

static int common_perm_rm(int op, struct path *dir,
			  struct dentry *dentry, u32 mask)
{
	struct inode *inode = dentry->d_inode;
	struct path_cond cond = { };

	if (!inode || !dir->mnt || !mediated_filesystem(inode))
		return 0;

	cond.uid = inode->i_uid;
	cond.mode = inode->i_mode;

	return common_perm_dir_dentry(op, dir, dentry, mask, &cond);
}

Project: linux
File: lsm.c

static int param_get_aabool(char *buffer, const struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;
	return param_get_bool(buffer, kp);
}

Project: linux
File: lsm.c

static int param_get_aauint(char *buffer, const struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;
	return param_get_uint(buffer, kp);
}

Project: linux
File: lsm.c

static int param_get_audit(char *buffer, struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;

	if (!apparmor_enabled)
		return -EINVAL;

	return sprintf(buffer, "%s", audit_mode_names[aa_g_audit]);
}

Project: linux
File: lsm.c

static int param_get_mode(char *buffer, struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;

	if (!apparmor_enabled)
		return -EINVAL;

	return sprintf(buffer, "%s", profile_mode_names[aa_g_profile_mode]);
}

Project: linux
File: lsm.c

static int param_set_aabool(const char *val, const struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;
	return param_set_bool(val, kp);
}

Project: linux
File: lsm.c

static int param_set_aalockpolicy(const char *val, const struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;
	if (aa_g_lock_policy)
		return -EACCES;
	return param_set_bool(val, kp);
}

Project: linux
File: lsm.c

static int param_set_aauint(const char *val, const struct kernel_param *kp)
{
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;
	return param_set_uint(val, kp);
}

Project: linux
File: lsm.c

static int param_set_audit(const char *val, struct kernel_param *kp)
{
	int i;
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;

	if (!apparmor_enabled)
		return -EINVAL;

	if (!val)
		return -EINVAL;

	for (i = 0; i < AUDIT_MAX_INDEX; i++) {
		if (strcmp(val, audit_mode_names[i]) == 0) {
			aa_g_audit = i;
			return 0;
		}
	}

	return -EINVAL;
}

Project: linux
File: lsm.c

static int param_set_mode(const char *val, struct kernel_param *kp)
{
	int i;
	if (!capable(CAP_MAC_ADMIN))
		return -EPERM;

	if (!apparmor_enabled)
		return -EINVAL;

	if (!val)
		return -EINVAL;

	for (i = 0; i < APPARMOR_NAMES_MAX_INDEX; i++) {
		if (strcmp(val, profile_mode_names[i]) == 0) {
			aa_g_profile_mode = i;
			return 0;
		}
	}

	return -EINVAL;
}