1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor /proc/<pid>/attr/ interface functions
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 */
10
11#include "include/apparmor.h"
12#include "include/cred.h"
13#include "include/policy.h"
14#include "include/policy_ns.h"
15#include "include/domain.h"
16#include "include/procattr.h"
17
18
19/**
20 * aa_getprocattr - Return the label information for @label
21 * @label: the label to print label info about  (NOT NULL)
22 * @string: Returns - string containing the label info (NOT NULL)
23 * @newline: indicates that a newline should be added
24 *
25 * Requires: label != NULL && string != NULL
26 *
27 * Creates a string containing the label information for @label.
28 *
29 * Returns: size of string placed in @string else error code on failure
30 */
31int aa_getprocattr(struct aa_label *label, char **string, bool newline)
32{
33	struct aa_ns *ns = labels_ns(label);
34	struct aa_ns *current_ns = aa_get_current_ns();
35	int len;
36
37	if (!aa_ns_visible(current_ns, ns, true)) {
38		aa_put_ns(current_ns);
39		return -EACCES;
40	}
41
42	len = aa_label_snxprint(NULL, 0, current_ns, label,
43				FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
44				FLAG_HIDDEN_UNCONFINED);
45	AA_BUG(len < 0);
46
47	*string = kmalloc(len + 2, GFP_KERNEL);
48	if (!*string) {
49		aa_put_ns(current_ns);
50		return -ENOMEM;
51	}
52
53	len = aa_label_snxprint(*string, len + 2, current_ns, label,
54				FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
55				FLAG_HIDDEN_UNCONFINED);
56	if (len < 0) {
57		aa_put_ns(current_ns);
58		return len;
59	}
60
61	if (newline)
62		(*string)[len++] = '\n';
63	(*string)[len] = 0;
64
65	aa_put_ns(current_ns);
66	return len;
67}
68
69/**
70 * split_token_from_name - separate a string of form  <token>^<name>
71 * @op: operation being checked
72 * @args: string to parse  (NOT NULL)
73 * @token: stores returned parsed token value  (NOT NULL)
74 *
75 * Returns: start position of name after token else NULL on failure
76 */
77static char *split_token_from_name(const char *op, char *args, u64 *token)
78{
79	char *name;
80
81	*token = simple_strtoull(args, &name, 16);
82	if ((name == args) || *name != '^') {
83		AA_ERROR("%s: Invalid input '%s'", op, args);
84		return ERR_PTR(-EINVAL);
85	}
86
87	name++;			/* skip ^ */
88	if (!*name)
89		name = NULL;
90	return name;
91}
92
93/**
94 * aa_setprocattr_changehat - handle procattr interface to change_hat
95 * @args: args received from writing to /proc/<pid>/attr/current (NOT NULL)
96 * @size: size of the args
97 * @flags: set of flags governing behavior
98 *
99 * Returns: %0 or error code if change_hat fails
100 */
101int aa_setprocattr_changehat(char *args, size_t size, int flags)
102{
103	char *hat;
104	u64 token;
105	const char *hats[16];		/* current hard limit on # of names */
106	int count = 0;
107
108	hat = split_token_from_name(OP_CHANGE_HAT, args, &token);
109	if (IS_ERR(hat))
110		return PTR_ERR(hat);
111
112	if (!hat && !token) {
113		AA_ERROR("change_hat: Invalid input, NULL hat and NULL magic");
114		return -EINVAL;
115	}
116
117	if (hat) {
118		/* set up hat name vector, args guaranteed null terminated
119		 * at args[size] by setprocattr.
120		 *
121		 * If there are multiple hat names in the buffer each is
122		 * separated by a \0.  Ie. userspace writes them pre tokenized
123		 */
124		char *end = args + size;
125		for (count = 0; (hat < end) && count < 16; ++count) {
126			char *next = hat + strlen(hat) + 1;
127			hats[count] = hat;
128			AA_DEBUG("%s: (pid %d) Magic 0x%llx count %d hat '%s'\n"
129				 , __func__, current->pid, token, count, hat);
130			hat = next;
131		}
132	} else
133		AA_DEBUG("%s: (pid %d) Magic 0x%llx count %d Hat '%s'\n",
134			 __func__, current->pid, token, count, "<NULL>");
135
136	return aa_change_hat(hats, count, token, flags);
137}
138