xref: /openbmc/linux/security/apparmor/procattr.c (revision 1f2bc06a)
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  *
24  * Requires: label != NULL && string != NULL
25  *
26  * Creates a string containing the label information for @label.
27  *
28  * Returns: size of string placed in @string else error code on failure
29  */
aa_getprocattr(struct aa_label * label,char ** string)30 int aa_getprocattr(struct aa_label *label, char **string)
31 {
32 	struct aa_ns *ns = labels_ns(label);
33 	struct aa_ns *current_ns = aa_get_current_ns();
34 	int len;
35 
36 	if (!aa_ns_visible(current_ns, ns, true)) {
37 		aa_put_ns(current_ns);
38 		return -EACCES;
39 	}
40 
41 	len = aa_label_snxprint(NULL, 0, current_ns, label,
42 				FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
43 				FLAG_HIDDEN_UNCONFINED);
44 	AA_BUG(len < 0);
45 
46 	*string = kmalloc(len + 2, GFP_KERNEL);
47 	if (!*string) {
48 		aa_put_ns(current_ns);
49 		return -ENOMEM;
50 	}
51 
52 	len = aa_label_snxprint(*string, len + 2, current_ns, label,
53 				FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
54 				FLAG_HIDDEN_UNCONFINED);
55 	if (len < 0) {
56 		aa_put_ns(current_ns);
57 		return len;
58 	}
59 
60 	(*string)[len] = '\n';
61 	(*string)[len + 1] = 0;
62 
63 	aa_put_ns(current_ns);
64 	return len + 1;
65 }
66 
67 /**
68  * split_token_from_name - separate a string of form  <token>^<name>
69  * @op: operation being checked
70  * @args: string to parse  (NOT NULL)
71  * @token: stores returned parsed token value  (NOT NULL)
72  *
73  * Returns: start position of name after token else NULL on failure
74  */
split_token_from_name(const char * op,char * args,u64 * token)75 static char *split_token_from_name(const char *op, char *args, u64 *token)
76 {
77 	char *name;
78 
79 	*token = simple_strtoull(args, &name, 16);
80 	if ((name == args) || *name != '^') {
81 		AA_ERROR("%s: Invalid input '%s'", op, args);
82 		return ERR_PTR(-EINVAL);
83 	}
84 
85 	name++;			/* skip ^ */
86 	if (!*name)
87 		name = NULL;
88 	return name;
89 }
90 
91 /**
92  * aa_setprocattr_changehat - handle procattr interface to change_hat
93  * @args: args received from writing to /proc/<pid>/attr/current (NOT NULL)
94  * @size: size of the args
95  * @flags: set of flags governing behavior
96  *
97  * Returns: %0 or error code if change_hat fails
98  */
aa_setprocattr_changehat(char * args,size_t size,int flags)99 int aa_setprocattr_changehat(char *args, size_t size, int flags)
100 {
101 	char *hat;
102 	u64 token;
103 	const char *hats[16];		/* current hard limit on # of names */
104 	int count = 0;
105 
106 	hat = split_token_from_name(OP_CHANGE_HAT, args, &token);
107 	if (IS_ERR(hat))
108 		return PTR_ERR(hat);
109 
110 	if (!hat && !token) {
111 		AA_ERROR("change_hat: Invalid input, NULL hat and NULL magic");
112 		return -EINVAL;
113 	}
114 
115 	if (hat) {
116 		/* set up hat name vector, args guaranteed null terminated
117 		 * at args[size] by setprocattr.
118 		 *
119 		 * If there are multiple hat names in the buffer each is
120 		 * separated by a \0.  Ie. userspace writes them pre tokenized
121 		 */
122 		char *end = args + size;
123 		for (count = 0; (hat < end) && count < 16; ++count) {
124 			char *next = hat + strlen(hat) + 1;
125 			hats[count] = hat;
126 			AA_DEBUG("%s: (pid %d) Magic 0x%llx count %d hat '%s'\n"
127 				 , __func__, current->pid, token, count, hat);
128 			hat = next;
129 		}
130 	} else
131 		AA_DEBUG("%s: (pid %d) Magic 0x%llx count %d Hat '%s'\n",
132 			 __func__, current->pid, token, count, "<NULL>");
133 
134 	return aa_change_hat(hats, count, token, flags);
135 }
136