1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/compat.h>
4 #include <linux/errno.h>
5 #include <linux/prctl.h>
6 #include <linux/random.h>
7 #include <linux/sched.h>
8 #include <asm/cpufeature.h>
9 #include <asm/pointer_auth.h>
10
ptrauth_prctl_reset_keys(struct task_struct * tsk,unsigned long arg)11 int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
12 {
13 struct ptrauth_keys_user *keys = &tsk->thread.keys_user;
14 unsigned long addr_key_mask = PR_PAC_APIAKEY | PR_PAC_APIBKEY |
15 PR_PAC_APDAKEY | PR_PAC_APDBKEY;
16 unsigned long key_mask = addr_key_mask | PR_PAC_APGAKEY;
17
18 if (!system_supports_address_auth() && !system_supports_generic_auth())
19 return -EINVAL;
20
21 if (is_compat_thread(task_thread_info(tsk)))
22 return -EINVAL;
23
24 if (!arg) {
25 ptrauth_keys_init_user(keys);
26 return 0;
27 }
28
29 if (arg & ~key_mask)
30 return -EINVAL;
31
32 if (((arg & addr_key_mask) && !system_supports_address_auth()) ||
33 ((arg & PR_PAC_APGAKEY) && !system_supports_generic_auth()))
34 return -EINVAL;
35
36 if (arg & PR_PAC_APIAKEY)
37 get_random_bytes(&keys->apia, sizeof(keys->apia));
38 if (arg & PR_PAC_APIBKEY)
39 get_random_bytes(&keys->apib, sizeof(keys->apib));
40 if (arg & PR_PAC_APDAKEY)
41 get_random_bytes(&keys->apda, sizeof(keys->apda));
42 if (arg & PR_PAC_APDBKEY)
43 get_random_bytes(&keys->apdb, sizeof(keys->apdb));
44 if (arg & PR_PAC_APGAKEY)
45 get_random_bytes(&keys->apga, sizeof(keys->apga));
46 ptrauth_keys_install_user(keys);
47
48 return 0;
49 }
50
arg_to_enxx_mask(unsigned long arg)51 static u64 arg_to_enxx_mask(unsigned long arg)
52 {
53 u64 sctlr_enxx_mask = 0;
54
55 WARN_ON(arg & ~PR_PAC_ENABLED_KEYS_MASK);
56 if (arg & PR_PAC_APIAKEY)
57 sctlr_enxx_mask |= SCTLR_ELx_ENIA;
58 if (arg & PR_PAC_APIBKEY)
59 sctlr_enxx_mask |= SCTLR_ELx_ENIB;
60 if (arg & PR_PAC_APDAKEY)
61 sctlr_enxx_mask |= SCTLR_ELx_ENDA;
62 if (arg & PR_PAC_APDBKEY)
63 sctlr_enxx_mask |= SCTLR_ELx_ENDB;
64 return sctlr_enxx_mask;
65 }
66
ptrauth_set_enabled_keys(struct task_struct * tsk,unsigned long keys,unsigned long enabled)67 int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
68 unsigned long enabled)
69 {
70 u64 sctlr;
71
72 if (!system_supports_address_auth())
73 return -EINVAL;
74
75 if (is_compat_thread(task_thread_info(tsk)))
76 return -EINVAL;
77
78 if ((keys & ~PR_PAC_ENABLED_KEYS_MASK) || (enabled & ~keys))
79 return -EINVAL;
80
81 preempt_disable();
82 sctlr = tsk->thread.sctlr_user;
83 sctlr &= ~arg_to_enxx_mask(keys);
84 sctlr |= arg_to_enxx_mask(enabled);
85 tsk->thread.sctlr_user = sctlr;
86 if (tsk == current)
87 update_sctlr_el1(sctlr);
88 preempt_enable();
89
90 return 0;
91 }
92
ptrauth_get_enabled_keys(struct task_struct * tsk)93 int ptrauth_get_enabled_keys(struct task_struct *tsk)
94 {
95 int retval = 0;
96
97 if (!system_supports_address_auth())
98 return -EINVAL;
99
100 if (is_compat_thread(task_thread_info(tsk)))
101 return -EINVAL;
102
103 if (tsk->thread.sctlr_user & SCTLR_ELx_ENIA)
104 retval |= PR_PAC_APIAKEY;
105 if (tsk->thread.sctlr_user & SCTLR_ELx_ENIB)
106 retval |= PR_PAC_APIBKEY;
107 if (tsk->thread.sctlr_user & SCTLR_ELx_ENDA)
108 retval |= PR_PAC_APDAKEY;
109 if (tsk->thread.sctlr_user & SCTLR_ELx_ENDB)
110 retval |= PR_PAC_APDBKEY;
111
112 return retval;
113 }
114