signal_compat.c (7435B)
1// SPDX-License-Identifier: GPL-2.0 2#include <linux/compat.h> 3#include <linux/uaccess.h> 4#include <linux/ptrace.h> 5 6/* 7 * The compat_siginfo_t structure and handing code is very easy 8 * to break in several ways. It must always be updated when new 9 * updates are made to the main siginfo_t, and 10 * copy_siginfo_to_user32() must be updated when the 11 * (arch-independent) copy_siginfo_to_user() is updated. 12 * 13 * It is also easy to put a new member in the compat_siginfo_t 14 * which has implicit alignment which can move internal structure 15 * alignment around breaking the ABI. This can happen if you, 16 * for instance, put a plain 64-bit value in there. 17 */ 18static inline void signal_compat_build_tests(void) 19{ 20 int _sifields_offset = offsetof(compat_siginfo_t, _sifields); 21 22 /* 23 * If adding a new si_code, there is probably new data in 24 * the siginfo. Make sure folks bumping the si_code 25 * limits also have to look at this code. Make sure any 26 * new fields are handled in copy_siginfo_to_user32()! 27 */ 28 BUILD_BUG_ON(NSIGILL != 11); 29 BUILD_BUG_ON(NSIGFPE != 15); 30 BUILD_BUG_ON(NSIGSEGV != 9); 31 BUILD_BUG_ON(NSIGBUS != 5); 32 BUILD_BUG_ON(NSIGTRAP != 6); 33 BUILD_BUG_ON(NSIGCHLD != 6); 34 BUILD_BUG_ON(NSIGSYS != 2); 35 36 /* This is part of the ABI and can never change in size: */ 37 BUILD_BUG_ON(sizeof(siginfo_t) != 128); 38 BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128); 39 40 /* This is a part of the ABI and can never change in alignment */ 41 BUILD_BUG_ON(__alignof__(siginfo_t) != 8); 42 BUILD_BUG_ON(__alignof__(compat_siginfo_t) != 4); 43 44 /* 45 * The offsets of all the (unioned) si_fields are fixed 46 * in the ABI, of course. Make sure none of them ever 47 * move and are always at the beginning: 48 */ 49 BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int)); 50#define CHECK_CSI_OFFSET(name) BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name)) 51 52 BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0); 53 BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4); 54 BUILD_BUG_ON(offsetof(siginfo_t, si_code) != 8); 55 56 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_signo) != 0); 57 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_errno) != 4); 58 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_code) != 8); 59 /* 60 * Ensure that the size of each si_field never changes. 61 * If it does, it is a sign that the 62 * copy_siginfo_to_user32() code below needs to updated 63 * along with the size in the CHECK_SI_SIZE(). 64 * 65 * We repeat this check for both the generic and compat 66 * siginfos. 67 * 68 * Note: it is OK for these to grow as long as the whole 69 * structure stays within the padding size (checked 70 * above). 71 */ 72#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((compat_siginfo_t *)0)->_sifields.name)) 73#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((siginfo_t *)0)->_sifields.name)) 74 75 CHECK_CSI_OFFSET(_kill); 76 CHECK_CSI_SIZE (_kill, 2*sizeof(int)); 77 CHECK_SI_SIZE (_kill, 2*sizeof(int)); 78 79 BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); 80 BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); 81 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0xC); 82 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); 83 84 CHECK_CSI_OFFSET(_timer); 85 CHECK_CSI_SIZE (_timer, 3*sizeof(int)); 86 CHECK_SI_SIZE (_timer, 6*sizeof(int)); 87 88 BUILD_BUG_ON(offsetof(siginfo_t, si_tid) != 0x10); 89 BUILD_BUG_ON(offsetof(siginfo_t, si_overrun) != 0x14); 90 BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18); 91 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_tid) != 0x0C); 92 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_overrun) != 0x10); 93 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14); 94 95 CHECK_CSI_OFFSET(_rt); 96 CHECK_CSI_SIZE (_rt, 3*sizeof(int)); 97 CHECK_SI_SIZE (_rt, 4*sizeof(int)); 98 99 BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); 100 BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); 101 BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18); 102 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C); 103 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); 104 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14); 105 106 CHECK_CSI_OFFSET(_sigchld); 107 CHECK_CSI_SIZE (_sigchld, 5*sizeof(int)); 108 CHECK_SI_SIZE (_sigchld, 8*sizeof(int)); 109 110 BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); 111 BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); 112 BUILD_BUG_ON(offsetof(siginfo_t, si_status) != 0x18); 113 BUILD_BUG_ON(offsetof(siginfo_t, si_utime) != 0x20); 114 BUILD_BUG_ON(offsetof(siginfo_t, si_stime) != 0x28); 115 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C); 116 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); 117 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_status) != 0x14); 118 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_utime) != 0x18); 119 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_stime) != 0x1C); 120 121#ifdef CONFIG_X86_X32_ABI 122 CHECK_CSI_OFFSET(_sigchld_x32); 123 CHECK_CSI_SIZE (_sigchld_x32, 7*sizeof(int)); 124 /* no _sigchld_x32 in the generic siginfo_t */ 125 BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime) != 0x18); 126 BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime) != 0x20); 127#endif 128 129 CHECK_CSI_OFFSET(_sigfault); 130 CHECK_CSI_SIZE (_sigfault, 4*sizeof(int)); 131 CHECK_SI_SIZE (_sigfault, 8*sizeof(int)); 132 133 BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10); 134 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C); 135 136 BUILD_BUG_ON(offsetof(siginfo_t, si_trapno) != 0x18); 137 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_trapno) != 0x10); 138 139 BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18); 140 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10); 141 142 BUILD_BUG_ON(offsetof(siginfo_t, si_lower) != 0x20); 143 BUILD_BUG_ON(offsetof(siginfo_t, si_upper) != 0x28); 144 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_lower) != 0x14); 145 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_upper) != 0x18); 146 147 BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20); 148 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14); 149 150 BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18); 151 BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20); 152 BUILD_BUG_ON(offsetof(siginfo_t, si_perf_flags) != 0x24); 153 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10); 154 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x14); 155 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_flags) != 0x18); 156 157 CHECK_CSI_OFFSET(_sigpoll); 158 CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int)); 159 CHECK_SI_SIZE (_sigpoll, 4*sizeof(int)); 160 161 BUILD_BUG_ON(offsetof(siginfo_t, si_band) != 0x10); 162 BUILD_BUG_ON(offsetof(siginfo_t, si_fd) != 0x18); 163 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_band) != 0x0C); 164 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_fd) != 0x10); 165 166 CHECK_CSI_OFFSET(_sigsys); 167 CHECK_CSI_SIZE (_sigsys, 3*sizeof(int)); 168 CHECK_SI_SIZE (_sigsys, 4*sizeof(int)); 169 170 BUILD_BUG_ON(offsetof(siginfo_t, si_call_addr) != 0x10); 171 BUILD_BUG_ON(offsetof(siginfo_t, si_syscall) != 0x18); 172 BUILD_BUG_ON(offsetof(siginfo_t, si_arch) != 0x1C); 173 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_call_addr) != 0x0C); 174 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_syscall) != 0x10); 175 BUILD_BUG_ON(offsetof(compat_siginfo_t, si_arch) != 0x14); 176 177 /* any new si_fields should be added here */ 178} 179 180void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact) 181{ 182 signal_compat_build_tests(); 183 184 if (!act) 185 return; 186 187 if (in_ia32_syscall()) 188 act->sa.sa_flags |= SA_IA32_ABI; 189 if (in_x32_syscall()) 190 act->sa.sa_flags |= SA_X32_ABI; 191}