diff options
Diffstat (limited to 'arch/x86/kernel/signal_compat.c')
| -rw-r--r-- | arch/x86/kernel/signal_compat.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c new file mode 100644 index 000000000..a7f3e12cf --- /dev/null +++ b/arch/x86/kernel/signal_compat.c @@ -0,0 +1,182 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/compat.h> +#include <linux/uaccess.h> +#include <linux/ptrace.h> + +/* + * The compat_siginfo_t structure and handing code is very easy + * to break in several ways. It must always be updated when new + * updates are made to the main siginfo_t, and + * copy_siginfo_to_user32() must be updated when the + * (arch-independent) copy_siginfo_to_user() is updated. + * + * It is also easy to put a new member in the compat_siginfo_t + * which has implicit alignment which can move internal structure + * alignment around breaking the ABI. This can happen if you, + * for instance, put a plain 64-bit value in there. + */ +static inline void signal_compat_build_tests(void) +{ + int _sifields_offset = offsetof(compat_siginfo_t, _sifields); + + /* + * If adding a new si_code, there is probably new data in + * the siginfo. Make sure folks bumping the si_code + * limits also have to look at this code. Make sure any + * new fields are handled in copy_siginfo_to_user32()! + */ + BUILD_BUG_ON(NSIGILL != 11); + BUILD_BUG_ON(NSIGFPE != 15); + BUILD_BUG_ON(NSIGSEGV != 9); + BUILD_BUG_ON(NSIGBUS != 5); + BUILD_BUG_ON(NSIGTRAP != 5); + BUILD_BUG_ON(NSIGCHLD != 6); + BUILD_BUG_ON(NSIGSYS != 1); + + /* This is part of the ABI and can never change in size: */ + BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128); + /* + * The offsets of all the (unioned) si_fields are fixed + * in the ABI, of course. Make sure none of them ever + * move and are always at the beginning: + */ + BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int)); +#define CHECK_CSI_OFFSET(name) BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name)) + + BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0); + BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4); + BUILD_BUG_ON(offsetof(siginfo_t, si_code) != 8); + + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_signo) != 0); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_errno) != 4); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_code) != 8); + /* + * Ensure that the size of each si_field never changes. + * If it does, it is a sign that the + * copy_siginfo_to_user32() code below needs to updated + * along with the size in the CHECK_SI_SIZE(). + * + * We repeat this check for both the generic and compat + * siginfos. + * + * Note: it is OK for these to grow as long as the whole + * structure stays within the padding size (checked + * above). + */ +#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((compat_siginfo_t *)0)->_sifields.name)) +#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((siginfo_t *)0)->_sifields.name)) + + CHECK_CSI_OFFSET(_kill); + CHECK_CSI_SIZE (_kill, 2*sizeof(int)); + CHECK_SI_SIZE (_kill, 2*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0xC); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); + + CHECK_CSI_OFFSET(_timer); + CHECK_CSI_SIZE (_timer, 3*sizeof(int)); + CHECK_SI_SIZE (_timer, 6*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_tid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_overrun) != 0x14); + BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_tid) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_overrun) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14); + + CHECK_CSI_OFFSET(_rt); + CHECK_CSI_SIZE (_rt, 3*sizeof(int)); + CHECK_SI_SIZE (_rt, 4*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); + BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14); + + CHECK_CSI_OFFSET(_sigchld); + CHECK_CSI_SIZE (_sigchld, 5*sizeof(int)); + CHECK_SI_SIZE (_sigchld, 8*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); + BUILD_BUG_ON(offsetof(siginfo_t, si_status) != 0x18); + BUILD_BUG_ON(offsetof(siginfo_t, si_utime) != 0x20); + BUILD_BUG_ON(offsetof(siginfo_t, si_stime) != 0x28); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_status) != 0x14); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_utime) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_stime) != 0x1C); + +#ifdef CONFIG_X86_X32_ABI + CHECK_CSI_OFFSET(_sigchld_x32); + CHECK_CSI_SIZE (_sigchld_x32, 7*sizeof(int)); + /* no _sigchld_x32 in the generic siginfo_t */ + BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime) != 0x20); +#endif + + CHECK_CSI_OFFSET(_sigfault); + CHECK_CSI_SIZE (_sigfault, 4*sizeof(int)); + CHECK_SI_SIZE (_sigfault, 8*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C); + + BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10); + + BUILD_BUG_ON(offsetof(siginfo_t, si_lower) != 0x20); + BUILD_BUG_ON(offsetof(siginfo_t, si_upper) != 0x28); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_lower) != 0x14); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_upper) != 0x18); + + BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14); + + CHECK_CSI_OFFSET(_sigpoll); + CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int)); + CHECK_SI_SIZE (_sigpoll, 4*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_band) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_fd) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_band) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_fd) != 0x10); + + CHECK_CSI_OFFSET(_sigsys); + CHECK_CSI_SIZE (_sigsys, 3*sizeof(int)); + CHECK_SI_SIZE (_sigsys, 4*sizeof(int)); + + BUILD_BUG_ON(offsetof(siginfo_t, si_call_addr) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_syscall) != 0x18); + BUILD_BUG_ON(offsetof(siginfo_t, si_arch) != 0x1C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_call_addr) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_syscall) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_arch) != 0x14); + + /* any new si_fields should be added here */ +} + +void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact) +{ + signal_compat_build_tests(); + + /* Don't leak in-kernel non-uapi flags to user-space */ + if (oact) + oact->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI); + + if (!act) + return; + + /* Don't let flags to be set from userspace */ + act->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI); + + if (in_ia32_syscall()) + act->sa.sa_flags |= SA_IA32_ABI; + if (in_x32_syscall()) + act->sa.sa_flags |= SA_X32_ABI; +} |