// SPDX-License-Identifier: GPL-2.0 #include #include #include /* * 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 != 8); BUILD_BUG_ON(NSIGFPE != 8); BUILD_BUG_ON(NSIGSEGV != 4); BUILD_BUG_ON(NSIGBUS != 5); BUILD_BUG_ON(NSIGTRAP != 4); 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)) /* * 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)); CHECK_CSI_OFFSET(_timer); CHECK_CSI_SIZE (_timer, 3*sizeof(int)); CHECK_SI_SIZE (_timer, 6*sizeof(int)); CHECK_CSI_OFFSET(_rt); CHECK_CSI_SIZE (_rt, 3*sizeof(int)); CHECK_SI_SIZE (_rt, 4*sizeof(int)); CHECK_CSI_OFFSET(_sigchld); CHECK_CSI_SIZE (_sigchld, 5*sizeof(int)); CHECK_SI_SIZE (_sigchld, 8*sizeof(int)); CHECK_CSI_OFFSET(_sigchld_x32); CHECK_CSI_SIZE (_sigchld_x32, 7*sizeof(int)); /* no _sigchld_x32 in the generic siginfo_t */ CHECK_CSI_OFFSET(_sigfault); CHECK_CSI_SIZE (_sigfault, 4*sizeof(int)); CHECK_SI_SIZE (_sigfault, 8*sizeof(int)); CHECK_CSI_OFFSET(_sigpoll); CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int)); CHECK_SI_SIZE (_sigpoll, 4*sizeof(int)); CHECK_CSI_OFFSET(_sigsys); CHECK_CSI_SIZE (_sigsys, 3*sizeof(int)); CHECK_SI_SIZE (_sigsys, 4*sizeof(int)); /* any new si_fields should be added here */ } void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact) { /* 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; } int __copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from, bool x32_ABI) { int err = 0; signal_compat_build_tests(); if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t))) return -EFAULT; put_user_try { /* If you change siginfo_t structure, please make sure that this code is fixed accordingly. It should never copy any pad contained in the structure to avoid security leaks, but must copy the generic 3 ints plus the relevant union member. */ put_user_ex(from->si_signo, &to->si_signo); put_user_ex(from->si_errno, &to->si_errno); put_user_ex(from->si_code, &to->si_code); if (from->si_code < 0) { put_user_ex(from->si_pid, &to->si_pid); put_user_ex(from->si_uid, &to->si_uid); put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr); } else { /* * First 32bits of unions are always present: * si_pid === si_band === si_tid === si_addr(LS half) */ put_user_ex(from->_sifields._pad[0], &to->_sifields._pad[0]); switch (siginfo_layout(from->si_signo, from->si_code)) { case SIL_FAULT: if (from->si_signo == SIGBUS && (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)) put_user_ex(from->si_addr_lsb, &to->si_addr_lsb); if (from->si_signo == SIGSEGV) { if (from->si_code == SEGV_BNDERR) { compat_uptr_t lower = (unsigned long)from->si_lower; compat_uptr_t upper = (unsigned long)from->si_upper; put_user_ex(lower, &to->si_lower); put_user_ex(upper, &to->si_upper); } if (from->si_code == SEGV_PKUERR) put_user_ex(from->si_pkey, &to->si_pkey); } break; case SIL_SYS: put_user_ex(from->si_syscall, &to->si_syscall); put_user_ex(from->si_arch, &to->si_arch); break; case SIL_CHLD: if (!x32_ABI) { put_user_ex(from->si_utime, &to->si_utime); put_user_ex(from->si_stime, &to->si_stime); } else { put_user_ex(from->si_utime, &to->_sifields._sigchld_x32._utime); put_user_ex(from->si_stime, &to->_sifields._sigchld_x32._stime); } put_user_ex(from->si_status, &to->si_status); /* FALL THROUGH */ case SIL_KILL: put_user_ex(from->si_uid, &to->si_uid); break; case SIL_POLL: put_user_ex(from->si_fd, &to->si_fd); break; case SIL_TIMER: put_user_ex(from->si_overrun, &to->si_overrun); put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr); break; case SIL_RT: put_user_ex(from->si_uid, &to->si_uid); put_user_ex(from->si_int, &to->si_int); break; } } } put_user_catch(err); return err; } /* from syscall's path, where we know the ABI */ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from) { return __copy_siginfo_to_user32(to, from, in_x32_syscall()); } int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from) { int err = 0; u32 ptr32; if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t))) return -EFAULT; get_user_try { get_user_ex(to->si_signo, &from->si_signo); get_user_ex(to->si_errno, &from->si_errno); get_user_ex(to->si_code, &from->si_code); get_user_ex(to->si_pid, &from->si_pid); get_user_ex(to->si_uid, &from->si_uid); get_user_ex(ptr32, &from->si_ptr); to->si_ptr = compat_ptr(ptr32); } get_user_catch(err); return err; }