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signal: refactor copy_siginfo_to_user32 

Factor out a copy_siginfo_to_external32 helper from
copy_siginfo_to_user32 that fills out the compat_siginfo, but does so
on a kernel space data structure.  With that we can let architectures
override copy_siginfo_to_user32 with their own implementations using
copy_siginfo_to_external32.  That allows moving the x32 SIGCHLD purely
to x86 architecture code.

As a nice side effect copy_siginfo_to_external32 also comes in handy
for avoiding a set_fs() call in the coredump code later on.

Contains improvements from Eric W. Biederman <ebiederm@xmission.com>
and Arnd Bergmann <arnd@arndb.de>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2020-05-05 12:12:53 +02:00 committed by Al Viro
parent 5456ffdee6
commit c3b3f52476
5 changed files with 96 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/ia32/ia32_signal.c
View File

@ -350,7 +350,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
unsafe_put_user(*(__u64 *)set, (__u64 *)&frame->uc.uc_sigmask, Efault);
user_access_end();
if (__copy_siginfo_to_user32(&frame->info, &ksig->info, false))
if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
return -EFAULT;
/* Set up registers for signal handler */

8
arch/x86/include/asm/compat.h
View File

@ -214,7 +214,11 @@ static inline bool in_compat_syscall(void)
#endif
struct compat_siginfo;
int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
const kernel_siginfo_t *from, bool x32_ABI);
#ifdef CONFIG_X86_X32_ABI
int copy_siginfo_to_user32(struct compat_siginfo __user *to,
const kernel_siginfo_t *from);
#define copy_siginfo_to_user32 copy_siginfo_to_user32
#endif /* CONFIG_X86_X32_ABI */
#endif /* _ASM_X86_COMPAT_H */

28
arch/x86/kernel/signal.c
View File

@ -37,6 +37,7 @@
#include <asm/vm86.h>
#ifdef CONFIG_X86_64
#include <linux/compat.h>
#include <asm/proto.h>
#include <asm/ia32_unistd.h>
#endif /* CONFIG_X86_64 */
@ -511,6 +512,31 @@ Efault:
}
#endif /* CONFIG_X86_32 */
#ifdef CONFIG_X86_X32_ABI
static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
const struct kernel_siginfo *from)
{
struct compat_siginfo new;
copy_siginfo_to_external32(&new, from);
if (from->si_signo == SIGCHLD) {
new._sifields._sigchld_x32._utime = from->si_utime;
new._sifields._sigchld_x32._stime = from->si_stime;
}
if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
return -EFAULT;
return 0;
}
int copy_siginfo_to_user32(struct compat_siginfo __user *to,
const struct kernel_siginfo *from)
{
if (in_x32_syscall())
return x32_copy_siginfo_to_user(to, from);
return __copy_siginfo_to_user32(to, from);
}
#endif /* CONFIG_X86_X32_ABI */
static int x32_setup_rt_frame(struct ksignal *ksig,
compat_sigset_t *set,
struct pt_regs *regs)
@ -543,7 +569,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
user_access_end();
if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true))
if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
return -EFAULT;
}

11
include/linux/compat.h
View File

@ -402,8 +402,15 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
unsigned long bitmap_size);
long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
unsigned long bitmap_size);
int copy_siginfo_from_user32(kernel_siginfo_t *to, const struct compat_siginfo __user *from);
int copy_siginfo_to_user32(struct compat_siginfo __user *to, const kernel_siginfo_t *from);
void copy_siginfo_to_external32(struct compat_siginfo *to,
const struct kernel_siginfo *from);
int copy_siginfo_from_user32(kernel_siginfo_t *to,
const struct compat_siginfo __user *from);
int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
const kernel_siginfo_t *from);
#ifndef copy_siginfo_to_user32
#define copy_siginfo_to_user32 __copy_siginfo_to_user32
#endif
int get_compat_sigevent(struct sigevent *event,
const struct compat_sigevent __user *u_event);

106
kernel/signal.c
View File

@ -3235,94 +3235,94 @@ int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
}
#ifdef CONFIG_COMPAT
int copy_siginfo_to_user32(struct compat_siginfo __user *to,
const struct kernel_siginfo *from)
#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
/**
* copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
* @to: compat siginfo destination
* @from: kernel siginfo source
*
* Note: This function does not work properly for the SIGCHLD on x32, but
* fortunately it doesn't have to. The only valid callers for this function are
* copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
* The latter does not care because SIGCHLD will never cause a coredump.
*/
void copy_siginfo_to_external32(struct compat_siginfo *to,
const struct kernel_siginfo *from)
{
return __copy_siginfo_to_user32(to, from, in_x32_syscall());
}
int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
const struct kernel_siginfo *from, bool x32_ABI)
#endif
{
struct compat_siginfo new;
memset(&new, 0, sizeof(new));
memset(to, 0, sizeof(*to));
new.si_signo = from->si_signo;
new.si_errno = from->si_errno;
new.si_code = from->si_code;
to->si_signo = from->si_signo;
to->si_errno = from->si_errno;
to->si_code = from->si_code;
switch(siginfo_layout(from->si_signo, from->si_code)) {
case SIL_KILL:
new.si_pid = from->si_pid;
new.si_uid = from->si_uid;
to->si_pid = from->si_pid;
to->si_uid = from->si_uid;
break;
case SIL_TIMER:
new.si_tid = from->si_tid;
new.si_overrun = from->si_overrun;
new.si_int = from->si_int;
to->si_tid = from->si_tid;
to->si_overrun = from->si_overrun;
to->si_int = from->si_int;
break;
case SIL_POLL:
new.si_band = from->si_band;
new.si_fd = from->si_fd;
to->si_band = from->si_band;
to->si_fd = from->si_fd;
break;
case SIL_FAULT:
new.si_addr = ptr_to_compat(from->si_addr);
to->si_addr = ptr_to_compat(from->si_addr);
#ifdef __ARCH_SI_TRAPNO
new.si_trapno = from->si_trapno;
to->si_trapno = from->si_trapno;
#endif
break;
case SIL_FAULT_MCEERR:
new.si_addr = ptr_to_compat(from->si_addr);
to->si_addr = ptr_to_compat(from->si_addr);
#ifdef __ARCH_SI_TRAPNO
new.si_trapno = from->si_trapno;
to->si_trapno = from->si_trapno;
#endif
new.si_addr_lsb = from->si_addr_lsb;
to->si_addr_lsb = from->si_addr_lsb;
break;
case SIL_FAULT_BNDERR:
new.si_addr = ptr_to_compat(from->si_addr);
to->si_addr = ptr_to_compat(from->si_addr);
#ifdef __ARCH_SI_TRAPNO
new.si_trapno = from->si_trapno;
to->si_trapno = from->si_trapno;
#endif
new.si_lower = ptr_to_compat(from->si_lower);
new.si_upper = ptr_to_compat(from->si_upper);
to->si_lower = ptr_to_compat(from->si_lower);
to->si_upper = ptr_to_compat(from->si_upper);
break;
case SIL_FAULT_PKUERR:
new.si_addr = ptr_to_compat(from->si_addr);
to->si_addr = ptr_to_compat(from->si_addr);
#ifdef __ARCH_SI_TRAPNO
new.si_trapno = from->si_trapno;
to->si_trapno = from->si_trapno;
#endif
new.si_pkey = from->si_pkey;
to->si_pkey = from->si_pkey;
break;
case SIL_CHLD:
new.si_pid = from->si_pid;
new.si_uid = from->si_uid;
new.si_status = from->si_status;
#ifdef CONFIG_X86_X32_ABI
if (x32_ABI) {
new._sifields._sigchld_x32._utime = from->si_utime;
new._sifields._sigchld_x32._stime = from->si_stime;
} else
#endif
{
new.si_utime = from->si_utime;
new.si_stime = from->si_stime;
}
to->si_pid = from->si_pid;
to->si_uid = from->si_uid;
to->si_status = from->si_status;
to->si_utime = from->si_utime;
to->si_stime = from->si_stime;
break;
case SIL_RT:
new.si_pid = from->si_pid;
new.si_uid = from->si_uid;
new.si_int = from->si_int;
to->si_pid = from->si_pid;
to->si_uid = from->si_uid;
to->si_int = from->si_int;
break;
case SIL_SYS:
new.si_call_addr = ptr_to_compat(from->si_call_addr);
new.si_syscall = from->si_syscall;
new.si_arch = from->si_arch;
to->si_call_addr = ptr_to_compat(from->si_call_addr);
to->si_syscall = from->si_syscall;
to->si_arch = from->si_arch;
break;
}
}
int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
const struct kernel_siginfo *from)
{
struct compat_siginfo new;
copy_siginfo_to_external32(&new, from);
if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
return -EFAULT;
return 0;
}