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Linux: Support __IPC_64 in sysvctl *ctl command arguments (bug 29771)

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Old applications pass __IPC_64 as part of the command argument because
old glibc did not check for unknown commands, and passed through the
arguments directly to the kernel, without adding __IPC_64.
Applications need to continue doing that for old glibc compatibility,
so this commit enables this approach in current glibc.

For msgctl and shmctl, if no translation is required, make
direct system calls, as we did before the time64 changes.  If
translation is required, mask __IPC_64 from the command argument.

For semctl, the union-in-vararg argument handling means that
translation is needed on all architectures.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
2022-11-08 14:15:02 +01:00
parent 38caf7a1cc
commit 22a46dee24
4 changed files with 63 additions and 26 deletions
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38
sysdeps/unix/sysv/linux/shmctl.c
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@@ -85,11 +85,19 @@ shmctl_syscall (int shmid, int cmd, shmctl_arg_t *buf)
int
__shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
{
#if __IPC_TIME64
#if IPC_CTL_NEED_TRANSLATION
# if __IPC_TIME64
struct kernel_shmid64_ds kshmid, *arg = NULL;
#else
# else
shmctl_arg_t *arg;
#endif
# endif
/* Some applications pass the __IPC_64 flag in cmd, to invoke
previously unsupported commands back when there was no EINVAL
error checking in glibc. Mask the flag for the switch statements
below. shmctl_syscall adds back the __IPC_64 flag for the actual
system call. */
cmd &= ~__IPC_64;
switch (cmd)
{
@@ -103,19 +111,19 @@ __shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
case IPC_STAT:
case SHM_STAT:
case SHM_STAT_ANY:
#if __IPC_TIME64
# if __IPC_TIME64
if (buf != NULL)
{
shmid64_to_kshmid64 (buf, &kshmid);
arg = &kshmid;
}
# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
if (cmd == IPC_SET)
arg->shm_perm.mode *= 0x10000U;
# endif
#else
# endif
# else
arg = buf;
#endif
# endif
break;
case IPC_INFO:
@@ -140,21 +148,25 @@ __shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
case IPC_STAT:
case SHM_STAT:
case SHM_STAT_ANY:
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
arg->shm_perm.mode >>= 16;
#else
# else
/* Old Linux kernel versions might not clear the mode padding. */
if (sizeof ((struct shmid_ds){0}.shm_perm.mode)
!= sizeof (__kernel_mode_t))
arg->shm_perm.mode &= 0xFFFF;
#endif
# endif
#if __IPC_TIME64
# if __IPC_TIME64
kshmid64_to_shmid64 (arg, buf);
#endif
# endif
}
return ret;
#else /* !IPC_CTL_NEED_TRANSLATION */
return shmctl_syscall (shmid, cmd, buf);
#endif
}
#if __TIMESIZE != 64
libc_hidden_def (__shmctl64)