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sysv: linux: Add 64-bit time_t variant for shmctl

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To provide a y2038 safe interface a new symbol __shmctl64 is added
and __shmctl is change to call it instead (it adds some extra buffer
copying for the 32 bit time_t implementation).

Two new structures are added:

  1. kernel_shmid64_ds: used internally only on 32-bit architectures
     to issue the syscall.  A handful of architectures (hppa, i386,
     mips, powerpc32, and sparc32) require specific implementations
     due to their kernel ABI.

  2. shmid_ds64: this is only for __TIMESIZE != 64 to use along with
     the 64-bit shmctl.  It is different than the kernel struct because
     the exported 64-bit time_t might require different alignment
     depending on the architecture ABI.

So the resulting implementation does:

  1. For 64-bit architectures it assumes shmid_ds already contains
     64-bit time_t fields and will result in just the __shmctl symbol
     using the __shmctl64 code.  The shmid_ds argument is passed as-is
     to the syscall.

  2. For 32-bit architectures with default 64-bit time_t (newer ABIs
     such riscv32 or arc), it will also result in only one exported
     symbol but with the required high/low time handling.

  3. Finally for 32-bit architecture with both 32-bit and 64-bit time_t
     support we follow the already set way to provide one symbol with
     64-bit time_t support and implement the 32-bit time_t support
     using of the 64-bit one.

     The default 32-bit symbol will allocate and copy the shmid_ds
     over multiple buffers, but this should be deprecated in favor
     of the __shmctl64 anyway.

Checked on i686-linux-gnu and x86_64-linux-gnu.  I also did some sniff
tests on powerpc, powerpc64, mips, mips64, armhf, sparcv9, and
sparc64.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Adhemerval Zanella
2020-06-30 14:08:22 -03:00
parent 7929d77985
commit ffd178c651
15 changed files with 336 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

191
sysdeps/unix/sysv/linux/shmctl.c
View File

@ -24,16 +24,55 @@
#include <errno.h>
#include <linux/posix_types.h> /* For __kernel_mode_t. */
#ifndef DEFAULT_VERSION
# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
# define DEFAULT_VERSION GLIBC_2_2
# else
# define DEFAULT_VERSION GLIBC_2_31
# endif
/* POSIX states ipc_perm mode should have type of mode_t. */
_Static_assert (sizeof ((struct shmid_ds){0}.shm_perm.mode)
== sizeof (mode_t),
"sizeof (shmid_ds.shm_perm.mode) != sizeof (mode_t)");
#if __IPC_TIME64 == 0
typedef struct shmid_ds shmctl_arg_t;
#else
# include <struct_kernel_shmid64_ds.h>
static void
shmid64_to_kshmid64 (const struct __shmid64_ds *shmid64,
struct kernel_shmid64_ds *kshmid)
{
kshmid->shm_perm = shmid64->shm_perm;
kshmid->shm_segsz = shmid64->shm_segsz;
kshmid->shm_atime = shmid64->shm_atime;
kshmid->shm_atime_high = shmid64->shm_atime >> 32;
kshmid->shm_dtime = shmid64->shm_dtime;
kshmid->shm_dtime_high = shmid64->shm_dtime >> 32;
kshmid->shm_ctime = shmid64->shm_ctime;
kshmid->shm_ctime_high = shmid64->shm_ctime >> 32;
kshmid->shm_cpid = shmid64->shm_cpid;
kshmid->shm_lpid = shmid64->shm_lpid;
kshmid->shm_nattch = shmid64->shm_nattch;
}
static void
kshmid64_to_shmid64 (const struct kernel_shmid64_ds *kshmid,
struct __shmid64_ds *shmid64)
{
shmid64->shm_perm = kshmid->shm_perm;
shmid64->shm_segsz = kshmid->shm_segsz;
shmid64->shm_atime = kshmid->shm_atime
| ((__time64_t) kshmid->shm_atime_high << 32);
shmid64->shm_dtime = kshmid->shm_dtime
| ((__time64_t) kshmid->shm_dtime_high << 32);
shmid64->shm_ctime = kshmid->shm_ctime
| ((__time64_t) kshmid->shm_ctime_high << 32);
shmid64->shm_cpid = kshmid->shm_cpid;
shmid64->shm_lpid = kshmid->shm_lpid;
shmid64->shm_nattch = kshmid->shm_nattch;
}
typedef struct kernel_shmid64_ds shmctl_arg_t;
#endif
static int
shmctl_syscall (int shmid, int cmd, struct shmid_ds *buf)
shmctl_syscall (int shmid, int cmd, shmctl_arg_t *buf)
{
#ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
return INLINE_SYSCALL_CALL (shmctl, shmid, cmd | __IPC_64, buf);
@ -45,46 +84,120 @@ shmctl_syscall (int shmid, int cmd, struct shmid_ds *buf)
/* Provide operations to control over shared memory segments. */
int
__new_shmctl (int shmid, int cmd, struct shmid_ds *buf)
__shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
{
/* POSIX states ipc_perm mode should have type of mode_t. */
_Static_assert (sizeof ((struct shmid_ds){0}.shm_perm.mode)
== sizeof (mode_t),
"sizeof (msqid_ds.msg_perm.mode) != sizeof (mode_t)");
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
struct shmid_ds tmpds;
if (cmd == IPC_SET)
#if __IPC_TIME64
struct kernel_shmid64_ds kshmid, *arg = NULL;
if (buf != NULL)
{
tmpds = *buf;
tmpds.shm_perm.mode *= 0x10000U;
buf = &tmpds;
shmid64_to_kshmid64 (buf, &kshmid);
arg = &kshmid;
}
#endif
int ret = shmctl_syscall (shmid, cmd, buf);
if (ret >= 0)
{
switch (cmd)
{
case IPC_STAT:
case SHM_STAT:
case SHM_STAT_ANY:
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
buf->shm_perm.mode >>= 16;
# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
if (cmd == IPC_SET)
arg->shm_perm.mode *= 0x10000U;
# endif
#else
/* Old Linux kernel versions might not clear the mode padding. */
if (sizeof ((struct shmid_ds){0}.shm_perm.mode)
!= sizeof (__kernel_mode_t))
buf->shm_perm.mode &= 0xFFFF;
shmctl_arg_t *arg = buf;
#endif
int ret = shmctl_syscall (shmid, cmd, arg);
if (ret < 0)
return ret;
switch (cmd)
{
case IPC_INFO:
case IPC_STAT:
case SHM_STAT:
case SHM_STAT_ANY:
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
arg->shm_perm.mode >>= 16;
#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
#if __IPC_TIME64
kshmid64_to_shmid64 (arg, buf);
#endif
}
}
return ret;
}
versioned_symbol (libc, __new_shmctl, shmctl, DEFAULT_VERSION);
#if __TIMESIZE != 64
libc_hidden_def (__shmctl64)
static void
shmid_to_shmid64 (struct __shmid64_ds *shm64, const struct shmid_ds *shm)
{
shm64->shm_perm = shm->shm_perm;
shm64->shm_segsz = shm->shm_segsz;
shm64->shm_atime = shm->shm_atime
| ((__time64_t) shm->__shm_atime_high << 32);
shm64->shm_dtime = shm->shm_dtime
| ((__time64_t) shm->__shm_dtime_high << 32);
shm64->shm_ctime = shm->shm_ctime
| ((__time64_t) shm->__shm_ctime_high << 32);
shm64->shm_cpid = shm->shm_cpid;
shm64->shm_lpid = shm->shm_lpid;
shm64->shm_nattch = shm->shm_nattch;
}
static void
shmid64_to_shmid (struct shmid_ds *shm, const struct __shmid64_ds *shm64)
{
shm->shm_perm = shm64->shm_perm;
shm->shm_segsz = shm64->shm_segsz;
shm->shm_atime = shm64->shm_atime;
shm->__shm_atime_high = 0;
shm->shm_dtime = shm64->shm_dtime;
shm->__shm_dtime_high = 0;
shm->shm_ctime = shm64->shm_ctime;
shm->__shm_ctime_high = 0;
shm->shm_cpid = shm64->shm_cpid;
shm->shm_lpid = shm64->shm_lpid;
shm->shm_nattch = shm64->shm_nattch;
}
int
__shmctl (int shmid, int cmd, struct shmid_ds *buf)
{
struct __shmid64_ds shmid64, *buf64 = NULL;
if (buf != NULL)
{
shmid_to_shmid64 (&shmid64, buf);
buf64 = &shmid64;
}
int ret = __shmctl64 (shmid, cmd, buf64);
if (ret < 0)
return ret;
switch (cmd)
{
case IPC_INFO:
case IPC_STAT:
case SHM_STAT:
case SHM_STAT_ANY:
shmid64_to_shmid (buf, buf64);
}
return ret;
}
#endif
#ifndef DEFAULT_VERSION
# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
# define DEFAULT_VERSION GLIBC_2_2
# else
# define DEFAULT_VERSION GLIBC_2_31
# endif
#endif
versioned_symbol (libc, __shmctl, shmctl, DEFAULT_VERSION);
#if defined __ASSUME_SYSVIPC_BROKEN_MODE_T \
&& SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_31)
@ -92,7 +205,7 @@ int
attribute_compat_text_section
__shmctl_mode16 (int shmid, int cmd, struct shmid_ds *buf)
{
return shmctl_syscall (shmid, cmd, buf);
return shmctl_syscall (shmid, cmd, (shmctl_arg_t *) buf);
}
compat_symbol (libc, __shmctl_mode16, shmctl, GLIBC_2_2);
#endif