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Add a personality to report 2.6.x version numbers

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I ran into a couple of programs which broke with the new Linux 3.0
version.  Some of those were binary only.  I tried to use LD_PRELOAD to
work around it, but it was quite difficult and in one case impossible
because of a mix of 32bit and 64bit executables.

For example, all kind of management software from HP doesnt work, unless
we pretend to run a 2.6 kernel.

  $ uname -a
  Linux svivoipvnx001 3.0.0-08107-g97cd98f #1062 SMP Fri Aug 12 18:11:45 CEST 2011 i686 i686 i386 GNU/Linux

  $ hpacucli ctrl all show

  Error: No controllers detected.

  $ rpm -qf /usr/sbin/hpacucli
  hpacucli-8.75-12.0

Another notable case is that Python now reports "linux3" from
sys.platform(); which in turn can break things that were checking
sys.platform() == "linux2":

  https://bugzilla.mozilla.org/show_bug.cgi?id=664564

It seems pretty clear to me though it's a bug in the apps that are using
'==' instead of .startswith(), but this allows us to unbreak broken
programs.

This patch adds a UNAME26 personality that makes the kernel report a
2.6.40+x version number instead.  The x is the x in 3.x.

I know this is somewhat ugly, but I didn't find a better workaround, and
compatibility to existing programs is important.

Some programs also read /proc/sys/kernel/osrelease.  This can be worked
around in user space with mount --bind (and a mount namespace)

To use:

  wget ftp://ftp.kernel.org/pub/linux/kernel/people/ak/uname26/uname26.c
  gcc -o uname26 uname26.c
  ./uname26 program

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andi Kleen 2011-08-19 16:15:10 -07:00 committed by Linus Torvalds
parent caca9510ff
commit be27425dcc
2 changed files with 39 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/personality.h
View file

@ -22,6 +22,7 @@ extern int __set_personality(unsigned int);
* These occupy the top three bytes.
*/
enum {
UNAME26 = 0x0020000,
ADDR_NO_RANDOMIZE = 0x0040000, /* disable randomization of VA space */
FDPIC_FUNCPTRS = 0x0080000, /* userspace function ptrs point to descriptors
* (signal handling)

38
kernel/sys.c
View file

@ -37,6 +37,8 @@
#include <linux/fs_struct.h>
#include <linux/gfp.h>
#include <linux/syscore_ops.h>
#include <linux/version.h>
#include <linux/ctype.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
@ -44,6 +46,8 @@
#include <linux/user_namespace.h>
#include <linux/kmsg_dump.h>
/* Move somewhere else to avoid recompiling? */
#include <generated/utsrelease.h>
#include <asm/uaccess.h>
#include <asm/io.h>
@ -1161,6 +1165,34 @@ DECLARE_RWSEM(uts_sem);
#define override_architecture(name) 0
#endif
/*
* Work around broken programs that cannot handle "Linux 3.0".
* Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40
*/
static int override_release(char __user *release, int len)
{
int ret = 0;
char buf[len];
if (current->personality & UNAME26) {
char *rest = UTS_RELEASE;
int ndots = 0;
unsigned v;
while (*rest) {
if (*rest == '.' && ++ndots >= 3)
break;
if (!isdigit(*rest) && *rest != '.')
break;
rest++;
}
v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
snprintf(buf, len, "2.6.%u%s", v, rest);
ret = copy_to_user(release, buf, len);
}
return ret;
}
SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
{
int errno = 0;
@ -1170,6 +1202,8 @@ SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
errno = -EFAULT;
up_read(&uts_sem);
if (!errno && override_release(name->release, sizeof(name->release)))
errno = -EFAULT;
if (!errno && override_architecture(name))
errno = -EFAULT;
return errno;
@ -1191,6 +1225,8 @@ SYSCALL_DEFINE1(uname, struct old_utsname __user *, name)
error = -EFAULT;
up_read(&uts_sem);
if (!error && override_release(name->release, sizeof(name->release)))
error = -EFAULT;
if (!error && override_architecture(name))
error = -EFAULT;
return error;
@ -1225,6 +1261,8 @@ SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name)
if (!error && override_architecture(name))
error = -EFAULT;
if (!error && override_release(name->release, sizeof(name->release)))
error = -EFAULT;
return error ? -EFAULT : 0;
}
#endif