glibc/patches/glibc-2.10.1-hardened-inittls-nosysenter.patch

   1 When building glibc PIE (which is not something upstream support),
   2 several modifications are necessary to the glibc build process.
   3
   4 First, any syscalls in PIEs must be of the PIC variant, otherwise
   5 textrels ensue.  Then, any syscalls made before the initialisation
   6 of the TLS will fail on i386, as the sysenter variant on i386 uses
   7 the TLS, giving rise to a chicken-and-egg situation.  This patch
   8 defines a PIC syscall variant that doesn't use sysenter, even when the sysenter
   9 version is normally used, and uses the non-sysenter version for the brk
  10 syscall that is performed by the TLS initialisation.  Further, the TLS
  11 initialisation is moved in this case prior to the initialisation of
  12 dl_osversion, as that requires further syscalls.
  13
  14 csu/libc-start.c: Move initial TLS initialization to before the
  15 initialisation of dl_osversion, when INTERNAL_SYSCALL_NOSYSENTER is defined
  16
  17 csu/libc-tls.c: Use the no-sysenter version of sbrk when
  18 INTERNAL_SYSCALL_NOSYSENTER is defined.
  19
  20 misc/sbrk.c: Define a no-sysenter version of sbrk, using the no-sysenter
  21 version of brk - if INTERNAL_SYSCALL_NOSYSENTER is defined.
  22
  23 misc/brk.c: Define a no-sysenter version of brk if
  24 INTERNAL_SYSCALL_NOSYSENTER is defined.
  25
  26 sysdeps/unix/sysv/linux/i386/sysdep.h: Define INTERNAL_SYSCALL_NOSYSENTER
  27 Make INTERNAL_SYSCALL always use the PIC variant, even if not SHARED.
  28
  29 Patch by Kevin F. Quinn <kevquinn@gentoo.org>
  30
  31 --- glibc-2.10.1/csu/libc-start.c
  32 +++ glibc-2.10.1/csu/libc-start.c
  33 @@ -28,6 +28,7 @@
  34  extern int __libc_multiple_libcs;
  35
  36  #include <tls.h>
  37 +#include <sysdep.h>
  38  #ifndef SHARED
  39  # include <dl-osinfo.h>
  40  extern void __pthread_initialize_minimal (void);
  41 @@ -129,6 +130,11 @@
  42  #  endif
  43    _dl_aux_init (auxvec);
  44  # endif
  45 +# ifdef INTERNAL_SYSCALL_NOSYSENTER
  46 +  /* Do the initial TLS initialization before _dl_osversion,
  47 +     since the latter uses the uname syscall.  */
  48 +  __pthread_initialize_minimal ();
  49 +# endif
  50  # ifdef DL_SYSDEP_OSCHECK
  51    if (!__libc_multiple_libcs)
  52      {
  53 @@ -138,10 +144,12 @@
  54      }
  55  # endif
  56
  57 +# ifndef INTERNAL_SYSCALL_NOSYSENTER
  58    /* Initialize the thread library at least a bit since the libgcc
  59       functions are using thread functions if these are available and
  60       we need to setup errno.  */
  61    __pthread_initialize_minimal ();
  62 +# endif
  63
  64    /* Set up the stack checker's canary.  */
  65    uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard ();
  66 --- glibc-2.10.1/csu/libc-tls.c
  67 +++ glibc-2.10.1/csu/libc-tls.c
  68 @@ -23,6 +23,7 @@
  69  #include <unistd.h>
  70  #include <stdio.h>
  71  #include <sys/param.h>
  72 +#include <sysdep.h>
  73
  74
  75  #ifdef SHARED
  76 @@ -29,6 +30,9 @@
  77   #error makefile bug, this file is for static only
  78  #endif
  79
  80 +#ifdef INTERNAL_SYSCALL_NOSYSENTER
  81 +extern void *__sbrk_nosysenter (intptr_t __delta);
  82 +#endif
  83  extern ElfW(Phdr) *_dl_phdr;
  84  extern size_t _dl_phnum;
  85
  86 @@ -141,14 +145,26 @@
  87
  88       The initialized value of _dl_tls_static_size is provided by dl-open.c
  89       to request some surplus that permits dynamic loading of modules with
  90 -     IE-model TLS.  */
  91 +     IE-model TLS.
  92 +
  93 +     Where the normal sbrk would use a syscall that needs the TLS (i386)
  94 +     use the special non-sysenter version instead.  */
  95  #if TLS_TCB_AT_TP
  96    tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign);
  97 +# ifdef INTERNAL_SYSCALL_NOSYSENTER
  98 +  tlsblock = __sbrk_nosysenter (tcb_offset + tcbsize + max_align);
  99 +# else
 100    tlsblock = __sbrk (tcb_offset + tcbsize + max_align);
 101 +# endif
 102  #elif TLS_DTV_AT_TP
 103    tcb_offset = roundup (tcbsize, align ?: 1);
 104 +# ifdef INTERNAL_SYSCALL_NOSYSENTER
 105 +  tlsblock = __sbrk_nosysenter (tcb_offset + memsz + max_align
 106 +                    + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
 107 +# else
 108    tlsblock = __sbrk (tcb_offset + memsz + max_align
 109                      + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
 110 +# endif
 111    tlsblock += TLS_PRE_TCB_SIZE;
 112  #else
 113    /* In case a model with a different layout for the TCB and DTV
 114 --- glibc-2.10.1/misc/sbrk.c
 115 +++ glibc-2.10.1/misc/sbrk.c
 116 @@ -18,6 +18,7 @@
 117
 118  #include <stdint.h>
 119  #include <unistd.h>
 120 +#include <sysdep.h>
 121
 122  /* Defined in brk.c.  */
 123  extern void *__curbrk;
 124 @@ -29,6 +30,35 @@
 125  /* Extend the process's data space by INCREMENT.
 126     If INCREMENT is negative, shrink data space by - INCREMENT.
 127     Return start of new space allocated, or -1 for errors.  */
 128 +#ifdef INTERNAL_SYSCALL_NOSYSENTER
 129 +/* This version is used by csu/libc-tls.c whem initialising the TLS
 130 +   if the SYSENTER version requires the TLS (which it does on i386).
 131 +   Obviously using the TLS before it is initialised is broken. */
 132 +extern int __brk_nosysenter (void *addr);
 133 +void *
 134 +__sbrk_nosysenter (intptr_t increment)
 135 +{
 136 +  void *oldbrk;
 137 +
 138 +  /* If this is not part of the dynamic library or the library is used
 139 +     via dynamic loading in a statically linked program update
 140 +     __curbrk from the kernel's brk value.  That way two separate
 141 +     instances of __brk and __sbrk can share the heap, returning
 142 +     interleaved pieces of it.  */
 143 +  if (__curbrk == NULL || __libc_multiple_libcs)
 144 +    if (__brk_nosysenter (0) < 0)              /* Initialize the break.  */
 145 +      return (void *) -1;
 146 +
 147 +  if (increment == 0)
 148 +    return __curbrk;
 149 +
 150 +  oldbrk = __curbrk;
 151 +  if (__brk_nosysenter (oldbrk + increment) < 0)
 152 +    return (void *) -1;
 153 +
 154 +  return oldbrk;
 155 +}
 156 +#endif
 157  void *
 158  __sbrk (intptr_t increment)
 159  {
 160 --- glibc-2.10.1/sysdeps/unix/sysv/linux/i386/brk.c
 161 +++ glibc-2.10.1/sysdeps/unix/sysv/linux/i386/brk.c
 162 @@ -31,6 +31,30 @@
 163     linker.  */
 164  weak_alias (__curbrk, ___brk_addr)
 165
 166 +#ifdef INTERNAL_SYSCALL_NOSYSENTER
 167 +/* This version is used by csu/libc-tls.c whem initialising the TLS
 168 + * if the SYSENTER version requires the TLS (which it does on i386).
 169 + * Obviously using the TLS before it is initialised is broken. */
 170 +int
 171 +__brk_nosysenter (void *addr)
 172 +{
 173 +  void *__unbounded newbrk;
 174 +
 175 +  INTERNAL_SYSCALL_DECL (err);
 176 +  newbrk = (void *__unbounded) INTERNAL_SYSCALL_NOSYSENTER (brk, err, 1,
 177 +                                                __ptrvalue (addr));
 178 +
 179 +  __curbrk = newbrk;
 180 +
 181 +  if (newbrk < addr)
 182 +    {
 183 +      __set_errno (ENOMEM);
 184 +      return -1;
 185 +    }
 186 +
 187 +  return 0;
 188 +}
 189 +#endif
 190  int
 191  __brk (void *addr)
 192  {
 193 --- glibc-2.10.1/sysdeps/unix/sysv/linux/i386/sysdep.h
 194 +++ glibc-2.10.1/sysdeps/unix/sysv/linux/i386/sysdep.h
 195 @@ -187,7 +187,7 @@
 196  /* The original calling convention for system calls on Linux/i386 is
 197     to use int $0x80.  */
 198  #ifdef I386_USE_SYSENTER
 199 -# ifdef SHARED
 200 +# if defined SHARED || defined __PIC__
 201  #  define ENTER_KERNEL call *%gs:SYSINFO_OFFSET
 202  # else
 203  #  define ENTER_KERNEL call *_dl_sysinfo
 204 @@ -358,7 +358,7 @@
 205     possible to use more than four parameters.  */
 206  #undef INTERNAL_SYSCALL
 207  #ifdef I386_USE_SYSENTER
 208 -# ifdef SHARED
 209 +# if defined SHARED || defined __PIC__
 210  #  define INTERNAL_SYSCALL(name, err, nr, args...) \
 211    ({                                                                         \
 212      register unsigned int resultvar;                                         \
 213 @@ -384,6 +384,18 @@
 214      : "0" (name), "i" (offsetof (tcbhead_t, sysinfo))                        \
 215        ASMFMT_##nr(args) : "memory", "cc");                                   \
 216      (int) resultvar; })
 217 +#  define INTERNAL_SYSCALL_NOSYSENTER(name, err, nr, args...) \
 218 +  ({                                                                         \
 219 +    register unsigned int resultvar;                                         \
 220 +    EXTRAVAR_##nr                                                            \
 221 +    asm volatile (                                                           \
 222 +    LOADARGS_NOSYSENTER_##nr                                                 \
 223 +    "movl %1, %%eax\n\t"                                                     \
 224 +    "int $0x80\n\t"                                                          \
 225 +    RESTOREARGS_NOSYSENTER_##nr                                                      \
 226 +    : "=a" (resultvar)                                                       \
 227 +    : "i" (__NR_##name) ASMFMT_##nr(args) : "memory", "cc");                 \
 228 +    (int) resultvar; })
 229  # else
 230  #  define INTERNAL_SYSCALL(name, err, nr, args...) \
 231    ({                                                                         \
 232 @@ -447,12 +459,20 @@
 233
 234  #define LOADARGS_0
 235  #ifdef __PIC__
 236 -# if defined I386_USE_SYSENTER && defined SHARED
 237 +# if defined I386_USE_SYSENTER && ( defined SHARED || defined __PIC__ )
 238  #  define LOADARGS_1 \
 239      "bpushl .L__X'%k3, %k3\n\t"
 240  #  define LOADARGS_5 \
 241      "movl %%ebx, %4\n\t"                                                     \
 242      "movl %3, %%ebx\n\t"
 243 +#  define LOADARGS_NOSYSENTER_1 \
 244 +    "bpushl .L__X'%k2, %k2\n\t"
 245 +#  define LOADARGS_NOSYSENTER_2        LOADARGS_NOSYSENTER_1
 246 +#  define LOADARGS_NOSYSENTER_3        LOADARGS_3
 247 +#  define LOADARGS_NOSYSENTER_4        LOADARGS_3
 248 +#  define LOADARGS_NOSYSENTER_5 \
 249 +    "movl %%ebx, %3\n\t"                                                     \
 250 +    "movl %2, %%ebx\n\t"
 251  # else
 252  #  define LOADARGS_1 \
 253      "bpushl .L__X'%k2, %k2\n\t"
 254 @@ -474,11 +495,18 @@
 255
 256  #define RESTOREARGS_0
 257  #ifdef __PIC__
 258 -# if defined I386_USE_SYSENTER && defined SHARED
 259 +# if defined I386_USE_SYSENTER && ( defined SHARED || defined __PIC__ )
 260  #  define RESTOREARGS_1 \
 261      "bpopl .L__X'%k3, %k3\n\t"
 262  #  define RESTOREARGS_5 \
 263      "movl %4, %%ebx"
 264 +#  define RESTOREARGS_NOSYSENTER_1 \
 265 +    "bpopl .L__X'%k2, %k2\n\t"
 266 +#  define RESTOREARGS_NOSYSENTER_2     RESTOREARGS_NOSYSENTER_1
 267 +#  define RESTOREARGS_NOSYSENTER_3     RESTOREARGS_3
 268 +#  define RESTOREARGS_NOSYSENTER_4     RESTOREARGS_3
 269 +#  define RESTOREARGS_NOSYSENTER_5 \
 270 +    "movl %3, %%ebx"
 271  # else
 272  #  define RESTOREARGS_1 \
 273      "bpopl .L__X'%k2, %k2\n\t"