sysdeps/unix/sysv/linux/dl-osinfo.h

   1 /* Operating system specific code for generic dynamic loader functions.  Linux.
   2    Copyright (C) 2000,2001,2002,2004,2005,2006 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <string.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <sys/utsname.h>
  24 #include <kernel-features.h>
  25 #include <dl-sysdep.h>
  26 #include <stdint.h>
  27 #include <hp-timing.h>
  28 #include <endian.h>
  29
  30 #ifndef MIN
  31 # define MIN(a,b) (((a)<(b))?(a):(b))
  32 #endif
  33
  34 #ifdef SHARED
  35 /* This is the function used in the dynamic linker to print the fatal error
  36    message.  */
  37 static inline void
  38 __attribute__ ((__noreturn__))
  39 dl_fatal (const char *str)
  40 {
  41   _dl_dprintf (2, str);
  42   _exit (1);
  43 }
  44 #endif
  45
  46 static inline int __attribute__ ((always_inline))
  47 _dl_discover_osversion (void)
  48 {
  49 #if (defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO) && defined SHARED
  50   if (GLRO(dl_sysinfo_map) != NULL)
  51     {
  52       /* If the kernel-supplied DSO contains a note indicating the kernel's
  53          version, we don't need to call uname or parse any strings.  */
  54
  55       static const struct
  56       {
  57         ElfW(Word) vendorlen;
  58         ElfW(Word) datalen;
  59         ElfW(Word) type;
  60         char vendor[8];
  61       } expected_note = { sizeof "Linux", sizeof (ElfW(Word)), 0, "Linux" };
  62       const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
  63       const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
  64       for (uint_fast16_t i = 0; i < phnum; ++i)
  65         if (phdr[i].p_type == PT_NOTE)
  66           {
  67             const ElfW(Addr) start = (phdr[i].p_vaddr
  68                                       + GLRO(dl_sysinfo_map)->l_addr);
  69             const struct
  70             {
  71               ElfW(Word) vendorlen;
  72               ElfW(Word) datalen;
  73               ElfW(Word) type;
  74             } *note = (const void *) start;
  75             while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
  76               {
  77                 if (!memcmp (note, &expected_note, sizeof expected_note))
  78                   return *(const ElfW(Word) *) ((const void *) note
  79                                                 + sizeof expected_note);
  80 #define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
  81                 note = ((const void *) (note + 1)
  82                         + ROUND (note->vendorlen) + ROUND (note->datalen));
  83               }
  84           }
  85     }
  86 #endif
  87
  88   char bufmem[64];
  89   char *buf = bufmem;
  90   unsigned int version;
  91   int parts;
  92   char *cp;
  93   struct utsname uts;
  94
  95   /* Try the uname system call.  */
  96   if (__uname (&uts))
  97     {
  98       /* This was not successful.  Now try reading the /proc filesystem.  */
  99       int fd = __open ("/proc/sys/kernel/osrelease", O_RDONLY);
 100       if (fd < 0)
 101         return -1;
 102       ssize_t reslen = __read (fd, bufmem, sizeof (bufmem));
 103       __close (fd);
 104       if (reslen <= 0)
 105         /* This also didn't work.  We give up since we cannot
 106            make sure the library can actually work.  */
 107         return -1;
 108       buf[MIN (reslen, (ssize_t) sizeof (bufmem) - 1)] = '\0';
 109     }
 110   else
 111     buf = uts.release;
 112
 113   /* Now convert it into a number.  The string consists of at most
 114      three parts.  */
 115   version = 0;
 116   parts = 0;
 117   cp = buf;
 118   while ((*cp >= '0') && (*cp <= '9'))
 119     {
 120       unsigned int here = *cp++ - '0';
 121
 122       while ((*cp >= '0') && (*cp <= '9'))
 123         {
 124           here *= 10;
 125           here += *cp++ - '0';
 126         }
 127
 128       ++parts;
 129       version <<= 8;
 130       version |= here;
 131
 132       if (*cp++ != '.')
 133         /* Another part following?  */
 134         break;
 135     }
 136
 137   if (parts < 3)
 138     version <<= 8 * (3 - parts);
 139
 140   return version;
 141 }
 142
 143 #define DL_SYSDEP_OSCHECK(FATAL)                                              \
 144   do {                                                                        \
 145     /* Test whether the kernel is new enough.  This test is only performed    \
 146        if the library is not compiled to run on all kernels.  */              \
 147                                                                               \
 148     int version = _dl_discover_osversion ();                                  \
 149     if (__builtin_expect (version >= 0, 1))                                   \
 150       {                                                                       \
 151         if (__builtin_expect (GLRO(dl_osversion) == 0, 1)                     \
 152             || GLRO(dl_osversion) > version)                                  \
 153           GLRO(dl_osversion) = version;                                       \
 154                                                                               \
 155         /* Now we can test with the required version.  */                     \
 156         if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION)   \
 157           /* Not sufficent.  */                                               \
 158           FATAL ("FATAL: kernel too old\n");                                  \
 159       }                                                                       \
 160     else if (__LINUX_KERNEL_VERSION > 0)                                      \
 161       FATAL ("FATAL: cannot determine kernel version\n");                     \
 162   } while (0)
 163
 164 static inline uintptr_t __attribute__ ((always_inline))
 165 _dl_setup_stack_chk_guard (void)
 166 {
 167   uintptr_t ret;
 168 #ifdef ENABLE_STACKGUARD_RANDOMIZE
 169   int fd = __open ("/dev/urandom", O_RDONLY);
 170   if (fd >= 0)
 171     {
 172       ssize_t reslen = __read (fd, &ret, sizeof (ret));
 173       __close (fd);
 174       if (reslen == (ssize_t) sizeof (ret))
 175         return ret;
 176     }
 177 #endif
 178   ret = 0;
 179   unsigned char *p = (unsigned char *) &ret;
 180   p[sizeof (ret) - 1] = 255;
 181   p[sizeof (ret) - 2] = '\n';
 182 #ifdef HP_TIMING_NOW
 183   hp_timing_t hpt;
 184   HP_TIMING_NOW (hpt);
 185   hpt = (hpt & 0xffff) << 8;
 186   ret ^= hpt;
 187 #endif
 188   uintptr_t stk;
 189   /* Avoid GCC being too smart.  */
 190   asm ("" : "=r" (stk) : "r" (p));
 191   stk &= 0x7ffff0;
 192 #if __BYTE_ORDER == __LITTLE_ENDIAN
 193   stk <<= (__WORDSIZE - 23);
 194 #elif __WORDSIZE == 64
 195   stk <<= 31;
 196 #endif
 197   ret ^= stk;
 198   /* Avoid GCC being too smart.  */
 199   p = (unsigned char *) &errno;
 200   asm ("" : "=r" (stk) : "r" (p));
 201   stk &= 0x7fff00;
 202 #if __BYTE_ORDER == __LITTLE_ENDIAN
 203   stk <<= (__WORDSIZE - 29);
 204 #else
 205   stk >>= 8;
 206 #endif
 207   ret ^= stk;
 208   return ret;
 209 }