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/sysctl.h>
  24 #include <sys/utsname.h>
  25 #include <kernel-features.h>
  26 #include <dl-sysdep.h>
  27 #include <stdint.h>
  28 #include <hp-timing.h>
  29 #include <endian.h>
  30
  31 #ifndef MIN
  32 # define MIN(a,b) (((a)<(b))?(a):(b))
  33 #endif
  34
  35 #ifdef SHARED
  36 /* This is the function used in the dynamic linker to print the fatal error
  37    message.  */
  38 static inline void
  39 __attribute__ ((__noreturn__))
  40 dl_fatal (const char *str)
  41 {
  42   _dl_dprintf (2, str);
  43   _exit (1);
  44 }
  45 #endif
  46
  47 static inline int __attribute__ ((always_inline))
  48 _dl_discover_osversion (void)
  49 {
  50 #if (defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO) && defined SHARED
  51   if (GLRO(dl_sysinfo_map) != NULL)
  52     {
  53       /* If the kernel-supplied DSO contains a note indicating the kernel's
  54          version, we don't need to call uname or parse any strings.  */
  55
  56       static const struct
  57       {
  58         ElfW(Word) vendorlen;
  59         ElfW(Word) datalen;
  60         ElfW(Word) type;
  61         char vendor[8];
  62       } expected_note = { sizeof "Linux", sizeof (ElfW(Word)), 0, "Linux" };
  63       const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
  64       const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
  65       for (uint_fast16_t i = 0; i < phnum; ++i)
  66         if (phdr[i].p_type == PT_NOTE)
  67           {
  68             const ElfW(Addr) start = (phdr[i].p_vaddr
  69                                       + GLRO(dl_sysinfo_map)->l_addr);
  70             const struct
  71             {
  72               ElfW(Word) vendorlen;
  73               ElfW(Word) datalen;
  74               ElfW(Word) type;
  75             } *note = (const void *) start;
  76             while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
  77               {
  78                 if (!memcmp (note, &expected_note, sizeof expected_note))
  79                   return *(const ElfW(Word) *) ((const void *) note
  80                                                 + sizeof expected_note);
  81 #define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
  82                 note = ((const void *) (note + 1)
  83                         + ROUND (note->vendorlen) + ROUND (note->datalen));
  84               }
  85           }
  86     }
  87 #endif
  88
  89   char bufmem[64];
  90   char *buf = bufmem;
  91   unsigned int version;
  92   int parts;
  93   char *cp;
  94   struct utsname uts;
  95
  96   /* Try the uname system call.  */
  97   if (__uname (&uts))
  98     {
  99       /* This was not successful.  Now try reading the /proc filesystem.  */
 100       int fd = __open ("/proc/sys/kernel/osrelease", O_RDONLY);
 101       if (fd < 0)
 102         return -1;
 103       ssize_t reslen = __read (fd, bufmem, sizeof (bufmem));
 104       __close (fd);
 105       if (reslen <= 0)
 106         /* This also didn't work.  We give up since we cannot
 107            make sure the library can actually work.  */
 108         return -1;
 109       buf[MIN (reslen, (ssize_t) sizeof (bufmem) - 1)] = '\0';
 110     }
 111   else
 112     buf = uts.release;
 113
 114   /* Now convert it into a number.  The string consists of at most
 115      three parts.  */
 116   version = 0;
 117   parts = 0;
 118   cp = buf;
 119   while ((*cp >= '0') && (*cp <= '9'))
 120     {
 121       unsigned int here = *cp++ - '0';
 122
 123       while ((*cp >= '0') && (*cp <= '9'))
 124         {
 125           here *= 10;
 126           here += *cp++ - '0';
 127         }
 128
 129       ++parts;
 130       version <<= 8;
 131       version |= here;
 132
 133       if (*cp++ != '.')
 134         /* Another part following?  */
 135         break;
 136     }
 137
 138   if (parts < 3)
 139     version <<= 8 * (3 - parts);
 140
 141   return version;
 142 }
 143
 144 #define DL_SYSDEP_OSCHECK(FATAL)                                              \
 145   do {                                                                        \
 146     /* Test whether the kernel is new enough.  This test is only performed    \
 147        if the library is not compiled to run on all kernels.  */              \
 148                                                                               \
 149     int version = _dl_discover_osversion ();                                  \
 150     if (__builtin_expect (version >= 0, 1))                                   \
 151       {                                                                       \
 152         if (__builtin_expect (GLRO(dl_osversion) == 0, 1)                     \
 153             || GLRO(dl_osversion) > version)                                  \
 154           GLRO(dl_osversion) = version;                                       \
 155                                                                               \
 156         /* Now we can test with the required version.  */                     \
 157         if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION)   \
 158           /* Not sufficent.  */                                               \
 159           FATAL ("FATAL: kernel too old\n");                                  \
 160       }                                                                       \
 161     else if (__LINUX_KERNEL_VERSION > 0)                                      \
 162       FATAL ("FATAL: cannot determine kernel version\n");                     \
 163   } while (0)
 164
 165 static inline uintptr_t __attribute__ ((always_inline))
 166 _dl_setup_stack_chk_guard (void)
 167 {
 168   uintptr_t ret;
 169 #ifdef ENABLE_STACKGUARD_RANDOMIZE
 170   int fd = __open ("/dev/urandom", O_RDONLY);
 171   if (fd >= 0)
 172     {
 173       ssize_t reslen = __read (fd, &ret, sizeof (ret));
 174       __close (fd);
 175       if (reslen == (ssize_t) sizeof (ret))
 176         return ret;
 177     }
 178 #endif
 179   ret = 0;
 180   unsigned char *p = (unsigned char *) &ret;
 181   p[sizeof (ret) - 1] = 255;
 182   p[sizeof (ret) - 2] = '\n';
 183 #ifdef HP_TIMING_NOW
 184   hp_timing_t hpt;
 185   HP_TIMING_NOW (hpt);
 186   hpt = (hpt & 0xffff) << 8;
 187   ret ^= hpt;
 188 #endif
 189   uintptr_t stk;
 190   /* Avoid GCC being too smart.  */
 191   asm ("" : "=r" (stk) : "r" (p));
 192   stk &= 0x7ffff0;
 193 #if __BYTE_ORDER == __LITTLE_ENDIAN
 194   stk <<= (__WORDSIZE - 23);
 195 #elif __WORDSIZE == 64
 196   stk <<= 31;
 197 #endif
 198   ret ^= stk;
 199   /* Avoid GCC being too smart.  */
 200   p = (unsigned char *) &errno;
 201   asm ("" : "=r" (stk) : "r" (p));
 202   stk &= 0x7fff00;
 203 #if __BYTE_ORDER == __LITTLE_ENDIAN
 204   stk <<= (__WORDSIZE - 29);
 205 #else
 206   stk >>= 8;
 207 #endif
 208   ret ^= stk;
 209   return ret;
 210 }