mirror of
https://sourceware.org/git/glibc.git
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404 lines
12 KiB
C
404 lines
12 KiB
C
/* Dynamic linker system dependencies for Linux.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <_itoa.h>
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#include <assert.h>
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#include <dl-auxv.h>
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#include <dl-hwcap-check.h>
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#include <dl-osinfo.h>
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#include <dl-procinfo.h>
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#include <dl-tunables.h>
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#include <elf.h>
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#include <entry.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <fpu_control.h>
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#include <ldsodefs.h>
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#include <libc-internal.h>
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#include <libintl.h>
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#include <not-cancel.h>
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#include <stdlib.h>
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#include <string.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/utsname.h>
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#include <tls.h>
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#include <unistd.h>
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#include <dl-machine.h>
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#ifdef SHARED
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extern char **_environ attribute_hidden;
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extern char _end[] attribute_hidden;
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/* Protect SUID program against misuse of file descriptors. */
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extern void __libc_check_standard_fds (void);
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int __libc_enable_secure attribute_relro = 0;
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rtld_hidden_data_def (__libc_enable_secure)
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/* This variable contains the lowest stack address ever used. */
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void *__libc_stack_end attribute_relro = NULL;
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rtld_hidden_data_def(__libc_stack_end)
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void *_dl_random attribute_relro = NULL;
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#ifndef DL_FIND_ARG_COMPONENTS
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# define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp) \
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do { \
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void **_tmp; \
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(argc) = *(long int *) cookie; \
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(argv) = (char **) ((long int *) cookie + 1); \
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(envp) = (argv) + (argc) + 1; \
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for (_tmp = (void **) (envp); *_tmp; ++_tmp) \
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continue; \
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(auxp) = (void *) ++_tmp; \
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} while (0)
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#endif
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#ifndef DL_STACK_END
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# define DL_STACK_END(cookie) ((void *) (cookie))
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#endif
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ElfW(Addr)
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_dl_sysdep_start (void **start_argptr,
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void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
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ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
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{
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const ElfW(Phdr) *phdr = NULL;
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ElfW(Word) phnum = 0;
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ElfW(Addr) user_entry;
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ElfW(auxv_t) *av;
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#ifdef NEED_DL_SYSINFO
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uintptr_t new_sysinfo = 0;
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#endif
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__libc_stack_end = DL_STACK_END (start_argptr);
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DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, _dl_argv, _environ,
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GLRO(dl_auxv));
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user_entry = (ElfW(Addr)) ENTRY_POINT;
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GLRO(dl_platform) = NULL; /* Default to nothing known about the platform. */
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/* NB: Default to a constant CONSTANT_MINSIGSTKSZ. */
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_Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),
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"CONSTANT_MINSIGSTKSZ is constant");
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GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ;
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for (av = GLRO(dl_auxv); av->a_type != AT_NULL; av++)
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switch (av->a_type)
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{
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case AT_PHDR:
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phdr = (void *) av->a_un.a_val;
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break;
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case AT_PHNUM:
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phnum = av->a_un.a_val;
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break;
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case AT_PAGESZ:
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GLRO(dl_pagesize) = av->a_un.a_val;
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break;
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case AT_ENTRY:
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user_entry = av->a_un.a_val;
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break;
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case AT_SECURE:
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__libc_enable_secure = av->a_un.a_val;
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break;
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case AT_PLATFORM:
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GLRO(dl_platform) = (void *) av->a_un.a_val;
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break;
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case AT_HWCAP:
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GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
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break;
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case AT_HWCAP2:
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GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
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break;
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case AT_CLKTCK:
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GLRO(dl_clktck) = av->a_un.a_val;
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break;
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case AT_FPUCW:
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GLRO(dl_fpu_control) = av->a_un.a_val;
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break;
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#ifdef NEED_DL_SYSINFO
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case AT_SYSINFO:
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new_sysinfo = av->a_un.a_val;
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break;
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#endif
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#ifdef NEED_DL_SYSINFO_DSO
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case AT_SYSINFO_EHDR:
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GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
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break;
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#endif
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case AT_RANDOM:
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_dl_random = (void *) av->a_un.a_val;
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break;
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case AT_MINSIGSTKSZ:
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GLRO(dl_minsigstacksize) = av->a_un.a_val;
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break;
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DL_PLATFORM_AUXV
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}
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dl_hwcap_check ();
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#ifdef NEED_DL_SYSINFO
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if (new_sysinfo != 0)
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{
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# ifdef NEED_DL_SYSINFO_DSO
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/* Only set the sysinfo value if we also have the vsyscall DSO. */
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if (GLRO(dl_sysinfo_dso) != 0)
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# endif
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GLRO(dl_sysinfo) = new_sysinfo;
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}
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#endif
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__tunables_init (_environ);
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/* Initialize DSO sorting algorithm after tunables. */
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_dl_sort_maps_init ();
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__brk (0); /* Initialize the break. */
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#ifdef DL_PLATFORM_INIT
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DL_PLATFORM_INIT;
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#endif
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/* Determine the length of the platform name. */
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if (GLRO(dl_platform) != NULL)
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GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
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if (__sbrk (0) == _end)
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/* The dynamic linker was run as a program, and so the initial break
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starts just after our bss, at &_end. The malloc in dl-minimal.c
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will consume the rest of this page, so tell the kernel to move the
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break up that far. When the user program examines its break, it
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will see this new value and not clobber our data. */
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__sbrk (GLRO(dl_pagesize)
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- ((_end - (char *) 0) & (GLRO(dl_pagesize) - 1)));
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/* If this is a SUID program we make sure that FDs 0, 1, and 2 are
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allocated. If necessary we are doing it ourself. If it is not
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possible we stop the program. */
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if (__builtin_expect (__libc_enable_secure, 0))
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__libc_check_standard_fds ();
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(*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));
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return user_entry;
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}
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void
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_dl_sysdep_start_cleanup (void)
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{
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}
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void
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_dl_show_auxv (void)
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{
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char buf[64];
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ElfW(auxv_t) *av;
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/* Terminate string. */
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buf[63] = '\0';
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/* The following code assumes that the AT_* values are encoded
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starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
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close by (otherwise the array will be too large). In case we have
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to support a platform where these requirements are not fulfilled
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some alternative implementation has to be used. */
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for (av = GLRO(dl_auxv); av->a_type != AT_NULL; ++av)
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{
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static const struct
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{
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const char label[22];
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enum { unknown = 0, dec, hex, str, ignore } form : 8;
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} auxvars[] =
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{
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[AT_EXECFD - 2] = { "EXECFD: ", dec },
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[AT_EXECFN - 2] = { "EXECFN: ", str },
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[AT_PHDR - 2] = { "PHDR: 0x", hex },
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[AT_PHENT - 2] = { "PHENT: ", dec },
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[AT_PHNUM - 2] = { "PHNUM: ", dec },
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[AT_PAGESZ - 2] = { "PAGESZ: ", dec },
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[AT_BASE - 2] = { "BASE: 0x", hex },
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[AT_FLAGS - 2] = { "FLAGS: 0x", hex },
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[AT_ENTRY - 2] = { "ENTRY: 0x", hex },
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[AT_NOTELF - 2] = { "NOTELF: ", hex },
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[AT_UID - 2] = { "UID: ", dec },
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[AT_EUID - 2] = { "EUID: ", dec },
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[AT_GID - 2] = { "GID: ", dec },
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[AT_EGID - 2] = { "EGID: ", dec },
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[AT_PLATFORM - 2] = { "PLATFORM: ", str },
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[AT_HWCAP - 2] = { "HWCAP: ", hex },
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[AT_CLKTCK - 2] = { "CLKTCK: ", dec },
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[AT_FPUCW - 2] = { "FPUCW: ", hex },
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[AT_DCACHEBSIZE - 2] = { "DCACHEBSIZE: 0x", hex },
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[AT_ICACHEBSIZE - 2] = { "ICACHEBSIZE: 0x", hex },
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[AT_UCACHEBSIZE - 2] = { "UCACHEBSIZE: 0x", hex },
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[AT_IGNOREPPC - 2] = { "IGNOREPPC", ignore },
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[AT_SECURE - 2] = { "SECURE: ", dec },
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[AT_BASE_PLATFORM - 2] = { "BASE_PLATFORM: ", str },
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[AT_SYSINFO - 2] = { "SYSINFO: 0x", hex },
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[AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex },
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[AT_RANDOM - 2] = { "RANDOM: 0x", hex },
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[AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex },
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[AT_MINSIGSTKSZ - 2] = { "MINSIGSTKSZ: ", dec },
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[AT_L1I_CACHESIZE - 2] = { "L1I_CACHESIZE: ", dec },
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[AT_L1I_CACHEGEOMETRY - 2] = { "L1I_CACHEGEOMETRY: 0x", hex },
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[AT_L1D_CACHESIZE - 2] = { "L1D_CACHESIZE: ", dec },
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[AT_L1D_CACHEGEOMETRY - 2] = { "L1D_CACHEGEOMETRY: 0x", hex },
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[AT_L2_CACHESIZE - 2] = { "L2_CACHESIZE: ", dec },
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[AT_L2_CACHEGEOMETRY - 2] = { "L2_CACHEGEOMETRY: 0x", hex },
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[AT_L3_CACHESIZE - 2] = { "L3_CACHESIZE: ", dec },
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[AT_L3_CACHEGEOMETRY - 2] = { "L3_CACHEGEOMETRY: 0x", hex },
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};
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unsigned int idx = (unsigned int) (av->a_type - 2);
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if ((unsigned int) av->a_type < 2u
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|| (idx < sizeof (auxvars) / sizeof (auxvars[0])
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&& auxvars[idx].form == ignore))
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continue;
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assert (AT_NULL == 0);
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assert (AT_IGNORE == 1);
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/* Some entries are handled in a special way per platform. */
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if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
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continue;
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if (idx < sizeof (auxvars) / sizeof (auxvars[0])
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&& auxvars[idx].form != unknown)
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{
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const char *val = (char *) av->a_un.a_val;
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if (__builtin_expect (auxvars[idx].form, dec) == dec)
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val = _itoa ((unsigned long int) av->a_un.a_val,
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buf + sizeof buf - 1, 10, 0);
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else if (__builtin_expect (auxvars[idx].form, hex) == hex)
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val = _itoa ((unsigned long int) av->a_un.a_val,
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buf + sizeof buf - 1, 16, 0);
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_dl_printf ("AT_%s%s\n", auxvars[idx].label, val);
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continue;
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}
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/* Unknown value: print a generic line. */
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char buf2[17];
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buf2[sizeof (buf2) - 1] = '\0';
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const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
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buf2 + sizeof buf2 - 1, 16, 0);
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const char *val = _itoa ((unsigned long int) av->a_type,
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buf + sizeof buf - 1, 16, 0);
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_dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
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}
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}
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#endif /* SHARED */
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int
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attribute_hidden
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_dl_discover_osversion (void)
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{
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#if defined NEED_DL_SYSINFO_DSO && defined SHARED
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if (GLRO(dl_sysinfo_map) != NULL)
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{
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/* If the kernel-supplied DSO contains a note indicating the kernel's
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version, we don't need to call uname or parse any strings. */
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static const struct
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{
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ElfW(Nhdr) hdr;
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char vendor[8];
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} expected_note = { { sizeof "Linux", sizeof (ElfW(Word)), 0 }, "Linux" };
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const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
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const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
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for (uint_fast16_t i = 0; i < phnum; ++i)
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if (phdr[i].p_type == PT_NOTE)
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{
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const ElfW(Addr) start = (phdr[i].p_vaddr
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+ GLRO(dl_sysinfo_map)->l_addr);
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const ElfW(Nhdr) *note = (const void *) start;
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while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
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{
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if (!memcmp (note, &expected_note, sizeof expected_note))
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return *(const ElfW(Word) *) ((const void *) note
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+ sizeof expected_note);
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#define ROUND(len) (((len) + sizeof note->n_type - 1) & -sizeof note->n_type)
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note = ((const void *) (note + 1)
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+ ROUND (note->n_namesz) + ROUND (note->n_descsz));
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#undef ROUND
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}
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}
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}
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#endif
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char bufmem[64];
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char *buf = bufmem;
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unsigned int version;
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int parts;
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char *cp;
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struct utsname uts;
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/* Try the uname system call. */
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if (__uname (&uts))
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{
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/* This was not successful. Now try reading the /proc filesystem. */
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int fd = __open64_nocancel ("/proc/sys/kernel/osrelease", O_RDONLY);
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if (fd < 0)
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return -1;
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ssize_t reslen = __read_nocancel (fd, bufmem, sizeof (bufmem));
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__close_nocancel (fd);
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if (reslen <= 0)
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/* This also didn't work. We give up since we cannot
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make sure the library can actually work. */
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return -1;
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buf[MIN (reslen, (ssize_t) sizeof (bufmem) - 1)] = '\0';
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}
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else
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buf = uts.release;
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/* Now convert it into a number. The string consists of at most
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three parts. */
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version = 0;
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parts = 0;
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cp = buf;
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while ((*cp >= '0') && (*cp <= '9'))
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{
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unsigned int here = *cp++ - '0';
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while ((*cp >= '0') && (*cp <= '9'))
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{
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here *= 10;
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here += *cp++ - '0';
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}
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++parts;
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version <<= 8;
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version |= here;
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if (*cp++ != '.' || parts == 3)
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/* Another part following? */
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break;
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}
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if (parts < 3)
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version <<= 8 * (3 - parts);
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return version;
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}
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