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glibc/elf/dl-load.c
Adhemerval Zanella 7edd3814b0 linux: Remove __stack_prot 
The __stack_prot is used by Linux to make the stack executable if
a modules requires it.  It is also marked as RELRO, which requires
to change the segment permission to RW to update it.

Also, there is no need to keep track of the flags: either the stack
will have the default permission of the ABI or should be change to
PROT_READ | PROT_WRITE | PROT_EXEC.  The only additional flag,
PROT_GROWSDOWN or PROT_GROWSUP, is Linux only and can be deducted
from _STACK_GROWS_DOWN/_STACK_GROWS_UP.

Also, the check_consistency function was already removed some time
ago.

Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-06-12 15:25:54 -03:00

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/* Map in a shared object's segments from the file.
Copyright (C) 1995-2024 Free Software Foundation, Inc.
Copyright The GNU Toolchain Authors.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <libintl.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <bits/wordsize.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <gnu/lib-names.h>
/* Type for the buffer we put the ELF header and hopefully the program
header. This buffer does not really have to be too large. In most
cases the program header follows the ELF header directly. If this
is not the case all bets are off and we can make the header
arbitrarily large and still won't get it read. This means the only
question is how large are the ELF and program header combined. The
ELF header 32-bit files is 52 bytes long and in 64-bit files is 64
bytes long. Each program header entry is again 32 and 56 bytes
long respectively. I.e., even with a file which has 10 program
header entries we only have to read 372B/624B respectively. Add to
this a bit of margin for program notes and reading 512B and 832B
for 32-bit and 64-bit files respectively is enough. If this
heuristic should really fail for some file the code in
`_dl_map_object_from_fd' knows how to recover. */
struct filebuf
{
ssize_t len;
#if __WORDSIZE == 32
# define FILEBUF_SIZE 512
#else
# define FILEBUF_SIZE 832
#endif
char buf[FILEBUF_SIZE] __attribute__ ((aligned (__alignof (ElfW(Ehdr)))));
};
#include "dynamic-link.h"
#include "get-dynamic-info.h"
#include <abi-tag.h>
#include <stackinfo.h>
#include <sysdep.h>
#include <stap-probe.h>
#include <libc-pointer-arith.h>
#include <array_length.h>
#include <dl-dst.h>
#include <dl-load.h>
#include <dl-map-segments.h>
#include <dl-unmap-segments.h>
#include <dl-machine-reject-phdr.h>
#include <dl-prop.h>
#include <not-cancel.h>
#include <endian.h>
#if BYTE_ORDER == BIG_ENDIAN
# define byteorder ELFDATA2MSB
#elif BYTE_ORDER == LITTLE_ENDIAN
# define byteorder ELFDATA2LSB
#else
# error "Unknown BYTE_ORDER " BYTE_ORDER
# define byteorder ELFDATANONE
#endif
#define STRING(x) __STRING (x)
/* This is the decomposed LD_LIBRARY_PATH search path. */
struct r_search_path_struct __rtld_env_path_list attribute_relro;
/* List of the hardware capabilities we might end up using. */
#ifdef SHARED
static const struct r_strlenpair *capstr attribute_relro;
static size_t ncapstr attribute_relro;
static size_t max_capstrlen attribute_relro;
#else
enum { ncapstr = 1, max_capstrlen = 0 };
#endif
/* Get the generated information about the trusted directories. Use
an array of concatenated strings to avoid relocations. See
gen-trusted-dirs.awk. */
#include "trusted-dirs.h"
static const char system_dirs[] = SYSTEM_DIRS;
static const size_t system_dirs_len[] =
{
SYSTEM_DIRS_LEN
};
#define nsystem_dirs_len array_length (system_dirs_len)
static bool
is_trusted_path_normalize (const char *path, size_t len)
{
if (len == 0)
return false;
char *npath = (char *) alloca (len + 2);
char *wnp = npath;
while (*path != '\0')
{
if (path[0] == '/')
{
if (path[1] == '.')
{
if (path[2] == '.' && (path[3] == '/' || path[3] == '\0'))
{
while (wnp > npath && *--wnp != '/')
;
path += 3;
continue;
}
else if (path[2] == '/' || path[2] == '\0')
{
path += 2;
continue;
}
}
if (wnp > npath && wnp[-1] == '/')
{
++path;
continue;
}
}
*wnp++ = *path++;
}
if (wnp == npath || wnp[-1] != '/')
*wnp++ = '/';
const char *trun = system_dirs;
for (size_t idx = 0; idx < nsystem_dirs_len; ++idx)
{
if (wnp - npath >= system_dirs_len[idx]
&& memcmp (trun, npath, system_dirs_len[idx]) == 0)
/* Found it. */
return true;
trun += system_dirs_len[idx] + 1;
}
return false;
}
/* Given a substring starting at INPUT, just after the DST '$' start
token, determine if INPUT contains DST token REF, following the
ELF gABI rules for DSTs:
* Longest possible sequence using the rules (greedy).
* Must start with a $ (enforced by caller).
* Must follow $ with one underscore or ASCII [A-Za-z] (caller
follows these rules for REF) or '{' (start curly quoted name).
* Must follow first two characters with zero or more [A-Za-z0-9_]
(enforced by caller) or '}' (end curly quoted name).
If the sequence is a DST matching REF then the length of the DST
(excluding the $ sign but including curly braces, if any) is
returned, otherwise 0. */
static size_t
is_dst (const char *input, const char *ref)
{
bool is_curly = false;
/* Is a ${...} input sequence? */
if (input[0] == '{')
{
is_curly = true;
++input;
}
/* Check for matching name, following closing curly brace (if
required), or trailing characters which are part of an
identifier. */
size_t rlen = strlen (ref);
if (strncmp (input, ref, rlen) != 0
|| (is_curly && input[rlen] != '}')
|| ((input[rlen] >= 'A' && input[rlen] <= 'Z')
|| (input[rlen] >= 'a' && input[rlen] <= 'z')
|| (input[rlen] >= '0' && input[rlen] <= '9')
|| (input[rlen] == '_')))
return 0;
if (is_curly)
/* Count the two curly braces. */
return rlen + 2;
else
return rlen;
}
/* INPUT should be the start of a path e.g DT_RPATH or name e.g.
DT_NEEDED. The return value is the number of known DSTs found. We
count all known DSTs regardless of __libc_enable_secure; the caller
is responsible for enforcing the security of the substitution rules
(usually _dl_dst_substitute). */
size_t
_dl_dst_count (const char *input)
{
size_t cnt = 0;
input = strchr (input, '$');
/* Most likely there is no DST. */
if (__glibc_likely (input == NULL))
return 0;
do
{
size_t len;
++input;
/* All DSTs must follow ELF gABI rules, see is_dst (). */
if ((len = is_dst (input, "ORIGIN")) != 0
|| (len = is_dst (input, "PLATFORM")) != 0
|| (len = is_dst (input, "LIB")) != 0)
++cnt;
/* There may be more than one DST in the input. */
input = strchr (input + len, '$');
}
while (input != NULL);
return cnt;
}
/* Process INPUT for DSTs and store in RESULT using the information
from link map L to resolve the DSTs. This function only handles one
path at a time and does not handle colon-separated path lists (see
fillin_rpath ()). Lastly the size of result in bytes should be at
least equal to the value returned by DL_DST_REQUIRED. Note that it
is possible for a DT_NEEDED, DT_AUXILIARY, and DT_FILTER entries to
have colons, but we treat those as literal colons here, not as path
list delimiters. */
char *
_dl_dst_substitute (struct link_map *l, const char *input, char *result)
{
/* Copy character-by-character from input into the working pointer
looking for any DSTs. We track the start of input and if we are
going to check for trusted paths, all of which are part of $ORIGIN
handling in SUID/SGID cases (see below). In some cases, like when
a DST cannot be replaced, we may set result to an empty string and
return. */
char *wp = result;
const char *start = input;
bool check_for_trusted = false;
do
{
if (__glibc_unlikely (*input == '$'))
{
const char *repl = NULL;
size_t len;
++input;
if ((len = is_dst (input, "ORIGIN")) != 0)
{
/* For SUID/GUID programs we normally ignore the path with
$ORIGIN in DT_RUNPATH, or DT_RPATH. However, there is
one exception to this rule, and it is:
* $ORIGIN appears as the first path element, and is
the only string in the path or is immediately
followed by a path separator and the rest of the
path,
and ...
* The path is rooted in a trusted directory.
This exception allows such programs to reference
shared libraries in subdirectories of trusted
directories. The use case is one of general
organization and deployment flexibility.
Trusted directories are usually such paths as "/lib64"
or "/usr/lib64", and the usual RPATHs take the form of
[$ORIGIN/../$LIB/somedir]. */
if (__glibc_unlikely (__libc_enable_secure)
&& !(input == start + 1
&& (input[len] == '\0' || input[len] == '/')))
repl = (const char *) -1;
else
repl = l->l_origin;
check_for_trusted = (__libc_enable_secure
&& l->l_type == lt_executable);
}
else if ((len = is_dst (input, "PLATFORM")) != 0)
repl = GLRO(dl_platform);
else if ((len = is_dst (input, "LIB")) != 0)
repl = DL_DST_LIB;
if (repl != NULL && repl != (const char *) -1)
{
wp = __stpcpy (wp, repl);
input += len;
}
else if (len != 0)
{
/* We found a valid DST that we know about, but we could
not find a replacement value for it, therefore we
cannot use this path and discard it. */
*result = '\0';
return result;
}
else
/* No DST we recognize. */
*wp++ = '$';
}
else
{
*wp++ = *input++;
}
}
while (*input != '\0');
/* In SUID/SGID programs, after $ORIGIN expansion the normalized
path must be rooted in one of the trusted directories. The $LIB
and $PLATFORM DST cannot in any way be manipulated by the caller
because they are fixed values that are set by the dynamic loader
and therefore any paths using just $LIB or $PLATFORM need not be
checked for trust, the authors of the binaries themselves are
trusted to have designed this correctly. Only $ORIGIN is tested in
this way because it may be manipulated in some ways with hard
links. */
if (__glibc_unlikely (check_for_trusted)
&& !is_trusted_path_normalize (result, wp - result))
{
*result = '\0';
return result;
}
*wp = '\0';
return result;
}
/* Return a malloc allocated copy of INPUT with all recognized DSTs
replaced. On some platforms it might not be possible to determine the
path from which the object belonging to the map is loaded. In this
case the path containing the DST is left out. On error NULL
is returned. */
static char *
expand_dynamic_string_token (struct link_map *l, const char *input)
{
/* We make two runs over the string. First we determine how large the
resulting string is and then we copy it over. Since this is no
frequently executed operation we are looking here not for performance
but rather for code size. */
size_t cnt;
size_t total;
char *result;
/* Determine the number of DSTs. */
cnt = _dl_dst_count (input);
/* If we do not have to replace anything simply copy the string. */
if (__glibc_likely (cnt == 0))
return __strdup (input);
/* Determine the length of the substituted string. */
total = DL_DST_REQUIRED (l, input, strlen (input), cnt);
/* Allocate the necessary memory. */
result = (char *) malloc (total + 1);
if (result == NULL)
return NULL;
return _dl_dst_substitute (l, input, result);
}
/* Add `name' to the list of names for a particular shared object.
`name' is expected to have been allocated with malloc and will
be freed if the shared object already has this name.
Returns false if the object already had this name. */
static void
add_name_to_object (struct link_map *l, const char *name)
{
struct libname_list *lnp, *lastp;
struct libname_list *newname;
size_t name_len;
lastp = NULL;
for (lnp = l->l_libname; lnp != NULL; lastp = lnp, lnp = lnp->next)
if (strcmp (name, lnp->name) == 0)
return;
name_len = strlen (name) + 1;
newname = (struct libname_list *) malloc (sizeof *newname + name_len);
if (newname == NULL)
{
/* No more memory. */
_dl_signal_error (ENOMEM, name, NULL, N_("cannot allocate name record"));
return;
}
/* The object should have a libname set from _dl_new_object. */
assert (lastp != NULL);
newname->name = memcpy (newname + 1, name, name_len);
newname->next = NULL;
newname->dont_free = 0;
/* CONCURRENCY NOTES:
Make sure the initialization of newname happens before its address is
read from the lastp->next store below.
GL(dl_load_lock) is held here (and by other writers, e.g. dlclose), so
readers of libname_list->next (e.g. _dl_check_caller or the reads above)
can use that for synchronization, however the read in _dl_name_match_p
may be executed without holding the lock during _dl_runtime_resolve
(i.e. lazy symbol resolution when a function of library l is called).
The release MO store below synchronizes with the acquire MO load in
_dl_name_match_p. Other writes need to synchronize with that load too,
however those happen either early when the process is single threaded
(dl_main) or when the library is unloaded (dlclose) and the user has to
synchronize library calls with unloading. */
atomic_store_release (&lastp->next, newname);
}
/* Standard search directories. */
struct r_search_path_struct __rtld_search_dirs attribute_relro;
static size_t max_dirnamelen;
static struct r_search_path_elem **
fillin_rpath (char *rpath, struct r_search_path_elem **result, const char *sep,
const char *what, const char *where, struct link_map *l)
{
char *cp;
size_t nelems = 0;
while ((cp = __strsep (&rpath, sep)) != NULL)
{
struct r_search_path_elem *dirp;
char *to_free = NULL;
size_t len = 0;
/* `strsep' can pass an empty string. */
if (*cp != '\0')
{
to_free = cp = expand_dynamic_string_token (l, cp);
/* expand_dynamic_string_token can return NULL in case of empty
path or memory allocation failure. */
if (cp == NULL)
continue;
/* Compute the length after dynamic string token expansion and
ignore empty paths. */
len = strlen (cp);
if (len == 0)
{
free (to_free);
continue;
}
/* Remove trailing slashes (except for "/"). */
while (len > 1 && cp[len - 1] == '/')
--len;
/* Now add one if there is none so far. */
if (len > 0 && cp[len - 1] != '/')
cp[len++] = '/';
}
/* See if this directory is already known. */
for (dirp = GL(dl_all_dirs); dirp != NULL; dirp = dirp->next)
if (dirp->dirnamelen == len && memcmp (cp, dirp->dirname, len) == 0)
break;
if (dirp != NULL)
{
/* It is available, see whether it's on our own list. */
size_t cnt;
for (cnt = 0; cnt < nelems; ++cnt)
if (result[cnt] == dirp)
break;
if (cnt == nelems)
result[nelems++] = dirp;
}
else
{
size_t cnt;
enum r_dir_status init_val;
size_t where_len = where ? strlen (where) + 1 : 0;
/* It's a new directory. Create an entry and add it. */
dirp = (struct r_search_path_elem *)
malloc (sizeof (*dirp) + ncapstr * sizeof (enum r_dir_status)
+ where_len + len + 1);
if (dirp == NULL)
_dl_signal_error (ENOMEM, NULL, NULL,
N_("cannot create cache for search path"));
dirp->dirname = ((char *) dirp + sizeof (*dirp)
+ ncapstr * sizeof (enum r_dir_status));
*((char *) __mempcpy ((char *) dirp->dirname, cp, len)) = '\0';
dirp->dirnamelen = len;
if (len > max_dirnamelen)
max_dirnamelen = len;
/* We have to make sure all the relative directories are
never ignored. The current directory might change and
all our saved information would be void. */
init_val = cp[0] != '/' ? existing : unknown;
for (cnt = 0; cnt < ncapstr; ++cnt)
dirp->status[cnt] = init_val;
dirp->what = what;
if (__glibc_likely (where != NULL))
dirp->where = memcpy ((char *) dirp + sizeof (*dirp) + len + 1
+ (ncapstr * sizeof (enum r_dir_status)),
where, where_len);
else
dirp->where = NULL;
dirp->next = GL(dl_all_dirs);
GL(dl_all_dirs) = dirp;
/* Put it in the result array. */
result[nelems++] = dirp;
}
free (to_free);
}
/* Terminate the array. */
result[nelems] = NULL;
return result;
}
static bool
decompose_rpath (struct r_search_path_struct *sps,
const char *rpath, struct link_map *l, const char *what)
{
/* Make a copy we can work with. */
const char *where = l->l_name;
char *cp;
struct r_search_path_elem **result;
size_t nelems;
/* Initialize to please the compiler. */
const char *errstring = NULL;
/* First see whether we must forget the RUNPATH and RPATH from this
object. */
if (__glibc_unlikely (GLRO(dl_inhibit_rpath) != NULL)
&& !__libc_enable_secure)
{
const char *inhp = GLRO(dl_inhibit_rpath);
do
{
const char *wp = where;
while (*inhp == *wp && *wp != '\0')
{
++inhp;
++wp;
}
if (*wp == '\0' && (*inhp == '\0' || *inhp == ':'))
{
/* This object is on the list of objects for which the
RUNPATH and RPATH must not be used. */
sps->dirs = (void *) -1;
return false;
}
while (*inhp != '\0')
if (*inhp++ == ':')
break;
}
while (*inhp != '\0');
}
/* Ignore empty rpaths. */
if (*rpath == '\0')
{
sps->dirs = (struct r_search_path_elem **) -1;
return false;
}
/* Make a writable copy. */
char *copy = __strdup (rpath);
if (copy == NULL)
{
errstring = N_("cannot create RUNPATH/RPATH copy");
goto signal_error;
}
/* Count the number of necessary elements in the result array. */
nelems = 0;
for (cp = copy; *cp != '\0'; ++cp)
if (*cp == ':')
++nelems;
/* Allocate room for the result. NELEMS + 1 is an upper limit for the
number of necessary entries. */
result = (struct r_search_path_elem **) malloc ((nelems + 1 + 1)
* sizeof (*result));
if (result == NULL)
{
free (copy);
errstring = N_("cannot create cache for search path");
signal_error:
_dl_signal_error (ENOMEM, NULL, NULL, errstring);
}
fillin_rpath (copy, result, ":", what, where, l);
/* Free the copied RPATH string. `fillin_rpath' make own copies if
necessary. */
free (copy);
/* There is no path after expansion. */
if (result[0] == NULL)
{
free (result);
sps->dirs = (struct r_search_path_elem **) -1;
return false;
}
sps->dirs = result;
/* The caller will change this value if we haven't used a real malloc. */
sps->malloced = 1;
return true;
}
/* Make sure cached path information is stored in *SP
and return true if there are any paths to search there. */
static bool
cache_rpath (struct link_map *l,
struct r_search_path_struct *sp,
int tag,
const char *what)
{
if (sp->dirs == (void *) -1)
return false;
if (sp->dirs != NULL)
return true;
if (l->l_info[tag] == NULL)
{
/* There is no path. */
sp->dirs = (void *) -1;
return false;
}
/* Make sure the cache information is available. */
return decompose_rpath (sp, (const char *) (D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[tag]->d_un.d_val),
l, what);
}
void
_dl_init_paths (const char *llp, const char *source,
const char *glibc_hwcaps_prepend,
const char *glibc_hwcaps_mask)
{
size_t idx;
const char *strp;
struct r_search_path_elem *pelem, **aelem;
size_t round_size;
struct link_map __attribute__ ((unused)) *l = NULL;
/* Initialize to please the compiler. */
const char *errstring = NULL;
/* Fill in the information about the application's RPATH and the
directories addressed by the LD_LIBRARY_PATH environment variable. */
#ifdef SHARED
/* Get the capabilities. */
capstr = _dl_important_hwcaps (glibc_hwcaps_prepend, glibc_hwcaps_mask,
&ncapstr, &max_capstrlen);
#endif
/* First set up the rest of the default search directory entries. */
aelem = __rtld_search_dirs.dirs = (struct r_search_path_elem **)
malloc ((nsystem_dirs_len + 1) * sizeof (struct r_search_path_elem *));
if (__rtld_search_dirs.dirs == NULL)
{
errstring = N_("cannot create search path array");
signal_error:
_dl_signal_error (ENOMEM, NULL, NULL, errstring);
}
round_size = ((2 * sizeof (struct r_search_path_elem) - 1
+ ncapstr * sizeof (enum r_dir_status))
/ sizeof (struct r_search_path_elem));
__rtld_search_dirs.dirs[0]
= malloc (nsystem_dirs_len * round_size
* sizeof (*__rtld_search_dirs.dirs[0]));
if (__rtld_search_dirs.dirs[0] == NULL)
{
errstring = N_("cannot create cache for search path");
goto signal_error;
}
__rtld_search_dirs.malloced = 0;
pelem = GL(dl_all_dirs) = __rtld_search_dirs.dirs[0];
strp = system_dirs;
idx = 0;
do
{
size_t cnt;
*aelem++ = pelem;
pelem->what = "system search path";
pelem->where = NULL;
pelem->dirname = strp;
pelem->dirnamelen = system_dirs_len[idx];
strp += system_dirs_len[idx] + 1;
/* System paths must be absolute. */
assert (pelem->dirname[0] == '/');
for (cnt = 0; cnt < ncapstr; ++cnt)
pelem->status[cnt] = unknown;
pelem->next = (++idx == nsystem_dirs_len ? NULL : (pelem + round_size));
pelem += round_size;
}
while (idx < nsystem_dirs_len);
max_dirnamelen = SYSTEM_DIRS_MAX_LEN;
*aelem = NULL;
/* This points to the map of the main object. If there is no main
object (e.g., under --help, use the dynamic loader itself as a
stand-in. */
l = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
#ifdef SHARED
if (l == NULL)
l = &GL (dl_rtld_map);
#endif
assert (l->l_type != lt_loaded);
if (l->l_info[DT_RUNPATH])
{
/* Allocate room for the search path and fill in information
from RUNPATH. */
decompose_rpath (&l->l_runpath_dirs,
(const void *) (D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_RUNPATH]->d_un.d_val),
l, "RUNPATH");
/* During rtld init the memory is allocated by the stub malloc,
prevent any attempt to free it by the normal malloc. */
l->l_runpath_dirs.malloced = 0;
/* The RPATH is ignored. */
l->l_rpath_dirs.dirs = (void *) -1;
}
else
{
l->l_runpath_dirs.dirs = (void *) -1;
if (l->l_info[DT_RPATH])
{
/* Allocate room for the search path and fill in information
from RPATH. */
decompose_rpath (&l->l_rpath_dirs,
(const void *) (D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_RPATH]->d_un.d_val),
l, "RPATH");
/* During rtld init the memory is allocated by the stub
malloc, prevent any attempt to free it by the normal
malloc. */
l->l_rpath_dirs.malloced = 0;
}
else
l->l_rpath_dirs.dirs = (void *) -1;
}
if (llp != NULL && *llp != '\0')
{
char *llp_tmp = strdupa (llp);
/* Decompose the LD_LIBRARY_PATH contents. First determine how many
elements it has. */
size_t nllp = 1;
for (const char *cp = llp_tmp; *cp != '\0'; ++cp)
if (*cp == ':' || *cp == ';')
++nllp;
__rtld_env_path_list.dirs = (struct r_search_path_elem **)
malloc ((nllp + 1) * sizeof (struct r_search_path_elem *));
if (__rtld_env_path_list.dirs == NULL)
{
errstring = N_("cannot create cache for search path");
goto signal_error;
}
(void) fillin_rpath (llp_tmp, __rtld_env_path_list.dirs, ":;",
source, NULL, l);
if (__rtld_env_path_list.dirs[0] == NULL)
{
free (__rtld_env_path_list.dirs);
__rtld_env_path_list.dirs = (void *) -1;
}
__rtld_env_path_list.malloced = 0;
}
else
__rtld_env_path_list.dirs = (void *) -1;
}
/* Process PT_GNU_PROPERTY program header PH in module L after
PT_LOAD segments are mapped. Only one NT_GNU_PROPERTY_TYPE_0
note is handled which contains processor specific properties.
FD is -1 for the kernel mapped main executable otherwise it is
the fd used for loading module L. */
void
_dl_process_pt_gnu_property (struct link_map *l, int fd, const ElfW(Phdr) *ph)
{
const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr);
const ElfW(Addr) size = ph->p_memsz;
const ElfW(Addr) align = ph->p_align;
/* The NT_GNU_PROPERTY_TYPE_0 note must be aligned to 4 bytes in
32-bit objects and to 8 bytes in 64-bit objects. Skip notes
with incorrect alignment. */
if (align != (__ELF_NATIVE_CLASS / 8))
return;
const ElfW(Addr) start = (ElfW(Addr)) note;
unsigned int last_type = 0;
while ((ElfW(Addr)) (note + 1) - start < size)
{
/* Find the NT_GNU_PROPERTY_TYPE_0 note. */
if (note->n_namesz == 4
&& note->n_type == NT_GNU_PROPERTY_TYPE_0
&& memcmp (note + 1, "GNU", 4) == 0)
{
/* Check for invalid property. */
if (note->n_descsz < 8
|| (note->n_descsz % sizeof (ElfW(Addr))) != 0)
return;
/* Start and end of property array. */
unsigned char *ptr = (unsigned char *) (note + 1) + 4;
unsigned char *ptr_end = ptr + note->n_descsz;
do
{
unsigned int type = *(unsigned int *) ptr;
unsigned int datasz = *(unsigned int *) (ptr + 4);
/* Property type must be in ascending order. */
if (type < last_type)
return;
ptr += 8;
if ((ptr + datasz) > ptr_end)
return;
last_type = type;
/* Target specific property processing. */
if (_dl_process_gnu_property (l, fd, type, datasz, ptr) == 0)
return;
/* Check the next property item. */
ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
}
while ((ptr_end - ptr) >= 8);
/* Only handle one NT_GNU_PROPERTY_TYPE_0. */
return;
}
note = ((const void *) note
+ ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
align));
}
}
/* Map in the shared object NAME, actually located in REALNAME, and already
opened on FD. */
#ifndef EXTERNAL_MAP_FROM_FD
static
#endif
struct link_map *
_dl_map_object_from_fd (const char *name, const char *origname, int fd,
struct filebuf *fbp, char *realname,
struct link_map *loader, int l_type, int mode,
void **stack_endp, Lmid_t nsid)
{
struct link_map *l = NULL;
const ElfW(Ehdr) *header;
const ElfW(Phdr) *phdr;
const ElfW(Phdr) *ph;
size_t maplength;
int type;
/* Initialize to keep the compiler happy. */
const char *errstring = NULL;
int errval = 0;
/* Get file information. To match the kernel behavior, do not fill
in this information for the executable in case of an explicit
loader invocation. */
struct r_file_id id;
if (mode & __RTLD_OPENEXEC)
{
assert (nsid == LM_ID_BASE);
memset (&id, 0, sizeof (id));
}
else
{
if (__glibc_unlikely (!_dl_get_file_id (fd, &id)))
{
errstring = N_("cannot stat shared object");
lose_errno:
errval = errno;
lose:
/* The file might already be closed. */
if (fd != -1)
__close_nocancel (fd);
if (l != NULL && l->l_map_start != 0)
_dl_unmap_segments (l);
if (l != NULL && l->l_origin != (char *) -1l)
free ((char *) l->l_origin);
if (l != NULL && !l->l_libname->dont_free)
free (l->l_libname);
if (l != NULL && l->l_phdr_allocated)
free ((void *) l->l_phdr);
free (l);
free (realname);
_dl_signal_error (errval, name, NULL, errstring);
}
/* Look again to see if the real name matched another already loaded. */
for (l = GL(dl_ns)[nsid]._ns_loaded; l != NULL; l = l->l_next)
if (!l->l_removed && _dl_file_id_match_p (&l->l_file_id, &id))
{
/* The object is already loaded.
Just bump its reference count and return it. */
__close_nocancel (fd);
/* If the name is not in the list of names for this object add
it. */
free (realname);
add_name_to_object (l, name);
return l;
}
}
#ifdef SHARED
/* When loading into a namespace other than the base one we must
avoid loading ld.so since there can only be one copy. Ever. */
if (__glibc_unlikely (nsid != LM_ID_BASE)
&& (_dl_file_id_match_p (&id, &GL(dl_rtld_map).l_file_id)
|| _dl_name_match_p (name, &GL(dl_rtld_map))))
{
/* This is indeed ld.so. Create a new link_map which refers to
the real one for almost everything. */
l = _dl_new_object (realname, name, l_type, loader, mode, nsid);
if (l == NULL)
goto fail_new;
/* Refer to the real descriptor. */
l->l_real = &GL(dl_rtld_map);
/* Copy l_addr and l_ld to avoid a GDB warning with dlmopen(). */
l->l_addr = l->l_real->l_addr;
l->l_ld = l->l_real->l_ld;
/* No need to bump the refcount of the real object, ld.so will
never be unloaded. */
__close_nocancel (fd);
/* Add the map for the mirrored object to the object list. */
_dl_add_to_namespace_list (l, nsid);
return l;
}
#endif
if (mode & RTLD_NOLOAD)
{
/* We are not supposed to load the object unless it is already
loaded. So return now. */
free (realname);
__close_nocancel (fd);
return NULL;
}
/* Print debugging message. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
_dl_debug_printf ("file=%s [%lu]; generating link map\n", name, nsid);
/* This is the ELF header. We read it in `open_verify'. */
header = (void *) fbp->buf;
/* Enter the new object in the list of loaded objects. */
l = _dl_new_object (realname, name, l_type, loader, mode, nsid);
if (__glibc_unlikely (l == NULL))
{
#ifdef SHARED
fail_new:
#endif
errstring = N_("cannot create shared object descriptor");
goto lose_errno;
}
/* Extract the remaining details we need from the ELF header
and then read in the program header table. */
l->l_entry = header->e_entry;
type = header->e_type;
l->l_phnum = header->e_phnum;
maplength = header->e_phnum * sizeof (ElfW(Phdr));
if (header->e_phoff + maplength <= (size_t) fbp->len)
phdr = (void *) (fbp->buf + header->e_phoff);
else
{
phdr = alloca (maplength);
if ((size_t) __pread64_nocancel (fd, (void *) phdr, maplength,
header->e_phoff) != maplength)
{
errstring = N_("cannot read file data");
goto lose_errno;
}
}
/* On most platforms presume that PT_GNU_STACK is absent and the stack is
* executable. Other platforms default to a nonexecutable stack and don't
* need PT_GNU_STACK to do so. */
unsigned int stack_flags = DEFAULT_STACK_PERMS;
{
/* Scan the program header table, collecting its load commands. */
struct loadcmd loadcmds[l->l_phnum];
size_t nloadcmds = 0;
bool has_holes = false;
bool empty_dynamic = false;
ElfW(Addr) p_align_max = 0;
/* The struct is initialized to zero so this is not necessary:
l->l_ld = 0;
l->l_phdr = 0;
l->l_addr = 0; */
for (ph = phdr; ph < &phdr[l->l_phnum]; ++ph)
switch (ph->p_type)
{
/* These entries tell us where to find things once the file's
segments are mapped in. We record the addresses it says
verbatim, and later correct for the run-time load address. */
case PT_DYNAMIC:
if (ph->p_filesz == 0)
empty_dynamic = true; /* Usually separate debuginfo. */
else
{
/* Debuginfo only files from "objcopy --only-keep-debug"
contain a PT_DYNAMIC segment with p_filesz == 0. Skip
such a segment to avoid a crash later. */
l->l_ld = (void *) ph->p_vaddr;
l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn));
l->l_ld_readonly = (ph->p_flags & PF_W) == 0;
}
break;
case PT_PHDR:
l->l_phdr = (void *) ph->p_vaddr;
break;
case PT_LOAD:
/* A load command tells us to map in part of the file.
We record the load commands and process them all later. */
if (__glibc_unlikely (((ph->p_vaddr - ph->p_offset)
& (GLRO(dl_pagesize) - 1)) != 0))
{
errstring
= N_("ELF load command address/offset not page-aligned");
goto lose;
}
struct loadcmd *c = &loadcmds[nloadcmds++];
c->mapstart = ALIGN_DOWN (ph->p_vaddr, GLRO(dl_pagesize));
c->mapend = ALIGN_UP (ph->p_vaddr + ph->p_filesz, GLRO(dl_pagesize));
c->dataend = ph->p_vaddr + ph->p_filesz;
c->allocend = ph->p_vaddr + ph->p_memsz;
/* Remember the maximum p_align. */
if (powerof2 (ph->p_align) && ph->p_align > p_align_max)
p_align_max = ph->p_align;
c->mapoff = ALIGN_DOWN (ph->p_offset, GLRO(dl_pagesize));
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (11, 0)
/* Suppress invalid GCC warning:
‘(((char *)loadcmds.113_68 + _933 + 16))[329406144173384849].mapend’ may be used uninitialized [-Wmaybe-uninitialized]
See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106008
*/
DIAG_IGNORE_NEEDS_COMMENT (11, "-Wmaybe-uninitialized");
#endif
/* Determine whether there is a gap between the last segment
and this one. */
if (nloadcmds > 1 && c[-1].mapend != c->mapstart)
has_holes = true;
DIAG_POP_NEEDS_COMMENT;
/* Optimize a common case. */
#if (PF_R | PF_W | PF_X) == 7 && (PROT_READ | PROT_WRITE | PROT_EXEC) == 7
c->prot = (PF_TO_PROT
>> ((ph->p_flags & (PF_R | PF_W | PF_X)) * 4)) & 0xf;
#else
c->prot = 0;
if (ph->p_flags & PF_R)
c->prot |= PROT_READ;
if (ph->p_flags & PF_W)
c->prot |= PROT_WRITE;
if (ph->p_flags & PF_X)
c->prot |= PROT_EXEC;
#endif
break;
case PT_TLS:
if (ph->p_memsz == 0)
/* Nothing to do for an empty segment. */
break;
l->l_tls_blocksize = ph->p_memsz;
l->l_tls_align = ph->p_align;
if (ph->p_align == 0)
l->l_tls_firstbyte_offset = 0;
else
l->l_tls_firstbyte_offset = ph->p_vaddr & (ph->p_align - 1);
l->l_tls_initimage_size = ph->p_filesz;
/* Since we don't know the load address yet only store the
offset. We will adjust it later. */
l->l_tls_initimage = (void *) ph->p_vaddr;
/* l->l_tls_modid is assigned below, once there is no
possibility for failure. */
if (l->l_type != lt_library
&& GL(dl_tls_dtv_slotinfo_list) == NULL)
{
#ifdef SHARED
/* We are loading the executable itself when the dynamic
linker was executed directly. The setup will happen
later. */
assert (l->l_prev == NULL || (mode & __RTLD_AUDIT) != 0);
#else
assert (false && "TLS not initialized in static application");
#endif
}
break;
case PT_GNU_STACK:
stack_flags = ph->p_flags;
break;
case PT_GNU_RELRO:
l->l_relro_addr = ph->p_vaddr;
l->l_relro_size = ph->p_memsz;
break;
}
if (__glibc_unlikely (nloadcmds == 0))
{
/* This only happens for a bogus object that will be caught with
another error below. But we don't want to go through the
calculations below using NLOADCMDS - 1. */
errstring = N_("object file has no loadable segments");
goto lose;
}
/* Align all PT_LOAD segments to the maximum p_align. */
for (size_t i = 0; i < nloadcmds; i++)
loadcmds[i].mapalign = p_align_max;
/* dlopen of an executable is not valid because it is not possible
to perform proper relocations, handle static TLS, or run the
ELF constructors. For PIE, the check needs the dynamic
section, so there is another check below. */
if (__glibc_unlikely (type != ET_DYN)
&& __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0))
{
/* This object is loaded at a fixed address. This must never
happen for objects loaded with dlopen. */
errstring = N_("cannot dynamically load executable");
goto lose;
}
/* This check recognizes most separate debuginfo files. */
if (__glibc_unlikely ((l->l_ld == 0 && type == ET_DYN) || empty_dynamic))
{
errstring = N_("object file has no dynamic section");
goto lose;
}
/* Length of the sections to be loaded. */
maplength = loadcmds[nloadcmds - 1].allocend - loadcmds[0].mapstart;
/* Now process the load commands and map segments into memory.
This is responsible for filling in:
l_map_start, l_map_end, l_addr, l_contiguous, l_phdr
*/
errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds,
maplength, has_holes, loader);
if (__glibc_unlikely (errstring != NULL))
{
/* Mappings can be in an inconsistent state: avoid unmap. */
l->l_map_start = l->l_map_end = 0;
goto lose;
}
}
if (l->l_ld != 0)
l->l_ld = (ElfW(Dyn) *) ((ElfW(Addr)) l->l_ld + l->l_addr);
elf_get_dynamic_info (l, false, false);
/* Make sure we are not dlopen'ing an object that has the
DF_1_NOOPEN flag set, or a PIE object. */
if ((__glibc_unlikely (l->l_flags_1 & DF_1_NOOPEN)
&& (mode & __RTLD_DLOPEN))
|| (__glibc_unlikely (l->l_flags_1 & DF_1_PIE)
&& __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0)))
{
if (l->l_flags_1 & DF_1_PIE)
errstring
= N_("cannot dynamically load position-independent executable");
else
errstring = N_("shared object cannot be dlopen()ed");
goto lose;
}
if (l->l_phdr == NULL)
{
/* The program header is not contained in any of the segments.
We have to allocate memory ourself and copy it over from out
temporary place. */
ElfW(Phdr) *newp = (ElfW(Phdr) *) malloc (header->e_phnum
* sizeof (ElfW(Phdr)));
if (newp == NULL)
{
errstring = N_("cannot allocate memory for program header");
goto lose_errno;
}
l->l_phdr = memcpy (newp, phdr,
(header->e_phnum * sizeof (ElfW(Phdr))));
l->l_phdr_allocated = 1;
}
else
/* Adjust the PT_PHDR value by the runtime load address. */
l->l_phdr = (ElfW(Phdr) *) ((ElfW(Addr)) l->l_phdr + l->l_addr);
if (__glibc_unlikely ((stack_flags &~ GL(dl_stack_flags)) & PF_X))
{
/* The stack is presently not executable, but this module
requires that it be executable. */
#if PTHREAD_IN_LIBC
errval = _dl_make_stacks_executable (stack_endp);
#else
errval = (*GL(dl_make_stack_executable_hook)) (stack_endp);
#endif
if (errval)
{
errstring = N_("\
cannot enable executable stack as shared object requires");
goto lose;
}
}
/* Adjust the address of the TLS initialization image. */
if (l->l_tls_initimage != NULL)
l->l_tls_initimage = (char *) l->l_tls_initimage + l->l_addr;
/* Process program headers again after load segments are mapped in
case processing requires accessing those segments. Scan program
headers backward so that PT_NOTE can be skipped if PT_GNU_PROPERTY
exits. */
for (ph = &l->l_phdr[l->l_phnum]; ph != l->l_phdr; --ph)
switch (ph[-1].p_type)
{
case PT_NOTE:
_dl_process_pt_note (l, fd, &ph[-1]);
break;
case PT_GNU_PROPERTY:
_dl_process_pt_gnu_property (l, fd, &ph[-1]);
break;
}
/* We are done mapping in the file. We no longer need the descriptor. */
if (__glibc_unlikely (__close_nocancel (fd) != 0))
{
errstring = N_("cannot close file descriptor");
goto lose_errno;
}
/* Signal that we closed the file. */
fd = -1;
/* Failures before this point are handled locally via lose.
There are no more failures in this function until return,
to change that the cleanup handling needs to be updated. */
/* If this is ET_EXEC, we should have loaded it as lt_executable. */
assert (type != ET_EXEC || l->l_type == lt_executable);
l->l_entry += l->l_addr;
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
_dl_debug_printf ("\
dynamic: 0x%0*lx base: 0x%0*lx size: 0x%0*zx\n\
entry: 0x%0*lx phdr: 0x%0*lx phnum: %*u\n\n",
(int) sizeof (void *) * 2,
(unsigned long int) l->l_ld,
(int) sizeof (void *) * 2,
(unsigned long int) l->l_addr,
(int) sizeof (void *) * 2, maplength,
(int) sizeof (void *) * 2,
(unsigned long int) l->l_entry,
(int) sizeof (void *) * 2,
(unsigned long int) l->l_phdr,
(int) sizeof (void *) * 2, l->l_phnum);
/* Set up the symbol hash table. */
_dl_setup_hash (l);
/* If this object has DT_SYMBOLIC set modify now its scope. We don't
have to do this for the main map. */
if ((mode & RTLD_DEEPBIND) == 0
&& __glibc_unlikely (l->l_info[DT_SYMBOLIC] != NULL)
&& &l->l_searchlist != l->l_scope[0])
{
/* Create an appropriate searchlist. It contains only this map.
This is the definition of DT_SYMBOLIC in SysVr4. */
l->l_symbolic_searchlist.r_list[0] = l;
l->l_symbolic_searchlist.r_nlist = 1;
/* Now move the existing entries one back. */
memmove (&l->l_scope[1], &l->l_scope[0],
(l->l_scope_max - 1) * sizeof (l->l_scope[0]));
/* Now add the new entry. */
l->l_scope[0] = &l->l_symbolic_searchlist;
}
/* Remember whether this object must be initialized first. */
if (l->l_flags_1 & DF_1_INITFIRST)
GL(dl_initfirst) = l;
/* Finally the file information. */
l->l_file_id = id;
#ifdef SHARED
/* When auditing is used the recorded names might not include the
name by which the DSO is actually known. Add that as well. */
if (__glibc_unlikely (origname != NULL))
add_name_to_object (l, origname);
/* When we profile the SONAME might be needed for something else but
loading. Add it right away. */
if (__glibc_unlikely (GLRO(dl_profile) != NULL)
&& l->l_info[DT_SONAME] != NULL)
add_name_to_object (l, ((const char *) D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_SONAME]->d_un.d_val));
#else
/* Audit modules only exist when linking is dynamic so ORIGNAME
cannot be non-NULL. */
assert (origname == NULL);
#endif
/* If we have newly loaded libc.so, update the namespace
description. */
if (GL(dl_ns)[nsid].libc_map == NULL
&& l->l_info[DT_SONAME] != NULL
&& strcmp (((const char *) D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0)
GL(dl_ns)[nsid].libc_map = l;
/* _dl_close can only eventually undo the module ID assignment (via
remove_slotinfo) if this function returns a pointer to a link
map. Therefore, delay this step until all possibilities for
failure have been excluded. */
if (l->l_tls_blocksize > 0
&& (__glibc_likely (l->l_type == lt_library)
/* If GL(dl_tls_dtv_slotinfo_list) == NULL, then rtld.c did
not set up TLS data structures, so don't use them now. */
|| __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL)))
/* Assign the next available module ID. */
_dl_assign_tls_modid (l);
#ifdef DL_AFTER_LOAD
DL_AFTER_LOAD (l);
#endif
/* Now that the object is fully initialized add it to the object list. */
_dl_add_to_namespace_list (l, nsid);
/* Skip auditing and debugger notification when called from 'sprof'. */
if (mode & __RTLD_SPROF)
return l;
/* Signal that we are going to add new objects. */
struct r_debug *r = _dl_debug_update (nsid);
if (r->r_state == RT_CONSISTENT)
{
#ifdef SHARED
/* Auditing checkpoint: we are going to add new objects. Since this
is called after _dl_add_to_namespace_list the namespace is guaranteed
to not be empty. */
if ((mode & __RTLD_AUDIT) == 0)
_dl_audit_activity_nsid (nsid, LA_ACT_ADD);
#endif
/* Notify the debugger we have added some objects. We need to
call _dl_debug_initialize in a static program in case dynamic
linking has not been used before. */
r->r_state = RT_ADD;
_dl_debug_state ();
LIBC_PROBE (map_start, 2, nsid, r);
}
else
assert (r->r_state == RT_ADD);
#ifdef SHARED
/* Auditing checkpoint: we have a new object. */
if (!GL(dl_ns)[l->l_ns]._ns_loaded->l_auditing)
_dl_audit_objopen (l, nsid);
#endif
return l;
}
/* Print search path. */
static void
print_search_path (struct r_search_path_elem **list,
const char *what, const char *name)
{
char buf[max_dirnamelen + max_capstrlen];
int first = 1;
_dl_debug_printf (" search path=");
while (*list != NULL && (*list)->what == what) /* Yes, ==. */
{
char *endp = __mempcpy (buf, (*list)->dirname, (*list)->dirnamelen);
size_t cnt;
for (cnt = 0; cnt < ncapstr; ++cnt)
if ((*list)->status[cnt] != nonexisting)
{
#ifdef SHARED
char *cp = __mempcpy (endp, capstr[cnt].str, capstr[cnt].len);
if (cp == buf || (cp == buf + 1 && buf[0] == '/'))
cp[0] = '\0';
else
cp[-1] = '\0';
#else
*endp = '\0';
#endif
_dl_debug_printf_c (first ? "%s" : ":%s", buf);
first = 0;
}
++list;
}
if (name != NULL)
_dl_debug_printf_c ("\t\t(%s from file %s)\n", what,
DSO_FILENAME (name));
else
_dl_debug_printf_c ("\t\t(%s)\n", what);
}
/* Open a file and verify it is an ELF file for this architecture. We
ignore only ELF files for other architectures. Non-ELF files and
ELF files with different header information cause fatal errors since
this could mean there is something wrong in the installation and the
user might want to know about this.
If FD is not -1, then the file is already open and FD refers to it.
In that case, FD is consumed for both successful and error returns. */
static int
open_verify (const char *name, int fd,
struct filebuf *fbp, struct link_map *loader,
int whatcode, int mode, bool *found_other_class, bool free_name)
{
/* This is the expected ELF header. */
#define ELF32_CLASS ELFCLASS32
#define ELF64_CLASS ELFCLASS64
#ifndef VALID_ELF_HEADER
# define VALID_ELF_HEADER(hdr,exp,size) (memcmp (hdr, exp, size) == 0)
# define VALID_ELF_OSABI(osabi) (osabi == ELFOSABI_SYSV)
# define VALID_ELF_ABIVERSION(osabi,ver) (ver == 0)
#elif defined MORE_ELF_HEADER_DATA
MORE_ELF_HEADER_DATA;
#endif
static const unsigned char expected[EI_NIDENT] =
{
[EI_MAG0] = ELFMAG0,
[EI_MAG1] = ELFMAG1,
[EI_MAG2] = ELFMAG2,
[EI_MAG3] = ELFMAG3,
[EI_CLASS] = ELFW(CLASS),
[EI_DATA] = byteorder,
[EI_VERSION] = EV_CURRENT,
[EI_OSABI] = ELFOSABI_SYSV,
[EI_ABIVERSION] = 0
};
/* Initialize it to make the compiler happy. */
const char *errstring = NULL;
int errval = 0;
#ifdef SHARED
/* Give the auditing libraries a chance. */
if (__glibc_unlikely (GLRO(dl_naudit) > 0))
{
const char *original_name = name;
name = _dl_audit_objsearch (name, loader, whatcode);
if (name == NULL)
return -1;
if (fd != -1 && name != original_name && strcmp (name, original_name))
{
/* An audit library changed what we're supposed to open,
so FD no longer matches it. */
__close_nocancel (fd);
fd = -1;
}
}
#endif
if (fd == -1)
/* Open the file. We always open files read-only. */
fd = __open64_nocancel (name, O_RDONLY | O_CLOEXEC);
if (fd != -1)
{
ElfW(Ehdr) *ehdr;
ElfW(Phdr) *phdr;
size_t maplength;
/* We successfully opened the file. Now verify it is a file
we can use. */
__set_errno (0);
fbp->len = 0;
assert (sizeof (fbp->buf) > sizeof (ElfW(Ehdr)));
/* Read in the header. */
do
{
ssize_t retlen = __read_nocancel (fd, fbp->buf + fbp->len,
sizeof (fbp->buf) - fbp->len);
if (retlen <= 0)
break;
fbp->len += retlen;
}
while (__glibc_unlikely (fbp->len < sizeof (ElfW(Ehdr))));
/* This is where the ELF header is loaded. */
ehdr = (ElfW(Ehdr) *) fbp->buf;
/* Now run the tests. */
if (__glibc_unlikely (fbp->len < (ssize_t) sizeof (ElfW(Ehdr))))
{
errval = errno;
errstring = (errval == 0
? N_("file too short") : N_("cannot read file data"));
lose:
if (free_name)
{
char *realname = (char *) name;
name = strdupa (realname);
free (realname);
}
__close_nocancel (fd);
_dl_signal_error (errval, name, NULL, errstring);
}
/* See whether the ELF header is what we expect. */
if (__glibc_unlikely (! VALID_ELF_HEADER (ehdr->e_ident, expected,
EI_ABIVERSION)
|| !VALID_ELF_ABIVERSION (ehdr->e_ident[EI_OSABI],
ehdr->e_ident[EI_ABIVERSION])
|| memcmp (&ehdr->e_ident[EI_PAD],
&expected[EI_PAD],
EI_NIDENT - EI_PAD) != 0))
{
/* Something is wrong. */
const Elf32_Word *magp = (const void *) ehdr->e_ident;
if (*magp !=
#if BYTE_ORDER == LITTLE_ENDIAN
((ELFMAG0 << (EI_MAG0 * 8))
| (ELFMAG1 << (EI_MAG1 * 8))
| (ELFMAG2 << (EI_MAG2 * 8))
| (ELFMAG3 << (EI_MAG3 * 8)))
#else
((ELFMAG0 << (EI_MAG3 * 8))
| (ELFMAG1 << (EI_MAG2 * 8))
| (ELFMAG2 << (EI_MAG1 * 8))
| (ELFMAG3 << (EI_MAG0 * 8)))
#endif
)
errstring = N_("invalid ELF header");
else if (ehdr->e_ident[EI_CLASS] != ELFW(CLASS))
{
/* This is not a fatal error. On architectures where
32-bit and 64-bit binaries can be run this might
happen. */
*found_other_class = true;
__close_nocancel (fd);
__set_errno (ENOENT);
return -1;
}
else if (ehdr->e_ident[EI_DATA] != byteorder)
{
if (BYTE_ORDER == BIG_ENDIAN)
errstring = N_("ELF file data encoding not big-endian");
else
errstring = N_("ELF file data encoding not little-endian");
}
else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT)
errstring
= N_("ELF file version ident does not match current one");
/* XXX We should be able so set system specific versions which are
allowed here. */
else if (!VALID_ELF_OSABI (ehdr->e_ident[EI_OSABI]))
errstring = N_("ELF file OS ABI invalid");
else if (!VALID_ELF_ABIVERSION (ehdr->e_ident[EI_OSABI],
ehdr->e_ident[EI_ABIVERSION]))
errstring = N_("ELF file ABI version invalid");
else if (memcmp (&ehdr->e_ident[EI_PAD], &expected[EI_PAD],
EI_NIDENT - EI_PAD) != 0)
errstring = N_("nonzero padding in e_ident");
else
/* Otherwise we don't know what went wrong. */
errstring = N_("internal error");
goto lose;
}
if (__glibc_unlikely (ehdr->e_version != EV_CURRENT))
{
errstring = N_("ELF file version does not match current one");
goto lose;
}
if (! __glibc_likely (elf_machine_matches_host (ehdr)))
{
__close_nocancel (fd);
__set_errno (ENOENT);
return -1;
}
else if (__glibc_unlikely (ehdr->e_type != ET_DYN
&& ehdr->e_type != ET_EXEC))
{
errstring = N_("only ET_DYN and ET_EXEC can be loaded");
goto lose;
}
else if (__glibc_unlikely (ehdr->e_phentsize != sizeof (ElfW(Phdr))))
{
errstring = N_("ELF file's phentsize not the expected size");
goto lose;
}
maplength = ehdr->e_phnum * sizeof (ElfW(Phdr));
if (ehdr->e_phoff + maplength <= (size_t) fbp->len)
phdr = (void *) (fbp->buf + ehdr->e_phoff);
else
{
phdr = alloca (maplength);
if ((size_t) __pread64_nocancel (fd, (void *) phdr, maplength,
ehdr->e_phoff) != maplength)
{
errval = errno;
errstring = N_("cannot read file data");
goto lose;
}
}
if (__glibc_unlikely (elf_machine_reject_phdr_p
(phdr, ehdr->e_phnum, fbp->buf, fbp->len,
loader, fd)))
{
__close_nocancel (fd);
__set_errno (ENOENT);
return -1;
}
}
return fd;
}
/* Try to open NAME in one of the directories in SPS. Return the fd, or -1.
If successful, fill in *REALNAME with the malloc'd full directory name. If
it turns out that none of the directories in SPS exists, SPS->DIRS is
replaced with (void *) -1, and the old value is free()d if SPS->MALLOCED is
true. */
static int
open_path (const char *name, size_t namelen, int mode,
struct r_search_path_struct *sps, char **realname,
struct filebuf *fbp, struct link_map *loader, int whatcode,
bool *found_other_class)
{
struct r_search_path_elem **dirs = sps->dirs;
char *buf;
int fd = -1;
const char *current_what = NULL;
int any = 0;
if (__glibc_unlikely (dirs == NULL))
/* We're called before _dl_init_paths when loading the main executable
given on the command line when rtld is run directly. */
return -1;
buf = alloca (max_dirnamelen + max_capstrlen + namelen);
do
{
struct r_search_path_elem *this_dir = *dirs;
size_t buflen = 0;
size_t cnt;
char *edp;
int here_any = 0;
/* If we are debugging the search for libraries print the path
now if it hasn't happened now. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS)
&& current_what != this_dir->what)
{
current_what = this_dir->what;
print_search_path (dirs, current_what, this_dir->where);
}
edp = (char *) __mempcpy (buf, this_dir->dirname, this_dir->dirnamelen);
for (cnt = 0; fd == -1 && cnt < ncapstr; ++cnt)
{
/* Skip this directory if we know it does not exist. */
if (this_dir->status[cnt] == nonexisting)
continue;
#ifdef SHARED
buflen =
((char *) __mempcpy (__mempcpy (edp, capstr[cnt].str,
capstr[cnt].len),
name, namelen)
- buf);
#else
buflen = (char *) __mempcpy (edp, name, namelen) - buf;
#endif
/* Print name we try if this is wanted. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
_dl_debug_printf (" trying file=%s\n", buf);
fd = open_verify (buf, -1, fbp, loader, whatcode, mode,
found_other_class, false);
if (this_dir->status[cnt] == unknown)
{
if (fd != -1)
this_dir->status[cnt] = existing;
/* Do not update the directory information when loading
auditing code. We must try to disturb the program as
little as possible. */
else if (loader == NULL
|| GL(dl_ns)[loader->l_ns]._ns_loaded->l_auditing == 0)
{
/* We failed to open machine dependent library. Let's
test whether there is any directory at all. */
struct __stat64_t64 st;
buf[buflen - namelen] = '\0';
if (__stat64_time64 (buf, &st) != 0
|| ! S_ISDIR (st.st_mode))
/* The directory does not exist or it is no directory. */
this_dir->status[cnt] = nonexisting;
else
this_dir->status[cnt] = existing;
}
}
/* Remember whether we found any existing directory. */
here_any |= this_dir->status[cnt] != nonexisting;
if (fd != -1 && __glibc_unlikely (mode & __RTLD_SECURE)
&& __libc_enable_secure)
{
/* This is an extra security effort to make sure nobody can
preload broken shared objects which are in the trusted
directories and so exploit the bugs. */
struct __stat64_t64 st;
if (__fstat64_time64 (fd, &st) != 0
|| (st.st_mode & S_ISUID) == 0)
{
/* The shared object cannot be tested for being SUID
or this bit is not set. In this case we must not
use this object. */
__close_nocancel (fd);
fd = -1;
/* We simply ignore the file, signal this by setting
the error value which would have been set by `open'. */
errno = ENOENT;
}
}
}
if (fd != -1)
{
*realname = (char *) malloc (buflen);
if (*realname != NULL)
{
memcpy (*realname, buf, buflen);
return fd;
}
else
{
/* No memory for the name, we certainly won't be able
to load and link it. */
__close_nocancel (fd);
return -1;
}
}
/* Continue the search if the file does not exist (ENOENT), if it can
not be accessed (EACCES), or if the a component in the path is not a
directory (for instance, if the component is a existing file meaning
essentially that the pathname is invalid - ENOTDIR). */
if (here_any && errno != ENOENT && errno != EACCES && errno != ENOTDIR)
return -1;
/* Remember whether we found anything. */
any |= here_any;
}
while (*++dirs != NULL);
/* Remove the whole path if none of the directories exists. */
if (__glibc_unlikely (! any))
{
/* Paths which were allocated using the minimal malloc() in ld.so
must not be freed using the general free() in libc. */
if (sps->malloced)
free (sps->dirs);
/* __rtld_search_dirs and __rtld_env_path_list are
attribute_relro, therefore avoid writing to them. */
if (sps != &__rtld_search_dirs && sps != &__rtld_env_path_list)
sps->dirs = (void *) -1;
}
return -1;
}
/* Map in the shared object file NAME. */
struct link_map *
_dl_map_object (struct link_map *loader, const char *name,
int type, int trace_mode, int mode, Lmid_t nsid)
{
int fd;
const char *origname = NULL;
char *realname;
char *name_copy;
struct link_map *l;
struct filebuf fb;
assert (nsid >= 0);
assert (nsid < GL(dl_nns));
/* Look for this name among those already loaded. */
for (l = GL(dl_ns)[nsid]._ns_loaded; l; l = l->l_next)
{
/* If the requested name matches the soname of a loaded object,
use that object. Elide this check for names that have not
yet been opened. */
if (__glibc_unlikely ((l->l_faked | l->l_removed) != 0))
continue;
if (!_dl_name_match_p (name, l))
{
const char *soname;
if (__glibc_likely (l->l_soname_added)
|| l->l_info[DT_SONAME] == NULL)
continue;
soname = ((const char *) D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_SONAME]->d_un.d_val);
if (strcmp (name, soname) != 0)
continue;
/* We have a match on a new name -- cache it. */
add_name_to_object (l, soname);
l->l_soname_added = 1;
}
/* We have a match. */
return l;
}
/* Display information if we are debugging. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES)
&& loader != NULL)
_dl_debug_printf ((mode & __RTLD_CALLMAP) == 0
? "\nfile=%s [%lu]; needed by %s [%lu]\n"
: "\nfile=%s [%lu]; dynamically loaded by %s [%lu]\n",
name, nsid, DSO_FILENAME (loader->l_name), loader->l_ns);
#ifdef SHARED
/* Give the auditing libraries a chance to change the name before we
try anything. */
if (__glibc_unlikely (GLRO(dl_naudit) > 0))
{
const char *before = name;
name = _dl_audit_objsearch (name, loader, LA_SER_ORIG);
if (name == NULL)
{
fd = -1;
goto no_file;
}
if (before != name && strcmp (before, name) != 0)
origname = before;
}
#endif
/* Will be true if we found a DSO which is of the other ELF class. */
bool found_other_class = false;
if (strchr (name, '/') == NULL)
{
/* Search for NAME in several places. */
size_t namelen = strlen (name) + 1;
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
_dl_debug_printf ("find library=%s [%lu]; searching\n", name, nsid);
fd = -1;
/* When the object has the RUNPATH information we don't use any
RPATHs. */
if (loader == NULL || loader->l_info[DT_RUNPATH] == NULL)
{
/* This is the executable's map (if there is one). Make sure that
we do not look at it twice. */
struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
bool did_main_map = false;
/* First try the DT_RPATH of the dependent object that caused NAME
to be loaded. Then that object's dependent, and on up. */
for (l = loader; l; l = l->l_loader)
if (cache_rpath (l, &l->l_rpath_dirs, DT_RPATH, "RPATH"))
{
fd = open_path (name, namelen, mode,
&l->l_rpath_dirs,
&realname, &fb, loader, LA_SER_RUNPATH,
&found_other_class);
if (fd != -1)
break;
did_main_map |= l == main_map;
}
/* If dynamically linked, try the DT_RPATH of the executable
itself. NB: we do this for lookups in any namespace. */
if (fd == -1 && !did_main_map
&& main_map != NULL && main_map->l_type != lt_loaded
&& cache_rpath (main_map, &main_map->l_rpath_dirs, DT_RPATH,
"RPATH"))
fd = open_path (name, namelen, mode,
&main_map->l_rpath_dirs,
&realname, &fb, loader ?: main_map, LA_SER_RUNPATH,
&found_other_class);
/* Also try DT_RUNPATH in the executable for LD_AUDIT dlopen
call. */
if (__glibc_unlikely (mode & __RTLD_AUDIT)
&& fd == -1 && !did_main_map
&& main_map != NULL && main_map->l_type != lt_loaded)
{
struct r_search_path_struct l_rpath_dirs;
l_rpath_dirs.dirs = NULL;
if (cache_rpath (main_map, &l_rpath_dirs,
DT_RUNPATH, "RUNPATH"))
fd = open_path (name, namelen, mode, &l_rpath_dirs,
&realname, &fb, loader ?: main_map,
LA_SER_RUNPATH, &found_other_class);
}
}
/* Try the LD_LIBRARY_PATH environment variable. */
if (fd == -1 && __rtld_env_path_list.dirs != (void *) -1)
fd = open_path (name, namelen, mode, &__rtld_env_path_list,
&realname, &fb,
loader ?: GL(dl_ns)[LM_ID_BASE]._ns_loaded,
LA_SER_LIBPATH, &found_other_class);
/* Look at the RUNPATH information for this binary. */
if (fd == -1 && loader != NULL
&& cache_rpath (loader, &loader->l_runpath_dirs,
DT_RUNPATH, "RUNPATH"))
fd = open_path (name, namelen, mode,
&loader->l_runpath_dirs, &realname, &fb, loader,
LA_SER_RUNPATH, &found_other_class);
#ifdef USE_LDCONFIG
if (fd == -1
&& (__glibc_likely ((mode & __RTLD_SECURE) == 0)
|| ! __libc_enable_secure)
&& __glibc_likely (GLRO(dl_inhibit_cache) == 0))
{
/* Check the list of libraries in the file /etc/ld.so.cache,
for compatibility with Linux's ldconfig program. */
char *cached = _dl_load_cache_lookup (name);
if (cached != NULL)
{
// XXX Correct to unconditionally default to namespace 0?
l = (loader
?: GL(dl_ns)[LM_ID_BASE]._ns_loaded
# ifdef SHARED
?: &GL(dl_rtld_map)
# endif
);
/* If the loader has the DF_1_NODEFLIB flag set we must not
use a cache entry from any of these directories. */
if (__glibc_unlikely (l->l_flags_1 & DF_1_NODEFLIB))
{
const char *dirp = system_dirs;
unsigned int cnt = 0;
do
{
if (memcmp (cached, dirp, system_dirs_len[cnt]) == 0)
{
/* The prefix matches. Don't use the entry. */
free (cached);
cached = NULL;
break;
}
dirp += system_dirs_len[cnt] + 1;
++cnt;
}
while (cnt < nsystem_dirs_len);
}
if (cached != NULL)
{
fd = open_verify (cached, -1,
&fb, loader ?: GL(dl_ns)[nsid]._ns_loaded,
LA_SER_CONFIG, mode, &found_other_class,
false);
if (__glibc_likely (fd != -1))
realname = cached;
else
free (cached);
}
}
}
#endif
/* Finally, try the default path. */
if (fd == -1
&& ((l = loader ?: GL(dl_ns)[nsid]._ns_loaded) == NULL
|| __glibc_likely (!(l->l_flags_1 & DF_1_NODEFLIB)))
&& __rtld_search_dirs.dirs != (void *) -1)
fd = open_path (name, namelen, mode, &__rtld_search_dirs,
&realname, &fb, l, LA_SER_DEFAULT, &found_other_class);
/* Add another newline when we are tracing the library loading. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
_dl_debug_printf ("\n");
}
else
{
/* The path may contain dynamic string tokens. */
realname = (loader
? expand_dynamic_string_token (loader, name)
: __strdup (name));
if (realname == NULL)
fd = -1;
else
{
fd = open_verify (realname, -1, &fb,
loader ?: GL(dl_ns)[nsid]._ns_loaded, 0, mode,
&found_other_class, true);
if (__glibc_unlikely (fd == -1))
free (realname);
}
}
#ifdef SHARED
no_file:
#endif
/* In case the LOADER information has only been provided to get to
the appropriate RUNPATH/RPATH information we do not need it
anymore. */
if (mode & __RTLD_CALLMAP)
loader = NULL;
if (__glibc_unlikely (fd == -1))
{
if (trace_mode)
{
/* We haven't found an appropriate library. But since we
are only interested in the list of libraries this isn't
so severe. Fake an entry with all the information we
have. */
static const Elf_Symndx dummy_bucket = STN_UNDEF;
/* Allocate a new object map. */
if ((name_copy = __strdup (name)) == NULL
|| (l = _dl_new_object (name_copy, name, type, loader,
mode, nsid)) == NULL)
{
free (name_copy);
_dl_signal_error (ENOMEM, name, NULL,
N_("cannot create shared object descriptor"));
}
/* Signal that this is a faked entry. */
l->l_faked = 1;
/* Since the descriptor is initialized with zero we do not
have do this here.
l->l_reserved = 0; */
l->l_buckets = &dummy_bucket;
l->l_nbuckets = 1;
l->l_relocated = 1;
/* Enter the object in the object list. */
_dl_add_to_namespace_list (l, nsid);
return l;
}
else if (found_other_class)
_dl_signal_error (0, name, NULL,
ELFW(CLASS) == ELFCLASS32
? N_("wrong ELF class: ELFCLASS64")
: N_("wrong ELF class: ELFCLASS32"));
else
_dl_signal_error (errno, name, NULL,
N_("cannot open shared object file"));
}
void *stack_end = __libc_stack_end;
return _dl_map_object_from_fd (name, origname, fd, &fb, realname, loader,
type, mode, &stack_end, nsid);
}
struct add_path_state
{
bool counting;
unsigned int idx;
Dl_serinfo *si;
char *allocptr;
};
static void
add_path (struct add_path_state *p, const struct r_search_path_struct *sps,
unsigned int flags)
{
if (sps->dirs != (void *) -1)
{
struct r_search_path_elem **dirs = sps->dirs;
do
{
const struct r_search_path_elem *const r = *dirs++;
if (p->counting)
{
p->si->dls_cnt++;
p->si->dls_size += MAX (2, r->dirnamelen);
}
else
{
Dl_serpath *const sp = &p->si->dls_serpath[p->idx++];
sp->dls_name = p->allocptr;
if (r->dirnamelen < 2)
*p->allocptr++ = r->dirnamelen ? '/' : '.';
else
p->allocptr = __mempcpy (p->allocptr,
r->dirname, r->dirnamelen - 1);
*p->allocptr++ = '\0';
sp->dls_flags = flags;
}
}
while (*dirs != NULL);
}
}
void
_dl_rtld_di_serinfo (struct link_map *loader, Dl_serinfo *si, bool counting)
{
if (counting)
{
si->dls_cnt = 0;
si->dls_size = 0;
}
struct add_path_state p =
{
.counting = counting,
.idx = 0,
.si = si,
.allocptr = (char *) &si->dls_serpath[si->dls_cnt]
};
# define add_path(p, sps, flags) add_path(p, sps, 0) /* XXX */
/* When the object has the RUNPATH information we don't use any RPATHs. */
if (loader->l_info[DT_RUNPATH] == NULL)
{
/* First try the DT_RPATH of the dependent object that caused NAME
to be loaded. Then that object's dependent, and on up. */
struct link_map *l = loader;
do
{
if (cache_rpath (l, &l->l_rpath_dirs, DT_RPATH, "RPATH"))
add_path (&p, &l->l_rpath_dirs, XXX_RPATH);
l = l->l_loader;
}
while (l != NULL);
/* If dynamically linked, try the DT_RPATH of the executable itself. */
if (loader->l_ns == LM_ID_BASE)
{
l = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
if (l != NULL && l->l_type != lt_loaded && l != loader)
if (cache_rpath (l, &l->l_rpath_dirs, DT_RPATH, "RPATH"))
add_path (&p, &l->l_rpath_dirs, XXX_RPATH);
}
}
/* Try the LD_LIBRARY_PATH environment variable. */
add_path (&p, &__rtld_env_path_list, XXX_ENV);
/* Look at the RUNPATH information for this binary. */
if (cache_rpath (loader, &loader->l_runpath_dirs, DT_RUNPATH, "RUNPATH"))
add_path (&p, &loader->l_runpath_dirs, XXX_RUNPATH);
/* XXX
Here is where ld.so.cache gets checked, but we don't have
a way to indicate that in the results for Dl_serinfo. */
/* Finally, try the default path. */
if (!(loader->l_flags_1 & DF_1_NODEFLIB))
add_path (&p, &__rtld_search_dirs, XXX_default);
if (counting)
/* Count the struct size before the string area, which we didn't
know before we completed dls_cnt. */
si->dls_size += (char *) &si->dls_serpath[si->dls_cnt] - (char *) si;
}
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