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Diffstat (limited to 'elf/rtld.c')
-rw-r--r--elf/rtld.c115
1 files changed, 96 insertions, 19 deletions
diff --git a/elf/rtld.c b/elf/rtld.c
index 8b75492..0736218 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -38,6 +38,12 @@ extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
ElfW(Addr) *user_entry));
extern void _dl_sysdep_start_cleanup (void);
+/* System-dependent function to read a file's whole contents
+ in the most convenient manner available. */
+extern void *_dl_sysdep_read_whole_file (const char *filename,
+ size_t *filesize_ptr,
+ int mmap_prot);
+
int _dl_argc;
char **_dl_argv;
const char *_dl_rpath;
@@ -138,6 +144,8 @@ dl_main (const ElfW(Phdr) *phdr,
enum { normal, list, verify, trace } mode;
struct link_map **preloads;
unsigned int npreloads;
+ size_t file_size;
+ char *file;
mode = getenv ("LD_TRACE_LOADED_OBJECTS") != NULL ? trace : normal;
@@ -296,8 +304,77 @@ of this helper program; chances are you did not intend to run this program.\n",
l->l_next = &_dl_rtld_map;
_dl_rtld_map.l_prev = l;
+ /* We have two ways to specify objects to preload: via environment
+ variable and via the file /etc/ld.so.preload. The later can also
+ be used when security is enabled. */
preloads = NULL;
npreloads = 0;
+
+ /* Read the contents of the file. */
+ file = _dl_sysdep_read_whole_file ("/etc/ld.so.preload", &file_size,
+ PROT_READ | PROT_WRITE);
+ if (file)
+ {
+ /* Parse the file. It contains names of libraries to be loaded,
+ separated by white spaces or `:'. It may also contain
+ comments introduced by `#'. */
+ char *problem;
+ char *runp;
+ size_t rest;
+
+ /* Eliminate comments. */
+ runp = file;
+ rest = file_size;
+ while (rest > 0)
+ {
+ char *comment = memchr (runp, '#', rest);
+ if (comment == NULL)
+ break;
+
+ rest -= comment - runp;
+ do
+ *comment = ' ';
+ while (--rest > 0 && *++comment != '\n');
+ }
+
+ /* We have one problematic case: if we have a name at the end of
+ the file without a trailing terminating characters, we cannot
+ place the \0. Handle the case separately. */
+ if (file[file_size - 1] != ' ' && file[file_size] != '\t'
+ && file[file_size] != '\n')
+ {
+ problem = &file[file_size];
+ while (problem > file && problem[-1] != ' ' && problem[-1] != '\t'
+ && problem[-1] != '\n')
+ --problem;
+
+ if (problem > file)
+ problem[-1] = '\0';
+ }
+ else
+ problem = NULL;
+
+ if (file != problem)
+ {
+ char *p;
+ runp = file;
+ while ((p = strsep (&runp, ": \t\n")) != NULL)
+ {
+ (void) _dl_map_object (NULL, p, lt_library);
+ ++npreloads;
+ }
+ }
+
+ if (problem != NULL)
+ {
+ char *p = strndupa (problem, file_size - (problem - file));
+ (void) _dl_map_object (NULL, p, lt_library);
+ }
+
+ /* We don't need the file anymore. */
+ __munmap (file, file_size);
+ }
+
if (! __libc_enable_secure)
{
const char *preloadlist = getenv ("LD_PRELOAD");
@@ -313,25 +390,25 @@ of this helper program; chances are you did not intend to run this program.\n",
(void) _dl_map_object (NULL, p, lt_library);
++npreloads;
}
-
- if (npreloads != 0)
- {
- /* Set up PRELOADS with a vector of the preloaded libraries. */
- struct link_map *l;
- unsigned int i;
- preloads = __alloca (npreloads * sizeof preloads[0]);
- l = _dl_rtld_map.l_next; /* End of the chain before preloads. */
- i = 0;
- do
- {
- preloads[i++] = l;
- l = l->l_next;
- } while (l);
- assert (i == npreloads);
- }
}
}
+ if (npreloads != 0)
+ {
+ /* Set up PRELOADS with a vector of the preloaded libraries. */
+ struct link_map *l;
+ unsigned int i;
+ preloads = __alloca (npreloads * sizeof preloads[0]);
+ l = _dl_rtld_map.l_next; /* End of the chain before preloads. */
+ i = 0;
+ do
+ {
+ preloads[i++] = l;
+ l = l->l_next;
+ } while (l);
+ assert (i == npreloads);
+ }
+
/* Load all the libraries specified by DT_NEEDED entries. If LD_PRELOAD
specified some libraries to load, these are inserted before the actual
dependencies in the executable's searchlist for symbol resolution. */
@@ -386,7 +463,7 @@ of this helper program; chances are you did not intend to run this program.\n",
char buf[20], *bp;
buf[sizeof buf - 1] = '\0';
bp = _itoa (l->l_addr, &buf[sizeof buf - 1], 16, 0);
- while (&buf[sizeof buf - 1] - bp < sizeof l->l_addr * 2)
+ while ((size_t) (&buf[sizeof buf - 1] - bp) < sizeof l->l_addr * 2)
*--bp = '0';
_dl_sysdep_message ("\t", l->l_libname, " => ", l->l_name,
" (0x", bp, ")\n", NULL);
@@ -403,12 +480,12 @@ of this helper program; chances are you did not intend to run this program.\n",
char buf[20], *bp;
buf[sizeof buf - 1] = '\0';
bp = _itoa (ref->st_value, &buf[sizeof buf - 1], 16, 0);
- while (&buf[sizeof buf - 1] - bp < sizeof loadbase * 2)
+ while ((size_t) (&buf[sizeof buf - 1] - bp) < sizeof loadbase * 2)
*--bp = '0';
_dl_sysdep_message (_dl_argv[i], " found at 0x", bp, NULL);
buf[sizeof buf - 1] = '\0';
bp = _itoa (loadbase, &buf[sizeof buf - 1], 16, 0);
- while (&buf[sizeof buf - 1] - bp < sizeof loadbase * 2)
+ while ((size_t) (&buf[sizeof buf - 1] - bp) < sizeof loadbase * 2)
*--bp = '0';
_dl_sysdep_message (" in object at 0x", bp, "\n", NULL);
}