Rod Evans <[EMAIL PROTECTED]> wrote:
> Joerg Schilling wrote:
> > Is there a way to reliably retrieve the path to a library?
> >
> > I tried to opendir("/proc/<pid>/path/")
> > and readdir()/readlink() the entries. If all library
> > names differ, this allows to find the path to any lib of
> > interest.
> >
> > Unfortunately, this does not help if there are two
> > libraries with the same name (e.g. /tmp/libm.so.2
> > and /lib/libm.so.2). Is there a way to get the
> > path that is related to a handle returned by dlopen()?
>
> You can use dlinfo() to get the origin of the dlopen()
> caller, together with the pathnames that were opened:
Thank you, but both do not help for the purpose I like to use it.
I need to get a path name that is reliable and useable for security checks.
I found a solution using dlsym and procfs.
The problem is that I need an address from inside the module in case
I like to get the name for an arbitrary library handle. Do you believe that it
should always work to try retrieving the address for "_DYNAMIC"?
The code below detects the case when somebody did rename or unlink the
object after it has been loaded:
#include <procfs.h>
getlibpath(handle, path, len)
void *handle;
char *path;
size_t len;
{
struct prmap pm;
int f;
char nbuf[PATH_MAX];
uintptr_t p;
int l = -1;
path[0] = '\0';
p = dlsym(handle, "_DYNAMIC");
if (p == NULL)
p = dlsym(handle, "_GLOBAL_OFFSET_TABLE_");
if (p == NULL)
p = dlsym(handle, "_PROCEDURE_LINKAGE_TABLE_");
if (p == NULL)
(-1);
snprintf(nbuf, sizeof (nbuf), "/proc/%lld/map",
(long long) getpid());
f = open(nbuf, 0);
if (f < 0)
return (-1);
while (read(f, &pm, sizeof (pm)) > 0) {
if (p >= pm.pr_vaddr && p <= (pm.pr_vaddr + pm.pr_size)) {
l = getxpath(pm.pr_mapname, path, len);
break;
}
}
close(f);
return (l);
}
int
getprocpath(path, len)
char *path;
size_t len;
{
return (getxpath("a.out", path, len));
}
int
getxpath(name, path, len)
char *name;
char *path;
size_t len;
{
DIR *d;
struct dirent *de;
char dbuf[1024];
char *dp;
char *n;
int l = -1;
path[0] = '\0';
snprintf(dbuf, sizeof (dbuf), "/proc/%lld/path/",
(long long) getpid());
d = opendir(dbuf);
if (d == NULL) {
perror("opendir");
exit(1);
}
dp = dbuf + strlen(dbuf);
while (de = readdir(d)) {
n = de->d_name;
if (strcmp(n, name))
continue;
snprintf(dp, sizeof (dbuf) - (dp - dbuf), "%s", n);
l = readlink(dbuf, path, len);
if (l >= 0 && l < len)
path[l] = '\0';
break;
}
return (l);
}
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
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