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bzip support in libsemanage and out of memory (userspace ticket 7)

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On Sun, 2010-01-24 at 21:29 +0100, Guido Trentalancia wrote:
> Hi !
>
> Has anybody had any time to look at this ticket:
> http://userspace.selinuxproject.org/trac/ticket/7 ?
>
> I have experienced the same issue and verified that the problem is actually triggered by the bzip support (as pointed out by Stephen Smalley back in August). In fact, if I use bzip-blocksize=0 in semanage.conf then the problem disappears...
>
> Otherwise with a default semanage.conf and bzip enabled, I get:
>
> libsepol.module_package_read_offsets: offset greater than file size (at 4, offset 200478 -> 8192 (No such file or directory).
> libsemanage.semanage_load_module: Error while reading from module file /etc/selinux/refpolicy/modules/tmp/base.pp. (No such file or directory).
> semodule:  Failed!
>
> I am using libsepol-2.0.41 and libsemanage-2.0.42.

Looking into this more closely, I believe this is another manifestation
of:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=543915#17

which was ultimately traced down to two issues:
1) A missing offset check in libsepol (fixed in libsepol 2.0.38), and
2) A bug / lack of binary mode support in the fmemopen implementation in
glibc that was later fixed, see:
http://sourceware.org/bugzilla/show_bug.cgi?id=6544

Maybe you have the older glibc still?

Looking at the libsemanage code though, I think we could in fact avoid
any dependency on fmemopen by using the native libsepol support for
operating on a memory region via sepol_policy_file_set_mem(), ala:

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
This commit is contained in:
Stephen Smalley 2010-01-25 13:55:33 -05:00
parent aafcaeb751
commit 0b2f9ef8f3
2 changed files with 10 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
libsemanage/src/direct_api.c
View File

@ -1371,16 +1371,12 @@ static int semanage_direct_list(semanage_handle_t * sh,
char *data = NULL;
if ((size = bunzip(sh, fp, &data)) > 0) {
fclose(fp);
fp = fmemopen(data, size, "rb");
if (!fp) {
ERR(sh, "Out of memory!");
goto cleanup;
}
sepol_policy_file_set_mem(pf, data, size);
} else {
rewind(fp);
__fsetlocking(fp, FSETLOCKING_BYCALLER);
sepol_policy_file_set_fp(pf, fp);
}
rewind(fp);
__fsetlocking(fp, FSETLOCKING_BYCALLER);
sepol_policy_file_set_fp(pf, fp);
if (sepol_module_package_info(pf, &type, &name, &version)) {
fclose(fp);
free(data);

14
libsemanage/src/semanage_store.c
View File

@ -1528,16 +1528,12 @@ static int semanage_load_module(semanage_handle_t * sh, const char *filename,
char *data = NULL;
if ((size = bunzip(sh, fp, &data)) > 0) {
fclose(fp);
fp = fmemopen(data, size, "rb");
if (!fp) {
ERR(sh, "Out of memory!");
goto cleanup;
}
sepol_policy_file_set_mem(pf, data, size);
} else {
rewind(fp);
__fsetlocking(fp, FSETLOCKING_BYCALLER);
sepol_policy_file_set_fp(pf, fp);
}
rewind(fp);
__fsetlocking(fp, FSETLOCKING_BYCALLER);
sepol_policy_file_set_fp(pf, fp);
sepol_policy_file_set_handle(pf, sh->sepolh);
if (sepol_module_package_read(*package, pf, 0) == -1) {
ERR(sh, "Error while reading from module file %s.", filename);