[v3,3/3] elf: Also try DT_RUNPATH for LD_AUDIT dlopen [BZ #28455]
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Build for i686
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Commit Message
DT_RUNPATH is only used to find the immediate dependencies of the
executable or shared object containing the DT_RUNPATH entry. Update
the glibc LD_AUDIT dlopen call to try the DT_RUNPATH entry of the
executable. This partially fixes BZ #28455.
---
elf/Makefile | 9 +++++++--
elf/dl-load.c | 15 +++++++++++++++
elf/tst-audit14a.c | 1 +
3 files changed, 23 insertions(+), 2 deletions(-)
create mode 100644 elf/tst-audit14a.c
Comments
On 12/8/21 10:25, H.J. Lu wrote:
> DT_RUNPATH is only used to find the immediate dependencies of the
> executable or shared object containing the DT_RUNPATH entry. Update
> the glibc LD_AUDIT dlopen call to try the DT_RUNPATH entry of the
> executable. This partially fixes BZ #28455.
Please post v4 split out.
> ---
> elf/Makefile | 9 +++++++--
> elf/dl-load.c | 15 +++++++++++++++
> elf/tst-audit14a.c | 1 +
> 3 files changed, 23 insertions(+), 2 deletions(-)
> create mode 100644 elf/tst-audit14a.c
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 4b5bdcb08e..aa6b24d790 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -247,10 +247,10 @@ ifneq ($(selinux-enabled),1)
> tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
> endif
> ifeq ($(have-depaudit),yes)
> -tests += tst-audit14 tst-audit15 tst-audit16
> +tests += tst-audit14 tst-audit15 tst-audit16 tst-audit14a
Please split one test per line and sort.
> ifeq ($(run-built-tests),yes)
> tests-special += $(objpfx)tst-audit14-cmp.out $(objpfx)tst-audit15-cmp.out \
> - $(objpfx)tst-audit16-cmp.out
> + $(objpfx)tst-audit16-cmp.out $(objpfx)tst-audit14a-cmp.out
Please split one test per line and sort.
> endif
> endif
> endif
> @@ -1521,6 +1521,8 @@ tst-auditmany-ENV = \
> LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so
> $(objpfx)tst-auditlogmod-1.so: $(libsupport)
> $(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so
> +LDFLAGS-tst-audit14a = -Wl,--audit=tst-auditlogmod-1.so,--enable-new-dtags
> +$(objpfx)tst-audit14a.out: $(objpfx)tst-auditlogmod-1.so
OK.
> LDFLAGS-tst-audit15 = \
> -Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so
> $(objpfx)tst-auditlogmod-2.so: $(libsupport)
> @@ -1547,6 +1549,9 @@ tst-audit17-ENV = LD_AUDIT=$(objpfx)tst-auditmod17.so
> $(objpfx)tst-audit14-cmp.out: tst-audit14.exp $(objpfx)tst-audit14.out
> cmp $^ > $@; \
> $(evaluate-test)
> +$(objpfx)tst-audit14a-cmp.out: tst-audit14.exp $(objpfx)tst-audit14a.out
> + cmp $^ > $@; \
> + $(evaluate-test)
OK.
> $(objpfx)tst-audit15-cmp.out: tst-audit15.exp $(objpfx)tst-audit15.out
> cmp $^ > $@; \
> $(evaluate-test)
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index bf8957e73c..1f424ea7c8 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
The preceding block is like this:
2146 /* When the object has the RUNPATH information we don't use any
2147 RPATHs. */
2148 if (loader == NULL || loader->l_info[DT_RUNPATH] == NULL)
2149 {
The entire design of this block is to look into DT_RPATH specifically
under two conditions:
(a) We don't know anything about the loading module, it is NULL, and
therefore we don't know if DT_RUNPATH was present, which if it
was present, would prevent the use of DT_RPATH.
(b) We have a loader, and we know it doesn't have DT_RUNPATH and so
we will look for DT_RPATH.
Your changes adds (c) to this case in which DT_RUNPATH is used, and
this seems to be logically distinct from the above two cases.
My suggestion is that the code you are adding should be in a distinct
block *after* the above block starting around line 2189.
We already have a block like this:
2189 /* Look at the RUNPATH information for this binary. */
2190 if (fd == -1 && loader != NULL
2191 && cache_rpath (loader, &loader->l_runpath_dirs,
2192 DT_RUNPATH, "RUNPATH"))
2193 fd = open_path (name, namelen, mode,
2194 &loader->l_runpath_dirs, &realname, &fb, loader,
2195 LA_SER_RUNPATH, &found_other_class);
I think it is logically more correct to add to this DT_RUNPATH handling
than ato add to the DT_RPATH handling above.
So after this block you might add:
/* When processing the lookup we may need to additionally try DT_RUNPATH
in the executable for a glibc internal dlopen call when looking for
audit modules. */
if (__glibc_unlikely (mode & __RTLD_AUDIT)
&& fd == -1)
{
...
}
The hard part is that you may want to know a few things:
(a) main_map (unavailable, but computable via GL(dl_ns)[LM_ID_BASE]._ns_loaded)
(b) did_main_map (unavailable)
* This seems like an optimization because if you already looked up via
main_map and it failed, doing it twice won't help, so you can refactor
did_main_map to function scope and retain the fact that you did this
check already if you want to keep the optimization.
Otherwise everything else is there to implement the fix.
> @@ -2175,6 +2175,21 @@ _dl_map_object (struct link_map *loader, const char *name,
> &main_map->l_rpath_dirs,
> &realname, &fb, loader ?: main_map, LA_SER_RUNPATH,
> &found_other_class);
> +
> + /* Also try DT_RUNPATH in the executable for glibc internal
> + 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. */
> diff --git a/elf/tst-audit14a.c b/elf/tst-audit14a.c
> new file mode 100644
> index 0000000000..c6232eacf2
> --- /dev/null
> +++ b/elf/tst-audit14a.c
> @@ -0,0 +1 @@
> +#include "tst-audit14.c"
>
On Mon, Dec 13, 2021 at 2:07 PM Carlos O'Donell <carlos@redhat.com> wrote:
>
> On 12/8/21 10:25, H.J. Lu wrote:
> > DT_RUNPATH is only used to find the immediate dependencies of the
> > executable or shared object containing the DT_RUNPATH entry. Update
> > the glibc LD_AUDIT dlopen call to try the DT_RUNPATH entry of the
> > executable. This partially fixes BZ #28455.
>
> Please post v4 split out.
>
> > ---
> > elf/Makefile | 9 +++++++--
> > elf/dl-load.c | 15 +++++++++++++++
> > elf/tst-audit14a.c | 1 +
> > 3 files changed, 23 insertions(+), 2 deletions(-)
> > create mode 100644 elf/tst-audit14a.c
> >
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 4b5bdcb08e..aa6b24d790 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -247,10 +247,10 @@ ifneq ($(selinux-enabled),1)
> > tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
> > endif
> > ifeq ($(have-depaudit),yes)
> > -tests += tst-audit14 tst-audit15 tst-audit16
> > +tests += tst-audit14 tst-audit15 tst-audit16 tst-audit14a
>
> Please split one test per line and sort.
Fixed.
> > ifeq ($(run-built-tests),yes)
> > tests-special += $(objpfx)tst-audit14-cmp.out $(objpfx)tst-audit15-cmp.out \
> > - $(objpfx)tst-audit16-cmp.out
> > + $(objpfx)tst-audit16-cmp.out $(objpfx)tst-audit14a-cmp.out
>
> Please split one test per line and sort.
Fixed.
> > endif
> > endif
> > endif
> > @@ -1521,6 +1521,8 @@ tst-auditmany-ENV = \
> > LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so
> > $(objpfx)tst-auditlogmod-1.so: $(libsupport)
> > $(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so
> > +LDFLAGS-tst-audit14a = -Wl,--audit=tst-auditlogmod-1.so,--enable-new-dtags
> > +$(objpfx)tst-audit14a.out: $(objpfx)tst-auditlogmod-1.so
>
> OK.
>
> > LDFLAGS-tst-audit15 = \
> > -Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so
> > $(objpfx)tst-auditlogmod-2.so: $(libsupport)
> > @@ -1547,6 +1549,9 @@ tst-audit17-ENV = LD_AUDIT=$(objpfx)tst-auditmod17.so
> > $(objpfx)tst-audit14-cmp.out: tst-audit14.exp $(objpfx)tst-audit14.out
> > cmp $^ > $@; \
> > $(evaluate-test)
> > +$(objpfx)tst-audit14a-cmp.out: tst-audit14.exp $(objpfx)tst-audit14a.out
> > + cmp $^ > $@; \
> > + $(evaluate-test)
>
> OK.
>
> > $(objpfx)tst-audit15-cmp.out: tst-audit15.exp $(objpfx)tst-audit15.out
> > cmp $^ > $@; \
> > $(evaluate-test)
> > diff --git a/elf/dl-load.c b/elf/dl-load.c
> > index bf8957e73c..1f424ea7c8 100644
> > --- a/elf/dl-load.c
> > +++ b/elf/dl-load.c
>
> The preceding block is like this:
>
> 2146 /* When the object has the RUNPATH information we don't use any
> 2147 RPATHs. */
> 2148 if (loader == NULL || loader->l_info[DT_RUNPATH] == NULL)
> 2149 {
>
> The entire design of this block is to look into DT_RPATH specifically
> under two conditions:
>
> (a) We don't know anything about the loading module, it is NULL, and
> therefore we don't know if DT_RUNPATH was present, which if it
> was present, would prevent the use of DT_RPATH.
>
> (b) We have a loader, and we know it doesn't have DT_RUNPATH and so
> we will look for DT_RPATH.
>
> Your changes adds (c) to this case in which DT_RUNPATH is used, and
> this seems to be logically distinct from the above two cases.
>
> My suggestion is that the code you are adding should be in a distinct
> block *after* the above block starting around line 2189.
>
> We already have a block like this:
> 2189 /* Look at the RUNPATH information for this binary. */
> 2190 if (fd == -1 && loader != NULL
> 2191 && cache_rpath (loader, &loader->l_runpath_dirs,
> 2192 DT_RUNPATH, "RUNPATH"))
> 2193 fd = open_path (name, namelen, mode,
> 2194 &loader->l_runpath_dirs, &realname, &fb, loader,
> 2195 LA_SER_RUNPATH, &found_other_class);
>
> I think it is logically more correct to add to this DT_RUNPATH handling
> than ato add to the DT_RPATH handling above.
>
> So after this block you might add:
>
> /* When processing the lookup we may need to additionally try DT_RUNPATH
> in the executable for a glibc internal dlopen call when looking for
> audit modules. */
> if (__glibc_unlikely (mode & __RTLD_AUDIT)
> && fd == -1)
> {
> ...
> }
Fixed.
> The hard part is that you may want to know a few things:
> (a) main_map (unavailable, but computable via GL(dl_ns)[LM_ID_BASE]._ns_loaded)
> (b) did_main_map (unavailable)
> * This seems like an optimization because if you already looked up via
> main_map and it failed, doing it twice won't help, so you can refactor
> did_main_map to function scope and retain the fact that you did this
> check already if you want to keep the optimization.
Fixed.
> Otherwise everything else is there to implement the fix.
>
Sent out the v4 patch.
Thanks.
@@ -247,10 +247,10 @@ ifneq ($(selinux-enabled),1)
tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
endif
ifeq ($(have-depaudit),yes)
-tests += tst-audit14 tst-audit15 tst-audit16
+tests += tst-audit14 tst-audit15 tst-audit16 tst-audit14a
ifeq ($(run-built-tests),yes)
tests-special += $(objpfx)tst-audit14-cmp.out $(objpfx)tst-audit15-cmp.out \
- $(objpfx)tst-audit16-cmp.out
+ $(objpfx)tst-audit16-cmp.out $(objpfx)tst-audit14a-cmp.out
endif
endif
endif
@@ -1521,6 +1521,8 @@ tst-auditmany-ENV = \
LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so
$(objpfx)tst-auditlogmod-1.so: $(libsupport)
$(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so
+LDFLAGS-tst-audit14a = -Wl,--audit=tst-auditlogmod-1.so,--enable-new-dtags
+$(objpfx)tst-audit14a.out: $(objpfx)tst-auditlogmod-1.so
LDFLAGS-tst-audit15 = \
-Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so
$(objpfx)tst-auditlogmod-2.so: $(libsupport)
@@ -1547,6 +1549,9 @@ tst-audit17-ENV = LD_AUDIT=$(objpfx)tst-auditmod17.so
$(objpfx)tst-audit14-cmp.out: tst-audit14.exp $(objpfx)tst-audit14.out
cmp $^ > $@; \
$(evaluate-test)
+$(objpfx)tst-audit14a-cmp.out: tst-audit14.exp $(objpfx)tst-audit14a.out
+ cmp $^ > $@; \
+ $(evaluate-test)
$(objpfx)tst-audit15-cmp.out: tst-audit15.exp $(objpfx)tst-audit15.out
cmp $^ > $@; \
$(evaluate-test)
@@ -2175,6 +2175,21 @@ _dl_map_object (struct link_map *loader, const char *name,
&main_map->l_rpath_dirs,
&realname, &fb, loader ?: main_map, LA_SER_RUNPATH,
&found_other_class);
+
+ /* Also try DT_RUNPATH in the executable for glibc internal
+ 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. */
new file mode 100644
@@ -0,0 +1 @@
+#include "tst-audit14.c"