Message ID | 20211208152501.1483087-4-hjl.tools@gmail.com |
---|---|
State | New |
Headers | show |
Series | Properly handle DT_RUNPATH | expand |
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.
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 ($(have-depaudit),yes) -tests += tst-audit14 tst-audit15 tst-audit16 +tests += tst-audit14 tst-audit15 tst-audit16 tst-audit14a ifeq ($(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) 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 @@ -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"