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Code Issues Releases Wiki Activity

Move preload_dso() to its own file and rename to sudo_preload_dso().

Browse Source 
It now takes an intercept fd as an optional argument instead of a
list of extra variables to add.  This lets us check whether it is
already set to the expected value (and add it if not).
sudo_intercept.so now uses sudo_preload_dso() to make sure that
LD_PRELOAD and SUDO_INTERCEPT_FD are set properly before executing.
This commit is contained in:
Todd C. Miller 2021-08-09 15:50:25 -06:00
parent 60e76e3e35
commit 9c3df47da9
7 changed files with 290 additions and 169 deletions
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1
MANIFEST
View File

@ -1105,6 +1105,7 @@ src/exec.c
src/exec_common.c src/exec_common.c
src/exec_monitor.c src/exec_monitor.c
src/exec_nopty.c src/exec_nopty.c
src/exec_preload.c
src/exec_pty.c src/exec_pty.c
src/get_pty.c src/get_pty.c
src/hooks.c src/hooks.c

97
src/Makefile.in
View File

@ -134,20 +134,23 @@ SHELL = @SHELL@
PROGS = @PROGS@ PROGS = @PROGS@
OBJS = conversation.o copy_file.o edit_open.o env_hooks.o exec.o \ OBJS = conversation.o copy_file.o edit_open.o env_hooks.o exec.o \
exec_common.o exec_monitor.o exec_nopty.o exec_pty.o get_pty.o hooks.o \ exec_common.o exec_monitor.o exec_nopty.o exec_preload.lo exec_pty.o \
intercept.pb-c.o limits.o load_plugins.o net_ifs.o parse_args.o \ get_pty.o hooks.o intercept.pb-c.lo limits.o load_plugins.o net_ifs.o \
preserve_fds.o signal.o sudo.o sudo_edit.o tcsetpgrp_nobg.o tgetpass.o \ parse_args.o preserve_fds.o signal.o sudo.o sudo_edit.o \
ttyname.o utmp.o @SUDO_OBJS@ tcsetpgrp_nobg.o tgetpass.o ttyname.o utmp.o @SUDO_OBJS@
IOBJS = $(OBJS:.o=.i) sesh.i IOBJS = $(OBJS:.o=.i) sesh.i
POBJS = $(IOBJS:.i=.plog) POBJS = $(IOBJS:.i=.plog)
SESH_OBJS = copy_file.o edit_open.o exec_common.o sesh.o SESH_OBJS = copy_file.o edit_open.o exec_common.o exec_preload.lo sesh.o
INTERCEPT_OBJS = exec_preload.lo sudo_intercept.lo sudo_intercept_common.lo \
intercept.pb-c.lo
CHECK_NET_IFS_OBJS = check_net_ifs.o net_ifs.o CHECK_NET_IFS_OBJS = check_net_ifs.o net_ifs.o
CHECK_NOEXEC_OBJS = check_noexec.o exec_common.o CHECK_NOEXEC_OBJS = check_noexec.o exec_common.o exec_preload.lo
CHECK_TTYNAME_OBJS = check_ttyname.o ttyname.o CHECK_TTYNAME_OBJS = check_ttyname.o ttyname.o
@ -201,8 +204,8 @@ $(devdir)/intercept.pb-c.c: $(srcdir)/intercept.proto
sudo: $(OBJS) $(LT_LIBS) @STATIC_SUDOERS@ sudo: $(OBJS) $(LT_LIBS) @STATIC_SUDOERS@
$(LIBTOOL) $(LTFLAGS) --mode=link $(CC) -o $@ $(OBJS) $(SUDO_LDFLAGS) $(ASAN_LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(LIBS) @STATIC_SUDOERS@ $(LIBTOOL) $(LTFLAGS) --mode=link $(CC) -o $@ $(OBJS) $(SUDO_LDFLAGS) $(ASAN_LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(LIBS) @STATIC_SUDOERS@
sudo_intercept.la: sudo_intercept.lo sudo_intercept_common.lo intercept.pb-c.lo sudo_intercept.la: $(INTERCEPT_OBJS)
$(LIBTOOL) $(LTFLAGS) --mode=link $(CC) $(LDFLAGS) $(LT_LDFLAGS) $(SSP_LDFLAGS) $(LT_LIBS) @LIBDL@ -o $@ sudo_intercept.lo sudo_intercept_common.lo intercept.pb-c.lo $(PRELOAD_MODULE) -avoid-version -rpath $(interceptdir) -shrext .so $(LIBTOOL) $(LTFLAGS) --mode=link $(CC) $(LDFLAGS) $(LT_LDFLAGS) $(ASAN_LDFLAGS) $(SSP_LDFLAGS) $(LT_LIBS) @LIBDL@ -o $@ $(INTERCEPT_OBJS) $(PRELOAD_MODULE) -avoid-version -rpath $(interceptdir) -shrext .so
sudo_noexec.la: sudo_noexec.lo sudo_noexec.la: sudo_noexec.lo
$(LIBTOOL) $(LTFLAGS) --mode=link $(CC) $(LDFLAGS) $(LT_LDFLAGS) $(SSP_LDFLAGS) @LIBDL@ -o $@ sudo_noexec.lo $(PRELOAD_MODULE) -avoid-version -rpath $(noexecdir) -shrext .so $(LIBTOOL) $(LTFLAGS) --mode=link $(CC) $(LDFLAGS) $(LT_LDFLAGS) $(SSP_LDFLAGS) @LIBDL@ -o $@ sudo_noexec.lo $(PRELOAD_MODULE) -avoid-version -rpath $(noexecdir) -shrext .so
@ -344,22 +347,8 @@ cleandir: realclean
.PHONY: clean mostlyclean distclean cleandir clobber realclean .PHONY: clean mostlyclean distclean cleandir clobber realclean
# *Not* auto-generated to avoid building with ASAN # *Not* auto-generated to avoid building with ASAN
sudo_intercept.lo: $(srcdir)/sudo_intercept.c $(incdir)/sudo_compat.h \
$(top_builddir)/config.h $(top_builddir)/pathnames.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/sudo_intercept.c
sudo_intercept_common.lo: $(srcdir)/sudo_intercept_common.c \
$(incdir)/sudo_compat.h $(incdir)/sudo_fatal.h \
$(incdir)/sudo_gettext.h $(incdir)/intercept.pb-c.h \
$(srcdir)/sudo_exec.h $(top_builddir)/config.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/sudo_intercept_common.c
intercept.pb-c.lo: $(srcdir)/intercept.pb-c.c $(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/intercept.pb-c.c
sudo_noexec.lo: $(srcdir)/sudo_noexec.c $(incdir)/sudo_compat.h \ sudo_noexec.lo: $(srcdir)/sudo_noexec.c $(incdir)/sudo_compat.h \
$(top_builddir)/config.h $(top_builddir)/pathnames.h $(top_builddir)/config.h $(top_builddir)/pathnames.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/sudo_noexec.c $(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/sudo_noexec.c
# Autogenerated dependencies, do not modify # Autogenerated dependencies, do not modify
@ -477,14 +466,16 @@ env_hooks.i: $(srcdir)/env_hooks.c $(incdir)/compat/stdbool.h \
$(CC) -E -o $@ $(CPPFLAGS) $< $(CC) -E -o $@ $(CPPFLAGS) $<
env_hooks.plog: env_hooks.i env_hooks.plog: env_hooks.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/env_hooks.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/env_hooks.c --i-file $< --output-file $@
exec.o: $(srcdir)/exec.c $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \ exec.o: $(srcdir)/exec.c $(incdir)/compat/stdbool.h $(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h $(incdir)/sudo_compat.h \
$(incdir)/sudo_conf.h $(incdir)/sudo_debug.h $(incdir)/sudo_event.h \ $(incdir)/sudo_conf.h $(incdir)/sudo_debug.h $(incdir)/sudo_event.h \
$(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \ $(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
$(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h $(incdir)/sudo_util.h \ $(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h $(incdir)/sudo_util.h \
$(srcdir)/sudo.h $(srcdir)/sudo_exec.h $(srcdir)/sudo_plugin_int.h \ $(srcdir)/sudo.h $(srcdir)/sudo_exec.h $(srcdir)/sudo_plugin_int.h \
$(top_builddir)/config.h $(top_builddir)/pathnames.h $(top_builddir)/config.h $(top_builddir)/pathnames.h
$(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/exec.c $(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/exec.c
exec.i: $(srcdir)/exec.c $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \ exec.i: $(srcdir)/exec.c $(incdir)/compat/stdbool.h $(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h $(incdir)/sudo_compat.h \
$(incdir)/sudo_conf.h $(incdir)/sudo_debug.h $(incdir)/sudo_event.h \ $(incdir)/sudo_conf.h $(incdir)/sudo_debug.h $(incdir)/sudo_event.h \
$(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \ $(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
$(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h $(incdir)/sudo_util.h \ $(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h $(incdir)/sudo_util.h \
@ -551,6 +542,24 @@ exec_nopty.i: $(srcdir)/exec_nopty.c $(incdir)/compat/stdbool.h \
$(CC) -E -o $@ $(CPPFLAGS) $< $(CC) -E -o $@ $(CPPFLAGS) $<
exec_nopty.plog: exec_nopty.i exec_nopty.plog: exec_nopty.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/exec_nopty.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/exec_nopty.c --i-file $< --output-file $@
exec_preload.lo: $(srcdir)/exec_preload.c $(incdir)/compat/stdbool.h \
$(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
$(incdir)/sudo_debug.h $(incdir)/sudo_event.h \
$(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
$(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h \
$(incdir)/sudo_util.h $(srcdir)/sudo.h $(srcdir)/sudo_exec.h \
$(top_builddir)/config.h $(top_builddir)/pathnames.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/exec_preload.c
exec_preload.i: $(srcdir)/exec_preload.c $(incdir)/compat/stdbool.h \
$(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
$(incdir)/sudo_debug.h $(incdir)/sudo_event.h \
$(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
$(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h \
$(incdir)/sudo_util.h $(srcdir)/sudo.h $(srcdir)/sudo_exec.h \
$(top_builddir)/config.h $(top_builddir)/pathnames.h
$(CC) -E -o $@ $(CPPFLAGS) $<
exec_preload.plog: exec_preload.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/exec_preload.c --i-file $< --output-file $@
exec_pty.o: $(srcdir)/exec_pty.c $(incdir)/compat/stdbool.h \ exec_pty.o: $(srcdir)/exec_pty.c $(incdir)/compat/stdbool.h \
$(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \ $(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
$(incdir)/sudo_debug.h $(incdir)/sudo_event.h \ $(incdir)/sudo_debug.h $(incdir)/sudo_event.h \
@ -605,11 +614,11 @@ hooks.i: $(srcdir)/hooks.c $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \
$(CC) -E -o $@ $(CPPFLAGS) $< $(CC) -E -o $@ $(CPPFLAGS) $<
hooks.plog: hooks.i hooks.plog: hooks.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/hooks.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/hooks.c --i-file $< --output-file $@
intercept.pb-c.o: $(srcdir)/intercept.pb-c.c $(incdir)/intercept.pb-c.h \ intercept.pb-c.lo: $(srcdir)/intercept.pb-c.c $(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h $(incdir)/protobuf-c/protobuf-c.h
$(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/intercept.pb-c.c $(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/intercept.pb-c.c
intercept.pb-c.i: $(srcdir)/intercept.pb-c.c $(incdir)/intercept.pb-c.h \ intercept.pb-c.i: $(srcdir)/intercept.pb-c.c $(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h $(incdir)/protobuf-c/protobuf-c.h
$(CC) -E -o $@ $(CPPFLAGS) $< $(CC) -E -o $@ $(CPPFLAGS) $<
intercept.pb-c.plog: intercept.pb-c.i intercept.pb-c.plog: intercept.pb-c.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/intercept.pb-c.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/intercept.pb-c.c --i-file $< --output-file $@
@ -833,6 +842,36 @@ sudo_edit.i: $(srcdir)/sudo_edit.c $(incdir)/compat/stdbool.h \
$(CC) -E -o $@ $(CPPFLAGS) $< $(CC) -E -o $@ $(CPPFLAGS) $<
sudo_edit.plog: sudo_edit.i sudo_edit.plog: sudo_edit.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/sudo_edit.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/sudo_edit.c --i-file $< --output-file $@
sudo_intercept.lo: $(srcdir)/sudo_intercept.c $(incdir)/compat/stdbool.h \
$(incdir)/sudo_compat.h $(top_builddir)/config.h \
$(top_builddir)/pathnames.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/sudo_intercept.c
sudo_intercept.i: $(srcdir)/sudo_intercept.c $(incdir)/compat/stdbool.h \
$(incdir)/sudo_compat.h $(top_builddir)/config.h \
$(top_builddir)/pathnames.h
$(CC) -E -o $@ $(CPPFLAGS) $<
sudo_intercept.plog: sudo_intercept.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/sudo_intercept.c --i-file $< --output-file $@
sudo_intercept_common.lo: $(srcdir)/sudo_intercept_common.c \
$(incdir)/compat/stdbool.h \
$(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h \
$(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
$(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
$(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h \
$(srcdir)/sudo_exec.h $(top_builddir)/config.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/sudo_intercept_common.c
sudo_intercept_common.i: $(srcdir)/sudo_intercept_common.c \
$(incdir)/compat/stdbool.h \
$(incdir)/intercept.pb-c.h \
$(incdir)/protobuf-c/protobuf-c.h \
$(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
$(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
$(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h \
$(srcdir)/sudo_exec.h $(top_builddir)/config.h
$(CC) -E -o $@ $(CPPFLAGS) $<
sudo_intercept_common.plog: sudo_intercept_common.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/sudo_intercept_common.c --i-file $< --output-file $@
tcsetpgrp_nobg.o: $(srcdir)/tcsetpgrp_nobg.c $(incdir)/compat/stdbool.h \ tcsetpgrp_nobg.o: $(srcdir)/tcsetpgrp_nobg.c $(incdir)/compat/stdbool.h \
$(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \ $(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
$(incdir)/sudo_debug.h $(incdir)/sudo_event.h \ $(incdir)/sudo_debug.h $(incdir)/sudo_event.h \

126
src/exec_common.c
View File

@ -36,125 +36,6 @@
#include "sudo.h" #include "sudo.h"
#include "sudo_exec.h" #include "sudo_exec.h"
#ifdef RTLD_PRELOAD_VAR
/*
* Add a DSO file to LD_PRELOAD or the system equivalent.
*/
static char **
preload_dso(char *envp[], const char *dso_file, char * const extra_envp[])
{
char *preload = NULL;
int env_len, extra_len = 0;
int preload_idx = -1;
bool present = false;
# ifdef RTLD_PRELOAD_ENABLE_VAR
bool enabled = false;
# else
const bool enabled = true;
# endif
debug_decl(preload_dso, SUDO_DEBUG_UTIL);
/*
* Preload a DSO file. For a list of LD_PRELOAD-alikes, see
* http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html
* XXX - need to support 32-bit and 64-bit variants
*/
/* Count entries in envp, looking for LD_PRELOAD as we go. */
for (env_len = 0; envp[env_len] != NULL; env_len++) {
if (preload_idx == -1 && strncmp(envp[env_len], RTLD_PRELOAD_VAR "=",
sizeof(RTLD_PRELOAD_VAR)) == 0) {
const char *cp = envp[env_len] + sizeof(RTLD_PRELOAD_VAR);
const char *end = cp + strlen(cp);
const char *ep;
const size_t dso_len = strlen(dso_file);
/* Check to see if dso_file is already present. */
for (cp = sudo_strsplit(cp, end, RTLD_PRELOAD_DELIM, &ep);
cp != NULL; cp = sudo_strsplit(NULL, end, RTLD_PRELOAD_DELIM,
&ep)) {
if ((size_t)(ep - cp) == dso_len) {
if (memcmp(cp, dso_file, dso_len) == 0) {
/* already present */
present = true;
break;
}
}
}
/* Save index of existing LD_PRELOAD variable. */
preload_idx = env_len;
continue;
}
# ifdef RTLD_PRELOAD_ENABLE_VAR
if (strncmp(envp[env_len], RTLD_PRELOAD_ENABLE_VAR "=", sizeof(RTLD_PRELOAD_ENABLE_VAR)) == 0) {
enabled = true;
continue;
}
# endif
}
if (extra_envp != NULL) {
for (extra_len = 0; extra_envp[extra_len] != NULL; extra_len++) {
continue;
}
}
/*
* Make a new copy of envp as needed.
* It would be nice to realloc the old envp[] but we don't know
* whether it was dynamically allocated. [TODO: plugin API]
*/
if (preload_idx == -1 || !enabled || extra_len != 0) {
const int env_size = env_len + 1 + (preload_idx == -1) + enabled + extra_len; // -V547
char **nenvp = reallocarray(NULL, env_size, sizeof(*envp));
if (nenvp == NULL)
sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
memcpy(nenvp, envp, env_len * sizeof(*envp));
if (extra_envp != NULL) {
for (extra_len = 0; extra_envp[extra_len] != NULL; extra_len++)
nenvp[env_len++] = extra_envp[extra_len];
}
nenvp[env_len] = NULL;
envp = nenvp;
}
/* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
if (!present) {
if (preload_idx == -1) {
# ifdef RTLD_PRELOAD_DEFAULT
asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, dso_file,
RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
# else
preload = sudo_new_key_val(RTLD_PRELOAD_VAR, dso_file);
# endif
if (preload == NULL) {
sudo_fatalx(U_("%s: %s"), __func__,
U_("unable to allocate memory"));
}
envp[env_len++] = preload;
envp[env_len] = NULL;
} else {
int len = asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR,
dso_file, RTLD_PRELOAD_DELIM, envp[preload_idx]);
if (len == -1) {
sudo_fatalx(U_("%s: %s"), __func__,
U_("unable to allocate memory"));
}
envp[preload_idx] = preload;
}
}
# ifdef RTLD_PRELOAD_ENABLE_VAR
if (!enabled) {
envp[env_len++] = RTLD_PRELOAD_ENABLE_VAR "=";
envp[env_len] = NULL;
}
# endif
debug_return_ptr(envp);
}
#endif /* RTLD_PRELOAD_VAR */
/* /*
* Disable execution of child processes in the command we are about * Disable execution of child processes in the command we are about
* to run. On systems with privilege sets, we can remove the exec * to run. On systems with privilege sets, we can remove the exec
@ -177,7 +58,7 @@ disable_execute(char *envp[], const char *dso)
#ifdef RTLD_PRELOAD_VAR #ifdef RTLD_PRELOAD_VAR
if (dso != NULL) if (dso != NULL)
envp = preload_dso(envp, dso, NULL); envp = sudo_preload_dso(envp, dso, -1);
#endif /* RTLD_PRELOAD_VAR */ #endif /* RTLD_PRELOAD_VAR */
debug_return_ptr(envp); debug_return_ptr(envp);
@ -191,7 +72,6 @@ static char **
enable_intercept(char *envp[], const char *dso, int intercept_fd) enable_intercept(char *envp[], const char *dso, int intercept_fd)
{ {
#ifdef RTLD_PRELOAD_VAR #ifdef RTLD_PRELOAD_VAR
char *env_add[] = { NULL, NULL };
debug_decl(enable_intercept, SUDO_DEBUG_UTIL); debug_decl(enable_intercept, SUDO_DEBUG_UTIL);
if (dso == NULL) if (dso == NULL)
@ -204,9 +84,7 @@ enable_intercept(char *envp[], const char *dso, int intercept_fd)
if (intercept_fd == -1) if (intercept_fd == -1)
sudo_fatal("%s", U_("unable to dup intercept fd")); sudo_fatal("%s", U_("unable to dup intercept fd"));
} }
if (asprintf(&env_add[0], "SUDO_INTERCEPT_FD=%d", intercept_fd) == -1) envp = sudo_preload_dso(envp, dso, intercept_fd);
debug_return_ptr(NULL);
envp = preload_dso(envp, dso, env_add);
#else #else
/* Intercept not supported, envp unchanged. */ /* Intercept not supported, envp unchanged. */
if (intercept_fd != -1) if (intercept_fd != -1)

199
src/exec_preload.c Normal file
View File

@ -0,0 +1,199 @@
/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "sudo.h"
#include "sudo_exec.h"
#ifdef RTLD_PRELOAD_VAR
/*
* Add a DSO file to LD_PRELOAD or the system equivalent.
*/
char **
sudo_preload_dso(char *envp[], const char *dso_file, int intercept_fd)
{
char *preload = NULL;
int env_len;
int preload_idx = -1;
int intercept_idx = -1;
bool fd_present = false;
bool dso_present = false;
# ifdef RTLD_PRELOAD_ENABLE_VAR
bool dso_enabled = false;
# else
const bool dso_enabled = true;
# endif
debug_decl(sudo_preload_dso, SUDO_DEBUG_UTIL);
/*
* Preload a DSO file. For a list of LD_PRELOAD-alikes, see
* http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html
* XXX - need to support 32-bit and 64-bit variants
*/
/* Count entries in envp, looking for LD_PRELOAD as we go. */
/* XXX - If multiple LD_PRELOAD should remove extras */
for (env_len = 0; envp[env_len] != NULL; env_len++) {
if (strncmp(envp[env_len], RTLD_PRELOAD_VAR "=", sizeof(RTLD_PRELOAD_VAR)) == 0) {
if (preload_idx == -1) {
const char *cp = envp[env_len] + sizeof(RTLD_PRELOAD_VAR);
const char *end = cp + strlen(cp);
const char *ep;
const size_t dso_len = strlen(dso_file);
/* Check to see if dso_file is already present. */
for (cp = sudo_strsplit(cp, end, RTLD_PRELOAD_DELIM, &ep);
cp != NULL; cp = sudo_strsplit(NULL, end, RTLD_PRELOAD_DELIM,
&ep)) {
if ((size_t)(ep - cp) == dso_len) {
if (memcmp(cp, dso_file, dso_len) == 0) {
/* already present */
dso_present = true;
break;
}
}
}
/* Save index of existing LD_PRELOAD variable. */
preload_idx = env_len;
} else {
/* Remove duplicate LD_PRELOAD. */
int i;
for (i = env_len; envp[i] != NULL; i++) {
envp[i] = envp[i + 1];
}
}
continue;
}
if (intercept_fd != -1 && strncmp(envp[env_len], "SUDO_INTERCEPT_FD=",
sizeof("SUDO_INTERCEPT_FD=")) == 0) {
if (intercept_idx == -1) {
const char *cp = envp[env_len] + sizeof("SUDO_INTERCEPT_FD=");
const char *errstr;
int fd;
fd = sudo_strtonum(cp, 0, INT_MAX, &errstr);
if (fd == intercept_fd && errstr == NULL)
fd_present = true;
/* Save index of existing SUDO_INTERCEPT_FD variable. */
intercept_idx = env_len;
} else {
/* Remove duplicate SUDO_INTERCEPT_FD. */
int i;
for (i = env_len; envp[i] != NULL; i++) {
envp[i] = envp[i + 1];
}
}
continue;
}
# ifdef RTLD_PRELOAD_ENABLE_VAR
if (strncmp(envp[env_len], RTLD_PRELOAD_ENABLE_VAR "=", sizeof(RTLD_PRELOAD_ENABLE_VAR)) == 0) {
dso_enabled = true;
continue;
}
# endif
}
/*
* Make a new copy of envp as needed.
* It would be nice to realloc the old envp[] but we don't know
* whether it was dynamically allocated. [TODO: plugin API]
*/
if (preload_idx == -1 || !dso_enabled || intercept_idx == -1) {
const int env_size = env_len + 1 + (preload_idx == -1) + dso_enabled + (intercept_idx == -1); // -V547
char **nenvp = reallocarray(NULL, env_size, sizeof(*envp));
if (nenvp == NULL) {
sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
debug_return_ptr(NULL);
}
memcpy(nenvp, envp, env_len * sizeof(*envp));
nenvp[env_len] = NULL;
envp = nenvp;
}
/* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
if (!dso_present) {
if (preload_idx == -1) {
# ifdef RTLD_PRELOAD_DEFAULT
asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, dso_file,
RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
# else
preload = sudo_new_key_val(RTLD_PRELOAD_VAR, dso_file);
# endif
if (preload == NULL) {
sudo_warnx(U_("%s: %s"), __func__,
U_("unable to allocate memory"));
/* XXX - leak */
debug_return_ptr(NULL);
}
envp[env_len++] = preload;
envp[env_len] = NULL;
} else {
int len = asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR,
dso_file, RTLD_PRELOAD_DELIM, envp[preload_idx]);
if (len == -1) {
sudo_warnx(U_("%s: %s"), __func__,
U_("unable to allocate memory"));
/* XXX - leak */
debug_return_ptr(NULL);
}
envp[preload_idx] = preload;
}
}
# ifdef RTLD_PRELOAD_ENABLE_VAR
if (!dso_enabled) {
envp[env_len++] = RTLD_PRELOAD_ENABLE_VAR "=";
envp[env_len] = NULL;
}
# endif
if (!fd_present && intercept_fd != -1) {
char *fdstr;
int len;
len = asprintf(&fdstr, "SUDO_INTERCEPT_FD=%d", intercept_fd);
if (len == -1) {
sudo_warnx(U_("%s: %s"), __func__,
U_("unable to allocate memory"));
/* XXX - leak */
debug_return_ptr(NULL);
}
if (intercept_idx != -1) {
envp[preload_idx] = fdstr;
} else {
envp[env_len++] = fdstr;
envp[env_len] = NULL;
}
}
debug_return_ptr(envp);
}
#endif /* RTLD_PRELOAD_VAR */

3
src/sudo_exec.h
View File

@ -117,4 +117,7 @@ bool utmp_login(const char *from_line, const char *to_line, int ttyfd,
const char *user); const char *user);
bool utmp_logout(const char *line, int status); bool utmp_logout(const char *line, int status);
/* exec_preload.c */
char **sudo_preload_dso(char *envp[], const char *dso_file, int intercept_fd);
#endif /* SUDO_EXEC_H */ #endif /* SUDO_EXEC_H */

18
src/sudo_intercept.c
View File

@ -63,14 +63,19 @@ my_execve(const char *cmnd, char * const argv[], char * const envp[])
{ {
char *ncmnd = NULL, **nargv = NULL, **nenvp = NULL; char *ncmnd = NULL, **nargv = NULL, **nenvp = NULL;
/* XXX - add SUDO_INTERCEPT_FD to environment as needed. */
if (command_allowed(cmnd, argv, envp, &ncmnd, &nargv, &nenvp)) { if (command_allowed(cmnd, argv, envp, &ncmnd, &nargv, &nenvp)) {
/* Execute the command using the "real" execve() function. */ /* Execute the command using the "real" execve() function. */
execve(ncmnd, nargv, nenvp); execve(ncmnd, nargv, nenvp);
} else { } else {
errno = EACCES; errno = EACCES;
} }
/* XXX - free ncmnd, nargv, nenvp */ if (ncmnd != cmnd)
free(ncmnd);
if (nargv != argv)
free(nargv);
if (nenvp != envp)
free(nenvp);
return -1; return -1;
} }
@ -113,14 +118,19 @@ execve(const char *cmnd, char * const argv[], char * const envp[])
return -1; return -1;
} }
/* XXX - add SUDO_INTERCEPT_FD to environment as needed. */
if (command_allowed(cmnd, argv, envp, &ncmnd, &nargv, &nenvp)) { if (command_allowed(cmnd, argv, envp, &ncmnd, &nargv, &nenvp)) {
/* Execute the command using the "real" execve() function. */ /* Execute the command using the "real" execve() function. */
return ((sudo_fn_execve_t)fn)(ncmnd, nargv, nenvp); return ((sudo_fn_execve_t)fn)(ncmnd, nargv, nenvp);
} else { } else {
errno = EACCES; errno = EACCES;
} }
/* XXX - free ncmnd, nargv, nenvp */ if (ncmnd != cmnd)
free(ncmnd);
if (nargv != argv)
free(nargv);
if (nenvp != envp)
free(nenvp);
return -1; return -1;
} }
#endif /* HAVE___INTERPOSE) */ #endif /* HAVE___INTERPOSE) */

15
src/sudo_intercept_common.c
View File

@ -44,6 +44,7 @@
#define SUDO_ERROR_WRAP 0 #define SUDO_ERROR_WRAP 0
#include "sudo_compat.h" #include "sudo_compat.h"
#include "sudo_conf.h"
#include "sudo_fatal.h" #include "sudo_fatal.h"
#include "sudo_exec.h" #include "sudo_exec.h"
#include "sudo_gettext.h" #include "sudo_gettext.h"
@ -51,7 +52,6 @@
extern char **environ; extern char **environ;
static pid_t mainpid = -1;
static int intercept_sock = -1; static int intercept_sock = -1;
/* /*
@ -66,7 +66,6 @@ sudo_interposer_init(void)
if (!initialized) { if (!initialized) {
initialized = true; initialized = true;
mainpid = getpid();
/* /*
* Missing SUDO_INTERCEPT_FD will result in execve() failure. * Missing SUDO_INTERCEPT_FD will result in execve() failure.
@ -203,14 +202,6 @@ command_allowed(const char *cmnd, char * const argv[], char * const envp[],
goto done; goto done;
} }
/* Don't allow the original process to be replaced. */
if (getpid() == mainpid) {
sudo_warnx("shell overwrite denied"); // XXX
// XXX debugging
errno = EACCES;
goto done;
}
/* /*
* We communicate with the main sudo process over a socket pair * We communicate with the main sudo process over a socket pair
* which is passed over the intercept_sock. The reason for not * which is passed over the intercept_sock. The reason for not
@ -285,8 +276,8 @@ command_allowed(const char *cmnd, char * const argv[], char * const envp[],
(*nargv)[len] = strdup(res->u.accept_msg->run_argv[len]); (*nargv)[len] = strdup(res->u.accept_msg->run_argv[len]);
} }
(*nargv)[len] = NULL; (*nargv)[len] = NULL;
/* XXX - add SUDO_INTERCEPT_FD to environment as needed. */ // XXX - bogus cast
*nenvp = (char **)envp; *nenvp = sudo_preload_dso((char **)envp, sudo_conf_intercept_path(), intercept_sock);
ret = true; ret = true;
break; break;
case POLICY_CHECK_RESULT__TYPE_REJECT_MSG: case POLICY_CHECK_RESULT__TYPE_REJECT_MSG: