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elf: Ignore loader debug env vars for setuid

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Loader already ignores LD_DEBUG, LD_DEBUG_OUTPUT, and
LD_TRACE_LOADED_OBJECTS. Both LD_WARN and LD_VERBOSE are similar to
LD_DEBUG, in the sense they enable additional checks and debug
information, so it makes sense to disable them.

Also add both LD_VERBOSE and LD_WARN on filtered environment variables
for setuid binaries.

Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
This commit is contained in:
Adhemerval Zanella
2023-11-22 17:43:23 -03:00
parent f85722f9cd
commit 876a12e513
3 changed files with 20 additions and 8 deletions
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22
elf/rtld.c
View File

@@ -2556,13 +2556,15 @@ process_envvars (struct dl_main_state *state)
{ {
case 4: case 4:
/* Warning level, verbose or not. */ /* Warning level, verbose or not. */
if (memcmp (envline, "WARN", 4) == 0) if (!__libc_enable_secure
&& memcmp (envline, "WARN", 4) == 0)
GLRO(dl_verbose) = envline[5] != '\0'; GLRO(dl_verbose) = envline[5] != '\0';
break; break;
case 5: case 5:
/* Debugging of the dynamic linker? */ /* Debugging of the dynamic linker? */
if (memcmp (envline, "DEBUG", 5) == 0) if (!__libc_enable_secure
&& memcmp (envline, "DEBUG", 5) == 0)
{ {
process_dl_debug (state, &envline[6]); process_dl_debug (state, &envline[6]);
break; break;
@@ -2577,7 +2579,8 @@ process_envvars (struct dl_main_state *state)
case 7: case 7:
/* Print information about versions. */ /* Print information about versions. */
if (memcmp (envline, "VERBOSE", 7) == 0) if (!__libc_enable_secure
&& memcmp (envline, "VERBOSE", 7) == 0)
{ {
state->version_info = envline[8] != '\0'; state->version_info = envline[8] != '\0';
break; break;
@@ -2636,7 +2639,8 @@ process_envvars (struct dl_main_state *state)
} }
/* Where to place the profiling data file. */ /* Where to place the profiling data file. */
if (memcmp (envline, "DEBUG_OUTPUT", 12) == 0) if (!__libc_enable_secure
&& memcmp (envline, "DEBUG_OUTPUT", 12) == 0)
{ {
debug_output = &envline[13]; debug_output = &envline[13];
break; break;
@@ -2657,7 +2661,8 @@ process_envvars (struct dl_main_state *state)
case 20: case 20:
/* The mode of the dynamic linker can be set. */ /* The mode of the dynamic linker can be set. */
if (memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0) if (!__libc_enable_secure
&& memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0)
{ {
state->mode = rtld_mode_trace; state->mode = rtld_mode_trace;
state->mode_trace_program state->mode_trace_program
@@ -2679,9 +2684,10 @@ process_envvars (struct dl_main_state *state)
} }
while (*nextp != '\0'); while (*nextp != '\0');
GLRO(dl_debug_mask) = 0; if (GLRO(dl_debug_mask) != 0
|| GLRO(dl_verbose) != 0
if (state->mode != rtld_mode_normal) || state->mode != rtld_mode_normal
|| state->version_info)
_exit (5); _exit (5);
} }
/* If we have to run the dynamic linker in debugging mode and the /* If we have to run the dynamic linker in debugging mode and the

4
elf/tst-env-setuid.c
View File

@@ -59,6 +59,10 @@ static const struct envvar_t filtered_envvars[] =
{ "MALLOC_TRACE", FILTERED_VALUE }, { "MALLOC_TRACE", FILTERED_VALUE },
{ "MALLOC_TRIM_THRESHOLD_", FILTERED_VALUE }, { "MALLOC_TRIM_THRESHOLD_", FILTERED_VALUE },
{ "RES_OPTIONS", FILTERED_VALUE }, { "RES_OPTIONS", FILTERED_VALUE },
{ "LD_DEBUG", "all" },
{ "LD_DEBUG_OUTPUT", "/tmp/some-file" },
{ "LD_WARN", FILTERED_VALUE },
{ "LD_VERBOSE", FILTERED_VALUE },
}; };
static const struct envvar_t unfiltered_envvars[] = static const struct envvar_t unfiltered_envvars[] =

2
sysdeps/generic/unsecvars.h
View File

@@ -16,6 +16,8 @@
"LD_PRELOAD\0" \ "LD_PRELOAD\0" \
"LD_PROFILE\0" \ "LD_PROFILE\0" \
"LD_SHOW_AUXV\0" \ "LD_SHOW_AUXV\0" \
"LD_VERBOSE\0" \
"LD_WARN\0" \
"LOCALDOMAIN\0" \ "LOCALDOMAIN\0" \
"LOCPATH\0" \ "LOCPATH\0" \
"MALLOC_ARENA_MAX\0" \ "MALLOC_ARENA_MAX\0" \