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From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Siddhesh Poyarekar <siddhesh@sourceware.org>
Subject: [PATCH v3 12/19] elf: Ignore LD_PROFILE for setuid binaries
Date: Mon,  6 Nov 2023 17:25:45 -0300	[thread overview]
Message-ID: <20231106202552.3404059-13-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20231106202552.3404059-1-adhemerval.zanella@linaro.org>

Loader does not ignore LD_PROFILE in secure-execution mode (different
than man-page states [1]), rather it uses a different path
(/var/profile) and ignore LD_PROFILE_OUTPUT.

Allowing secure-execution profiling is already a non good security
boundary, since it enables different code paths and extra OS access by
the process.  But by ignoring LD_PROFILE_OUTPUT, the resulting profile
file might also be acceded in a racy manner since the file name does not
use any process-specific information (such as pid, timing, etc.).

Another side-effect is it forces lazy binding even on libraries that
might be with DF_BIND_NOW.

[1] https://man7.org/linux/man-pages/man8/ld.so.8.html
---
 elf/Makefile         |  3 +++
 elf/rtld.c           |  8 +++-----
 elf/tst-env-setuid.c | 12 +++++++++++-
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/elf/Makefile b/elf/Makefile
index 52981c19d0..08896bb895 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -2983,3 +2983,6 @@ $(objpfx)tst-dlclose-lazy.out: \
   $(objpfx)tst-dlclose-lazy-mod1.so $(objpfx)tst-dlclose-lazy-mod2.so
 
 tst-env-setuid-ARGS = -- $(host-test-program-cmd)
+
+# Reuse a module with a SONAME, to specific as the LD_PROFILE.
+$(objpfx)tst-env-setuid: $(objpfx)tst-sonamemove-runmod2.so
diff --git a/elf/rtld.c b/elf/rtld.c
index 51b6d9f326..a09cf2a9df 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -361,6 +361,7 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
     ._dl_fpu_control = _FPU_DEFAULT,
     ._dl_pagesize = EXEC_PAGESIZE,
     ._dl_inhibit_cache = 0,
+    ._dl_profile_output = "/var/tmp",
 
     /* Function pointers.  */
     ._dl_debug_printf = _dl_debug_printf,
@@ -2534,10 +2535,6 @@ process_envvars (struct dl_main_state *state)
   char *envline;
   char *debug_output = NULL;
 
-  /* This is the default place for profiling data file.  */
-  GLRO(dl_profile_output)
-    = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
-
   while ((envline = _dl_next_ld_env_entry (&runp)) != NULL)
     {
       size_t len = 0;
@@ -2586,7 +2583,8 @@ process_envvars (struct dl_main_state *state)
 	    }
 
 	  /* Which shared object shall be profiled.  */
-	  if (memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0')
+	  if (!__libc_enable_secure
+	      && memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0')
 	    GLRO(dl_profile) = &envline[8];
 	  break;
 
diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c
index ba295a6a14..76b8e1fb45 100644
--- a/elf/tst-env-setuid.c
+++ b/elf/tst-env-setuid.c
@@ -34,6 +34,9 @@ static char SETGID_CHILD[] = "setgid-child";
 
 #define FILTERED_VALUE   "some-filtered-value"
 #define UNFILTERED_VALUE "some-unfiltered-value"
+/* It assumes no other programs is being profile with a library with same
+   SONAME using the default folder.  */
+#define PROFILE_LIB      "tst-sonamemove-runmod2.so"
 
 struct envvar_t
 {
@@ -50,7 +53,7 @@ static const struct envvar_t filtered_envvars[] =
   { "LD_HWCAP_MASK",           FILTERED_VALUE },
   { "LD_LIBRARY_PATH",         FILTERED_VALUE },
   { "LD_PRELOAD",              FILTERED_VALUE },
-  { "LD_PROFILE",              FILTERED_VALUE },
+  { "LD_PROFILE",              "tst-sonamemove-runmod2.so" },
   { "MALLOC_ARENA_MAX",        FILTERED_VALUE },
   { "MALLOC_PERTURB_",         FILTERED_VALUE },
   { "MALLOC_TRACE",            FILTERED_VALUE },
@@ -87,6 +90,13 @@ test_child (void)
       ret |= !(env != NULL && strcmp (env, e->value) == 0);
     }
 
+  /* Also check if no profile file was created.  */
+  {
+    char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB);
+    ret |= !access (profilepath, R_OK);
+    free (profilepath);
+  }
+
   return ret;
 }
 
-- 
2.34.1


  parent reply	other threads:[~2023-11-06 20:26 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-06 20:25 [PATCH v3 00/19] Improve loader environment variable handling Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 01/19] elf: Remove /etc/suid-debug support Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 02/19] elf: Add GLIBC_TUNABLES to unsecvars Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 03/19] elf: Ignore GLIBC_TUNABLES for setuid/setgid binaries Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 04/19] elf: Add all malloc tunable to unsecvars Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 05/19] elf: Do not process invalid tunable format Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 06/19] elf: Do not parse ill-formatted strings Adhemerval Zanella
2023-11-20 21:48   ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 07/19] elf: Fix _dl_debug_vdprintf to work before self-relocation Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 08/19] elf: Emit warning if tunable is ill-formatted Adhemerval Zanella
2023-11-20 21:50   ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 09/19] x86: Use dl-symbol-redir-ifunc.h on cpu-tunables Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 10/19] s390: " Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 11/19] elf: Do not duplicate the GLIBC_TUNABLES string Adhemerval Zanella
2023-11-20 22:44   ` Siddhesh Poyarekar
2023-11-21 18:12     ` Adhemerval Zanella Netto
2023-11-22 11:39       ` Adhemerval Zanella Netto
2023-11-22 12:23       ` Siddhesh Poyarekar
2023-11-22 13:03         ` Adhemerval Zanella Netto
2023-11-22 13:24           ` Siddhesh Poyarekar
2023-11-22 14:13             ` Adhemerval Zanella Netto
2023-11-06 20:25 ` Adhemerval Zanella [this message]
2023-11-20 22:47   ` [PATCH v3 12/19] elf: Ignore LD_PROFILE for setuid binaries Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 13/19] elf: Remove LD_PROFILE for static binaries Adhemerval Zanella
2023-11-20 22:55   ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 14/19] elf: Ignore loader debug env vars for setuid Adhemerval Zanella
2023-11-20 22:57   ` Siddhesh Poyarekar
2023-11-21 18:24     ` Adhemerval Zanella Netto
2023-11-06 20:25 ` [PATCH v3 15/19] elf: Remove any_debug from dl_main_state Adhemerval Zanella
2023-11-20 22:58   ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 16/19] elf: Ignore LD_LIBRARY_PATH and debug env var for setuid for static Adhemerval Zanella
2023-11-20 22:59   ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 17/19] elf: Add comments on how LD_AUDIT and LD_PRELOAD handle __libc_enable_secure Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 18/19] elf: Ignore LD_BIND_NOW and LD_BIND_NOT for setuid binaries Adhemerval Zanella
2023-11-20 23:02   ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 19/19] elf: Refactor process_envvars Adhemerval Zanella
2023-11-20 23:09   ` Siddhesh Poyarekar
2023-11-21 19:00     ` Adhemerval Zanella Netto
2023-11-20 23:12 ` [PATCH v3 00/19] Improve loader environment variable handling Siddhesh Poyarekar
2023-11-21 19:37   ` Adhemerval Zanella Netto

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