For b/13901604 (suid-root exe + unsecure environment variable => wrong __google_auxv...

diff --git a/README.google b/README.google
index 3ffd7d28e1a0bbdb14b1239703066f15e92e213a..775e6b81e8aeb302e6e0406c59a817d445d25ddc 100644 (file)
--- a/README.google
+++ b/README.google
@@ -366,3 +366,11 @@ stdio-common/tmpnam.c
   b/6115789
   TODO(ppluzhnikov): revert this after cleanup.
   (ppluzhnikov, google-local)
+
+csu/elf-init.c
+sysdeps/i386/start.S
+sysdeps/x86_64/start.S
+  For b/13901604, revert local changes to sysdeps/{i386,x86_64}/elf/start.S,
+  and initialize __google_auxv in __libc_csu_init instead.
+  (ppluzhnikov, google-local)
+

diff --git a/csu/elf-init.c b/csu/elf-init.c
index 4daf673e67cf771fa888a379799e20bcbf607596..d064d6969ea725a7e1dba3da94acd89437493c18 100644 (file)
--- a/csu/elf-init.c
+++ b/csu/elf-init.c
@@ -35,6 +35,8 @@
 
 #include <stddef.h>
 
+# include <link.h>  // For ElfW.
+
 
 /* These magic symbols are provided by the linker.  */
 extern void (*__preinit_array_start []) (int, char **, char **)
@@ -77,6 +79,18 @@ __libc_csu_init (int argc, char **argv, char **envp)
     for (i = 0; i < size; i++)
       (*__preinit_array_start [i]) (argc, argv, envp);
   }
+
+  extern ElfW(auxv_t) *__google_auxv;  /* Defined in dl-init.c  */
+  /* _dl_init() is never called for fully-static binary.
+     Initialize __google_auxv here.  */
+  if (__google_auxv == NULL)
+    {
+      char **e;
+
+      for (e = envp; *e; ++e) /* Skip.  */;
+      __google_auxv = (ElfW(auxv_t) *) ++e;
+    }
+
 #endif
 
 #ifndef NO_INITFINI

diff --git a/sysdeps/i386/start.S b/sysdeps/i386/start.S
index 2b8c671a6edfb57b7c0c71bdd1be0d6678ba9869..b79bff2dfcba6cdec8bb5cec415574b788613527 100644 (file)
--- a/sysdeps/i386/start.S
+++ b/sysdeps/i386/start.S
@@ -59,7 +59,6 @@ _start:
        /* Clear the frame pointer.  The ABI suggests this be done, to mark
           the outermost frame obviously.  */
        xorl %ebp, %ebp
-       call __google_init
 
        /* Extract the arguments as encoded on the stack and set up
           the arguments for `main': argc, argv.  envp will be determined
@@ -123,64 +122,6 @@ _start:
        ret
 #endif
 
-/*
-  %esp         The stack contains the arguments and environment:
-               0(%esp)                         ra
-               1*4(%esp)                       argc
-               2*4(%esp)                       argv[0]
-               ...
-               (argc+2)*4(%esp)                NULL
-               (argc+3)*4(%esp)                envp[0]
-               ...
-               (argc+2+env_count+1)*4(%esp)    NULL
-                (argc+2+env_count+2)*4(%esp)   auxv[0]
-               ...
-*/
-
-__google_init:
-#ifdef SHARED
-       call 1b
-       addl $_GLOBAL_OFFSET_TABLE_, %ebx
-       leal __google_argc@GOTOFF(%ebx), %ecx
-#else
-       leal __google_argc, %ecx
-#endif
-       movl 4(%esp), %eax
-       movl %eax, 0(%ecx)
-       push %esp
-       pop %eax
-       addl $2*4, %eax
-#ifdef SHARED
-       leal __google_argv@GOTOFF(%ebx), %ecx
-#else
-       leal __google_argv, %ecx
-#endif
-       movl %eax, 0(%ecx)
-/* The next loop could be omitted if we are to trust argc from the kernel.  */
-1:     cmpl $0, 0(%eax)  /* while(argv[i++] != 0) skip; */
-       je 2f
-       addl $4, %eax
-       jmp 1b
-2:     addl $4, %eax
-#ifdef SHARED
-       leal __google_envp@GOTOFF(%ebx), %ecx
-#else
-       leal __google_envp, %ecx
-#endif
-       movl %eax, 0(%ecx)
-3:     cmpl $0, 0(%eax)  /* while (envp[i++] != 0) skip; */
-       je 4f
-       addl $4, %eax
-       jmp 3b
-4:     addl $4, %eax
-#ifdef SHARED
-       leal __google_auxv@GOTOFF(%ebx), %ecx
-#else
-       leal __google_auxv, %ecx
-#endif
-       movl %eax, 0(%ecx)
-       ret
-
 /* To fulfill the System V/i386 ABI we need this symbol.  Yuck, it's so
    meaningless since we don't support machines < 80386.  */
        .section .rodata
@@ -196,14 +137,3 @@ __data_start:
        .long 0
        .weak data_start
        data_start = __data_start
-
-/* The {argc,argv,envp} variables are not exposed to keep the interface narrow
-   (we don't need anything except auxv right now). If/when they are needed,
-   simply mark them with ".globl".  */
-__google_argc: .long 0
-__google_argv: .long 0
-__google_envp: .long 0
-       .globl __google_auxv
-__google_auxv: .long 0
-
-

diff --git a/sysdeps/x86_64/start.S b/sysdeps/x86_64/start.S
index 09020cffe19a7ba89f7bd523b6a2d67852b3481c..e3d4ff8e20e0f451e074f7cb63066ec660b52a5e 100644 (file)
--- a/sysdeps/x86_64/start.S
+++ b/sysdeps/x86_64/start.S
@@ -65,7 +65,6 @@ _start:
        /* Clear the frame pointer.  The ABI suggests this be done, to mark
           the outermost frame obviously.  */
        xorl %ebp, %ebp
-       call __google_init
 
        /* Extract the arguments as encoded on the stack and set up
           the arguments for __libc_start_main (int (*main) (int, char **, char **),
@@ -126,46 +125,6 @@ _start:
        hlt                     /* Crash if somehow `exit' does return.  */
        cfi_endproc
 
-/*
-   %rsp                The stack contains the arguments and environment:
-               0(%rsp)                         ra
-               1*8(%rsp)                       argc
-               2*8(%rsp)                       argv[0]
-               ...
-               (argc+2)*8(%rsp)                NULL
-               (argc+3)*8(%rsp)                envp[0]
-               ...
-               (argc+2+env_count+1)*8(%rsp)    NULL
-                (argc+2+env_count+2)*8(%rsp)   auxv[0]
-               ...
-*/
-__google_init:
-       leaq __google_argc(%rip), %rbx  /* %rbx = &__google_argc  */
-       movq 8(%rsp), %rax
-       movq %rax, 0(%rbx)
-       push %rsp
-       pop %rax
-       addq $2*8, %rax
-       leaq __google_argv(%rip), %rbx
-       movq %rax, 0(%rbx)
-/* The next loop could be omitted if we are to trust argc from the kernel.  */
-1:     cmpq $0, 0(%rax)  /* while(argv[i++] != 0) skip; */
-       je 2f
-       addq $8, %rax
-       jmp 1b
-2:     addq $8, %rax
-       leaq __google_envp(%rip), %rbx
-       movq %rax, 0(%rbx)
-3:     cmpq $0, 0(%rax)  /* while (envp[i++] != 0) skip; */
-       je 4f
-       addq $8, %rax
-       jmp 3b
-4:     addq $8, %rax
-       leaq __google_auxv(%rip), %rbx
-       movq %rax, 0(%rbx)
-       ret
-
-
 /* Define a symbol for the first piece of initialized data.  */
        .data
        .globl __data_start
@@ -173,13 +132,3 @@ __data_start:
        .long 0
        .weak data_start
        data_start = __data_start
-
-       .p2align 3
-/* The {argc,argv,envp} variables are not exposed to keep the interface narrow
-   (we don't need anything except auxv right now). If/when they are needed,
-   simply mark them with ".globl".  */
-__google_argc: .quad 0
-__google_argv: .quad 0
-__google_envp: .quad 0
-       .globl __google_auxv
-__google_auxv: .quad 0