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authorEric Andersen <andersen@codepoet.org>2004-01-02 23:34:13 +0000
committerEric Andersen <andersen@codepoet.org>2004-01-02 23:34:13 +0000
commitfb84603f8c45fdafdaa750490785fc1b15541386 (patch)
tree257c50f56dfb4d90e775b83a915ae21d9f39bb04 /libc/sysdeps
parentcadff3f10e8f20f8db0e2878abf90fb16eba797a (diff)
Peter S. Mazinger writes:
Hello Erik! I have made some cosmetical changes to the files, removed the added SCRT=-fPIC option from building the crt0.S file (but it is a requirement to build them with -fPIC), and changed some comments. I have left the ldso.c patch with PIE_SUPPORT ifdefs, but consider applying it w/o them (see some earlier comment from PaX Team on this issue, as it is considered a bug). To have it work correctly, you'll also need removing COMPLETELY_PIC. One thing is missing: PIE_SUPPORT should be usable only for i386 (for now). Also added the support for propolice protection (that works for me and catches memcpy/strcpy attacks (but needs a special gcc version). Thanks, Peter
Diffstat (limited to 'libc/sysdeps')
-rw-r--r--libc/sysdeps/linux/common/Makefile3
-rw-r--r--libc/sysdeps/linux/common/ssp.c97
-rw-r--r--libc/sysdeps/linux/i386/Makefile10
-rw-r--r--libc/sysdeps/linux/i386/crt0.S25
4 files changed, 133 insertions, 2 deletions
diff --git a/libc/sysdeps/linux/common/Makefile b/libc/sysdeps/linux/common/Makefile
index cfd95300f..5b5034095 100644
--- a/libc/sysdeps/linux/common/Makefile
+++ b/libc/sysdeps/linux/common/Makefile
@@ -33,6 +33,9 @@ endif
ifeq ($(strip $(UCLIBC_PROFILING)),y)
CSRC+=gmon.c
endif
+ifeq ($(strip $(UCLIBC_PROPOLICE)),y)
+CSRC+=ssp.c
+endif
COBJS=$(patsubst %.c,%.o, $(CSRC))
MSRC=syscalls.c
diff --git a/libc/sysdeps/linux/common/ssp.c b/libc/sysdeps/linux/common/ssp.c
new file mode 100644
index 000000000..135892c37
--- /dev/null
+++ b/libc/sysdeps/linux/common/ssp.c
@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#ifdef _POSIX_SOURCE
+#include <signal.h>
+#endif
+
+#if defined(HAVE_SYSLOG)
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#include <sys/syslog.h>
+#ifndef _PATH_LOG
+#define _PATH_LOG "/dev/log"
+#endif
+#endif
+
+long __guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
+
+void __guard_setup (void)
+{
+ int fd;
+ if (__guard[0]!=0) return;
+ fd = open ("/dev/urandom", 0);
+ if (fd != -1) {
+ ssize_t size = read (fd, (char*)&__guard, sizeof(__guard));
+ close (fd) ;
+ if (size == sizeof(__guard)) return;
+ }
+ /* If a random generator can't be used, the protector switches the guard
+ to the "terminator canary" */
+ ((char*)__guard)[0] = 0; ((char*)__guard)[1] = 0;
+ ((char*)__guard)[2] = '\n'; ((char*)__guard)[3] = 255;
+}
+
+void __stack_smash_handler (char func[], int damaged)
+{
+#if defined (__GNU_LIBRARY__)
+ extern char * __progname;
+#endif
+ const char message[] = ": stack smashing attack in function ";
+ int bufsz = 512, len;
+ char buf[bufsz];
+#if defined(HAVE_SYSLOG)
+ int LogFile;
+ struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */
+#endif
+#ifdef _POSIX_SOURCE
+ {
+ sigset_t mask;
+ sigfillset(&mask);
+ sigdelset(&mask, SIGABRT); /* Block all signal handlers */
+ sigprocmask(SIG_BLOCK, &mask, NULL); /* except SIGABRT */
+ }
+#endif
+
+ strcpy(buf, "<2>"); len=3; /* send LOG_CRIT */
+#if defined (__GNU_LIBRARY__)
+ strncat(buf, __progname, bufsz-len-1); len = strlen(buf);
+#endif
+ if (bufsz>len) {strncat(buf, message, bufsz-len-1); len = strlen(buf);}
+ if (bufsz>len) {strncat(buf, func, bufsz-len-1); len = strlen(buf);}
+ /* print error message */
+ write (STDERR_FILENO, buf+3, len-3);
+#if defined(HAVE_SYSLOG)
+ if ((LogFile = socket(AF_UNIX, SOCK_DGRAM, 0)) != -1) {
+
+ /*
+ * Send "found" message to the "/dev/log" path
+ */
+ SyslogAddr.sun_family = AF_UNIX;
+ (void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
+ sizeof(SyslogAddr.sun_path) - 1);
+ SyslogAddr.sun_path[sizeof(SyslogAddr.sun_path) - 1] = '\0';
+ sendto(LogFile, buf, len, 0, (struct sockaddr *)&SyslogAddr,
+ sizeof(SyslogAddr));
+ }
+#endif
+
+#ifdef _POSIX_SOURCE
+ { /* Make sure the default handler is associated with SIGABRT */
+ struct sigaction sa;
+
+ memset(&sa, 0, sizeof(struct sigaction));
+ sigfillset(&sa.sa_mask); /* Block all signals */
+ sa.sa_flags = 0;
+ sa.sa_handler = SIG_DFL;
+ sigaction(SIGABRT, &sa, NULL);
+ (void)kill(getpid(), SIGABRT);
+ }
+#endif
+ _exit(127);
+}
+
diff --git a/libc/sysdeps/linux/i386/Makefile b/libc/sysdeps/linux/i386/Makefile
index 9ba60f59e..c7f88b681 100644
--- a/libc/sysdeps/linux/i386/Makefile
+++ b/libc/sysdeps/linux/i386/Makefile
@@ -22,6 +22,9 @@ ASFLAGS=$(CFLAGS)
CRT0_SRC = crt0.S
CRT0_OBJ = crt0.o crt1.o gcrt1.o
+ifeq ($(strip $(UCLIBC_PIE_SUPPORT)),y)
+CRT0_OBJ += Scrt0.o Scrt1.o
+endif
CRT0_DEPS=gmon-start.S
CTOR_TARGETS=$(TOPDIR)lib/crti.o $(TOPDIR)lib/crtn.o
@@ -44,6 +47,13 @@ $(LIBC): ar-target
ar-target: $(OBJS) $(CRT0_OBJ) $(CTOR_TARGETS)
$(AR) $(ARFLAGS) $(LIBC) $(OBJS)
cp $(CRT0_OBJ) $(TOPDIR)lib/
+ifeq ($(strip $(UCLIBC_PIE_SUPPORT)),y)
+ifeq ($(strip $(UCLIBC_CTOR_DTOR)),y)
+ $(RM) $(TOPDIR)lib/Scrt0.o
+else
+ mv $(TOPDIR)lib/Scrt0.o $(TOPDIR)lib/Scrt1.o
+endif
+endif
$(CRT0_OBJ): $(CRT0_SRC)
$(CC) $(CFLAGS) -DL_$* $< -c -o $*.o
diff --git a/libc/sysdeps/linux/i386/crt0.S b/libc/sysdeps/linux/i386/crt0.S
index a488d6508..e7df6992b 100644
--- a/libc/sysdeps/linux/i386/crt0.S
+++ b/libc/sysdeps/linux/i386/crt0.S
@@ -18,6 +18,7 @@ Cambridge, MA 02139, USA. */
/* Based on the code from GNU libc, but hacked up by John Beppu and Erik Andersen */
+/* adapted by PaX Team for ET_DYN/PIE binaries */
/*
When we enter this piece of code, the program stack looks like this:
@@ -37,7 +38,7 @@ Cambridge, MA 02139, USA. */
.global _start
.type _start,%function
-#if defined L_crt0 || ! defined __UCLIBC_CTOR_DTOR__
+#if defined L_crt0 || defined L_Scrt0 || ! defined __UCLIBC_CTOR_DTOR__
.type __uClibc_main,%function
#else
.weak _init
@@ -74,10 +75,22 @@ _start:
pushl %ebp /* callers %ebp (frame pointer) */
movl %esp,%ebp /* mark callers stack frame as invalid */
-#if (defined L_crt1 || defined L_gcrt1 ) && defined __UCLIBC_CTOR_DTOR__
+#if defined L_Scrt0 || defined L_Scrt1
+ call .L0
+.L0:
+ pop %edx
+ addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%edx
+#endif
+
+#if (defined L_crt1 || defined L_Scrt1 || defined L_gcrt1 ) && defined __UCLIBC_CTOR_DTOR__
/* Push .init and .fini arguments to __uClibc_start_main() on the stack */
+#ifdef L_Scrt1
+ pushl _fini@GOT(%edx)
+ pushl _init@GOT(%edx)
+#else
pushl $_fini
pushl $_init
+#endif
/* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */
pushl %eax /* Environment pointer */
@@ -85,15 +98,23 @@ _start:
pushl %ecx /* And the argument count */
/* Ok, now run uClibc's main() -- shouldn't return */
+#ifdef L_Scrt1
+ call *__uClibc_start_main@GOT(%edx)
+#else
call __uClibc_start_main
+#endif
#else
/* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */
pushl %eax /* Environment pointer */
pushl %ebx /* Argument pointer */
pushl %ecx /* And the argument count */
+#ifdef L_Scrt0
+ call *__uClibc_main@GOT(%edx)
+#else
call __uClibc_main
#endif
+#endif
/* Crash if somehow `exit' returns anyways. */
hlt