From 34497c50a8497148e3b0232659f58ffaf4931b06 Mon Sep 17 00:00:00 2001
From: liujian <liujianliu.liu@huawei.com>
Date: Mon, 31 May 2021 21:46:41 +0800
Subject: [PATCH] bash-2.05a-interpreter

---
 config.h.in   |   6 +++
 configure.ac  |   2 +-
 execute_cmd.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+), 1 deletion(-)

diff --git a/config.h.in b/config.h.in
index ab316d4..11d1d68 100644
--- a/config.h.in
+++ b/config.h.in
@@ -775,6 +775,9 @@
 /* Define if you have the pselect function.  */
 #undef HAVE_PSELECT
 
+/* Define if you have the pread function. */
+#undef HAVE_PREAD
+
 /* Define if you have the putenv function.  */
 #undef HAVE_PUTENV
 
@@ -981,6 +984,9 @@
 /* Define if you have the <dlfcn.h> header file.  */
 #undef HAVE_DLFCN_H
 
+/* Define if you have the <elf.h> header file.  */
+#undef HAVE_ELF_H
+
 /* Define if you have the <grp.h> header file.  */
 #undef HAVE_GRP_H
 
diff --git a/configure.ac b/configure.ac
index 2fe3e7d..f1b7f1b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -827,7 +827,7 @@ dnl checks for system calls
 AC_CHECK_FUNCS(dup2 eaccess fcntl getdtablesize getentropy getgroups \
 		gethostname getpagesize getpeername getrandom getrlimit \
 		getrusage gettimeofday kill killpg lstat pselect readlink \
-		select setdtablesize setitimer tcgetpgrp uname ulimit waitpid)
+		select setdtablesize setitimer tcgetpgrp uname ulimit waitpid pread)
 AC_REPLACE_FUNCS(rename)
 
 dnl checks for c library functions
diff --git a/execute_cmd.c b/execute_cmd.c
index d2a0dd7..374843d 100644
--- a/execute_cmd.c
+++ b/execute_cmd.c
@@ -41,6 +41,10 @@
 #  include <unistd.h>
 #endif
 
+#ifdef HAVE_ELF_H
+# include <elf.h>
+#endif
+
 #include "posixtime.h"
 
 #if defined (HAVE_SYS_RESOURCE_H) && !defined (RLIMTYPE)
@@ -5832,6 +5836,14 @@ shell_execve (command, args, env)
 	{
 	  /* The file has the execute bits set, but the kernel refuses to
 	     run it for some reason.  See why. */
+#if defined (HAVE_HASH_BANG_EXEC) || defined (HAVE_ELF_H)
+	int fd = open (command, O_RDONLY);
+
+	if (fd >= 0)
+		sample_len = read (fd, sample, sizeof (sample));
+	else
+		sample_len = -1;
+#endif
 #if defined (HAVE_HASH_BANG_EXEC)
 	  READ_SAMPLE_BUF (command, sample, sample_len);
 	  if (sample_len > 0)
@@ -5841,6 +5853,7 @@ shell_execve (command, args, env)
 	      char *interp;
 	      int ilen;
 
+	      close (fd);
 	      interp = getinterp (sample, sample_len, (int *)NULL);
 	      ilen = strlen (interp);
 	      errno = i;
@@ -5856,6 +5869,137 @@ shell_execve (command, args, env)
 	      return (EX_NOEXEC);
 	    }
 #endif
+#if defined (HAVE_ELF_H)
+	  if (i == ENOENT
+	      && sample_len > EI_NIDENT
+	      && memcmp (sample, ELFMAG, SELFMAG) == 0)
+	    {
+	      off_t offset = -1;
+
+	      /* It is an ELF file.  Now determine whether it is dynamically
+		 linked and if yes, get the offset of the interpreter
+		 string.  */
+	      if (sample[EI_CLASS] == ELFCLASS32
+		  && sample_len > sizeof (Elf32_Ehdr))
+		{
+		  Elf32_Ehdr ehdr;
+		  Elf32_Phdr *phdr;
+		  int nphdr;
+
+		  /* We have to copy the data since the sample buffer
+		     might not be aligned correctly to be accessed as
+		     an Elf32_Ehdr struct.  */
+		  memcpy (&ehdr, sample, sizeof (Elf32_Ehdr));
+
+		  nphdr = ehdr.e_phnum;
+		  phdr = (Elf32_Phdr *) malloc (nphdr * ehdr.e_phentsize);
+		  if (phdr != NULL)
+		    {
+#ifdef HAVE_PREAD
+		      sample_len = pread (fd, phdr, nphdr * ehdr.e_phentsize,
+					  ehdr.e_phoff);
+#else
+		      if (lseek (fd, ehdr.e_phoff, SEEK_SET) != -1)
+			sample_len = read (fd, phdr,
+					   nphdr * ehdr.e_phentsize);
+		      else
+			sample_len = -1;
+#endif
+		      if (sample_len == nphdr * ehdr.e_phentsize)
+			while (nphdr-- > 0)
+			  if (phdr[nphdr].p_type == PT_INTERP)
+			    {
+			      offset = phdr[nphdr].p_offset;
+			      break;
+			    }
+		      free (phdr);
+		    }
+		}
+	      else if (sample[EI_CLASS] == ELFCLASS64
+		       && sample_len > sizeof (Elf64_Ehdr))
+		{
+		  Elf64_Ehdr ehdr;
+		  Elf64_Phdr *phdr;
+		  int nphdr;
+
+		  /* We have to copy the data since the sample buffer
+		     might not be aligned correctly to be accessed as
+		     an Elf64_Ehdr struct.  */
+		  memcpy (&ehdr, sample, sizeof (Elf64_Ehdr));
+
+		  nphdr = ehdr.e_phnum;
+		  phdr = (Elf64_Phdr *) malloc (nphdr * ehdr.e_phentsize);
+		  if (phdr != NULL)
+		    {
+#ifdef HAVE_PREAD
+		      sample_len = pread (fd, phdr, nphdr * ehdr.e_phentsize,
+					  ehdr.e_phoff);
+#else
+		      if (lseek (fd, ehdr.e_phoff, SEEK_SET) != -1)
+			sample_len = read (fd, phdr,
+					   nphdr * ehdr.e_phentsize);
+		      else
+			sample_len = -1;
+#endif
+		      if (sample_len == nphdr * ehdr.e_phentsize)
+			while (nphdr-- > 0)
+			  if (phdr[nphdr].p_type == PT_INTERP)
+			    {
+			      offset = phdr[nphdr].p_offset;
+			      break;
+			    }
+		      free (phdr);
+		    }
+		}
+
+	      if (offset != -1)
+		{
+		  size_t maxlen = 0;
+		  size_t actlen = 0;
+		  char *interp = NULL;
+
+		  do
+		    {
+		      if (actlen == maxlen)
+			{
+			  char *newinterp = realloc (interp, maxlen += 200);
+			  if (newinterp == NULL)
+			    {
+			      actlen = 0;
+			      break;
+			    }
+			  interp = newinterp;
+
+#ifdef HAVE_PREAD
+			  actlen = pread (fd, interp, maxlen, offset);
+#else
+			  if (lseek (fd, offset, SEEK_SET) != -1)
+			    actlen = read (fd, interp, maxlen);
+			  else
+			    actlen = -1;
+#endif
+			}
+		    }
+		  while (actlen > 0 && memchr (interp, '\0', actlen) == NULL);
+
+		  if (actlen > 0)
+		    {
+		      close (fd);
+		      errno = i;
+		      sys_error ("%s: %s: bad ELF interpreter", command,
+				 interp);
+		      free (interp);
+		      return (EX_NOEXEC);
+		    }
+
+		  free (interp);
+		}
+	    }
+#endif
+#if defined (HAVE_HASH_BANG_EXEC) || defined (HAVE_ELF_H)
+	  close (fd);
+#endif
+
 	  errno = i;
 	  file_error (command);
 	}
-- 
2.23.0