Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f23513e8d96cf5e6cf8d2ff0cb5dd6bbc33995e4
Commit:     f23513e8d96cf5e6cf8d2ff0cb5dd6bbc33995e4
Parent:     4a2d44590a603be292addce9c263982043416666
Author:     Ulrich Drepper <[EMAIL PROTECTED]>
AuthorDate: Sun Jul 15 23:40:32 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Jul 16 09:05:45 2007 -0700

    Introduce O_CLOEXEC
    
    The problem is as follows: in multi-threaded code (or more correctly: all
    code using clone() with CLONE_FILES) we have a race when exec'ing.
    
       thread #1                       thread #2
    
       fd=open()
    
                                       fork + exec
    
      fcntl(fd,F_SETFD,FD_CLOEXEC)
    
    In some applications this can happen frequently.  Take a web browser.  One
    thread opens a file and another thread starts, say, an external PDF viewer.
     The result can even be a security issue if that open file descriptor
    refers to a sensitive file and the external program can somehow be tricked
    into using that descriptor.
    
    Just adding O_CLOEXEC support to open() doesn't solve the whole set of
    problems.  There are other ways to create file descriptors (socket,
    epoll_create, Unix domain socket transfer, etc).  These can and should be
    addressed separately though.  open() is such an easy case that it makes not
    much sense putting the fix off.
    
    The test program:
    
    #include <errno.h>
    #include <fcntl.h>
    #include <stdio.h>
    #include <unistd.h>
    
    #ifndef O_CLOEXEC
    # define O_CLOEXEC 02000000
    #endif
    
    int
    main (int argc, char *argv[])
    {
      int fd;
      if (argc > 1)
        {
          fd = atol (argv[1]);
          printf ("child: fd = %d\n", fd);
          if (fcntl (fd, F_GETFD) == 0 || errno != EBADF)
            {
              puts ("file descriptor valid in child");
              return 1;
            }
          return 0;
        }
    
      fd = open ("/proc/self/exe", O_RDONLY | O_CLOEXEC);
      printf ("in parent: new fd = %d\n", fd);
      char buf[20];
      snprintf (buf, sizeof (buf), "%d", fd);
      execl ("/proc/self/exe", argv[0], buf, NULL);
      puts ("execl failed");
      return 1;
    }
    
    [EMAIL PROTECTED]: parisc fix]
    Signed-off-by: Ulrich Drepper <[EMAIL PROTECTED]>
    Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
    Cc: Davide Libenzi <[EMAIL PROTECTED]>
    Cc: Michael Kerrisk <[EMAIL PROTECTED]>
    Cc: Chris Zankel <[EMAIL PROTECTED]>
    Signed-off-by: Kyle McMartin <[EMAIL PROTECTED]>
    Acked-by: David S. Miller <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 fs/open.c                   |   14 +++++++++++---
 include/asm-generic/fcntl.h |    3 +++
 include/asm-parisc/fcntl.h  |   29 +++++++++++++++--------------
 3 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 0d515d1..e6991c1 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -855,7 +855,7 @@ EXPORT_SYMBOL(dentry_open);
 /*
  * Find an empty file descriptor entry, and mark it busy.
  */
-int get_unused_fd(void)
+static int get_unused_fd_flags(int flags)
 {
        struct files_struct * files = current->files;
        int fd, error;
@@ -891,7 +891,10 @@ repeat:
        }
 
        FD_SET(fd, fdt->open_fds);
-       FD_CLR(fd, fdt->close_on_exec);
+       if (flags & O_CLOEXEC)
+               FD_SET(fd, fdt->close_on_exec);
+       else
+               FD_CLR(fd, fdt->close_on_exec);
        files->next_fd = fd + 1;
 #if 1
        /* Sanity check */
@@ -907,6 +910,11 @@ out:
        return error;
 }
 
+int get_unused_fd(void)
+{
+       return get_unused_fd_flags(0);
+}
+
 EXPORT_SYMBOL(get_unused_fd);
 
 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
@@ -959,7 +967,7 @@ long do_sys_open(int dfd, const char __user *filename, int 
flags, int mode)
        int fd = PTR_ERR(tmp);
 
        if (!IS_ERR(tmp)) {
-               fd = get_unused_fd();
+               fd = get_unused_fd_flags(flags);
                if (fd >= 0) {
                        struct file *f = do_filp_open(dfd, tmp, flags, mode);
                        if (IS_ERR(f)) {
diff --git a/include/asm-generic/fcntl.h b/include/asm-generic/fcntl.h
index c154b9d..b847741 100644
--- a/include/asm-generic/fcntl.h
+++ b/include/asm-generic/fcntl.h
@@ -48,6 +48,9 @@
 #ifndef O_NOATIME
 #define O_NOATIME      01000000
 #endif
+#ifndef O_CLOEXEC
+#define O_CLOEXEC      02000000        /* set close_on_exec */
+#endif
 #ifndef O_NDELAY
 #define O_NDELAY       O_NONBLOCK
 #endif
diff --git a/include/asm-parisc/fcntl.h b/include/asm-parisc/fcntl.h
index 317851f..1e1c824 100644
--- a/include/asm-parisc/fcntl.h
+++ b/include/asm-parisc/fcntl.h
@@ -3,21 +3,22 @@
 
 /* open/fcntl - O_SYNC is only implemented on blocks devices and on files
    located on an ext2 file system */
-#define O_APPEND       00000010
-#define O_BLKSEEK      00000100 /* HPUX only */
-#define O_CREAT                00000400 /* not fcntl */
-#define O_EXCL         00002000 /* not fcntl */
-#define O_LARGEFILE    00004000
-#define O_SYNC         00100000
-#define O_NONBLOCK     00200004 /* HPUX has separate NDELAY & NONBLOCK */
-#define O_NOCTTY       00400000 /* not fcntl */
-#define O_DSYNC                01000000 /* HPUX only */
-#define O_RSYNC                02000000 /* HPUX only */
-#define O_NOATIME      04000000
+#define O_APPEND       000000010
+#define O_BLKSEEK      000000100 /* HPUX only */
+#define O_CREAT                000000400 /* not fcntl */
+#define O_EXCL         000002000 /* not fcntl */
+#define O_LARGEFILE    000004000
+#define O_SYNC         000100000
+#define O_NONBLOCK     000200004 /* HPUX has separate NDELAY & NONBLOCK */
+#define O_NOCTTY       000400000 /* not fcntl */
+#define O_DSYNC                001000000 /* HPUX only */
+#define O_RSYNC                002000000 /* HPUX only */
+#define O_NOATIME      004000000
+#define O_CLOEXEC      010000000 /* set close_on_exec */
 
-#define O_DIRECTORY    00010000 /* must be a directory */
-#define O_NOFOLLOW     00000200 /* don't follow links */
-#define O_INVISIBLE    04000000 /* invisible I/O, for DMAPI/XDSM */
+#define O_DIRECTORY    000010000 /* must be a directory */
+#define O_NOFOLLOW     000000200 /* don't follow links */
+#define O_INVISIBLE    004000000 /* invisible I/O, for DMAPI/XDSM */
 
 #define F_GETLK64      8
 #define F_SETLK64      9
-
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