Split 'flush_old_exec' into two functions

commit 221af7f87b97431e3ee21ce4b0e77d5411cf1549 upstream.

'flush_old_exec()' is the point of no return when doing an execve(), and
it is pretty badly misnamed.  It doesn't just flush the old executable
environment, it also starts up the new one.

Which is very inconvenient for things like setting up the new
personality, because we want the new personality to affect the starting
of the new environment, but at the same time we do _not_ want the new
personality to take effect if flushing the old one fails.

As a result, the x86-64 '32-bit' personality is actually done using this
insane "I'm going to change the ABI, but I haven't done it yet" bit
(TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the
personality, but just the "pending" bit, so that "flush_thread()" can do
the actual personality magic.

This patch in no way changes any of that insanity, but it does split the
'flush_old_exec()' function up into a preparatory part that can fail
(still called flush_old_exec()), and a new part that will actually set
up the new exec environment (setup_new_exec()).  All callers are changed
to trivially comply with the new world order.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index 24de74214940c6dc18d96604b71531917820e0be..54a5abf123f37ff3320d3e61a303a7d610dc2e6a 100644 (file)
--- a/arch/sh/kernel/process_64.c
+++ b/arch/sh/kernel/process_64.c
@@ -367,7 +367,7 @@ void exit_thread(void)
 void flush_thread(void)
 {
 
-       /* Called by fs/exec.c (flush_old_exec) to remove traces of a
+       /* Called by fs/exec.c (setup_new_exec) to remove traces of a
         * previously running executable. */
 #ifdef CONFIG_SH_FPU
        if (last_task_used_math == current) {

diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index 652e80ffbf456e95c25e55c4bf8ae2fdd0175b36..a59b0946c432993be49f0647c78a032c4e913974 100644 (file)
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -308,15 +308,17 @@ static int load_aout_binary(struct linux_binprm *bprm, struct pt_regs *regs)
        if (retval)
                return retval;
 
-       regs->cs = __USER32_CS;
-       regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
-               regs->r13 = regs->r14 = regs->r15 = 0;
-
        /* OK, This is the point of no return */
        set_personality(PER_LINUX);
        set_thread_flag(TIF_IA32);
        clear_thread_flag(TIF_ABI_PENDING);
 
+       setup_new_exec(bprm);
+
+       regs->cs = __USER32_CS;
+       regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
+               regs->r13 = regs->r14 = regs->r15 = 0;
+
        current->mm->end_code = ex.a_text +
                (current->mm->start_code = N_TXTADDR(ex));
        current->mm->end_data = ex.a_data +

diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index b639dcf7c778cfc6f81eca964c8c6748a5840949..0133b5a30413a6ae95db005d41e7d3fb9a24dbcd 100644 (file)
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -263,6 +263,7 @@ static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 #else
        set_personality(PER_LINUX);
 #endif
+       setup_new_exec(bprm);
 
        current->mm->end_code = ex.a_text +
                (current->mm->start_code = N_TXTADDR(ex));

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 7c1e65d54872bfea6611743a8ea7636c9dca2949..e9b214a1dfc8b7e2b29aebb7489306be3ec3d02e 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -662,27 +662,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                        if (elf_interpreter[elf_ppnt->p_filesz - 1] != '\0')
                                goto out_free_interp;
 
-                       /*
-                        * The early SET_PERSONALITY here is so that the lookup
-                        * for the interpreter happens in the namespace of the 
-                        * to-be-execed image.  SET_PERSONALITY can select an
-                        * alternate root.
-                        *
-                        * However, SET_PERSONALITY is NOT allowed to switch
-                        * this task into the new images's memory mapping
-                        * policy - that is, TASK_SIZE must still evaluate to
-                        * that which is appropriate to the execing application.
-                        * This is because exit_mmap() needs to have TASK_SIZE
-                        * evaluate to the size of the old image.
-                        *
-                        * So if (say) a 64-bit application is execing a 32-bit
-                        * application it is the architecture's responsibility
-                        * to defer changing the value of TASK_SIZE until the
-                        * switch really is going to happen - do this in
-                        * flush_thread().      - akpm
-                        */
-                       SET_PERSONALITY(loc->elf_ex);
-
                        interpreter = open_exec(elf_interpreter);
                        retval = PTR_ERR(interpreter);
                        if (IS_ERR(interpreter))
@@ -730,9 +709,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                /* Verify the interpreter has a valid arch */
                if (!elf_check_arch(&loc->interp_elf_ex))
                        goto out_free_dentry;
-       } else {
-               /* Executables without an interpreter also need a personality  */
-               SET_PERSONALITY(loc->elf_ex);
        }
 
        /* Flush all traces of the currently running executable */
@@ -752,7 +728,8 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 
        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
                current->flags |= PF_RANDOMIZE;
-       arch_pick_mmap_layout(current->mm);
+
+       setup_new_exec(bprm);
 
        /* Do this so that we can load the interpreter, if need be.  We will
           change some of these later */

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 20fbeced472b82c8653e963bc8fe2bb2455c0023..9fdbda9278756286467ff8451763bdf767801a5e 100644 (file)
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -313,6 +313,9 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
         * defunct, deceased, etc. after this point we have to exit via
         * error_kill */
        set_personality(PER_LINUX_FDPIC);
+
+       setup_new_exec(bprm);
+
        set_binfmt(&elf_fdpic_format);
 
        current->mm->start_code = 0;

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index e92f229e3c6e9d994d61f5581625c35c2bde6bd7..4510022659c59adf8fb8faefafc0157b7789a9c2 100644 (file)
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -521,6 +521,7 @@ static int load_flat_file(struct linux_binprm * bprm,
 
                /* OK, This is the point of no return */
                set_personality(PER_LINUX_32BIT);
+               setup_new_exec(bprm);
        }
 
        /*

diff --git a/fs/binfmt_som.c b/fs/binfmt_som.c
index eff74b9c9e77cf8f0b933adb2addcc9aac899a46..35cf0023ddb823060326902eb2c23d7f0ecaa7e1 100644 (file)
--- a/fs/binfmt_som.c
+++ b/fs/binfmt_som.c
@@ -227,6 +227,7 @@ load_som_binary(struct linux_binprm * bprm, struct pt_regs * regs)
        /* OK, This is the point of no return */
        current->flags &= ~PF_FORKNOEXEC;
        current->personality = PER_HPUX;
+       setup_new_exec(bprm);
 
        /* Set the task size for HP-UX processes such that
         * the gateway page is outside the address space.

diff --git a/fs/exec.c b/fs/exec.c
index 172ceb6edde4df6ff8520cd9951b3bc2ca86b2c2..b7ce707b922d2ae184250ca4a8d33eb1424f77c2 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -928,9 +928,7 @@ void set_task_comm(struct task_struct *tsk, char *buf)
 
 int flush_old_exec(struct linux_binprm * bprm)
 {
-       char * name;
-       int i, ch, retval;
-       char tcomm[sizeof(current->comm)];
+       int retval;
 
        /*
         * Make sure we have a private signal table and that
@@ -950,6 +948,20 @@ int flush_old_exec(struct linux_binprm * bprm)
                goto out;
 
        bprm->mm = NULL;                /* We're using it now */
+       return 0;
+
+out:
+       return retval;
+}
+EXPORT_SYMBOL(flush_old_exec);
+
+void setup_new_exec(struct linux_binprm * bprm)
+{
+       int i, ch;
+       char * name;
+       char tcomm[sizeof(current->comm)];
+
+       arch_pick_mmap_layout(current->mm);
 
        /* This is the point of no return */
        current->sas_ss_sp = current->sas_ss_size = 0;
@@ -1006,14 +1018,8 @@ int flush_old_exec(struct linux_binprm * bprm)
                        
        flush_signal_handlers(current, 0);
        flush_old_files(current->files);
-
-       return 0;
-
-out:
-       return retval;
 }
-
-EXPORT_SYMBOL(flush_old_exec);
+EXPORT_SYMBOL(setup_new_exec);
 
 /*
  * Prepare credentials and lock ->cred_guard_mutex.

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 2046b5b8af48ae094d0182b143450b5459b67b30..f1da7e4549a0a90b18ee61157ce4eeb4d879d0c5 100644 (file)
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -101,6 +101,7 @@ extern int prepare_binprm(struct linux_binprm *);
 extern int __must_check remove_arg_zero(struct linux_binprm *);
 extern int search_binary_handler(struct linux_binprm *,struct pt_regs *);
 extern int flush_old_exec(struct linux_binprm * bprm);
+extern void setup_new_exec(struct linux_binprm * bprm);
 
 extern int suid_dumpable;
 #define SUID_DUMP_DISABLE      0       /* No setuid dumping */

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 338733b03c8fd0691e98b84d6da817c33abb2ca1..1e174cacf3e5b26456b2a05b9e26be7ce69f17ea 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1296,7 +1296,7 @@ struct task_struct {
        char comm[TASK_COMM_LEN]; /* executable name excluding path
                                     - access with [gs]et_task_comm (which lock
                                       it with task_lock())
-                                    - initialized normally by flush_old_exec */
+                                    - initialized normally by setup_new_exec */
 /* file system info */
        int link_count, total_link_count;
 #ifdef CONFIG_SYSVIPC