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>

diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index 1192398ef582ad9e0b4fe7b5d41bdc61b76c4ca1..44aa119df783351f76e004c679e0e5122cd682de 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 2a4d073d2cf12124830ddcd2879485c5f61629b0..435d2a5323daf466b208b00ff22955f09873ebe7 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 b9b3bb51b1e485ff0caa0b7555d468804b552b9a..1ed37ba72343f2f62990a32cd95e586d8c0b02a9 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 456cfcf7da0db051958d5a47f5e2c7ff80891897..e7a0bb47252c75dc50c437c3bdd5ca69ed73cdb2 100644 (file)
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -321,6 +321,9 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
        set_personality(PER_LINUX_FDPIC);
        if (elf_read_implies_exec(&exec_params.hdr, executable_stack))
                current->personality |= READ_IMPLIES_EXEC;
+
+       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 a2796651e75690eb8e8a875146be852bfb1d637b..ca88c4687b840747e5a97d01dd680f0ae765639b 100644 (file)
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -519,6 +519,7 @@ 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 ba112bd4a339c93995b66bd639175a37c95a084b..b2ad94e25da70957806127d96549855234b1063e 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -931,9 +931,7 @@ 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
@@ -953,6 +951,20 @@ 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;
@@ -1009,14 +1021,8 @@ 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 aece486ac7349b8463ace95585b2fa9379a04ab3..340f441fbdfe25f178502d1f13ecd4687ec75119 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 0f67914a43c9137f37d925a298750f0dd4647e85..d3dce7db81d6dfa71321d403a48f3febd34cb337 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1354,7 +1354,7 @@ 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