Split 'flush_old_exec' into two functions

'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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index 31f80c61b031ad5ada25630e17c71a543c9fc59a..ec79faf6f0216153897a4e664044e214c5a4c8b2 100644 (file)
--- a/arch/sh/kernel/process_64.c
+++ b/arch/sh/kernel/process_64.c
@@ -368,7 +368,7 @@ 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 346b69405363b7419d7d4b591b240074d72bff6b..fdd3970991722d9ff70306cb6a6635c832c11ea8 100644 (file)
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -264,6 +264,7 @@ 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 edd90c49003cff3b2fdf62ecb0e406007369eedb..fd5b2ea5d2993bbafa4b370fee3aba3f172577c0 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 c57d9ce5ff7ef85605786fc26200b3fe76df93df..18d77297ccc8ae470a12078d496e7519e443d012 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 d4a00ea1054c63f0401bb0b1ef0e78a245df8851..42c6b4a54445620856c1e0ab7814bf7f763dba9c 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 2a9b5330cc5e9ada9c23f41c6007996f58b6b938..cc8560f6c9b06f93aea947744c737b62c19c1eb3 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 632b02e34ec72b17564602f9c944996e4889a9cf..675c3f44c2ea22bae6fe3b649eabf1dff72cf0df 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -941,9 +941,7 @@ 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
@@ -963,6 +961,20 @@ 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;
@@ -1019,14 +1031,8 @@ 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 cd4349bdc34efd2b5044eb8f83e0e4f98e211817..89c6249fc561a0eaf38f5d01e850f70d52726dd5 100644 (file)
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -109,6 +109,7 @@ 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 6f7bba93929bf5c55434b6fb196af320087e9c11..abdfacc58653e976b58af1cbe2b5d60821f0b931 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1369,7 +1369,7 @@ 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