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![Neil Horman](/assets/img/avatar_default.png)
For some time /proc/sys/kernel/core_pattern has been able to set its output destination as a pipe, allowing a user space helper to receive and intellegently process a core. This infrastructure however has some shortcommings which can be enhanced. Specifically: 1) The coredump code in the kernel should ignore RLIMIT_CORE limitation when core_pattern is a pipe, since file system resources are not being consumed in this case, unless the user application wishes to save the core, at which point the app is restricted by usual file system limits and restrictions. 2) The core_pattern code should be able to parse and pass options to the user space helper as an argv array. The real core limit of the uid of the crashing proces should also be passable to the user space helper (since it is overridden to zero when called). 3) Some miscellaneous bugs need to be cleaned up (specifically the recognition of a recursive core dump, should the user mode helper itself crash. Also, the core dump code in the kernel should not wait for the user mode helper to exit, since the same context is responsible for writing to the pipe, and a read of the pipe by the user mode helper will result in a deadlock. This patch: Remove the check of RLIMIT_CORE if core_pattern is a pipe. In the event that core_pattern is a pipe, the entire core will be fed to the user mode helper. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Cc: <martin.pitt@ubuntu.com> Cc: <wwoods@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
321 lines
7.8 KiB
C
321 lines
7.8 KiB
C
/*
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* linux/fs/binfmt_som.c
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*
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* These are the functions used to load SOM format executables as used
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* by HP-UX.
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*
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* Copyright 1999 Matthew Wilcox <willy@bofh.ai>
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* based on binfmt_elf which is
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* Copyright 1993, 1994: Eric Youngdale (ericy@cais.com).
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/stat.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/errno.h>
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#include <linux/signal.h>
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#include <linux/binfmts.h>
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#include <linux/som.h>
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#include <linux/string.h>
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#include <linux/file.h>
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#include <linux/fcntl.h>
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#include <linux/ptrace.h>
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#include <linux/slab.h>
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#include <linux/shm.h>
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#include <linux/personality.h>
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#include <linux/init.h>
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#include <asm/a.out.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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#include <linux/elf.h>
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static int load_som_binary(struct linux_binprm * bprm, struct pt_regs * regs);
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static int load_som_library(struct file *);
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/*
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* If we don't support core dumping, then supply a NULL so we
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* don't even try.
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*/
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#if 0
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static int som_core_dump(long signr, struct pt_regs *regs, unsigned long limit);
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#else
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#define som_core_dump NULL
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#endif
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#define SOM_PAGESTART(_v) ((_v) & ~(unsigned long)(SOM_PAGESIZE-1))
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#define SOM_PAGEOFFSET(_v) ((_v) & (SOM_PAGESIZE-1))
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#define SOM_PAGEALIGN(_v) (((_v) + SOM_PAGESIZE - 1) & ~(SOM_PAGESIZE - 1))
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static struct linux_binfmt som_format = {
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.module = THIS_MODULE,
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.load_binary = load_som_binary,
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.load_shlib = load_som_library,
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.core_dump = som_core_dump,
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.min_coredump = SOM_PAGESIZE
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};
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/*
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* create_som_tables() parses the env- and arg-strings in new user
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* memory and creates the pointer tables from them, and puts their
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* addresses on the "stack", returning the new stack pointer value.
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*/
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static void create_som_tables(struct linux_binprm *bprm)
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{
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char **argv, **envp;
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int argc = bprm->argc;
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int envc = bprm->envc;
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unsigned long p;
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unsigned long *sp;
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/* Word-align the stack pointer */
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sp = (unsigned long *)((bprm->p + 3) & ~3);
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envp = (char **) sp;
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sp += envc + 1;
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argv = (char **) sp;
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sp += argc + 1;
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__put_user((unsigned long) envp,++sp);
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__put_user((unsigned long) argv,++sp);
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__put_user(argc, ++sp);
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bprm->p = (unsigned long) sp;
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p = current->mm->arg_start;
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while (argc-- > 0) {
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__put_user((char *)p,argv++);
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p += strlen_user((char *)p);
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}
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__put_user(NULL, argv);
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current->mm->arg_end = current->mm->env_start = p;
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while (envc-- > 0) {
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__put_user((char *)p,envp++);
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p += strlen_user((char *)p);
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}
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__put_user(NULL, envp);
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current->mm->env_end = p;
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}
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static int check_som_header(struct som_hdr *som_ex)
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{
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int *buf = (int *)som_ex;
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int i, ck;
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if (som_ex->system_id != SOM_SID_PARISC_1_0 &&
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som_ex->system_id != SOM_SID_PARISC_1_1 &&
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som_ex->system_id != SOM_SID_PARISC_2_0)
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return -ENOEXEC;
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if (som_ex->a_magic != SOM_EXEC_NONSHARE &&
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som_ex->a_magic != SOM_EXEC_SHARE &&
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som_ex->a_magic != SOM_EXEC_DEMAND)
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return -ENOEXEC;
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if (som_ex->version_id != SOM_ID_OLD &&
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som_ex->version_id != SOM_ID_NEW)
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return -ENOEXEC;
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ck = 0;
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for (i=0; i<32; i++)
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ck ^= buf[i];
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if (ck != 0)
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return -ENOEXEC;
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return 0;
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}
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static int map_som_binary(struct file *file,
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const struct som_exec_auxhdr *hpuxhdr)
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{
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unsigned long code_start, code_size, data_start, data_size;
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unsigned long bss_start, som_brk;
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int retval;
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int prot = PROT_READ | PROT_EXEC;
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int flags = MAP_FIXED|MAP_PRIVATE|MAP_DENYWRITE|MAP_EXECUTABLE;
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mm_segment_t old_fs = get_fs();
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set_fs(get_ds());
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code_start = SOM_PAGESTART(hpuxhdr->exec_tmem);
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code_size = SOM_PAGEALIGN(hpuxhdr->exec_tsize);
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current->mm->start_code = code_start;
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current->mm->end_code = code_start + code_size;
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down_write(¤t->mm->mmap_sem);
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retval = do_mmap(file, code_start, code_size, prot,
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flags, SOM_PAGESTART(hpuxhdr->exec_tfile));
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up_write(¤t->mm->mmap_sem);
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if (retval < 0 && retval > -1024)
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goto out;
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data_start = SOM_PAGESTART(hpuxhdr->exec_dmem);
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data_size = SOM_PAGEALIGN(hpuxhdr->exec_dsize);
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current->mm->start_data = data_start;
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current->mm->end_data = bss_start = data_start + data_size;
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down_write(¤t->mm->mmap_sem);
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retval = do_mmap(file, data_start, data_size,
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prot | PROT_WRITE, flags,
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SOM_PAGESTART(hpuxhdr->exec_dfile));
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up_write(¤t->mm->mmap_sem);
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if (retval < 0 && retval > -1024)
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goto out;
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som_brk = bss_start + SOM_PAGEALIGN(hpuxhdr->exec_bsize);
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current->mm->start_brk = current->mm->brk = som_brk;
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down_write(¤t->mm->mmap_sem);
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retval = do_mmap(NULL, bss_start, som_brk - bss_start,
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prot | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, 0);
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up_write(¤t->mm->mmap_sem);
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if (retval > 0 || retval < -1024)
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retval = 0;
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out:
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set_fs(old_fs);
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return retval;
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}
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/*
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* These are the functions used to load SOM executables and shared
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* libraries. There is no binary dependent code anywhere else.
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*/
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static int
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load_som_binary(struct linux_binprm * bprm, struct pt_regs * regs)
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{
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int som_exec_fileno;
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int retval;
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unsigned int size;
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unsigned long som_entry;
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struct som_hdr *som_ex;
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struct som_exec_auxhdr *hpuxhdr;
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struct files_struct *files;
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/* Get the exec-header */
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som_ex = (struct som_hdr *) bprm->buf;
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retval = check_som_header(som_ex);
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if (retval != 0)
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goto out;
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/* Now read in the auxiliary header information */
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retval = -ENOMEM;
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size = som_ex->aux_header_size;
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if (size > SOM_PAGESIZE)
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goto out;
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hpuxhdr = kmalloc(size, GFP_KERNEL);
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if (!hpuxhdr)
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goto out;
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retval = kernel_read(bprm->file, som_ex->aux_header_location,
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(char *) hpuxhdr, size);
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if (retval != size) {
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if (retval >= 0)
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retval = -EIO;
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goto out_free;
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}
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files = current->files; /* Refcounted so ok */
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retval = unshare_files();
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if (retval < 0)
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goto out_free;
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if (files == current->files) {
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put_files_struct(files);
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files = NULL;
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}
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retval = get_unused_fd();
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if (retval < 0)
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goto out_free;
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get_file(bprm->file);
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fd_install(som_exec_fileno = retval, bprm->file);
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/* Flush all traces of the currently running executable */
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retval = flush_old_exec(bprm);
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if (retval)
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goto out_free;
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/* OK, This is the point of no return */
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current->flags &= ~PF_FORKNOEXEC;
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current->personality = PER_HPUX;
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/* Set the task size for HP-UX processes such that
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* the gateway page is outside the address space.
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* This can be fixed later, but for now, this is much
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* easier.
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*/
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current->thread.task_size = 0xc0000000;
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/* Set map base to allow enough room for hp-ux heap growth */
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current->thread.map_base = 0x80000000;
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retval = map_som_binary(bprm->file, hpuxhdr);
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if (retval < 0)
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goto out_free;
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som_entry = hpuxhdr->exec_entry;
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kfree(hpuxhdr);
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set_binfmt(&som_format);
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compute_creds(bprm);
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setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
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create_som_tables(bprm);
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current->mm->start_stack = bprm->p;
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#if 0
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printk("(start_brk) %08lx\n" , (unsigned long) current->mm->start_brk);
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printk("(end_code) %08lx\n" , (unsigned long) current->mm->end_code);
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printk("(start_code) %08lx\n" , (unsigned long) current->mm->start_code);
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printk("(end_data) %08lx\n" , (unsigned long) current->mm->end_data);
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printk("(start_stack) %08lx\n" , (unsigned long) current->mm->start_stack);
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printk("(brk) %08lx\n" , (unsigned long) current->mm->brk);
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#endif
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map_hpux_gateway_page(current,current->mm);
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start_thread_som(regs, som_entry, bprm->p);
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if (current->ptrace & PT_PTRACED)
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send_sig(SIGTRAP, current, 0);
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return 0;
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/* error cleanup */
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out_free:
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kfree(hpuxhdr);
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out:
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return retval;
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}
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static int load_som_library(struct file *f)
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{
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/* No lib support in SOM yet. gizza chance.. */
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return -ENOEXEC;
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}
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/* Install the SOM loader.
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* N.B. We *rely* on the table being the right size with the
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* right number of free slots...
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*/
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static int __init init_som_binfmt(void)
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{
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return register_binfmt(&som_format);
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}
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static void __exit exit_som_binfmt(void)
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{
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/* Remove the SOM loader. */
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unregister_binfmt(&som_format);
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}
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core_initcall(init_som_binfmt);
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module_exit(exit_som_binfmt);
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