237 lines
7.2 KiB
Diff
237 lines
7.2 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Peter Jones <pjones@redhat.com>
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Date: Mon, 21 Mar 2022 17:46:35 -0400
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Subject: [PATCH] nx: set page permissions for loaded modules.
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For NX, we need to set write and executable permissions on the sections
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of grub modules when we load them.
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On sections with SHF_ALLOC set, which is typically everything except
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.modname and the symbol and string tables, this patch clears the Read
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Only flag on sections that have the ELF flag SHF_WRITE set, and clears
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the No eXecute flag on sections with SHF_EXECINSTR set. In all other
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cases it sets both flags.
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Signed-off-by: Peter Jones <pjones@redhat.com>
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[rharwood: arm tgptr -> tgaddr]
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Signed-off-by: Robbie Harwood <rharwood@redhat.com>
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---
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grub-core/kern/dl.c | 102 +++++++++++++++++++++++++++++++++++++++++++++-------
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include/grub/dl.h | 44 +++++++++++++++++++++++
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2 files changed, 133 insertions(+), 13 deletions(-)
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diff --git a/grub-core/kern/dl.c b/grub-core/kern/dl.c
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index 775b367287e..25666ae383f 100644
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--- a/grub-core/kern/dl.c
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+++ b/grub-core/kern/dl.c
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@@ -277,6 +277,8 @@ grub_dl_load_segments (grub_dl_t mod, const Elf_Ehdr *e)
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#endif
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char *ptr;
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+ grub_dprintf ("modules", "loading segments for \"%s\"\n", mod->name);
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+
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arch_addralign = grub_arch_dl_min_alignment ();
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for (i = 0, s = (const Elf_Shdr *)((const char *) e + e->e_shoff);
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@@ -378,6 +380,7 @@ grub_dl_load_segments (grub_dl_t mod, const Elf_Ehdr *e)
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ptr += got;
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#endif
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+ grub_dprintf ("modules", "done loading segments for \"%s\"\n", mod->name);
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return GRUB_ERR_NONE;
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}
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@@ -645,6 +648,7 @@ grub_dl_relocate_symbols (grub_dl_t mod, void *ehdr)
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Elf_Shdr *s;
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unsigned i;
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+ grub_dprintf ("modules", "relocating symbols for \"%s\"\n", mod->name);
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for (i = 0, s = (Elf_Shdr *) ((char *) e + e->e_shoff);
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i < e->e_shnum;
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i++, s = (Elf_Shdr *) ((char *) s + e->e_shentsize))
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@@ -653,22 +657,92 @@ grub_dl_relocate_symbols (grub_dl_t mod, void *ehdr)
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grub_dl_segment_t seg;
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grub_err_t err;
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- /* Find the target segment. */
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- for (seg = mod->segment; seg; seg = seg->next)
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- if (seg->section == s->sh_info)
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- break;
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+ seg = grub_dl_find_segment(mod, s->sh_info);
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+ if (!seg)
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+ continue;
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- if (seg)
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- {
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- if (!mod->symtab)
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- return grub_error (GRUB_ERR_BAD_MODULE, "relocation without symbol table");
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+ if (!mod->symtab)
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+ return grub_error (GRUB_ERR_BAD_MODULE, "relocation without symbol table");
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- err = grub_arch_dl_relocate_symbols (mod, ehdr, s, seg);
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- if (err)
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- return err;
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- }
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+ err = grub_arch_dl_relocate_symbols (mod, ehdr, s, seg);
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+ if (err)
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+ return err;
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}
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+ grub_dprintf ("modules", "done relocating symbols for \"%s\"\n", mod->name);
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+ return GRUB_ERR_NONE;
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+}
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+
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+static grub_err_t
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+grub_dl_set_mem_attrs (grub_dl_t mod, void *ehdr)
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+{
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+ unsigned i;
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+ const Elf_Shdr *s;
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+ const Elf_Ehdr *e = ehdr;
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+#if !defined (__i386__) && !defined (__x86_64__) && !defined(__riscv)
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+ grub_size_t arch_addralign = grub_arch_dl_min_alignment ();
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+ grub_addr_t tgaddr;
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+ grub_uint64_t tgsz;
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+#endif
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+
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+ grub_dprintf ("modules", "updating memory attributes for \"%s\"\n",
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+ mod->name);
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+ for (i = 0, s = (const Elf_Shdr *)((const char *) e + e->e_shoff);
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+ i < e->e_shnum;
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+ i++, s = (const Elf_Shdr *)((const char *) s + e->e_shentsize))
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+ {
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+ grub_dl_segment_t seg;
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+ grub_uint64_t set_attrs = GRUB_MEM_ATTR_R;
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+ grub_uint64_t clear_attrs = GRUB_MEM_ATTR_W|GRUB_MEM_ATTR_X;
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+
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+ seg = grub_dl_find_segment(mod, i);
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+ if (!seg)
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+ continue;
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+
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+ if (seg->size == 0 || !(s->sh_flags & SHF_ALLOC))
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+ continue;
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+
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+ if (s->sh_flags & SHF_WRITE)
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+ {
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+ set_attrs |= GRUB_MEM_ATTR_W;
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+ clear_attrs &= ~GRUB_MEM_ATTR_W;
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+ }
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+
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+ if (s->sh_flags & SHF_EXECINSTR)
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+ {
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+ set_attrs |= GRUB_MEM_ATTR_X;
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+ clear_attrs &= ~GRUB_MEM_ATTR_X;
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+ }
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+
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+ grub_dprintf ("modules", "setting memory attrs for section \"%s\" to -%s%s%s+%s%s%s\n",
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+ grub_dl_get_section_name(e, s),
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+ (clear_attrs & GRUB_MEM_ATTR_R) ? "r" : "",
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+ (clear_attrs & GRUB_MEM_ATTR_W) ? "w" : "",
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+ (clear_attrs & GRUB_MEM_ATTR_X) ? "x" : "",
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+ (set_attrs & GRUB_MEM_ATTR_R) ? "r" : "",
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+ (set_attrs & GRUB_MEM_ATTR_W) ? "w" : "",
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+ (set_attrs & GRUB_MEM_ATTR_X) ? "x" : "");
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+ grub_update_mem_attrs ((grub_addr_t)(seg->addr), seg->size, set_attrs, clear_attrs);
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+ }
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+
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+#if !defined (__i386__) && !defined (__x86_64__) && !defined(__riscv)
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+ tgaddr = grub_min((grub_addr_t)mod->tramp, (grub_addr_t)mod->got);
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+ tgsz = grub_max((grub_addr_t)mod->trampptr, (grub_addr_t)mod->gotptr) - tgaddr;
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+
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+ if (tgsz)
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+ {
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+ tgsz = ALIGN_UP(tgsz, arch_addralign);
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+
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+ grub_dprintf ("modules", "updating attributes for GOT and trampolines\n",
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+ mod->name);
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+ grub_update_mem_attrs (tgaddr, tgsz, GRUB_MEM_ATTR_R|GRUB_MEM_ATTR_X,
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+ GRUB_MEM_ATTR_W);
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+ }
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+#endif
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+
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+ grub_dprintf ("modules", "done updating module memory attributes for \"%s\"\n",
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+ mod->name);
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+
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return GRUB_ERR_NONE;
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}
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@@ -705,6 +779,7 @@ grub_dl_load_core_noinit (void *addr, grub_size_t size)
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mod->ref_count = 1;
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grub_dprintf ("modules", "relocating to %p\n", mod);
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+
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/* Me, Vladimir Serbinenko, hereby I add this module check as per new
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GNU module policy. Note that this license check is informative only.
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Modules have to be licensed under GPLv3 or GPLv3+ (optionally
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@@ -718,7 +793,8 @@ grub_dl_load_core_noinit (void *addr, grub_size_t size)
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|| grub_dl_resolve_dependencies (mod, e)
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|| grub_dl_load_segments (mod, e)
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|| grub_dl_resolve_symbols (mod, e)
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- || grub_dl_relocate_symbols (mod, e))
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+ || grub_dl_relocate_symbols (mod, e)
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+ || grub_dl_set_mem_attrs (mod, e))
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{
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mod->fini = 0;
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grub_dl_unload (mod);
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diff --git a/include/grub/dl.h b/include/grub/dl.h
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index 9f86765c8e9..1e1262a283b 100644
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--- a/include/grub/dl.h
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+++ b/include/grub/dl.h
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@@ -27,6 +27,7 @@
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#include <grub/elf.h>
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#include <grub/list.h>
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#include <grub/misc.h>
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+#include <grub/mm.h>
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#endif
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/*
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@@ -267,6 +268,49 @@ grub_dl_is_persistent (grub_dl_t mod)
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return mod->persistent;
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}
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+static inline const char *
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+grub_dl_get_section_name (const Elf_Ehdr *e, const Elf_Shdr *s)
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+{
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+ Elf_Shdr *str_s;
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+ const char *str;
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+
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+ str_s = (Elf_Shdr *) ((char *) e + e->e_shoff + e->e_shstrndx * e->e_shentsize);
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+ str = (char *) e + str_s->sh_offset;
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+
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+ return str + s->sh_name;
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+}
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+
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+static inline long
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+grub_dl_find_section_index (Elf_Ehdr *e, const char *name)
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+{
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+ Elf_Shdr *s;
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+ const char *str;
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+ unsigned i;
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+
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+ s = (Elf_Shdr *) ((char *) e + e->e_shoff + e->e_shstrndx * e->e_shentsize);
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+ str = (char *) e + s->sh_offset;
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+
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+ for (i = 0, s = (Elf_Shdr *) ((char *) e + e->e_shoff);
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+ i < e->e_shnum;
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+ i++, s = (Elf_Shdr *) ((char *) s + e->e_shentsize))
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+ if (grub_strcmp (str + s->sh_name, name) == 0)
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+ return (long)i;
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+ return -1;
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+}
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+
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+/* Return the segment for a section of index N */
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+static inline grub_dl_segment_t
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+grub_dl_find_segment (grub_dl_t mod, unsigned n)
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+{
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+ grub_dl_segment_t seg;
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+
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+ for (seg = mod->segment; seg; seg = seg->next)
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+ if (seg->section == n)
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+ return seg;
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+
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+ return NULL;
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+}
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+
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#endif
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void * EXPORT_FUNC(grub_resolve_symbol) (const char *name);
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