From 9cd8812d8b2b1648a40c05e02787c375d5ce5cd4 Mon Sep 17 00:00:00 2001
From: Yip Coekjan <69834864+Coekjan@users.noreply.github.com>
Date: Tue, 2 Jul 2024 19:47:48 +0800
Subject: Handle `.relr.dyn` section (#1626)

---
 src/elfs/elfload_dump.c      | 12 ++++++++++++
 src/elfs/elfloader.c         | 28 ++++++++++++++++++++++++++++
 src/elfs/elfloader_private.h |  3 +++
 src/elfs/elfparser.c         |  9 +++++++++
 4 files changed, 52 insertions(+)

(limited to 'src/elfs')

diff --git a/src/elfs/elfload_dump.c b/src/elfs/elfload_dump.c
index 2a8189b5..62cedcf6 100644
--- a/src/elfs/elfload_dump.c
+++ b/src/elfs/elfload_dump.c
@@ -367,6 +367,18 @@ void DumpRelATable(elfheader_t *h, int cnt, Elf64_Rela *rela, const char* name)
     }
 }
 
+void DumpRelRTable(elfheader_t *h, int cnt, Elf64_Relr *relr, const char *name)
+{
+    if(box64_dump && h->relr) {
+        const char* elfname = ElfName(h);
+        printf_dump(LOG_NEVER, "ELF Dump %s Table(%d) @%p\n", name, cnt, relr);
+        for (int i = 0; i<cnt; ++i)
+            printf_dump(LOG_NEVER, "  %s:%s[%d] = %p\n", elfname, name,
+                i, (void*)relr[i]);
+        printf_dump(LOG_NEVER, "ELF Dump %s Table=====\n", name);
+    }
+}
+
 void DumpBinary(char* p, int sz)
 {
     // dump p as 
diff --git a/src/elfs/elfloader.c b/src/elfs/elfloader.c
index efb0ef57..fab47ad6 100644
--- a/src/elfs/elfloader.c
+++ b/src/elfs/elfloader.c
@@ -784,12 +784,40 @@ int RelocateElfRELA(lib_t *maplib, lib_t *local_maplib, int bindnow, int deepbin
     }
     return bindnow?ret_ok:0;
 }
+
+int RelocateElfRELR(elfheader_t *head, int cnt, Elf64_Relr *relr) {
+    Elf64_Addr *where = NULL;
+    for (int i = 0; i < cnt; i++) {
+        Elf64_Relr p = relr[i];
+        if ((p & 1) == 0) {
+            where = (Elf64_Addr *)(p + head->delta);
+            printf_dump(LOG_NEVER, "Apply (even) RELR %p -> %p\n", *where, *where + head->delta);
+            *where++ += head->delta;
+        } else {
+            for (long j = 0; (p >>= 1) != 0; j++)
+                if ((p & 1) != 0) {
+                    printf_dump(LOG_NEVER, "Apply (odd) RELR %p -> %p\n", where[j], where[j] + head->delta);
+                    where[j] += head->delta;
+                }
+            where += CHAR_BIT * sizeof(Elf64_Relr) - 1;
+        }
+    }
+    return 0;
+}
+
 int RelocateElf(lib_t *maplib, lib_t *local_maplib, int bindnow, int deepbind, elfheader_t* head)
 {
     if((head->flags&DF_BIND_NOW) && !bindnow) {
         bindnow = 1;
         printf_log(LOG_DEBUG, "Forcing %s to Bind Now\n", head->name);
     }
+    if(head->relr) {
+        int cnt = head->relrsz / head->relrent;
+        DumpRelRTable(head, cnt, (Elf64_Relr *)(head->relr + head->delta), "RelR");
+        printf_dump(LOG_DEBUG, "Applying %d Relocation(s) without Addend for %s bindnow=%d, deepbind=%d\n", cnt, head->name, bindnow, deepbind);
+        if(RelocateElfRELR(head, cnt, (Elf64_Relr *)(head->relr + head->delta)))
+            return -1;
+    }
     if(head->rel) {
         int cnt = head->relsz / head->relent;
         DumpRelTable(head, cnt, (Elf64_Rel *)(head->rel + head->delta), "Rel");
diff --git a/src/elfs/elfloader_private.h b/src/elfs/elfloader_private.h
index 91b3b510..d813488c 100644
--- a/src/elfs/elfloader_private.h
+++ b/src/elfs/elfloader_private.h
@@ -68,6 +68,9 @@ typedef struct elfheader_s {
     uintptr_t   rela;
     size_t      relasz;
     int         relaent;
+    uintptr_t   relr;
+    size_t      relrsz;
+    int         relrent;
     uintptr_t   jmprel;
     size_t      pltsz;
     int         pltent;
diff --git a/src/elfs/elfparser.c b/src/elfs/elfparser.c
index fb6e4637..545503c9 100644
--- a/src/elfs/elfparser.c
+++ b/src/elfs/elfparser.c
@@ -219,6 +219,15 @@ elfheader_t* ParseElfHeader(FILE* f, const char* name, int exec)
                 case DT_RELAENT:
                     h->relaent = val;
                     break;
+                case DT_RELR:
+                    h->relr = ptr;
+                    break;
+                case DT_RELRSZ:
+                    h->relrsz = val;
+                    break;
+                case DT_RELRENT:
+                    h->relrent = val;
+                    break;
                 case DT_PLTGOT:
                     h->pltgot = ptr;
                     break;
-- 
cgit 1.4.1