Author: kib
Date: Wed Mar 16 15:34:16 2016
New Revision: 296939
URL: https://svnweb.freebsd.org/changeset/base/296939
Log:
MFC r296319:
Fix handling of DT_TEXTREL for an object with more than one read-only
segment.
PR: 207631
Modified:
stable/10/libexec/rtld-elf/map_object.c
stable/10/libexec/rtld-elf/rtld.c
stable/10/libexec/rtld-elf/rtld.h
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/libexec/rtld-elf/map_object.c
==============================================================================
--- stable/10/libexec/rtld-elf/map_object.c Wed Mar 16 15:31:09 2016
(r296938)
+++ stable/10/libexec/rtld-elf/map_object.c Wed Mar 16 15:34:16 2016
(r296939)
@@ -39,7 +39,6 @@
#include "rtld.h"
static Elf_Ehdr *get_elf_header(int, const char *);
-static int convert_prot(int); /* Elf flags -> mmap protection */
static int convert_flags(int); /* Elf flags -> mmap flags */
/*
@@ -439,7 +438,7 @@ obj_new(void)
* Given a set of ELF protection flags, return the corresponding protection
* flags for MMAP.
*/
-static int
+int
convert_prot(int elfflags)
{
int prot = 0;
Modified: stable/10/libexec/rtld-elf/rtld.c
==============================================================================
--- stable/10/libexec/rtld-elf/rtld.c Wed Mar 16 15:31:09 2016
(r296938)
+++ stable/10/libexec/rtld-elf/rtld.c Wed Mar 16 15:34:16 2016
(r296939)
@@ -2578,6 +2578,40 @@ relocate_object_dag(Obj_Entry *root, boo
}
/*
+ * Prepare for, or clean after, relocating an object marked with
+ * DT_TEXTREL or DF_TEXTREL. Before relocating, all read-only
+ * segments are remapped read-write. After relocations are done, the
+ * segment's permissions are returned back to the modes specified in
+ * the phdrs. If any relocation happened, or always for wired
+ * program, COW is triggered.
+ */
+static int
+reloc_textrel_prot(Obj_Entry *obj, bool before)
+{
+ const Elf_Phdr *ph;
+ void *base;
+ size_t l, sz;
+ int prot;
+
+ for (l = obj->phsize / sizeof(*ph), ph = obj->phdr; l > 0;
+ l--, ph++) {
+ if (ph->p_type != PT_LOAD || (ph->p_flags & PF_W) != 0)
+ continue;
+ base = obj->relocbase + trunc_page(ph->p_vaddr);
+ sz = round_page(ph->p_vaddr + ph->p_filesz) -
+ trunc_page(ph->p_vaddr);
+ prot = convert_prot(ph->p_flags) | (before ? PROT_WRITE : 0);
+ if (mprotect(base, sz, prot) == -1) {
+ _rtld_error("%s: Cannot write-%sable text segment: %s",
+ obj->path, before ? "en" : "dis",
+ rtld_strerror(errno));
+ return (-1);
+ }
+ }
+ return (0);
+}
+
+/*
* Relocate single object.
* Returns 0 on success, or -1 on failure.
*/
@@ -2599,28 +2633,17 @@ relocate_object(Obj_Entry *obj, bool bin
return (-1);
}
- if (obj->textrel) {
- /* There are relocations to the write-protected text segment. */
- if (mprotect(obj->mapbase, obj->textsize,
- PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
- _rtld_error("%s: Cannot write-enable text segment: %s",
- obj->path, rtld_strerror(errno));
- return (-1);
- }
- }
+ /* There are relocations to the write-protected text segment. */
+ if (obj->textrel && reloc_textrel_prot(obj, true) != 0)
+ return (-1);
/* Process the non-PLT non-IFUNC relocations. */
if (reloc_non_plt(obj, rtldobj, flags, lockstate))
return (-1);
- if (obj->textrel) { /* Re-protected the text segment. */
- if (mprotect(obj->mapbase, obj->textsize,
- PROT_READ|PROT_EXEC) == -1) {
- _rtld_error("%s: Cannot write-protect text segment: %s",
- obj->path, rtld_strerror(errno));
- return (-1);
- }
- }
+ /* Re-protected the text segment. */
+ if (obj->textrel && reloc_textrel_prot(obj, false) != 0)
+ return (-1);
/* Set the special PLT or GOT entries. */
init_pltgot(obj);
Modified: stable/10/libexec/rtld-elf/rtld.h
==============================================================================
--- stable/10/libexec/rtld-elf/rtld.h Wed Mar 16 15:31:09 2016
(r296938)
+++ stable/10/libexec/rtld-elf/rtld.h Wed Mar 16 15:34:16 2016
(r296939)
@@ -398,6 +398,7 @@ void *allocate_module_tls(int index);
bool allocate_tls_offset(Obj_Entry *obj);
void free_tls_offset(Obj_Entry *obj);
const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
+int convert_prot(int elfflags);
/*
* MD function declarations.
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