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Musl loader updates: relr support and relocation of init_array entries
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Signed-off-by: Vikas Tikoo <vikasamar@gmail.com>
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@vtikoo
vtikoo committed Jun 20, 2023
1 parent 7953bd8 commit d5386c6
Showing 1 changed file with 118 additions and 17 deletions.
135 changes: 118 additions & 17 deletions third_party/musl/crt/patch.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -126,6 +126,32 @@ index 92d5c179..e94deece 100644
}

#define VDSO_USEFUL
diff --git a/include/elf.h b/include/elf.h
index 549f92c1..5c4740b9 100644
--- a/include/elf.h
+++ b/include/elf.h
@@ -385,7 +385,8 @@ typedef struct {
#define SHT_PREINIT_ARRAY 16
#define SHT_GROUP 17
#define SHT_SYMTAB_SHNDX 18
-#define SHT_NUM 19
+#define SHT_RELR 19
+#define SHT_NUM 20
#define SHT_LOOS 0x60000000
#define SHT_GNU_ATTRIBUTES 0x6ffffff5
#define SHT_GNU_HASH 0x6ffffff6
@@ -751,7 +752,10 @@ typedef struct {
#define DT_PREINIT_ARRAY 32
#define DT_PREINIT_ARRAYSZ 33
#define DT_SYMTAB_SHNDX 34
-#define DT_NUM 35
+#define DT_RELRSZ 35
+#define DT_RELR 36
+#define DT_RELRENT 37
+#define DT_NUM 38
#define DT_LOOS 0x6000000d
#define DT_HIOS 0x6ffff000
#define DT_LOPROC 0x70000000
diff --git a/include/math.h b/include/math.h
index 14f28ec8..09b5790d 100644
--- a/include/math.h
Expand Down Expand Up @@ -261,7 +287,7 @@ index 20d50f2c..17cd6ac3 100644
+{
+}
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index afec985a..9f9b618d 100644
index afec985a..f8b2fc6c 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -3,6 +3,7 @@
Expand Down Expand Up @@ -303,7 +329,17 @@ index afec985a..9f9b618d 100644
struct debug {
int ver;
void *head;
@@ -217,6 +236,14 @@ static int search_vec(size_t *v, size_t *r, size_t key)
@@ -204,7 +223,8 @@ static void decode_vec(size_t *v, size_t *a, size_t cnt)
size_t i;
for (i=0; i<cnt; i++) a[i] = 0;
for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
- a[0] |= 1UL<<v[0];
+ if (v[0] < 8*sizeof(long))
+ a[0] |= 1UL<<v[0];
a[v[0]] = v[1];
}
}
@@ -217,6 +237,14 @@ static int search_vec(size_t *v, size_t *r, size_t key)
return 1;
}

Expand All @@ -318,7 +354,31 @@ index afec985a..9f9b618d 100644
static uint32_t sysv_hash(const char *s0)
{
const unsigned char *s = (void *)s0;
@@ -658,6 +685,25 @@ static void *map_library(int fd, struct dso *dso)
@@ -511,6 +539,23 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
}
}

+static void do_relr_relocs(struct dso *dso, size_t *relr, size_t relr_size)
+{
+ unsigned char *base = dso->base;
+ size_t *reloc_addr;
+ for (; relr_size; relr++, relr_size-=sizeof(size_t))
+ if ((relr[0]&1) == 0) {
+ reloc_addr = laddr(dso, relr[0]);
+ *reloc_addr++ += (size_t)base;
+ } else {
+ int i = 0;
+ for (size_t bitmap=relr[0]; (bitmap>>=1); i++)
+ if (bitmap&1)
+ reloc_addr[i] += (size_t)base;
+ reloc_addr += 8*sizeof(size_t)-1;
+ }
+}
+
static void redo_lazy_relocs()
{
struct dso *p = lazy_head, *next;
@@ -658,6 +703,25 @@ static void *map_library(int fd, struct dso *dso)
ph->p_memsz < DEFAULT_STACK_MAX ?
ph->p_memsz : DEFAULT_STACK_MAX;
}
Expand All @@ -344,15 +404,15 @@ index afec985a..9f9b618d 100644
}
if (ph->p_type != PT_LOAD) continue;
nsegs++;
@@ -895,6 +941,7 @@ static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
@@ -895,6 +959,7 @@ static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
static void decode_dyn(struct dso *p)
{
size_t dyn[DYN_CNT];
+ size_t* dynval_ptr = 0;
decode_vec(p->dynv, dyn, DYN_CNT);
p->syms = laddr(p, dyn[DT_SYMTAB]);
p->strings = laddr(p, dyn[DT_STRTAB]);
@@ -906,8 +953,21 @@ static void decode_dyn(struct dso *p)
@@ -906,8 +971,21 @@ static void decode_dyn(struct dso *p)
p->rpath_orig = p->strings + dyn[DT_RUNPATH];
if (dyn[0]&(1<<DT_PLTGOT))
p->got = laddr(p, dyn[DT_PLTGOT]);
Expand All @@ -375,7 +435,7 @@ index afec985a..9f9b618d 100644
if (search_vec(p->dynv, dyn, DT_VERSYM))
p->versym = laddr(p, *dyn);
}
@@ -1043,38 +1103,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
@@ -1043,38 +1121,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
fd = path_open(name, p->rpath, buf, sizeof buf);
}
if (fd == -1) {
Expand Down Expand Up @@ -415,15 +475,43 @@ index afec985a..9f9b618d 100644
fd = path_open(name, sys_path, buf, sizeof buf);
}
pathname = buf;
@@ -1098,6 +1127,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
@@ -1098,6 +1145,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
map = noload ? 0 : map_library(fd, &temp_dso);
close(fd);
if (!map) return 0;
+ myst_add_symbol_file(pathname, temp_dso.map, temp_dso.map_len);

/* Avoid the danger of getting two versions of libc mapped into the
* same process when an absolute pathname was used. The symbols
@@ -1683,6 +1713,13 @@ void __dls2b(size_t *sp, size_t *auxv)
@@ -1334,6 +1382,7 @@ static void reloc_all(struct dso *p)
2+(dyn[DT_PLTREL]==DT_RELA));
do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
+ do_relr_relocs(p, laddr(p, dyn[DT_RELR]), dyn[DT_RELRSZ]);

if (head != &ldso && p->relro_start != p->relro_end &&
mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
@@ -1498,7 +1547,18 @@ static void do_init_fini(struct dso **queue)
if (dyn[0] & (1<<DT_INIT_ARRAY)) {
size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
- while (n--) ((void (*)(void))*fn++)();
+ while (n--)
+ {
+ /* If function address is an offset, displace by base address*/
+ if (*fn < (size_t)p->base)
+ {
+ size_t fn_relocated = *fn + (size_t)p->base;
+ ((void (*)(void))fn_relocated)();
+ }
+ else
+ ((void (*)(void))*fn)();
+ fn++;
+ }
}

pthread_mutex_lock(&init_fini_lock);
@@ -1683,6 +1743,13 @@ void __dls2b(size_t *sp, size_t *auxv)
else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp, auxv);
}

Expand All @@ -437,7 +525,7 @@ index afec985a..9f9b618d 100644
/* Stage 3 of the dynamic linker is called with the dynamic linker/libc
* fully functional. Its job is to load (if not already loaded) and
* process dependencies and relocations for the main application and
@@ -1716,6 +1753,10 @@ void __dls3(size_t *sp, size_t *auxv)
@@ -1716,6 +1783,10 @@ void __dls3(size_t *sp, size_t *auxv)
env_path = getenv("LD_LIBRARY_PATH");
env_preload = getenv("LD_PRELOAD");
}
Expand All @@ -448,23 +536,23 @@ index afec985a..9f9b618d 100644

/* If the main program was already loaded by the kernel,
* AT_PHDR will point to some location other than the dynamic
@@ -1797,6 +1838,7 @@ void __dls3(size_t *sp, size_t *auxv)
@@ -1797,6 +1868,7 @@ void __dls3(size_t *sp, size_t *auxv)
dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
_exit(1);
}
+ myst_add_symbol_file(argv[0], app.map, app.map_len);
close(fd);
ldso.name = ldname;
app.name = argv[0];
@@ -1936,6 +1978,7 @@ void __dls3(size_t *sp, size_t *auxv)
@@ -1936,6 +2008,7 @@ void __dls3(size_t *sp, size_t *auxv)
/* Determine if malloc was interposed by a replacement implementation
* so that calloc and the memalign family can harden against the
* possibility of incomplete replacement. */
+
if (find_sym(head, "malloc", 1).dso != &ldso)
__malloc_replaced = 1;

@@ -1955,7 +1998,13 @@ void __dls3(size_t *sp, size_t *auxv)
@@ -1955,7 +2028,13 @@ void __dls3(size_t *sp, size_t *auxv)

errno = 0;

Expand All @@ -478,7 +566,7 @@ index afec985a..9f9b618d 100644
for(;;);
}

@@ -2058,6 +2107,10 @@ void *dlopen(const char *file, int mode)
@@ -2058,6 +2137,10 @@ void *dlopen(const char *file, int mode)
pthread_mutex_lock(&init_fini_lock);
if (!p->constructed) ctor_queue = queue_ctors(p);
pthread_mutex_unlock(&init_fini_lock);
Expand All @@ -489,15 +577,15 @@ index afec985a..9f9b618d 100644
if (!p->relocated && (mode & RTLD_LAZY)) {
prepare_lazy(p);
for (i=0; p->deps[i]; i++)
@@ -2100,6 +2153,7 @@ end:
@@ -2100,6 +2183,7 @@ end:
free(ctor_queue);
}
pthread_setcancelstate(cs, 0);
+ myst_load_symbols();
return p;
}

@@ -2272,11 +2326,16 @@ no_redir:
@@ -2272,11 +2356,16 @@ no_redir:
return __dlsym(p, s, ra);
}

Expand All @@ -514,7 +602,7 @@ index afec985a..9f9b618d 100644
for(current = head; current;) {
info.dlpi_addr = (uintptr_t)current->base;
info.dlpi_name = current->name;
@@ -2289,12 +2348,11 @@ int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void
@@ -2289,12 +2378,11 @@ int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void

ret = (callback)(&info, sizeof (info), data);

Expand All @@ -529,7 +617,7 @@ index afec985a..9f9b618d 100644
return ret;
}

@@ -2302,7 +2360,7 @@ static void error(const char *fmt, ...)
@@ -2302,7 +2390,7 @@ static void error(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
Expand Down Expand Up @@ -766,6 +854,19 @@ index cbabde47..e78515e4 100644
+size_t __strftime_l(char *restrict, size_t, const char *restrict, const struct tm *restrict, locale_t);

#endif
diff --git a/src/internal/dynlink.h b/src/internal/dynlink.h
index 764e3a1a..0171c71a 100644
--- a/src/internal/dynlink.h
+++ b/src/internal/dynlink.h
@@ -93,7 +93,7 @@ struct fdpic_dummy_loadmap {
#endif

#define AUX_CNT 32
-#define DYN_CNT 32
+#define DYN_CNT 37

typedef void (*stage2_func)(unsigned char *, size_t *);

diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 5742dfc5..fe718786 100644
--- a/src/internal/pthread_impl.h
Expand Down

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