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-rw-r--r--src/internal/dynlink.h17
-rw-r--r--src/ldso/dlstart.c65
-rw-r--r--src/ldso/dynlink.c134
3 files changed, 202 insertions, 14 deletions
diff --git a/src/internal/dynlink.h b/src/internal/dynlink.h
index 369f183e..b9333926 100644
--- a/src/internal/dynlink.h
+++ b/src/internal/dynlink.h
@@ -49,16 +49,27 @@ struct fdpic_loadmap {
struct fdpic_loadseg segs[];
};
+struct fdpic_dummy_loadmap {
+ unsigned short version, nsegs;
+ struct fdpic_loadseg segs[1];
+};
+
#include "reloc.h"
-#define IS_RELATIVE(x) ( \
+#ifndef DL_FDPIC
+#define DL_FDPIC 0
+#endif
+
+#if !DL_FDPIC
+#define IS_RELATIVE(x,s) ( \
(R_TYPE(x) == REL_RELATIVE) || \
(R_TYPE(x) == REL_SYM_OR_REL && !R_SYM(x)) )
-
-#define IS_FDPIC_RELATIVE(x,s) ( ( \
+#else
+#define IS_RELATIVE(x,s) ( ( \
(R_TYPE(x) == REL_FUNCDESC_VAL) || \
(R_TYPE(x) == REL_SYMBOLIC) ) \
&& (((s)[R_SYM(x)].st_info & 0xf) == STT_SECTION) )
+#endif
#ifndef NEED_MIPS_GOT_RELOCS
#define NEED_MIPS_GOT_RELOCS 0
diff --git a/src/ldso/dlstart.c b/src/ldso/dlstart.c
index e84e073e..46f50114 100644
--- a/src/ldso/dlstart.c
+++ b/src/ldso/dlstart.c
@@ -33,10 +33,70 @@ void _dlstart_c(size_t *sp, size_t *dynv)
for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT)
aux[auxv[i]] = auxv[i+1];
+#if DL_FDPIC
+ struct fdpic_loadseg *segs, fakeseg;
+ size_t j;
+ if (dynv) {
+ /* crt_arch.h entry point asm is responsible for reserving
+ * space and moving the extra fdpic arguments to the stack
+ * vector where they are easily accessible from C. */
+ segs = ((struct fdpic_loadmap *)(sp[-1] ? sp[-1] : sp[-2]))->segs;
+ } else {
+ /* If dynv is null, the entry point was started from loader
+ * that is not fdpic-aware. We can assume normal fixed-
+ * displacement ELF loading was performed, but when ldso was
+ * run as a command, finding the Ehdr is a heursitic: we
+ * have to assume Phdrs start in the first 4k of the file. */
+ base = aux[AT_BASE];
+ if (!base) base = aux[AT_PHDR] & -4096;
+ segs = &fakeseg;
+ segs[0].addr = base;
+ segs[0].p_vaddr = 0;
+ segs[0].p_memsz = -1;
+ Ehdr *eh = (void *)base;
+ Phdr *ph = (void *)(base + eh->e_phoff);
+ size_t phnum = eh->e_phnum;
+ size_t phent = eh->e_phentsize;
+ while (phnum-- && ph->p_type != PT_DYNAMIC)
+ ph = (void *)((size_t)ph + phent);
+ dynv = (void *)(base + ph->p_vaddr);
+ }
+#endif
+
for (i=0; i<DYN_CNT; i++) dyn[i] = 0;
for (i=0; dynv[i]; i+=2) if (dynv[i]<DYN_CNT)
dyn[dynv[i]] = dynv[i+1];
+#if DL_FDPIC
+ for (i=0; i<DYN_CNT; i++) {
+ if (i==DT_RELASZ || i==DT_RELSZ) continue;
+ if (!dyn[i]) continue;
+ for (j=0; dyn[i]-segs[j].p_vaddr >= segs[j].p_memsz; j++);
+ dyn[i] += segs[j].addr - segs[j].p_vaddr;
+ }
+ base = 0;
+
+ const Sym *syms = (void *)dyn[DT_SYMTAB];
+
+ rel = (void *)dyn[DT_RELA];
+ rel_size = dyn[DT_RELASZ];
+ for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
+ if (!IS_RELATIVE(rel[1], syms)) continue;
+ for (j=0; rel[0]-segs[j].p_vaddr >= segs[j].p_memsz; j++);
+ size_t *rel_addr = (void *)
+ (rel[0] + segs[j].addr - segs[j].p_vaddr);
+ if (R_TYPE(rel[1]) == REL_FUNCDESC_VAL) {
+ *rel_addr += segs[rel_addr[1]].addr
+ - segs[rel_addr[1]].p_vaddr
+ + syms[R_SYM(rel[1])].st_value;
+ rel_addr[1] = dyn[DT_PLTGOT];
+ } else {
+ size_t val = syms[R_SYM(rel[1])].st_value;
+ for (j=0; val-segs[j].p_vaddr >= segs[j].p_memsz; j++);
+ *rel_addr = rel[2] + segs[j].addr - segs[j].p_vaddr + val;
+ }
+ }
+#else
/* If the dynamic linker is invoked as a command, its load
* address is not available in the aux vector. Instead, compute
* the load address as the difference between &_DYNAMIC and the
@@ -68,7 +128,7 @@ void _dlstart_c(size_t *sp, size_t *dynv)
rel = (void *)(base+dyn[DT_REL]);
rel_size = dyn[DT_RELSZ];
for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) {
- if (!IS_RELATIVE(rel[1])) continue;
+ if (!IS_RELATIVE(rel[1], 0)) continue;
size_t *rel_addr = (void *)(base + rel[0]);
*rel_addr += base;
}
@@ -76,10 +136,11 @@ void _dlstart_c(size_t *sp, size_t *dynv)
rel = (void *)(base+dyn[DT_RELA]);
rel_size = dyn[DT_RELASZ];
for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
- if (!IS_RELATIVE(rel[1])) continue;
+ if (!IS_RELATIVE(rel[1], 0)) continue;
size_t *rel_addr = (void *)(base + rel[0]);
*rel_addr = base + rel[2];
}
+#endif
stage2_func dls2;
GETFUNCSYM(&dls2, __dls2, base+dyn[DT_PLTGOT]);
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 4b52a5a6..4903dbd2 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -42,7 +42,11 @@ struct td_index {
};
struct dso {
+#if DL_FDPIC
+ struct fdpic_loadmap *loadmap;
+#else
unsigned char *base;
+#endif
char *name;
size_t *dynv;
struct dso *next, *prev;
@@ -75,6 +79,16 @@ struct dso {
struct td_index *td_index;
struct dso *fini_next;
char *shortname;
+#if DL_FDPIC
+ unsigned char *base;
+#else
+ struct fdpic_loadmap *loadmap;
+#endif
+ struct funcdesc {
+ void *addr;
+ size_t *got;
+ } *funcdescs;
+ size_t *got;
char buf[];
};
@@ -112,6 +126,8 @@ static struct debug debug;
static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
static size_t static_tls_cnt;
static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
+static struct fdpic_loadmap *app_loadmap;
+static struct fdpic_dummy_loadmap app_dummy_loadmap;
struct debug *_dl_debug_addr = &debug;
@@ -123,7 +139,20 @@ static int dl_strcmp(const char *l, const char *r)
#define strcmp(l,r) dl_strcmp(l,r)
/* Compute load address for a virtual address in a given dso. */
+#ifdef DL_FDPIC
+static void *laddr(const struct dso *p, size_t v)
+{
+ size_t j=0;
+ if (!p->loadmap) return p->base + v;
+ for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
+ return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
+}
+#define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
+ laddr(p, v), (p)->got })
+#else
#define laddr(p, v) (void *)((p)->base + (v))
+#define fpaddr(p, v) ((void (*)())laddr(p, v))
+#endif
static void decode_vec(size_t *v, size_t *a, size_t cnt)
{
@@ -284,7 +313,7 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
}
for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
- if (skip_relative && IS_RELATIVE(rel[1])) continue;
+ if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
type = R_TYPE(rel[1]);
if (type == REL_NONE) continue;
sym_index = R_SYM(rel[1]);
@@ -293,7 +322,9 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
sym = syms + sym_index;
name = strings + sym->st_name;
ctx = type==REL_COPY ? head->next : head;
- def = find_sym(ctx, name, type==REL_PLT);
+ def = (sym->st_info&0xf) == STT_SECTION
+ ? (struct symdef){ .dso = dso, .sym = sym }
+ : find_sym(ctx, name, type==REL_PLT);
if (!def.sym && (sym->st_shndx != SHN_UNDEF
|| sym->st_info>>4 != STB_WEAK)) {
error("Error relocating %s: %s: symbol not found",
@@ -349,6 +380,15 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
*(uint32_t *)reloc_addr = sym_val + addend
- (size_t)reloc_addr;
break;
+ case REL_FUNCDESC:
+ *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
+ + (def.sym - def.dso->syms)) : 0;
+ break;
+ case REL_FUNCDESC_VAL:
+ if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
+ else *reloc_addr = sym_val;
+ reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
+ break;
case REL_DTPMOD:
*reloc_addr = def.dso->tls_id;
break;
@@ -430,6 +470,7 @@ static void reclaim_gaps(struct dso *dso)
Phdr *ph = dso->phdr;
size_t phcnt = dso->phnum;
+ if (DL_FDPIC) return; // FIXME
for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
if (ph->p_type!=PT_LOAD) continue;
if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
@@ -698,6 +739,8 @@ static void decode_dyn(struct dso *p)
p->rpath_orig = p->strings + dyn[DT_RPATH];
if (dyn[0]&(1<<DT_RUNPATH))
p->rpath_orig = p->strings + dyn[DT_RUNPATH];
+ if (dyn[0]&(1<<DT_PLTGOT))
+ p->got = laddr(p, dyn[DT_PLTGOT]);
if (search_vec(p->dynv, dyn, DT_GNU_HASH))
p->ghashtab = laddr(p, *dyn);
if (search_vec(p->dynv, dyn, DT_VERSYM))
@@ -723,6 +766,46 @@ static size_t count_syms(struct dso *p)
return nsym;
}
+static void *dl_mmap(size_t n)
+{
+ void *p;
+ int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
+#ifdef SYS_mmap2
+ p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
+#else
+ p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
+#endif
+ return p == MAP_FAILED ? 0 : p;
+}
+
+static void makefuncdescs(struct dso *p)
+{
+ static int self_done;
+ size_t nsym = count_syms(p);
+ size_t i, size = nsym * sizeof(*p->funcdescs);
+
+ if (!self_done) {
+ p->funcdescs = dl_mmap(size);
+ self_done = 1;
+ } else {
+ p->funcdescs = malloc(size);
+ }
+ if (!p->funcdescs) {
+ if (!runtime) a_crash();
+ error("Error allocating function descriptors for %s", p->name);
+ longjmp(*rtld_fail, 1);
+ }
+ for (i=0; i<nsym; i++) {
+ if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
+ p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
+ p->funcdescs[i].got = p->got;
+ } else {
+ p->funcdescs[i].addr = 0;
+ p->funcdescs[i].got = 0;
+ }
+ }
+}
+
static struct dso *load_library(const char *name, struct dso *needed_by)
{
char buf[2*NAME_MAX+2];
@@ -902,6 +985,8 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
p->prev = tail;
tail = p;
+ if (DL_FDPIC) makefuncdescs(p);
+
if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
return p;
@@ -1034,7 +1119,7 @@ static void do_fini()
}
#ifndef NO_LEGACY_INITFINI
if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
- ((void (*)(void))laddr(p, dyn[DT_FINI]))();
+ fpaddr(p, dyn[DT_FINI])();
#endif
}
}
@@ -1057,7 +1142,7 @@ static void do_init_fini(struct dso *p)
}
#ifndef NO_LEGACY_INITFINI
if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
- ((void (*)(void))laddr(p, dyn[DT_INIT]))();
+ fpaddr(p, dyn[DT_INIT])();
#endif
if (dyn[0] & (1<<DT_INIT_ARRAY)) {
size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
@@ -1196,16 +1281,33 @@ static void update_tls_size()
void __dls2(unsigned char *base, size_t *sp)
{
- Ehdr *ehdr = (void *)base;
- ldso.base = base;
+ if (DL_FDPIC) {
+ void *p1 = (void *)sp[-2];
+ void *p2 = (void *)sp[-1];
+ if (!p1) {
+ size_t *auxv, aux[AUX_CNT];
+ for (auxv=sp+1+*sp+1; *auxv; auxv++); auxv++;
+ decode_vec(auxv, aux, AUX_CNT);
+ if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
+ else ldso.base = (void *)(aux[AT_PHDR] & -4096);
+ }
+ app_loadmap = p2 ? p1 : 0;
+ ldso.loadmap = p2 ? p2 : p1;
+ ldso.base = laddr(&ldso, 0);
+ } else {
+ ldso.base = base;
+ }
+ Ehdr *ehdr = (void *)ldso.base;
ldso.name = ldso.shortname = "libc.so";
ldso.global = 1;
ldso.phnum = ehdr->e_phnum;
- ldso.phdr = (void *)(base + ehdr->e_phoff);
+ ldso.phdr = laddr(&ldso, ehdr->e_phoff);
ldso.phentsize = ehdr->e_phentsize;
kernel_mapped_dso(&ldso);
decode_dyn(&ldso);
+ if (DL_FDPIC) makefuncdescs(&ldso);
+
/* Prepare storage for to save clobbered REL addends so they
* can be reused in stage 3. There should be very few. If
* something goes wrong and there are a huge number, abort
@@ -1217,7 +1319,7 @@ void __dls2(unsigned char *base, size_t *sp)
size_t symbolic_rel_cnt = 0;
apply_addends_to = rel;
for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
- if (!IS_RELATIVE(rel[1])) symbolic_rel_cnt++;
+ if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
size_t addends[symbolic_rel_cnt+1];
saved_addends = addends;
@@ -1231,7 +1333,8 @@ void __dls2(unsigned char *base, size_t *sp)
* symbolically as a barrier against moving the address
* load across the above relocation processing. */
struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
- ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
+ if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
+ else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
}
/* Stage 3 of the dynamic linker is called with the dynamic linker/libc
@@ -1298,6 +1401,7 @@ _Noreturn void __dls3(size_t *sp)
app.tls_align = phdr->p_align;
}
}
+ if (DL_FDPIC) app.loadmap = app_loadmap;
if (app.tls_size) app.tls_image = laddr(&app, tls_image);
if (interp_off) ldso.name = laddr(&app, interp_off);
if ((aux[0] & (1UL<<AT_EXECFN))
@@ -1384,6 +1488,16 @@ _Noreturn void __dls3(size_t *sp)
}
app.global = 1;
decode_dyn(&app);
+ if (DL_FDPIC) {
+ makefuncdescs(&app);
+ if (!app.loadmap) {
+ app.loadmap = (void *)&app_dummy_loadmap;
+ app.loadmap->nsegs = 1;
+ app.loadmap->segs[0].addr = (size_t)app.base;
+ app.loadmap->segs[0].p_memsz = -1;
+ }
+ argv[-3] = (void *)app.loadmap;
+ }
/* Attach to vdso, if provided by the kernel */
if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
@@ -1512,6 +1626,8 @@ void *dlopen(const char *file, int mode)
free(p->td_index);
p->td_index = tmp;
}
+ if (p->funcdescs)
+ free(p->funcdescs);
if (p->rpath != p->rpath_orig)
free(p->rpath);
free(p->deps);
generated by cgit v1.2.1 (git 2.18.0) at 2025-10-31 08:37:06 +0000