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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-pink 1.4.1 (git 2.36.1) at 2024-10-31 20:37:29 +0000