xref: /illumos-gate/usr/src/cmd/sgs/rtld/common/elf.c (revision 0904e7ec)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 *	Copyright (c) 1988 AT&T
 *	  All Rights Reserved
 *
 * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * Copyright (c) 2012, Joyent, Inc.  All rights reserved.
 */

/*
 * Object file dependent support for ELF objects.
 */

#include	<stdio.h>
#include	<sys/procfs.h>
#include	<sys/mman.h>
#include	<sys/debug.h>
#include	<string.h>
#include	<limits.h>
#include	<dlfcn.h>
#include	<debug.h>
#include	<conv.h>
#include	"_rtld.h"
#include	"_audit.h"
#include	"_elf.h"
#include	"_inline_gen.h"
#include	"_inline_reloc.h"
#include	"msg.h"

/*
 * Default and secure dependency search paths.
 */
static Spath_defn _elf_def_dirs[] = {
#if	defined(_ELF64)
	{ MSG_ORIG(MSG_PTH_LIB_64),		MSG_PTH_LIB_64_SIZE },
	{ MSG_ORIG(MSG_PTH_USRLIB_64),		MSG_PTH_USRLIB_64_SIZE },
#else
	{ MSG_ORIG(MSG_PTH_LIB),		MSG_PTH_LIB_SIZE },
	{ MSG_ORIG(MSG_PTH_USRLIB),		MSG_PTH_USRLIB_SIZE },
#endif
	{ 0, 0 }
};

static Spath_defn _elf_sec_dirs[] = {
#if	defined(_ELF64)
	{ MSG_ORIG(MSG_PTH_LIBSE_64),		MSG_PTH_LIBSE_64_SIZE },
	{ MSG_ORIG(MSG_PTH_USRLIBSE_64),	MSG_PTH_USRLIBSE_64_SIZE },
#else
	{ MSG_ORIG(MSG_PTH_LIBSE),		MSG_PTH_LIBSE_SIZE },
	{ MSG_ORIG(MSG_PTH_USRLIBSE),		MSG_PTH_USRLIBSE_SIZE },
#endif
	{ 0, 0 }
};

Alist	*elf_def_dirs = NULL;
Alist	*elf_sec_dirs = NULL;

/*
 * Defines for local functions.
 */
static void	elf_dladdr(ulong_t, Rt_map *, Dl_info *, void **, int);
static Addr	elf_entry_point(void);
static int	elf_fix_name(const char *, Rt_map *, Alist **, Aliste, uint_t);
static Alist	**elf_get_def_dirs(void);
static Alist	**elf_get_sec_dirs(void);
static char	*elf_get_so(const char *, const char *, size_t, size_t);
static int	elf_needed(Lm_list *, Aliste, Rt_map *, int *);

/*
 * Functions and data accessed through indirect pointers.
 */
Fct elf_fct = {
	elf_verify,
	elf_new_lmp,
	elf_entry_point,
	elf_needed,
	lookup_sym,
	elf_reloc,
	elf_get_def_dirs,
	elf_get_sec_dirs,
	elf_fix_name,
	elf_get_so,
	elf_dladdr,
	dlsym_handle
};

/*
 * Default and secure dependency search paths.
 */
static Alist **
elf_get_def_dirs()
{
	if (elf_def_dirs == NULL)
		set_dirs(&elf_def_dirs, _elf_def_dirs, LA_SER_DEFAULT);
	return (&elf_def_dirs);
}

static Alist **
elf_get_sec_dirs()
{
	if (elf_sec_dirs == NULL)
		set_dirs(&elf_sec_dirs, _elf_sec_dirs, LA_SER_SECURE);
	return (&elf_sec_dirs);
}

/*
 * For a.out we have actual work to do here, on ELF we just perform path
 * expansion.
 */
static int
elf_fix_name(const char *name, Rt_map *clmp, Alist **alpp, Aliste alni,
    uint_t orig)
{
	return (expand_paths(clmp, name, alpp, alni, orig, 0));
}

/*
 * Determine whether this object requires capabilities.
 */
inline static int
elf_cap_check(Fdesc *fdp, Ehdr *ehdr, Rej_desc *rej)
{
	Phdr	*phdr;
	Cap	*cap = NULL;
	Dyn	*dyn = NULL;
	char	*str = NULL;
	Addr	base;
	uint_t	cnt, dyncnt;

	/*
	 * If this is a shared object, the base address of the shared object is
	 * added to all address values defined within the object.  Otherwise, if
	 * this is an executable, all object addresses are used as is.
	 */
	if (ehdr->e_type == ET_EXEC)
		base = 0;
	else
		base = (Addr)ehdr;

	/* LINTED */
	phdr = (Phdr *)((char *)ehdr + ehdr->e_phoff);
	for (cnt = 0; cnt < ehdr->e_phnum; cnt++, phdr++) {
		if (phdr->p_type == PT_DYNAMIC) {
			/* LINTED */
			dyn = (Dyn *)((uintptr_t)phdr->p_vaddr + base);
			dyncnt = phdr->p_filesz / sizeof (Dyn);
		} else if (phdr->p_type == PT_SUNWCAP) {
			/* LINTED */
			cap = (Cap *)((uintptr_t)phdr->p_vaddr + base);
		}
	}

	if (cap) {
		/*
		 * From the .dynamic section, determine the associated string
		 * table.  Required for CA_SUNW_MACH and CA_SUNW_PLAT
		 * processing.
		 */
		while (dyn && dyncnt) {
			if (dyn->d_tag == DT_NULL) {
				break;
			} else if (dyn->d_tag == DT_STRTAB) {
				str = (char *)(dyn->d_un.d_ptr + base);
				break;
			}
			dyn++, dyncnt--;
		}
	}

	/*
	 * Establish any alternative capabilities, and validate this object
	 * if it defines it's own capabilities information.
	 */
	return (cap_check_fdesc(fdp, cap, str, rej));
}

/*
 * Determine if we have been given an ELF file and if so determine if the file
 * is compatible.  Returns 1 if true, else 0 and sets the reject descriptor
 * with associated error information.
 */
Fct *
elf_verify(caddr_t addr, size_t size, Fdesc *fdp, const char *name,
    Rej_desc *rej)
{
	Ehdr	*ehdr;
	char	*caddr = (char *)addr;

	/*
	 * Determine if we're an elf file.  If not simply return, we don't set
	 * any rejection information as this test allows use to scroll through
	 * the objects we support (ELF, AOUT).
	 */
	if (size < sizeof (Ehdr) ||
	    caddr[EI_MAG0] != ELFMAG0 ||
	    caddr[EI_MAG1] != ELFMAG1 ||
	    caddr[EI_MAG2] != ELFMAG2 ||
	    caddr[EI_MAG3] != ELFMAG3) {
		return (NULL);
	}

	/*
	 * Check class and encoding.
	 */
	/* LINTED */
	ehdr = (Ehdr *)addr;
	if (ehdr->e_ident[EI_CLASS] != M_CLASS) {
		rej->rej_type = SGS_REJ_CLASS;
		rej->rej_info = (uint_t)ehdr->e_ident[EI_CLASS];
		return (NULL);
	}
	if (ehdr->e_ident[EI_DATA] != M_DATA) {
		rej->rej_type = SGS_REJ_DATA;
		rej->rej_info = (uint_t)ehdr->e_ident[EI_DATA];
		return (NULL);
	}
	if ((ehdr->e_type != ET_REL) && (ehdr->e_type != ET_EXEC) &&
	    (ehdr->e_type != ET_DYN)) {
		rej->rej_type = SGS_REJ_TYPE;
		rej->rej_info = (uint_t)ehdr->e_type;
		return (NULL);
	}

	/*
	 * Verify ELF version.
	 */
	if (ehdr->e_version > EV_CURRENT) {
		rej->rej_type = SGS_REJ_VERSION;
		rej->rej_info = (uint_t)ehdr->e_version;
		return (NULL);
	}

	/*
	 * Verify machine specific flags.
	 */
	if (elf_mach_flags_check(rej, ehdr) == 0)
		return (NULL);

	/*
	 * Verify any capability requirements.  Note, if this object is a shared
	 * object that is explicitly defined on the ldd(1) command line, and it
	 * contains an incompatible capabilities requirement, then inform the
	 * user, but continue processing.
	 */
	if (elf_cap_check(fdp, ehdr, rej) == 0) {
		Rt_map	*lmp = lml_main.lm_head;

		if ((lml_main.lm_flags & LML_FLG_TRC_LDDSTUB) && lmp &&
		    (FLAGS1(lmp) & FL1_RT_LDDSTUB) && (NEXT(lmp) == NULL)) {
			/* LINTED */
			(void) printf(MSG_INTL(ldd_warn[rej->rej_type]), name,
			    rej->rej_str);
			return (&elf_fct);
		}
		return (NULL);
	}
	return (&elf_fct);
}

/*
 * The runtime linker employs lazy loading to provide the libraries needed for
 * debugging, preloading .o's and dldump().  As these are seldom used, the
 * standard startup of ld.so.1 doesn't initialize all the information necessary
 * to perform plt relocation on ld.so.1's link-map.  The first time lazy loading
 * is called we get here to perform these initializations:
 *
 *  -	elf_needed() is called to establish any ld.so.1 dependencies.  These
 *	dependencies should all be lazy loaded, so this routine is typically a
 *	no-op.  However, we call elf_needed() for completeness, in case any
 *	NEEDED initialization is required.
 *
 *  -	For intel, ld.so.1's JMPSLOT relocations need relative updates. These
 *	are by default skipped thus delaying all relative relocation processing
 *	on every invocation of ld.so.1.
 */
int
elf_rtld_load()
{
	Lm_list	*lml = &lml_rtld;
	Rt_map	*lmp = lml->lm_head;

	if (lml->lm_flags & LML_FLG_PLTREL)
		return (1);

	if (elf_needed(lml, ALIST_OFF_DATA, lmp, NULL) == 0)
		return (0);

#if	defined(__i386)
	/*
	 * This is a kludge to give ld.so.1 a performance benefit on i386.
	 * It's based around two factors.
	 *
	 *  -	JMPSLOT relocations (PLT's) actually need a relative relocation
	 *	applied to the GOT entry so that they can find PLT0.
	 *
	 *  -	ld.so.1 does not exercise *any* PLT's before it has made a call
	 *	to elf_lazy_load().  This is because all dynamic dependencies
	 *	are recorded as lazy dependencies.
	 */
	(void) elf_reloc_relative_count((ulong_t)JMPREL(lmp),
	    (ulong_t)(PLTRELSZ(lmp) / RELENT(lmp)), (ulong_t)RELENT(lmp),
	    (ulong_t)ADDR(lmp), lmp, NULL, 0);
#endif
	lml->lm_flags |= LML_FLG_PLTREL;
	return (1);
}

/*
 * Lazy load an object.
 */
Rt_map *
elf_lazy_load(Rt_map *clmp, Slookup *slp, uint_t ndx, const char *sym,
    uint_t flags, Grp_hdl **hdl, int *in_nfavl)
{
	Alist		*palp = NULL;
	Rt_map		*nlmp;
	Dyninfo		*dip = &DYNINFO(clmp)[ndx], *pdip;
	const char	*name;
	Lm_list		*lml = LIST(clmp);
	Aliste		lmco;

	/*
	 * If this dependency should be ignored, or has already been processed,
	 * we're done.
	 */
	if (((nlmp = (Rt_map *)dip->di_info) != NULL) ||
	    (dip->di_flags & (FLG_DI_IGNORE | FLG_DI_LDD_DONE)))
		return (nlmp);

	/*
	 * If we're running under ldd(1), indicate that this dependency has been
	 * processed (see test above).  It doesn't matter whether the object is
	 * successfully loaded or not, this flag simply ensures that we don't
	 * repeatedly attempt to load an object that has already failed to load.
	 * To do so would create multiple failure diagnostics for the same
	 * object under ldd(1).
	 */
	if (lml->lm_flags & LML_FLG_TRC_ENABLE)
		dip->di_flags |= FLG_DI_LDD_DONE;

	/*
	 * Determine the initial dependency name.
	 */
	name = dip->di_name;
	DBG_CALL(Dbg_file_lazyload(clmp, name, sym));

	/*
	 * If this object needs to establish its own group, make sure a handle
	 * is created.
	 */
	if (dip->di_flags & FLG_DI_GROUP)
		flags |= (FLG_RT_SETGROUP | FLG_RT_PUBHDL);

	/*
	 * Lazy dependencies are identified as DT_NEEDED entries with a
	 * DF_P1_LAZYLOAD flag in the previous DT_POSFLAG_1 element.  The
	 * dynamic information element that corresponds to the DT_POSFLAG_1
	 * entry is free, and thus used to store the present entrance
	 * identifier.  This identifier is used to prevent multiple attempts to
	 * load a failed lazy loadable dependency within the same runtime linker
	 * operation.  However, future attempts to reload this dependency are
	 * still possible.
	 */
	if (ndx && (pdip = dip - 1) && (pdip->di_flags & FLG_DI_POSFLAG1))
		pdip->di_info = (void *)slp->sl_id;

	/*
	 * Expand the requested name if necessary.
	 */
	if (elf_fix_name(name, clmp, &palp, AL_CNT_NEEDED, 0) == 0)
		return (NULL);

	/*
	 * Establish a link-map control list for this request.
	 */
	if ((lmco = create_cntl(lml, 0)) == 0) {
		remove_alist(&palp, 1);
		return (NULL);
	}

	/*
	 * Load the associated object.
	 */
	dip->di_info = nlmp =
	    load_one(lml, lmco, palp, clmp, MODE(clmp), flags, hdl, in_nfavl);

	/*
	 * Remove any expanded pathname infrastructure.  Reduce the pending lazy
	 * dependency count of the caller, together with the link-map lists
	 * count of objects that still have lazy dependencies pending.
	 */
	remove_alist(&palp, 1);
	if (--LAZY(clmp) == 0)
		LIST(clmp)->lm_lazy--;

	/*
	 * Finish processing the objects associated with this request, and
	 * create an association between the caller and this dependency.
	 */
	if (nlmp && ((bind_one(clmp, nlmp, BND_NEEDED) == 0) ||
	    ((nlmp = analyze_lmc(lml, lmco, nlmp, clmp, in_nfavl)) == NULL) ||
	    (relocate_lmc(lml, lmco, clmp, nlmp, in_nfavl) == 0)))
		dip->di_info = nlmp = NULL;

	/*
	 * If this lazyload has failed, and we've created a new link-map
	 * control list to which this request has added objects, then remove
	 * all the objects that have been associated to this request.
	 */
	if ((nlmp == NULL) && (lmco != ALIST_OFF_DATA))
		remove_lmc(lml, clmp, lmco, name);

	/*
	 * Remove any temporary link-map control list.
	 */
	if (lmco != ALIST_OFF_DATA)
		remove_cntl(lml, lmco);

	/*
	 * If this lazy loading failed, record the fact, and bump the lazy
	 * counts.
	 */
	if (nlmp == NULL) {
		dip->di_flags |= FLG_DI_LAZYFAIL;
		if (LAZY(clmp)++ == 0)
			LIST(clmp)->lm_lazy++;
	}

	return (nlmp);
}

/*
 * Return the entry point of the ELF executable.
 */
static Addr
elf_entry_point(void)
{
	Rt_map	*lmp = lml_main.lm_head;
	Ehdr	*ehdr = (Ehdr *)ADDR(lmp);
	Addr	addr = (Addr)(ehdr->e_entry);

	if ((FLAGS(lmp) & FLG_RT_FIXED) == 0)
		addr += ADDR(lmp);

	return (addr);
}

/*
 * Determine if a dependency requires a particular version and if so verify
 * that the version exists in the dependency.
 */
int
elf_verify_vers(const char *name, Rt_map *clmp, Rt_map *nlmp)
{
	Verneed		*vnd = VERNEED(clmp);
	int		_num, num = VERNEEDNUM(clmp);
	char		*cstrs = (char *)STRTAB(clmp);
	Lm_list		*lml = LIST(clmp);

	/*
	 * Traverse the callers version needed information and determine if any
	 * specific versions are required from the dependency.
	 */
	DBG_CALL(Dbg_ver_need_title(LIST(clmp), NAME(clmp)));
	for (_num = 1; _num <= num; _num++,
	    vnd = (Verneed *)((Xword)vnd + vnd->vn_next)) {
		Half		cnt = vnd->vn_cnt;
		Vernaux		*vnap;
		char		*nstrs, *need;

		/*
		 * Determine if a needed entry matches this dependency.
		 */
		need = (char *)(cstrs + vnd->vn_file);
		if (strcmp(name, need) != 0)
			continue;

		if ((lml->lm_flags & LML_FLG_TRC_VERBOSE) &&
		    ((FLAGS1(clmp) & FL1_RT_LDDSTUB) == 0))
			(void) printf(MSG_INTL(MSG_LDD_VER_FIND), name);

		/*
		 * Validate that each version required actually exists in the
		 * dependency.
		 */
		nstrs = (char *)STRTAB(nlmp);

		for (vnap = (Vernaux *)((Xword)vnd + vnd->vn_aux); cnt;
		    cnt--, vnap = (Vernaux *)((Xword)vnap + vnap->vna_next)) {
			char		*version, *define;
			Verdef		*vdf = VERDEF(nlmp);
			ulong_t		_num, num = VERDEFNUM(nlmp);
			int		found = 0;

			/*
			 * Skip validation of versions that are marked
			 * INFO. This optimization is used for versions
			 * that are inherited by another version. Verification
			 * of the inheriting version is sufficient.
			 *
			 * Such versions are recorded in the object for the
			 * benefit of VERSYM entries that refer to them. This
			 * provides a purely diagnostic benefit.
			 */
			if (vnap->vna_flags & VER_FLG_INFO)
				continue;

			version = (char *)(cstrs + vnap->vna_name);
			DBG_CALL(Dbg_ver_need_entry(lml, 0, need, version));

			for (_num = 1; _num <= num; _num++,
			    vdf = (Verdef *)((Xword)vdf + vdf->vd_next)) {
				Verdaux		*vdap;

				if (vnap->vna_hash != vdf->vd_hash)
					continue;

				vdap = (Verdaux *)((Xword)vdf + vdf->vd_aux);
				define = (char *)(nstrs + vdap->vda_name);
				if (strcmp(version, define) != 0)
					continue;

				found++;
				break;
			}

			/*
			 * If we're being traced print out any matched version
			 * when the verbose (-v) option is in effect.  Always
			 * print any unmatched versions.
			 */
			if (lml->lm_flags & LML_FLG_TRC_ENABLE) {
				/* BEGIN CSTYLED */
				if (found) {
				    if (!(lml->lm_flags & LML_FLG_TRC_VERBOSE))
					continue;

				    (void) printf(MSG_ORIG(MSG_LDD_VER_FOUND),
					need, version, NAME(nlmp));
				} else {
				    if (rtld_flags & RT_FL_SILENCERR)
					continue;

				    (void) printf(MSG_INTL(MSG_LDD_VER_NFOUND),
					need, version);
				}
				/* END CSTYLED */
				continue;
			}

			/*
			 * If the version hasn't been found then this is a
			 * candidate for a fatal error condition.  Weak
			 * version definition requirements are silently
			 * ignored.  Also, if the image inspected for a version
			 * definition has no versioning recorded at all then
			 * silently ignore this (this provides better backward
			 * compatibility to old images created prior to
			 * versioning being available).  Both of these skipped
			 * diagnostics are available under tracing (see above).
			 */
			if ((found == 0) && (num != 0) &&
			    (!(vnap->vna_flags & VER_FLG_WEAK))) {
				eprintf(lml, ERR_FATAL,
				    MSG_INTL(MSG_VER_NFOUND), need, version,
				    NAME(clmp));
				return (0);
			}
		}
	}
	DBG_CALL(Dbg_ver_need_done(lml));
	return (1);
}

/*
 * Search through the dynamic section for DT_NEEDED entries and perform one
 * of two functions.  If only the first argument is specified then load the
 * defined shared object, otherwise add the link map representing the defined
 * link map the the dlopen list.
 */
static int
elf_needed(Lm_list *lml, Aliste lmco, Rt_map *clmp, int *in_nfavl)
{
	Alist		*palp = NULL;
	Dyn		*dyn;
	Dyninfo		*dip;
	Word		lmflags = lml->lm_flags;

	/*
	 * A DYNINFO() structure is created during link-map generation that
	 * parallels the DYN() information, and defines any flags that
	 * influence a dependencies loading.
	 */
	for (dyn = DYN(clmp), dip = DYNINFO(clmp);
	    !(dip->di_flags & FLG_DI_IGNORE); dyn++, dip++) {
		uint_t		flags = 0, silent = 0;
		const char	*name = dip->di_name;
		Rt_map		*nlmp = NULL;

		if ((dip->di_flags & FLG_DI_NEEDED) == 0)
			continue;

		/*
		 * Skip any deferred dependencies, unless ldd(1) has forced
		 * their processing.  By default, deferred dependencies are
		 * only processed when an explicit binding to an individual
		 * deferred reference is made.
		 */
		if ((dip->di_flags & FLG_DI_DEFERRED) &&
		    ((rtld_flags & RT_FL_DEFERRED) == 0))
			continue;

		/*
		 * NOTE, libc.so.1 can't be lazy loaded.  Although a lazy
		 * position flag won't be produced when a RTLDINFO .dynamic
		 * entry is found (introduced with the UPM in Solaris 10), it
		 * was possible to mark libc for lazy loading on previous
		 * releases.  To reduce the overhead of testing for this
		 * occurrence, only carry out this check for the first object
		 * on the link-map list (there aren't many applications built
		 * without libc).
		 */
		if ((dip->di_flags & FLG_DI_LAZY) && (lml->lm_head == clmp) &&
		    (strcmp(name, MSG_ORIG(MSG_FIL_LIBC)) == 0))
			dip->di_flags &= ~FLG_DI_LAZY;

		/*
		 * Don't bring in lazy loaded objects yet unless we've been
		 * asked to attempt to load all available objects (crle(1) sets
		 * LD_FLAGS=loadavail).  Even under RTLD_NOW we don't process
		 * this - RTLD_NOW will cause relocation processing which in
		 * turn might trigger lazy loading, but its possible that the
		 * object has a lazy loaded file with no bindings (i.e., it
		 * should never have been a dependency in the first place).
		 */
		if (dip->di_flags & FLG_DI_LAZY) {
			if ((lmflags & LML_FLG_LOADAVAIL) == 0) {
				LAZY(clmp)++;
				continue;
			}

			/*
			 * Silence any error messages - see description under
			 * elf_lookup_filtee().
			 */
			if ((rtld_flags & RT_FL_SILENCERR) == 0) {
				rtld_flags |= RT_FL_SILENCERR;
				silent = 1;
			}
		}

		DBG_CALL(Dbg_file_needed(clmp, name));

		/*
		 * If we're running under ldd(1), indicate that this dependency
		 * has been processed.  It doesn't matter whether the object is
		 * successfully loaded or not, this flag simply ensures that we
		 * don't repeatedly attempt to load an object that has already
		 * failed to load.  To do so would create multiple failure
		 * diagnostics for the same object under ldd(1).
		 */
		if (lml->lm_flags & LML_FLG_TRC_ENABLE)
			dip->di_flags |= FLG_DI_LDD_DONE;

		/*
		 * Identify any group permission requirements.
		 */
		if (dip->di_flags & FLG_DI_GROUP)
			flags = (FLG_RT_SETGROUP | FLG_RT_PUBHDL);

		/*
		 * Establish the objects name, load it and establish a binding
		 * with the caller.
		 */
		if ((elf_fix_name(name, clmp, &palp, AL_CNT_NEEDED, 0) == 0) ||
		    ((nlmp = load_one(lml, lmco, palp, clmp, MODE(clmp),
		    flags, 0, in_nfavl)) == NULL) ||
		    (bind_one(clmp, nlmp, BND_NEEDED) == 0))
			nlmp = NULL;

		/*
		 * Clean up any infrastructure, including the removal of the
		 * error suppression state, if it had been previously set in
		 * this routine.
		 */
		remove_alist(&palp, 0);

		if (silent)
			rtld_flags &= ~RT_FL_SILENCERR;

		if ((dip->di_info = (void *)nlmp) == NULL) {
			/*
			 * If the object could not be mapped, continue if error
			 * suppression is established or we're here with ldd(1).
			 */
			if ((MODE(clmp) & RTLD_CONFGEN) || (lmflags &
			    (LML_FLG_LOADAVAIL | LML_FLG_TRC_ENABLE)))
				continue;
			else {
				remove_alist(&palp, 1);
				return (0);
			}
		}
	}

	if (LAZY(clmp))
		lml->lm_lazy++;

	remove_alist(&palp, 1);
	return (1);
}

/*
 * A null symbol interpretor.  Used if a filter has no associated filtees.
 */
/* ARGSUSED0 */
static int
elf_null_find_sym(Slookup *slp, Sresult *srp, uint_t *binfo, int *in_nfavl)
{
	return (0);
}

/*
 * Disable filtee use.
 */
static void
elf_disable_filtee(Rt_map *lmp, Dyninfo *dip)
{
	if ((dip->di_flags & FLG_DI_SYMFLTR) == 0) {
		/*
		 * If this is an object filter, null out the reference name.
		 */
		if (OBJFLTRNDX(lmp) != FLTR_DISABLED) {
			REFNAME(lmp) = NULL;
			OBJFLTRNDX(lmp) = FLTR_DISABLED;

			/*
			 * Indicate that this filtee is no longer available.
			 */
			if (dip->di_flags & FLG_DI_STDFLTR)
				SYMINTP(lmp) = elf_null_find_sym;

		}
	} else if (dip->di_flags & FLG_DI_STDFLTR) {
		/*
		 * Indicate that this standard filtee is no longer available.
		 */
		if (SYMSFLTRCNT(lmp))
			SYMSFLTRCNT(lmp)--;
	} else {
		/*
		 * Indicate that this auxiliary filtee is no longer available.
		 */
		if (SYMAFLTRCNT(lmp))
			SYMAFLTRCNT(lmp)--;
	}
	dip->di_flags &= ~MSK_DI_FILTER;
}

/*
 * Find symbol interpreter - filters.
 * This function is called when the symbols from a shared object should
 * be resolved from the shared objects filtees instead of from within itself.
 *
 * A symbol name of 0 is used to trigger filtee loading.
 */
static int
_elf_lookup_filtee(Slookup *slp, Sresult *srp, uint_t *binfo, uint_t ndx,
    int *in_nfavl)
{
	const char	*name = slp->sl_name, *filtees;
	Rt_map		*clmp = slp->sl_cmap;
	Rt_map		*ilmp = slp->sl_imap;
	Pdesc		*pdp;
	int		any;
	Dyninfo		*dip = &DYNINFO(ilmp)[ndx];
	Lm_list		*lml = LIST(ilmp);
	Aliste		idx;

	/*
	 * Indicate that the filter has been used.  If a binding already exists
	 * to the caller, indicate that this object is referenced.  This insures
	 * we don't generate false unreferenced diagnostics from ldd -u/U or
	 * debugging.  Don't create a binding regardless, as this filter may
	 * have been dlopen()'ed.
	 */
	if (name && (ilmp != clmp)) {
		Word	tracing = (LIST(clmp)->lm_flags &
		    (LML_FLG_TRC_UNREF | LML_FLG_TRC_UNUSED));

		if (tracing || DBG_ENABLED) {
			Bnd_desc	*bdp;
			Aliste		idx;

			FLAGS1(ilmp) |= FL1_RT_USED;

			if ((tracing & LML_FLG_TRC_UNREF) || DBG_ENABLED) {
				for (APLIST_TRAVERSE(CALLERS(ilmp), idx, bdp)) {
					if (bdp->b_caller == clmp) {
						bdp->b_flags |= BND_REFER;
						break;
					}
				}
			}
		}
	}

	/*
	 * If this is the first call to process this filter, establish the
	 * filtee list.  If a configuration file exists, determine if any
	 * filtee associations for this filter, and its filtee reference, are
	 * defined.  Otherwise, process the filtee reference.  Any token
	 * expansion is also completed at this point (i.e., $PLATFORM).
	 */
	filtees = dip->di_name;
	if (dip->di_info == NULL) {
		if (rtld_flags2 & RT_FL2_FLTCFG) {
			elf_config_flt(lml, PATHNAME(ilmp), filtees,
			    (Alist **)&dip->di_info, AL_CNT_FILTEES);
		}
		if (dip->di_info == NULL) {
			DBG_CALL(Dbg_file_filter(lml, NAME(ilmp), filtees, 0));
			if ((lml->lm_flags &
			    (LML_FLG_TRC_VERBOSE | LML_FLG_TRC_SEARCH)) &&
			    ((FLAGS1(ilmp) & FL1_RT_LDDSTUB) == 0))
				(void) printf(MSG_INTL(MSG_LDD_FIL_FILTER),
				    NAME(ilmp), filtees);

			if (expand_paths(ilmp, filtees, (Alist **)&dip->di_info,
			    AL_CNT_FILTEES, 0, 0) == 0) {
				elf_disable_filtee(ilmp, dip);
				return (0);
			}
		}
	}

	/*
	 * Traverse the filtee list, dlopen()'ing any objects specified and
	 * using their group handle to lookup the symbol.
	 */
	any = 0;
	for (ALIST_TRAVERSE((Alist *)dip->di_info, idx, pdp)) {
		int	mode;
		Grp_hdl	*ghp;
		Rt_map	*nlmp = NULL;

		if (pdp->pd_plen == 0)
			continue;

		/*
		 * Establish the mode of the filtee from the filter.  As filtees
		 * are loaded via a dlopen(), make sure that RTLD_GROUP is set
		 * and the filtees aren't global.  It would be nice to have
		 * RTLD_FIRST used here also, but as filters got out long before
		 * RTLD_FIRST was introduced it's a little too late now.
		 */
		mode = MODE(ilmp) | RTLD_GROUP;
		mode &= ~RTLD_GLOBAL;

		/*
		 * Insure that any auxiliary filter can locate symbols from its
		 * caller.
		 */
		if (dip->di_flags & FLG_DI_AUXFLTR)
			mode |= RTLD_PARENT;

		/*
		 * Process any capability directory.  Establish a new link-map
		 * control list from which to analyze any newly added objects.
		 */
		if ((pdp->pd_info == NULL) && (pdp->pd_flags & PD_TKN_CAP)) {
			const char	*dir = pdp->pd_pname;
			Aliste		lmco;

			/*
			 * Establish a link-map control list for this request.
			 */
			if ((lmco = create_cntl(lml, 0)) == 0)
				return (0);

			/*
			 * Determine the capability filtees.  If none can be
			 * found, provide suitable diagnostics.
			 */
			DBG_CALL(Dbg_cap_filter(lml, dir, ilmp));
			if (cap_filtees((Alist **)&dip->di_info, idx, dir,
			    lmco, ilmp, clmp, filtees, mode,
			    (FLG_RT_PUBHDL | FLG_RT_CAP), in_nfavl) == 0) {
				if ((lml->lm_flags & LML_FLG_TRC_ENABLE) &&
				    (dip->di_flags & FLG_DI_AUXFLTR) &&
				    (rtld_flags & RT_FL_WARNFLTR)) {
					(void) printf(
					    MSG_INTL(MSG_LDD_CAP_NFOUND), dir);
				}
				DBG_CALL(Dbg_cap_filter(lml, dir, 0));
			}

			/*
			 * Re-establish the originating path name descriptor,
			 * as the expansion of capabilities filtees may have
			 * re-allocated the controlling Alist.  Mark this
			 * original pathname descriptor as unused so that the
			 * descriptor isn't revisited for processing.  Any real
			 * capabilities filtees have been added as new pathname
			 * descriptors following this descriptor.
			 */
			pdp = alist_item((Alist *)dip->di_info, idx);
			pdp->pd_flags &= ~PD_TKN_CAP;
			pdp->pd_plen = 0;

			/*
			 * Now that any capability objects have been processed,
			 * remove any temporary link-map control list.
			 */
			if (lmco != ALIST_OFF_DATA)
				remove_cntl(lml, lmco);
		}

		if (pdp->pd_plen == 0)
			continue;

		/*
		 * Process an individual filtee.
		 */
		if (pdp->pd_info == NULL) {
			const char	*filtee = pdp->pd_pname;
			int		audit = 0;

			DBG_CALL(Dbg_file_filtee(lml, NAME(ilmp), filtee, 0));

			ghp = NULL;

			/*
			 * Determine if the reference link map is already
			 * loaded.  As an optimization compare the filtee with
			 * our interpretor.  The most common filter is
			 * libdl.so.1, which is a filter on ld.so.1.
			 */
#if	defined(_ELF64)
			if (strcmp(filtee, MSG_ORIG(MSG_PTH_RTLD_64)) == 0) {
#else
			if (strcmp(filtee, MSG_ORIG(MSG_PTH_RTLD)) == 0) {
#endif
				uint_t	hflags, rdflags, cdflags;

				/*
				 * Establish any flags for the handle (Grp_hdl).
				 *
				 *  -	This is a special, public, ld.so.1
				 *	handle.
				 *  -	Only the first object on this handle
				 *	can supply symbols.
				 *  -	This handle provides a filtee.
				 *
				 * Essentially, this handle allows a caller to
				 * reference the dl*() family of interfaces from
				 * ld.so.1.
				 */
				hflags = (GPH_PUBLIC | GPH_LDSO |
				    GPH_FIRST | GPH_FILTEE);

				/*
				 * Establish the flags for the referenced
				 * dependency descriptor (Grp_desc).
				 *
				 *  -	ld.so.1 is available for dlsym().
				 *  -	ld.so.1 is available to relocate
				 *	against.
				 *  -	There's no need to add an dependencies
				 *	to this handle.
				 */
				rdflags = (GPD_DLSYM | GPD_RELOC);

				/*
				 * Establish the flags for this callers