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Support for a new environment variable, LD_ELF_HINTS_PATH for overriding

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the rtld hints file.  This environment variable would be unset if the
process is considered as tainted with setuid/setgid.  This feature gives
a convenient way of using a custom set of shared library that is not
located in the default location and switch back.

Feature requested by:	iXsystems
Original patch by:	John Hixson
MFC after:		2 weeks
This commit is contained in:
Xin LI 2009-03-23 16:49:00 +00:00
parent 485cf78203
commit 569e2ef6a9
2 changed files with 15 additions and 3 deletions
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7
libexec/rtld-elf/rtld.1
View File

@ -28,7 +28,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd May 15, 2008
.Dd March 23, 2009
.Dt RTLD 1
.Os
.Sh NAME
@ -116,6 +116,11 @@ If set, disables the use of
and
.Ev LD_LIBMAP .
This variable is unset for set-user-ID and set-group-ID programs.
.It Ev LD_ELF_HINTS_PATH
This variable will override the default location of
.Dq hints
file.
This variable is unset for set-user-ID and set-group-ID programs.
.It Ev LD_LIBRARY_PATH
A colon separated list of directories, overriding the default search path
for shared libraries.

11
libexec/rtld-elf/rtld.c
View File

@ -162,6 +162,7 @@ static char *ld_debug; /* Environment variable for debugging */
static char *ld_library_path; /* Environment variable for search path */
static char *ld_preload; /* Environment variable for libraries to
load first */
static char *ld_elf_hints_path; /* Environment variable for alternative hints path */
static char *ld_tracing; /* Called from ldd to print libs */
static char *ld_utrace; /* Use utrace() to log events. */
static Obj_Entry *obj_list; /* Head of linked list of shared objects */
@ -370,17 +371,23 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
unsetenv(LD_ "LIBRARY_PATH");
unsetenv(LD_ "LIBMAP_DISABLE");
unsetenv(LD_ "DEBUG");
unsetenv(LD_ "ELF_HINTS_PATH");
}
ld_debug = getenv(LD_ "DEBUG");
libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL;
libmap_override = getenv(LD_ "LIBMAP");
ld_library_path = getenv(LD_ "LIBRARY_PATH");
ld_preload = getenv(LD_ "PRELOAD");
ld_elf_hints_path = getenv(LD_ "ELF_HINTS_PATH");
dangerous_ld_env = libmap_disable || (libmap_override != NULL) ||
(ld_library_path != NULL) || (ld_preload != NULL);
(ld_library_path != NULL) || (ld_preload != NULL) ||
(ld_elf_hints_path != NULL);
ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS");
ld_utrace = getenv(LD_ "UTRACE");
if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
ld_elf_hints_path = _PATH_ELF_HINTS;
if (ld_debug != NULL && *ld_debug != '\0')
debug = 1;
dbg("%s is initialized, base address = %p", __progname,
@ -1240,7 +1247,7 @@ gethints(void)
/* Keep from trying again in case the hints file is bad. */
hints = "";
if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
return NULL;
if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
hdr.magic != ELFHINTS_MAGIC ||