[RFC][PATCH v6 00/20] Implementation of RTLD_SHARED for dlmopen
Vivek Das Mohapatra
vivek@collabora.com
Tue Dec 15 18:44:40 GMT 2020
This is a revision of a previous patchset that I posted here
regarding https://sourceware.org/bugzilla/show_bug.cgi?id=22745
Introduction:
=======================================================================
As discussed in the URL above dlmopen requires a mechanism for
[optionally] sharing some objects between more than one namespace.
The following patchset provides an implementation for this: If an
object is loaded with the new RTLD_SHARED flag we instead ensure
that a "master" copy exists (and is flagged as no-delete) in the
main namespace and a thin wrapper or clone is placed in the target
namespace.
This patch series should address all the comments received on the
earlier (v1) series, and fixes a bug in the previous (v2) series
which left the r_debug struct in an inconsistent state when creating
a proxy triggered the initial load of a DSO into the main namespace.
=======================================================================
In addition this patch series implements the following:
- dlmopen will implicitly apply RTLD_SHARED to the libc/libpthread group
(requires a patched binutils/ld so that the libc family DSOs can
be flagged as requiring this behaviour)
- binutils patchset accepted upstream;
- https://sourceware.org/git/?p=binutils-gdb.git
- commit 8a87b2791181eb7fc1533ffaeb95df8d87d41493
- LD_AUDIT paths will NOT apply this implict sharing rule:
audit libraries will continue to be completely isolated.
- The mechanism for tagging DSOs as implicitly shared has been changed
from a DT_FLAGS_1 flag to a DT_VALRNGHI/LO range dynamic section tag.
(Based on feedback on the binutils side of this patch series).
- DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
- A flag RTLD_ISOLATE which is used inernally to suppress RTLD_SHARED
behaviour when audit libraries are being loaded, and is also made available
to users who really want a completely separate copy of glibc in their new
namespace.
- Tests for the new dlmopen behaviour
I have not yet implemented, but plan to address once this series is
accepted/acceptable:
- Sensible RTLD_GLOBAL semantics for dlmopened DSOs in non-base namespaces
- dl_iterate_ns_phdr (cf dl_iterate_phdr but taking a namespace argument)
Vivek Das Mohapatra (20):
Declare and describe the dlmopen RTLD_SHARED flag
include/link.h: Update the link_map struct to allow proxies
elf/dl-object.c: Implement a helper function to proxy link_map entries
elf/dl-load.c, elf-dl-open.c: Implement RTLD_SHARED dlmopen proxying
elf/dl-fini.c: Handle proxy link_map entries in the shutdown path
elf/dl-init.c: Skip proxied link map entries in the dl init path
elf/dl-open.c: Don't try libc linit in namespaces with no libc mapping
elf/dl-open.c: when creating a proxy check the libc_map in NS 0
Define a new dynamic section tag - DT_GNU_FLAGS_1
Abstract the loaded-DSO search code into a private helper function
Compare loaded DSOs by file ID and check for DF_GNU_1_UNIQUE
Use the new DSO finder helper function since we have it
Use the DSO search helper to check for preloaded DT_GNU_UNIQUE DSOs
When loading DSOs into alternate namespaces check for DT_GNU_UNIQUE
Suppress audit calls when a (new) namespace is empty
Suppress inter-namespace DSO sharing for audit libraries
dlsym, dlvsym should be able to look up symbols via DSO proxies
Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE dynamic section+flag to glibc DSOs
Add dlmopen / RTLD_SHARED tests
Restore separate libc loading for the TLS/namespace storage test
Makeconfig | 1 +
Makerules | 2 +-
bits/dlfcn.h | 10 +
elf/Makefile | 97 ++-
elf/dl-close.c | 43 +-
elf/dl-fini.c | 6 +-
elf/dl-init.c | 4 +-
elf/dl-load.c | 227 +++++-
elf/dl-object.c | 84 +++
elf/dl-open.c | 108 ++-
elf/dl-sym.c | 14 +
elf/elf.h | 7 +-
elf/get-dynamic-info.h | 12 +
elf/rtld.c | 2 +-
elf/tst-dlmopen-auditmod.c | 23 +
elf/tst-dlmopen-common.h | 33 +
elf/tst-dlmopen-main.h | 1022 ++++++++++++++++++++++++++
elf/tst-dlmopen-modules.h | 20 +
elf/tst-dlmopen-rtld-audit-shared1.c | 11 +
elf/tst-dlmopen-rtld-audit-shared2.c | 11 +
elf/tst-dlmopen-rtld-audit-shared3.c | 11 +
elf/tst-dlmopen-rtld-audit-shared4.c | 11 +
elf/tst-dlmopen-rtld-audit-shared5.c | 11 +
elf/tst-dlmopen-rtld-audit-shared6.c | 11 +
elf/tst-dlmopen-rtld-audit-unique1.c | 11 +
elf/tst-dlmopen-rtld-audit-unique2.c | 11 +
elf/tst-dlmopen-rtld-audit-unique3.c | 11 +
elf/tst-dlmopen-rtld-audit-unique4.c | 11 +
elf/tst-dlmopen-rtld-audit-unique5.c | 11 +
elf/tst-dlmopen-rtld-audit-unique6.c | 11 +
elf/tst-dlmopen-rtld-shared1.c | 11 +
elf/tst-dlmopen-rtld-shared1.h | 65 ++
elf/tst-dlmopen-rtld-shared2.c | 11 +
elf/tst-dlmopen-rtld-shared2.h | 67 ++
elf/tst-dlmopen-rtld-shared3.c | 11 +
elf/tst-dlmopen-rtld-shared3.h | 44 ++
elf/tst-dlmopen-rtld-shared4.c | 11 +
elf/tst-dlmopen-rtld-shared4.h | 15 +
elf/tst-dlmopen-rtld-shared5.c | 11 +
elf/tst-dlmopen-rtld-shared5.h | 26 +
elf/tst-dlmopen-rtld-shared6.c | 11 +
elf/tst-dlmopen-rtld-shared6.h | 37 +
elf/tst-dlmopen-rtld-unique1.c | 11 +
elf/tst-dlmopen-rtld-unique1.h | 87 +++
elf/tst-dlmopen-rtld-unique2.c | 11 +
elf/tst-dlmopen-rtld-unique2.h | 26 +
elf/tst-dlmopen-rtld-unique3.c | 11 +
elf/tst-dlmopen-rtld-unique3.h | 14 +
elf/tst-dlmopen-rtld-unique4.c | 11 +
elf/tst-dlmopen-rtld-unique4.h | 15 +
elf/tst-dlmopen-rtld-unique5.c | 11 +
elf/tst-dlmopen-rtld-unique5.h | 59 ++
elf/tst-dlmopen-rtld-unique6.c | 11 +
elf/tst-dlmopen-rtld-unique6.h | 52 ++
elf/tst-dlmopen-sharedmod-norm.c | 11 +
elf/tst-dlmopen-sharedmod-uniq.c | 11 +
elf/tst-dlmopen-std-do-test.h | 11 +
elf/tst-tls-ie-dlmopen.c | 4 +-
iconvdata/Makefile | 1 +
include/elf.h | 2 +
include/link.h | 7 +-
nptl/Makefile | 2 +-
sysdeps/generic/ldsodefs.h | 9 +
sysdeps/mips/bits/dlfcn.h | 10 +
64 files changed, 2492 insertions(+), 62 deletions(-)
create mode 100644 elf/tst-dlmopen-auditmod.c
create mode 100644 elf/tst-dlmopen-common.h
create mode 100644 elf/tst-dlmopen-main.h
create mode 100644 elf/tst-dlmopen-modules.h
create mode 100644 elf/tst-dlmopen-rtld-audit-shared1.c
create mode 100644 elf/tst-dlmopen-rtld-audit-shared2.c
create mode 100644 elf/tst-dlmopen-rtld-audit-shared3.c
create mode 100644 elf/tst-dlmopen-rtld-audit-shared4.c
create mode 100644 elf/tst-dlmopen-rtld-audit-shared5.c
create mode 100644 elf/tst-dlmopen-rtld-audit-shared6.c
create mode 100644 elf/tst-dlmopen-rtld-audit-unique1.c
create mode 100644 elf/tst-dlmopen-rtld-audit-unique2.c
create mode 100644 elf/tst-dlmopen-rtld-audit-unique3.c
create mode 100644 elf/tst-dlmopen-rtld-audit-unique4.c
create mode 100644 elf/tst-dlmopen-rtld-audit-unique5.c
create mode 100644 elf/tst-dlmopen-rtld-audit-unique6.c
create mode 100644 elf/tst-dlmopen-rtld-shared1.c
create mode 100644 elf/tst-dlmopen-rtld-shared1.h
create mode 100644 elf/tst-dlmopen-rtld-shared2.c
create mode 100644 elf/tst-dlmopen-rtld-shared2.h
create mode 100644 elf/tst-dlmopen-rtld-shared3.c
create mode 100644 elf/tst-dlmopen-rtld-shared3.h
create mode 100644 elf/tst-dlmopen-rtld-shared4.c
create mode 100644 elf/tst-dlmopen-rtld-shared4.h
create mode 100644 elf/tst-dlmopen-rtld-shared5.c
create mode 100644 elf/tst-dlmopen-rtld-shared5.h
create mode 100644 elf/tst-dlmopen-rtld-shared6.c
create mode 100644 elf/tst-dlmopen-rtld-shared6.h
create mode 100644 elf/tst-dlmopen-rtld-unique1.c
create mode 100644 elf/tst-dlmopen-rtld-unique1.h
create mode 100644 elf/tst-dlmopen-rtld-unique2.c
create mode 100644 elf/tst-dlmopen-rtld-unique2.h
create mode 100644 elf/tst-dlmopen-rtld-unique3.c
create mode 100644 elf/tst-dlmopen-rtld-unique3.h
create mode 100644 elf/tst-dlmopen-rtld-unique4.c
create mode 100644 elf/tst-dlmopen-rtld-unique4.h
create mode 100644 elf/tst-dlmopen-rtld-unique5.c
create mode 100644 elf/tst-dlmopen-rtld-unique5.h
create mode 100644 elf/tst-dlmopen-rtld-unique6.c
create mode 100644 elf/tst-dlmopen-rtld-unique6.h
create mode 100644 elf/tst-dlmopen-sharedmod-norm.c
create mode 100644 elf/tst-dlmopen-sharedmod-uniq.c
create mode 100644 elf/tst-dlmopen-std-do-test.h
--
2.20.1
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