From 1f702603e7125a390b5cdf5ce00539781cfcc86a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 20 Nov 2020 17:14:19 -0600 Subject: exec: Simplify unshare_files Now that exec no longer needs to return the unshared files to their previous value there is no reason to return displaced. Instead when unshare_fd creates a copy of the file table, call put_files_struct before returning from unshare_files. Acked-by: Christian Brauner v1: https://lkml.kernel.org/r/20200817220425.9389-2-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20201120231441.29911-2-ebiederm@xmission.com Signed-off-by: Eric W. Biederman --- fs/coredump.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'fs/coredump.c') diff --git a/fs/coredump.c b/fs/coredump.c index 0cd9056d79cc..abf807235262 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -585,7 +585,6 @@ void do_coredump(const kernel_siginfo_t *siginfo) int ispipe; size_t *argv = NULL; int argc = 0; - struct files_struct *displaced; /* require nonrelative corefile path and be extra careful */ bool need_suid_safe = false; bool core_dumped = false; @@ -791,11 +790,9 @@ void do_coredump(const kernel_siginfo_t *siginfo) } /* get us an unshared descriptor table; almost always a no-op */ - retval = unshare_files(&displaced); + retval = unshare_files(); if (retval) goto close_fail; - if (displaced) - put_files_struct(displaced); if (!dump_interrupted()) { /* * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would -- cgit v1.2.3 From c39ab6de227306f331b47e7b6b51c2c7eaf0eeaf Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 25 Nov 2020 15:51:32 -0600 Subject: coredump: Document coredump code exclusively used by cell spufs Oleg Nesterov recently asked[1] why is there an unshare_files in do_coredump. After digging through all of the callers of lookup_fd it turns out that it is arch/powerpc/platforms/cell/spufs/coredump.c:coredump_next_context that needs the unshare_files in do_coredump. Looking at the history[2] this code was also the only piece of coredump code that required the unshare_files when the unshare_files was added. Looking at that code it turns out that cell is also the only architecture that implements elf_coredump_extra_notes_size and elf_coredump_extra_notes_write. I looked at the gdb repo[3] support for cell has been removed[4] in binutils 2.34. Geoff Levand reports he is still getting questions on how to run modern kernels on the PS3, from people using 3rd party firmware so this code is not dead. According to Wikipedia the last PS3 shipped in Japan sometime in 2017. So it will probably be a little while before everyone's hardware dies. Add some comments briefly documenting the coredump code that exists only to support cell spufs to make it easier to understand the coredump code. Eventually the hardware will be dead, or their won't be userspace tools, or the coredump code will be refactored and it will be too difficult to update a dead architecture and these comments make it easy to tell where to pull to remove cell spufs support. [1] https://lkml.kernel.org/r/20201123175052.GA20279@redhat.com [2] 179e037fc137 ("do_coredump(): make sure that descriptor table isn't shared") [3] git://sourceware.org/git/binutils-gdb.git [4] abf516c6931a ("Remove Cell Broadband Engine debugging support"). Link: https://lkml.kernel.org/r/87h7pdnlzv.fsf_-_@x220.int.ebiederm.org Signed-off-by: Eric W. Biederman --- fs/binfmt_elf.c | 2 ++ fs/coredump.c | 1 + 2 files changed, 3 insertions(+) (limited to 'fs/coredump.c') diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index b6b3d052ca86..c1996f0aeaed 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -2198,6 +2198,7 @@ static int elf_core_dump(struct coredump_params *cprm) { size_t sz = get_note_info_size(&info); + /* For cell spufs */ sz += elf_coredump_extra_notes_size(); phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL); @@ -2261,6 +2262,7 @@ static int elf_core_dump(struct coredump_params *cprm) if (!write_note_info(&info, cprm)) goto end_coredump; + /* For cell spufs */ if (elf_coredump_extra_notes_write(cprm)) goto end_coredump; diff --git a/fs/coredump.c b/fs/coredump.c index abf807235262..3ff17eea812e 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -790,6 +790,7 @@ void do_coredump(const kernel_siginfo_t *siginfo) } /* get us an unshared descriptor table; almost always a no-op */ + /* The cell spufs coredump code reads the file descriptor tables */ retval = unshare_files(); if (retval) goto close_fail; -- cgit v1.2.3