Messages in this thread | | | Date | Thu, 18 Aug 2022 22:44:02 +0200 | Subject | Re: + lib-dump_stack-add-dump_stack_print_cmdline-and-wire-up-in-dump_stack_print_info.patch added to mm-nonmm-unstable branch | From | Helge Deller <> |
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On 8/18/22 07:50, Alexey Dobriyan wrote: > On Wed, Aug 17, 2022 at 12:55:40PM -0700, Andrew Morton wrote: >> Add the function dump_stack_print_cmdline() which can be used by arch code >> to print the command line of the current processs. This function is >> useful in arch code when dumping information for a faulting process. >> >> Wire this function up in the dump_stack_print_info() function to include >> the dumping of the command line for architectures which use >> dump_stack_print_info(). >> >> As an example, with this patch a failing glibc testcase (which uses >> ld.so.1 as starting program) up to now reported just "ld.so.1" failing: >> >> do_page_fault() command='ld.so.1' type=15 address=0x565921d8 in libc.so[f7339000+1bb000] >> trap #15: Data TLB miss fault, vm_start = 0x0001a000, vm_end = 0x0001b000 >> >> and now it reports in addition: >> >> ld.so.1[1151] cmdline: /home/gnu/glibc/objdir/elf/ld.so.1 --library-path = >> /home/gnu/glibc/objdir:/home/gnu/glibc/objdir/math:/home/gnu/ >> /home/gnu/glibc/objdir/malloc/tst-safe-linking-malloc-hugetlb1 >> >> Josh Triplett noted that dumping such command line parameters into syslog >> may theoretically lead to information disclosure. That's why this patch >> checks the value of the kptr_restrict sysctl variable and will not print >> any information if kptr_restrict==2, and will not show the program >> parameters if kptr_restrict==1. > > This whole feature needs its own sysctl. How is "kernel pointer restriction" > is related to "dump full command line to syslog at segfault"?
Usually if you enable one of those b/c of security concerns, then you probably want to enable the other as well. So, to some degree it makes sense. The original discussion is here: https://lore.kernel.org/lkml/a0bf15a2-2f9c-5603-3adb-ffa705572a92@gmx.de/T/#mfa009226e45e2420db5e7f4e980e381be6434448
But I'm fine with adding another sysctl too, if that's the preferred solution. If so, any suggestions? And, the sysctl could be added later too...
> I've checked my non-customised Fedora system and kptr_restrict is 0. > It looks like Centos and Ubuntu ship with kptr_restrict=1.
... which seems ok then, IMHO.
> There was a patch recently to hide specific command line options from > /proc/*/cmdline because some programs accept passwords from the command > line.
Do you have a link to that?
Helge
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