This set of changes implements kernel_execve to remove the need for kernel threads to pass in pointers to in-kernel data structures to functions that take __user pointers. Which is part of the greater removal of set_fs work. This set of changes makes do_execve static and so I have updated the comments. This affects the comments in the x86 entry point code and the comments in tomoyo. I believe I have updated them correctly. If not please let me know. I have moved the calls of copy_strings before the call of security_bprm_creds_for_exec. Which might be of interest to the security folks. I can't see that it matters but I have copied the security folks just to be certain. By moving the initialization of the new stack that copy_strings does earlier it becomes possible to copy all of the parameters to exec before anything else is done which makes it possible to have one function kernel_execve that uncondtionally handles copying parameters from kernel space, and another function do_execveat_common which handles copying parameters from userspace. This work was inspired by Christoph Hellwig's similar patchset, which my earlier work to remove the file parameter to do_execveat_common conflicted with. https://lore.kernel.org/linux-fsdevel/20200627072704.2447163-1-hch@xxxxxx/ I figured that after causing all of that trouble for the set_fs work the least I could do is implement the change myself. The big practical change from Christoph's work is that he did not separate out the copying of parameters from the rest of the work of exec, which did not help the maintainability of the code. Please let me know if you see something wrong. This set of changes is against my exec-next branch: https://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git exec-next Eric W. Biederman (7): exec: Remove unnecessary spaces from binfmts.h exec: Factor out alloc_bprm exec: Move initialization of bprm->filename into alloc_bprm exec: Move bprm_mm_init into alloc_bprm exec: Factor bprm_execve out of do_execve_common exec: Factor bprm_stack_limits out of prepare_arg_pages exec: Implement kernel_execve arch/x86/entry/entry_32.S | 2 +- arch/x86/entry/entry_64.S | 2 +- arch/x86/kernel/unwind_frame.c | 2 +- fs/exec.c | 301 ++++++++++++++++++++++++++++------------- include/linux/binfmts.h | 20 ++- init/main.c | 4 +- kernel/umh.c | 6 +- security/tomoyo/common.h | 2 +- security/tomoyo/domain.c | 4 +- security/tomoyo/tomoyo.c | 4 +- 10 files changed, 224 insertions(+), 123 deletions(-) Eric
