This patch set adds execveat(2) for x86, and is derived from Meredydd Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528). The primary aim of adding an execveat syscall is to allow an implementation of fexecve(3) that does not rely on the /proc filesystem. The current glibc version of fexecve(3) is implemented via /proc, which causes problems in sandboxed or otherwise restricted environments. Given the desire for a /proc-free fexecve() implementation, HPA suggested (https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be an appropriate generalization. Also, having a new syscall means that it can take a flags argument without back-compatibility concerns. The current implementation just defines the AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be added in future -- for example, flags for new namespaces (as suggested at https://lkml.org/lkml/2006/7/11/474). Related history: - https://lkml.org/lkml/2006/12/27/123 is an example of someone realizing that fexecve() is likely to fail in a chroot environment. - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered documenting the /proc requirement of fexecve(3) in its manpage, to "prevent other people from wasting their time". - https://bugzilla.kernel.org/show_bug.cgi?id=74481 documented that it's not possible to fexecve() a file descriptor for a script with close-on-exec set (which is possible with the implementation here). - https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a problem where a process that did setuid() could not fexecve() because it no longer had access to /proc/self/fd; this has since been fixed. Changes since v4, suggested by Eric W. Biederman: - Use empty filename with AT_EMPTY_PATH flag rather than NULL pathname to request fexecve-like behaviour. - Build pathname as "/dev/fd/<fd>/<filename>" (or "/dev/fd/<fd>") rather than using d_path(). - Patch against v3.17 (bfe01a5ba249) Changes since Meredydd's v3 patch: - Added a selftest. - Added a man page. - Left open_exec() signature untouched to reduce patch impact elsewhere (as suggested by Al Viro). - Filled in bprm->filename with d_path() into a buffer, to avoid use of potentially-ephemeral dentry->d_name. - Patch against v3.14 (455c6fdbd21916). David Drysdale (2): syscalls,x86: implement execveat() system call syscalls,x86: add selftest for execveat(2) arch/x86/ia32/audit.c | 1 + arch/x86/ia32/ia32entry.S | 1 + arch/x86/kernel/audit_64.c | 1 + arch/x86/kernel/entry_64.S | 28 +++ arch/x86/syscalls/syscall_32.tbl | 1 + arch/x86/syscalls/syscall_64.tbl | 2 + arch/x86/um/sys_call_table_64.c | 1 + fs/exec.c | 130 ++++++++++++-- fs/namei.c | 2 +- include/linux/compat.h | 3 + include/linux/fs.h | 1 + include/linux/sched.h | 4 + include/linux/syscalls.h | 4 + include/uapi/asm-generic/unistd.h | 4 +- kernel/sys_ni.c | 3 + lib/audit.c | 3 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/exec/.gitignore | 6 + tools/testing/selftests/exec/Makefile | 22 +++ tools/testing/selftests/exec/execveat.c | 295 ++++++++++++++++++++++++++++++++ 20 files changed, 497 insertions(+), 16 deletions(-) create mode 100644 tools/testing/selftests/exec/.gitignore create mode 100644 tools/testing/selftests/exec/Makefile create mode 100644 tools/testing/selftests/exec/execveat.c -- 2.1.0.rc2.206.gedb03e5 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
