On Wed, Jan 15, 2020 at 01:19:16PM +0100, Laurent Vivier wrote: > Le 07/01/2020 à 15:50, Laurent Vivier a écrit : > > Hi, > > > > this change is simple, easy to read and understand but it is really > > needed by user space application interpreter to know the status of the > > system configuration. > > > > Could we have a comment saying if there is a problem or if it is good to > > be merged? > > Anyone? FWIW, one thing that looks worrying here is that these bits become userland ABI after this patch - specific values passed in that thing can't be changed. And no a single mention of that in fs/binfmt_misc.c, leaving a nasty trap. As far as one can tell, their values are fair game for reordering, etc. - not even visible outside of fs/binfmt_misc.c; purely internal constants. And the effect of such modifications after your patch will not be "everything breaks, patch gets caught by somebody's tests" - it will be a quiet breakage for some users. > >> #define MISC_FMT_OPEN_BINARY (1 << 30) > >> #define MISC_FMT_CREDENTIALS (1 << 29) > >> #define MISC_FMT_OPEN_FILE (1 << 28) > >> +#define MISC_FMT_FLAGS_MASK (MISC_FMT_PRESERVE_ARGV0 | MISC_FMT_OPEN_BINARY | \ > >> + MISC_FMT_CREDENTIALS | MISC_FMT_OPEN_FILE) IOW, you are making those parts of userland ABI cast in stone forever. Whether this bit assignment does make sense or not, such things really should not be hidden.
