[PATCH 0/1] MR366: loader: Refactor argv/envp/auxv management.
Collect scattered variables holding stack addresses (e.g. pargc, argv, envp, auxv) in one place. This facilitates modifying stack values (e.g. removing argv[0], switching stacks due to address conflict with reserved regions) without leaving pointer variables stale. Signed-off-by: Jinoh Kang <jinoh.kang.kr(a)gmail.com> -- https://gitlab.winehq.org/wine/wine/-/merge_requests/366
From: Jinoh Kang <jinoh.kang.kr(a)gmail.com> Collect scattered variables holding stack addresses (e.g. pargc, argv, envp, auxv) in one place. This facilitates modifying stack values (e.g. removing argv[0], switching stacks due to address conflict with reserved regions) without leaving pointer variables stale. Signed-off-by: Jinoh Kang <jinoh.kang.kr(a)gmail.com> --- loader/preloader.c | 146 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 115 insertions(+), 31 deletions(-) diff --git a/loader/preloader.c b/loader/preloader.c index 585be50624f..c3dae88ecd0 100644 --- a/loader/preloader.c +++ b/loader/preloader.c @@ -164,6 +164,25 @@ struct wld_auxv } a_un; }; +/* Aggregates information about initial program stack and variables + * (e.g. argv and envp) that reside in it. + */ +struct stackarg_info +{ + void *stack; + int argc; + char **argv; + char **envp; + struct wld_auxv *auxv; + struct wld_auxv *auxv_end; +}; + +/* Currently only contains the main stackarg_info. */ +struct preloader_state +{ + struct stackarg_info s; +}; + /* * The __bb_init_func is an empty function only called when file is * compiled with gcc flags "-fprofile-arcs -ftest-coverage". This @@ -674,6 +693,13 @@ static inline void *wld_memset( void *dest, int val, size_t len ) return dest; } +static size_t wld_strlen( const char *str ) +{ + const char *ptr = str; + while (*ptr) ptr++; + return ptr - str; +} + /* * wld_printf - just the basics * @@ -794,6 +820,74 @@ static void dump_auxiliary( struct wld_auxv *av ) } #endif +/* + * parse_stackargs + * + * parse out the initial stack for argv, envp, and etc., and store the + * information into the given stackarg_info structure. + */ +static void parse_stackargs( struct stackarg_info *outinfo, void *stack ) +{ + int argc; + char **argv, **envp, **env_end; + struct wld_auxv *auxv, *auxv_end; + + argc = *(int *)stack; + argv = (char **)stack + 1; + envp = argv + (unsigned int)argc + 1; + + env_end = envp; + while (*env_end++) + ; + auxv = (struct wld_auxv *)env_end; + + auxv_end = auxv; + while ((auxv_end++)->a_type != AT_NULL) + ; + + outinfo->stack = stack; + outinfo->argc = argc; + outinfo->argv = argv; + outinfo->envp = envp; + outinfo->auxv = auxv; + outinfo->auxv_end = auxv_end; +} + +/* + * stackargs_getenv + * + * Retrieve the value of an environment variable from stackarg_info. + */ +static char *stackargs_getenv( const struct stackarg_info *info, const char *name ) +{ + size_t namelen = wld_strlen( name ); + char **envp; + + for (envp = info->envp; *envp; envp++) + { + if (wld_strncmp( *envp, name, namelen ) == 0 && + (*envp)[namelen] == '=') return *envp + namelen + 1; + } + + return NULL; +} + +/* + * stackargs_shift_args + * + * Remove the specific number of arguments from the start of argv. + */ +static void stackargs_shift_args( struct stackarg_info *info, int num_args ) +{ + info->stack = (char **)info->stack + num_args; + info->argc -= num_args; + info->argv = (char **)info->stack + 1; + + wld_memset( info->stack, 0, sizeof(char *) ); + /* Don't coalesce zeroing and setting argc -- we *might* support big endian in the future */ + *(int *)info->stack = info->argc; +} + /* * set_auxiliary_values * @@ -1369,47 +1463,36 @@ static void set_process_name( int argc, char *argv[] ) */ void* wld_start( void **stack ) { - long i, *pargc; - char **argv, **p; - char *interp, *reserve = NULL; - struct wld_auxv new_av[8], delete_av[3], *av; + long i; + char *interp, *reserve; + struct wld_auxv new_av[8], delete_av[3]; struct wld_link_map main_binary_map, ld_so_map; struct wine_preload_info **wine_main_preload_info; + struct preloader_state state = { 0 }; - pargc = *stack; - argv = (char **)pargc + 1; - if (*pargc < 2) fatal_error( "Usage: %s wine_binary [args]\n", argv[0] ); + parse_stackargs( &state.s, *stack ); - /* skip over the parameters */ - p = argv + *pargc + 1; + if (state.s.argc < 2) fatal_error( "Usage: %s wine_binary [args]\n", state.s.argv[0] ); - /* skip over the environment */ - while (*p) - { - static const char res[] = "WINEPRELOADRESERVE="; - if (!wld_strncmp( *p, res, sizeof(res)-1 )) reserve = *p + sizeof(res) - 1; - p++; - } - - av = (struct wld_auxv *)(p+1); - page_size = get_auxiliary( av, AT_PAGESZ, 4096 ); + page_size = get_auxiliary( state.s.auxv, AT_PAGESZ, 4096 ); page_mask = page_size - 1; preloader_start = (char *)_start - ((unsigned long)_start & page_mask); preloader_end = (char *)((unsigned long)(_end + page_mask) & ~page_mask); #ifdef DUMP_AUX_INFO - wld_printf( "stack = %p\n", *stack ); - for( i = 0; i < *pargc; i++ ) wld_printf("argv[%lx] = %s\n", i, argv[i]); - dump_auxiliary( av ); + wld_printf( "stack = %p\n", state.s.stack ); + for( i = 0; i < state.s.argc; i++ ) wld_printf("argv[%lx] = %s\n", i, state.s.argv[i]); + dump_auxiliary( state.s.auxv ); #endif /* reserve memory that Wine needs */ + reserve = stackargs_getenv( &state.s, "WINEPRELOADRESERVE" ); if (reserve) preload_reserve( reserve ); for (i = 0; preload_info[i].size; i++) { - if ((char *)av >= (char *)preload_info[i].addr && - (char *)pargc <= (char *)preload_info[i].addr + preload_info[i].size) + if ((char *)state.s.auxv >= (char *)preload_info[i].addr && + (char *)state.s.stack <= (char *)preload_info[i].addr + preload_info[i].size) { remove_preload_range( i ); i--; @@ -1436,7 +1519,7 @@ void* wld_start( void **stack ) wld_mprotect( (char *)0x80000000 - page_size, page_size, PROT_EXEC | PROT_READ ); /* load the main binary */ - map_so_lib( argv[1], &main_binary_map ); + map_so_lib( state.s.argv[1], &main_binary_map ); /* load the ELF interpreter */ interp = (char *)main_binary_map.l_addr + main_binary_map.l_interp; @@ -1453,14 +1536,14 @@ void* wld_start( void **stack ) SET_NEW_AV( 2, AT_PHNUM, main_binary_map.l_phnum ); SET_NEW_AV( 3, AT_PAGESZ, page_size ); SET_NEW_AV( 4, AT_BASE, ld_so_map.l_addr ); - SET_NEW_AV( 5, AT_FLAGS, get_auxiliary( av, AT_FLAGS, 0 ) ); + SET_NEW_AV( 5, AT_FLAGS, get_auxiliary( state.s.auxv, AT_FLAGS, 0 ) ); SET_NEW_AV( 6, AT_ENTRY, main_binary_map.l_entry ); SET_NEW_AV( 7, AT_NULL, 0 ); #undef SET_NEW_AV i = 0; /* delete sysinfo values if addresses conflict */ - if (is_in_preload_range( av, AT_SYSINFO ) || is_in_preload_range( av, AT_SYSINFO_EHDR )) + if (is_in_preload_range( state.s.auxv, AT_SYSINFO ) || is_in_preload_range( state.s.auxv, AT_SYSINFO_EHDR )) { delete_av[i++].a_type = AT_SYSINFO; delete_av[i++].a_type = AT_SYSINFO_EHDR; @@ -1468,11 +1551,12 @@ void* wld_start( void **stack ) delete_av[i].a_type = AT_NULL; /* get rid of first argument */ - set_process_name( *pargc, argv ); - pargc[1] = pargc[0] - 1; - *stack = pargc + 1; + set_process_name( state.s.argc, state.s.argv ); + stackargs_shift_args( &state.s, 1 ); - set_auxiliary_values( av, new_av, delete_av, stack ); + *stack = state.s.stack; + set_auxiliary_values( state.s.auxv, new_av, delete_av, stack ); + /* state is invalid from this point onward */ #ifdef DUMP_AUX_INFO wld_printf("new stack = %p\n", *stack); -- GitLab https://gitlab.winehq.org/wine/wine/-/merge_requests/366
This merge request was closed by Jinoh Kang. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/366
participants (2)
-
Jinoh Kang -
Jinoh Kang (＠iamahuman)