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ftpd: do not use nasty tricks for re-execing if we are on MMU machine.

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On NOMMU, code is alomost the same, on MMU:

function                                             old     new   delta
handle_dir_common                                    223     390    +167
ftpd_main                                           2306    2231     -75
popen_ls                                             203       -    -203
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/1 up/down: 167/-278)         Total: -111 bytes
This commit is contained in:
Denis Vlasenko 2009-03-18 14:12:22 +00:00
parent 1432cb4bd9
commit 5b492ee876
1 changed files with 57 additions and 22 deletions
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75
networking/ftpd.c
View File

@ -87,7 +87,9 @@ enum {
struct globals {
int pasv_listen_fd;
int proc_self_fd;
#if !BB_MMU
int root_fd;
#endif
int local_file_fd;
unsigned end_time;
unsigned timeout;
@ -615,7 +617,13 @@ static int
popen_ls(const char *opt)
{
char *cwd;
const char *argv[5] = { "ftpd", opt, NULL, G.ftp_arg, NULL };
const char *argv[] = {
"ftpd",
opt,
BB_MMU ? "--" : NULL,
G.ftp_arg,
NULL
};
struct fd_pair outfd;
pid_t pid;
@ -623,25 +631,40 @@ popen_ls(const char *opt)
xpiped_pair(outfd);
/*fflush(NULL); - so far we dont use stdio on output */
pid = vfork();
switch (pid) {
case -1: /* failure */
bb_perror_msg_and_die("vfork");
case 0: /* child */
/* NB: close _first_, then move fds! */
pid = BB_MMU ? fork() : vfork();
if (pid < 0)
bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
if (pid == 0) {
/* child */
#if !BB_MMU
if (fchdir(G.root_fd) != 0)
_exit(127);
close(G.root_fd);
#endif
/* NB: close _first_, then move fd! */
close(outfd.rd);
xmove_fd(outfd.wr, STDOUT_FILENO);
/* Opening /dev/null in chroot is hard.
* Just making sure STDIN_FILENO is opened
* to something harmless. Paranoia,
* ls won't read it anyway */
close(STDIN_FILENO);
/* xopen("/dev/null", O_RDONLY); - chroot may lack it! */
if (fchdir(G.proc_self_fd) == 0) {
close(G.proc_self_fd);
argv[2] = cwd;
dup(STDOUT_FILENO); /* copy will become STDIN_FILENO */
#if !BB_MMU
/* ftpd ls helper chdirs to argv[2],
* preventing peer from seeing /proc/self
* preventing peer from seeing real root we are in now
*/
execv("exe", (char**) argv);
}
argv[2] = cwd;
/* + 1: we must use relative path here if in chroot.
* For example, execv("/proc/self/exe") will fail, since
* it looks for "/proc/self/exe" _relative to chroot!_ */
execv(CONFIG_BUSYBOX_EXEC_PATH + 1, (char**) argv);
_exit(127);
#else
memset(&G, 0, sizeof(G));
exit(ls_main(ARRAY_SIZE(argv) - 1, (char**) argv));
#endif
}
/* parent */
@ -1006,15 +1029,21 @@ enum {
const_TYPE = mk_const4('T', 'Y', 'P', 'E'),
const_USER = mk_const4('U', 'S', 'E', 'R'),
#if !BB_MMU
OPT_l = (1 << 0),
OPT_1 = (1 << 1),
OPT_v = (1 << 2),
OPT_S = (1 << 3),
OPT_w = (1 << 4),
#endif
OPT_v = (1 << ((!BB_MMU) * 2 + 0)),
OPT_S = (1 << ((!BB_MMU) * 2 + 1)),
OPT_w = (1 << ((!BB_MMU) * 2 + 2)) * ENABLE_FEATURE_FTP_WRITE,
};
int ftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
#if !BB_MMU
int ftpd_main(int argc, char **argv)
#else
int ftpd_main(int argc UNUSED_PARAM, char **argv)
#endif
{
unsigned abs_timeout;
smallint opts;
@ -1024,16 +1053,20 @@ int ftpd_main(int argc, char **argv)
abs_timeout = 1 * 60 * 60;
G.timeout = 2 * 60;
opt_complementary = "t+:T+:vv";
#if BB_MMU
opts = getopt32(argv, "vS" USE_FEATURE_FTP_WRITE("w") "t:T:", &G.timeout, &abs_timeout, &G.verbose);
#else
opts = getopt32(argv, "l1vS" USE_FEATURE_FTP_WRITE("w") "t:T:", &G.timeout, &abs_timeout, &G.verbose);
if (opts & (OPT_l|OPT_1)) {
/* Our secret backdoor to ls */
memset(&G, 0, sizeof(G));
/* TODO: pass -n too? */
/* --group-directories-first would be nice, but ls don't do that yet */
xchdir(argv[2]);
argv[2] = (char*)"--";
memset(&G, 0, sizeof(G));
return ls_main(argc, argv);
}
#endif
if (abs_timeout | G.timeout) {
if (abs_timeout == 0)
abs_timeout = INT_MAX;
@ -1065,7 +1098,9 @@ int ftpd_main(int argc, char **argv)
if (logmode)
applet_name = xasprintf("%s[%u]", applet_name, (int)getpid());
G.proc_self_fd = xopen("/proc/self", O_RDONLY | O_DIRECTORY);
#if !BB_MMU
G.root_fd = xopen("/", O_RDONLY | O_DIRECTORY);
#endif
if (argv[optind]) {
xchdir(argv[optind]);