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ash,hush: fix "saved" redirected fds still visible in children

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Based on a patch by Mark Marshall <mark.marshall@omicronenergy.com>

function                                             old     new   delta
dup_CLOEXEC                                            -      49     +49
fcntl_F_DUPFD                                         46       -     -46

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-03-28 18:35:07 +02:00
parent e4defe826b
commit 9acd63c92c
14 changed files with 92 additions and 13 deletions
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16
shell/ash.c
View File

@ -255,6 +255,9 @@ typedef long arith_t;
# define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
#endif
#ifndef F_DUPFD_CLOEXEC
# define F_DUPFD_CLOEXEC F_DUPFD
#endif
#ifndef PIPE_BUF
# define PIPE_BUF 4096 /* amount of buffering in a pipe */
#endif
@ -5448,12 +5451,15 @@ dup2_or_raise(int from, int to)
return newfd;
}
static int
fcntl_F_DUPFD(int fd, int avoid_fd)
dup_CLOEXEC(int fd, int avoid_fd)
{
int newfd;
repeat:
newfd = fcntl(fd, F_DUPFD, avoid_fd + 1);
if (newfd < 0) {
newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
if (newfd >= 0) {
if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
fcntl(newfd, F_SETFD, FD_CLOEXEC);
} else { /* newfd < 0 */
if (errno == EBUSY)
goto repeat;
if (errno == EINTR)
@ -5569,7 +5575,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq)
for (i = 0; sq->two_fd[i].orig_fd != EMPTY; i++) {
/* If we collide with an already moved fd... */
if (fd == sq->two_fd[i].moved_to) {
new_fd = fcntl_F_DUPFD(fd, avoid_fd);
new_fd = dup_CLOEXEC(fd, avoid_fd);
sq->two_fd[i].moved_to = new_fd;
TRACE(("redirect_fd %d: already busy, moving to %d\n", fd, new_fd));
if (new_fd < 0) /* what? */
@ -5584,7 +5590,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq)
}
/* If this fd is open, we move and remember it; if it's closed, new_fd = CLOSED (-1) */
new_fd = fcntl_F_DUPFD(fd, avoid_fd);
new_fd = dup_CLOEXEC(fd, avoid_fd);
TRACE(("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, new_fd));
if (new_fd < 0) {
if (errno != EBADF)

5
shell/ash_test/ash-redir/redir_children_should_not_see_saved_fd_1.right Normal file
View File

@ -0,0 +1,5 @@
/proc/self/fd
/proc/self/fd/0
/proc/self/fd/1
/proc/self/fd/2
/proc/self/fd/3

6
shell/ash_test/ash-redir/redir_children_should_not_see_saved_fd_1.tests Executable file
View File

@ -0,0 +1,6 @@
# The "find" should not see "saved" (duplicated) fd #1
# Explicitly use bbox find, since other implementations of "find"
# may open other descriptors as well.
busybox find /proc/self/fd >tmp_$$.out
cat tmp_$$.out
rm -f tmp_$$.out

5
shell/ash_test/ash-redir/redir_children_should_not_see_saved_fd_2.right Normal file
View File

@ -0,0 +1,5 @@
/proc/self/fd
/proc/self/fd/0
/proc/self/fd/1
/proc/self/fd/2
/proc/self/fd/3

6
shell/ash_test/ash-redir/redir_children_should_not_see_saved_fd_2.tests Executable file
View File

@ -0,0 +1,6 @@
# The "find" should not see "saved" (duplicated) fd #1
# Explicitly use bbox find, since other implementations of "find"
# may open other descriptors as well.
{ busybox find /proc/self/fd; } >tmp_$$.out
cat tmp_$$.out
rm -f tmp_$$.out

5
shell/ash_test/ash-redir/redir_children_should_not_see_saved_fd_3.right Normal file
View File

@ -0,0 +1,5 @@
/proc/self/fd
/proc/self/fd/0
/proc/self/fd/1
/proc/self/fd/2
/proc/self/fd/3

6
shell/ash_test/ash-redir/redir_children_should_not_see_saved_fd_3.tests Executable file
View File

@ -0,0 +1,6 @@
# The "find" should not see "saved" (duplicated) fd #1
# Explicitly use bbox find, since other implementations of "find"
# may open other descriptors as well.
{ busybox find /proc/self/fd; true; } >tmp_$$.out
cat tmp_$$.out
rm -f tmp_$$.out

23
shell/hush.c
View File

@ -1501,12 +1501,15 @@ static void free_strings(char **strings)
free(strings);
}
static int fcntl_F_DUPFD(int fd, int avoid_fd)
static int dup_CLOEXEC(int fd, int avoid_fd)
{
int newfd;
repeat:
newfd = fcntl(fd, F_DUPFD, avoid_fd + 1);
if (newfd < 0) {
newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
if (newfd >= 0) {
if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
fcntl(newfd, F_SETFD, FD_CLOEXEC);
} else { /* newfd < 0 */
if (errno == EBUSY)
goto repeat;
if (errno == EINTR)
@ -6890,7 +6893,7 @@ static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
if (sq) for (; sq[i].orig_fd >= 0; i++) {
/* If we collide with an already moved fd... */
if (fd == sq[i].moved_to) {
sq[i].moved_to = fcntl_F_DUPFD(sq[i].moved_to, avoid_fd);
sq[i].moved_to = dup_CLOEXEC(sq[i].moved_to, avoid_fd);
debug_printf_redir("redirect_fd %d: already busy, moving to %d\n", fd, sq[i].moved_to);
if (sq[i].moved_to < 0) /* what? */
xfunc_die();
@ -6904,7 +6907,7 @@ static struct squirrel *add_squirrel(struct squirrel *sq, int fd, int avoid_fd)
}
/* If this fd is open, we move and remember it; if it's closed, moved_to = -1 */
moved_to = fcntl_F_DUPFD(fd, avoid_fd);
moved_to = dup_CLOEXEC(fd, avoid_fd);
debug_printf_redir("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, moved_to);
if (moved_to < 0 && errno != EBADF)
xfunc_die();
@ -7622,6 +7625,10 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
*/
close_saved_fds_and_FILE_fds();
//FIXME: should also close saved redir fds
//This casuses test failures in
//redir_children_should_not_see_saved_fd_2.tests
//redir_children_should_not_see_saved_fd_3.tests
//if you replace "busybox find" with just "find" in them
/* Without this, "rm -i FILE" can't be ^C'ed: */
switch_off_special_sigs(G.special_sig_mask);
debug_printf_exec("running applet '%s'\n", argv[0]);
@ -9347,7 +9354,7 @@ int hush_main(int argc, char **argv)
G_saved_tty_pgrp = 0;
/* try to dup stdin to high fd#, >= 255 */
G_interactive_fd = fcntl_F_DUPFD(STDIN_FILENO, 254);
G_interactive_fd = dup_CLOEXEC(STDIN_FILENO, 254);
if (G_interactive_fd < 0) {
/* try to dup to any fd */
G_interactive_fd = dup(STDIN_FILENO);
@ -9420,10 +9427,10 @@ int hush_main(int argc, char **argv)
#elif ENABLE_HUSH_INTERACTIVE
/* No job control compiled in, only prompt/line editing */
if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
G_interactive_fd = fcntl_F_DUPFD(STDIN_FILENO, 254);
G_interactive_fd = dup_CLOEXEC(STDIN_FILENO, 254);
if (G_interactive_fd < 0) {
/* try to dup to any fd */
G_interactive_fd = dup(STDIN_FILENO);
G_interactive_fd = dup_CLOEXEC(STDIN_FILENO);
if (G_interactive_fd < 0)
/* give up */
G_interactive_fd = 0;

5
shell/hush_test/hush-redir/redir_children_should_not_see_saved_fd_1.right Normal file
View File

@ -0,0 +1,5 @@
/proc/self/fd
/proc/self/fd/0
/proc/self/fd/1
/proc/self/fd/2
/proc/self/fd/3

6
shell/hush_test/hush-redir/redir_children_should_not_see_saved_fd_1.tests Executable file
View File

@ -0,0 +1,6 @@
# The "find" should not see "saved" (duplicated) fd #1
# Explicitly use bbox find, since other implementations of "find"
# may open other descriptors as well.
busybox find /proc/self/fd >tmp_$$.out
cat tmp_$$.out
rm -f tmp_$$.out

5
shell/hush_test/hush-redir/redir_children_should_not_see_saved_fd_2.right Normal file
View File

@ -0,0 +1,5 @@
/proc/self/fd
/proc/self/fd/0
/proc/self/fd/1
/proc/self/fd/2
/proc/self/fd/3

6
shell/hush_test/hush-redir/redir_children_should_not_see_saved_fd_2.tests Executable file
View File

@ -0,0 +1,6 @@
# The "find" should not see "saved" (duplicated) fd #1
# Explicitly use bbox find, since other implementations of "find"
# may open other descriptors as well.
{ busybox find /proc/self/fd; } >tmp_$$.out
cat tmp_$$.out
rm -f tmp_$$.out

5
shell/hush_test/hush-redir/redir_children_should_not_see_saved_fd_3.right Normal file
View File

@ -0,0 +1,5 @@
/proc/self/fd
/proc/self/fd/0
/proc/self/fd/1
/proc/self/fd/2
/proc/self/fd/3

6
shell/hush_test/hush-redir/redir_children_should_not_see_saved_fd_3.tests Executable file
View File

@ -0,0 +1,6 @@
# The "find" should not see "saved" (duplicated) fd #1
# Explicitly use bbox find, since other implementations of "find"
# may open other descriptors as well.
{ busybox find /proc/self/fd; true; } >tmp_$$.out
cat tmp_$$.out
rm -f tmp_$$.out