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-rw-r--r--lib/libc/gen/exec.c67
-rw-r--r--lib/libc/gen/posix_spawn.c44
-rw-r--r--lib/libc/tests/gen/Makefile9
-rw-r--r--lib/libc/tests/gen/posix_spawn_test.c39
-rw-r--r--lib/libc/tests/gen/spawnp_enoexec.sh4
5 files changed, 139 insertions, 24 deletions
diff --git a/lib/libc/gen/exec.c b/lib/libc/gen/exec.c
index e20ff42d3c90..0bd8be738dca 100644
--- a/lib/libc/gen/exec.c
+++ b/lib/libc/gen/exec.c
@@ -49,6 +49,9 @@ __FBSDID("$FreeBSD$");
extern char **environ;
+static const char execvPe_err_preamble[] = "execvP: ";
+static const char execvPe_err_trailer[] = ": path too long\n";
+
int
execl(const char *name, const char *arg, ...)
{
@@ -149,8 +152,8 @@ execvPe(const char *name, const char *path, char * const *argv,
const char **memp;
size_t cnt, lp, ln;
int eacces, save_errno;
- char *cur, buf[MAXPATHLEN];
- const char *p, *bp;
+ char buf[MAXPATHLEN];
+ const char *bp, *np, *op, *p;
struct stat sb;
eacces = 0;
@@ -158,7 +161,7 @@ execvPe(const char *name, const char *path, char * const *argv,
/* If it's an absolute or relative path name, it's easy. */
if (strchr(name, '/')) {
bp = name;
- cur = NULL;
+ op = NULL;
goto retry;
}
bp = buf;
@@ -169,23 +172,30 @@ execvPe(const char *name, const char *path, char * const *argv,
return (-1);
}
- cur = alloca(strlen(path) + 1);
- if (cur == NULL) {
- errno = ENOMEM;
- return (-1);
- }
- strcpy(cur, path);
- while ((p = strsep(&cur, ":")) != NULL) {
+ op = path;
+ ln = strlen(name);
+ while (op != NULL) {
+ np = strchrnul(op, ':');
+
/*
* It's a SHELL path -- double, leading and trailing colons
* mean the current directory.
*/
- if (*p == '\0') {
+ if (np == op) {
+ /* Empty component. */
p = ".";
lp = 1;
- } else
- lp = strlen(p);
- ln = strlen(name);
+ } else {
+ /* Non-empty component. */
+ p = op;
+ lp = np - op;
+ }
+
+ /* Advance to the next component or terminate after this. */
+ if (*np == '\0')
+ op = NULL;
+ else
+ op = np + 1;
/*
* If the path is too long complain. This is a possible
@@ -193,10 +203,11 @@ execvPe(const char *name, const char *path, char * const *argv,
* the user may execute the wrong program.
*/
if (lp + ln + 2 > sizeof(buf)) {
- (void)_write(STDERR_FILENO, "execvP: ", 8);
+ (void)_write(STDERR_FILENO, execvPe_err_preamble,
+ sizeof(execvPe_err_preamble) - 1);
(void)_write(STDERR_FILENO, p, lp);
- (void)_write(STDERR_FILENO, ": path too long\n",
- 16);
+ (void)_write(STDERR_FILENO, execvPe_err_trailer,
+ sizeof(execvPe_err_trailer) - 1);
continue;
}
bcopy(p, buf, lp);
@@ -215,14 +226,28 @@ retry: (void)_execve(bp, argv, envp);
case ENOEXEC:
for (cnt = 0; argv[cnt]; ++cnt)
;
- memp = alloca((cnt + 2) * sizeof(char *));
+
+ /*
+ * cnt may be 0 above; always allocate at least
+ * 3 entries so that we can at least fit "sh", bp, and
+ * the NULL terminator. We can rely on cnt to take into
+ * account the NULL terminator in all other scenarios,
+ * as we drop argv[0].
+ */
+ memp = alloca(MAX(3, cnt + 2) * sizeof(char *));
if (memp == NULL) {
/* errno = ENOMEM; XXX override ENOEXEC? */
goto done;
}
- memp[0] = "sh";
- memp[1] = bp;
- bcopy(argv + 1, memp + 2, cnt * sizeof(char *));
+ if (cnt > 0) {
+ memp[0] = argv[0];
+ memp[1] = bp;
+ bcopy(argv + 1, memp + 2, cnt * sizeof(char *));
+ } else {
+ memp[0] = "sh";
+ memp[1] = bp;
+ memp[2] = NULL;
+ }
(void)_execve(_PATH_BSHELL,
__DECONST(char **, memp), envp);
goto done;
diff --git a/lib/libc/gen/posix_spawn.c b/lib/libc/gen/posix_spawn.c
index 5f4e74825362..805e42780be3 100644
--- a/lib/libc/gen/posix_spawn.c
+++ b/lib/libc/gen/posix_spawn.c
@@ -28,6 +28,7 @@
__FBSDID("$FreeBSD$");
#include "namespace.h"
+#include <sys/param.h>
#include <sys/queue.h>
#include <sys/wait.h>
@@ -202,8 +203,20 @@ struct posix_spawn_args {
volatile int error;
};
+#define PSPAWN_STACK_ALIGNMENT 16
+#define PSPAWN_STACK_ALIGNBYTES (PSPAWN_STACK_ALIGNMENT - 1)
+#define PSPAWN_STACK_ALIGN(sz) \
+ (((sz) + PSPAWN_STACK_ALIGNBYTES) & ~PSPAWN_STACK_ALIGNBYTES)
+
#if defined(__i386__) || defined(__amd64__)
+/*
+ * Below we'll assume that _RFORK_THREAD_STACK_SIZE is appropriately aligned for
+ * the posix_spawn() case where we do not end up calling _execvpe and won't ever
+ * try to allocate space on the stack for argv[].
+ */
#define _RFORK_THREAD_STACK_SIZE 4096
+_Static_assert((_RFORK_THREAD_STACK_SIZE % PSPAWN_STACK_ALIGNMENT) == 0,
+ "Inappropriate stack size alignment");
#endif
static int
@@ -244,10 +257,36 @@ do_posix_spawn(pid_t *pid, const char *path,
pid_t p;
#ifdef _RFORK_THREAD_STACK_SIZE
char *stack;
+ size_t cnt, stacksz;
+
+ stacksz = _RFORK_THREAD_STACK_SIZE;
+ if (use_env_path) {
+ /*
+ * We need to make sure we have enough room on the stack for the
+ * potential alloca() in execvPe if it gets kicked back an
+ * ENOEXEC from execve(2), plus the original buffer we gave
+ * ourselves; this protects us in the event that the caller
+ * intentionally or inadvertently supplies enough arguments to
+ * make us blow past the stack we've allocated from it.
+ */
+ for (cnt = 0; argv[cnt] != NULL; ++cnt)
+ ;
+ stacksz += MAX(3, cnt + 2) * sizeof(char *);
+ stacksz = PSPAWN_STACK_ALIGN(stacksz);
+ }
- stack = malloc(_RFORK_THREAD_STACK_SIZE);
+ /*
+ * aligned_alloc is not safe to use here, because we can't guarantee
+ * that aligned_alloc and free will be provided by the same
+ * implementation. We've actively hit at least one application that
+ * will provide its own malloc/free but not aligned_alloc leading to
+ * a free by the wrong allocator.
+ */
+ stack = malloc(stacksz);
if (stack == NULL)
return (ENOMEM);
+ stacksz = (((uintptr_t)stack + stacksz) & ~PSPAWN_STACK_ALIGNBYTES) -
+ (uintptr_t)stack;
#endif
psa.path = path;
psa.fa = fa;
@@ -271,8 +310,7 @@ do_posix_spawn(pid_t *pid, const char *path,
* parent. Because of this, we must use rfork_thread instead while
* almost every other arch stores the return address in a register.
*/
- p = rfork_thread(RFSPAWN, stack + _RFORK_THREAD_STACK_SIZE,
- _posix_spawn_thr, &psa);
+ p = rfork_thread(RFSPAWN, stack + stacksz, _posix_spawn_thr, &psa);
free(stack);
#else
p = rfork(RFSPAWN);
diff --git a/lib/libc/tests/gen/Makefile b/lib/libc/tests/gen/Makefile
index a1ba16d47f1b..738e5a0d5369 100644
--- a/lib/libc/tests/gen/Makefile
+++ b/lib/libc/tests/gen/Makefile
@@ -20,6 +20,15 @@ ATF_TESTS_C+= wordexp_test
# TODO: t_siginfo (fixes require further inspection)
# TODO: t_sethostname_test (consistently screws up the hostname)
+FILESGROUPS+= posix_spawn_test_FILES
+
+posix_spawn_test_FILES= spawnp_enoexec.sh
+posix_spawn_test_FILESDIR= ${TESTSDIR}
+posix_spawn_test_FILESMODE= 0755
+posix_spawn_test_FILESOWN= root
+posix_spawn_test_FILESGRP= wheel
+posix_spawn_test_FILESPACKAGE= ${PACKAGE}
+
CFLAGS+= -DTEST_LONG_DOUBLE
# Not sure why this isn't defined for all architectures, since most
diff --git a/lib/libc/tests/gen/posix_spawn_test.c b/lib/libc/tests/gen/posix_spawn_test.c
index e04d103e1a30..5e2c485473d0 100644
--- a/lib/libc/tests/gen/posix_spawn_test.c
+++ b/lib/libc/tests/gen/posix_spawn_test.c
@@ -93,11 +93,50 @@ ATF_TC_BODY(posix_spawn_no_such_command_negative_test, tc)
}
}
+ATF_TC_WITHOUT_HEAD(posix_spawnp_enoexec_fallback);
+ATF_TC_BODY(posix_spawnp_enoexec_fallback, tc)
+{
+ char buf[FILENAME_MAX];
+ char *myargs[2];
+ int error, status;
+ pid_t pid, waitres;
+
+ snprintf(buf, sizeof(buf), "%s/spawnp_enoexec.sh",
+ atf_tc_get_config_var(tc, "srcdir"));
+ myargs[0] = buf;
+ myargs[1] = NULL;
+ error = posix_spawnp(&pid, myargs[0], NULL, NULL, myargs, myenv);
+ ATF_REQUIRE(error == 0);
+ waitres = waitpid(pid, &status, 0);
+ ATF_REQUIRE(waitres == pid);
+ ATF_REQUIRE(WIFEXITED(status) && WEXITSTATUS(status) == 42);
+}
+
+ATF_TC_WITHOUT_HEAD(posix_spawnp_enoexec_fallback_null_argv0);
+ATF_TC_BODY(posix_spawnp_enoexec_fallback_null_argv0, tc)
+{
+ char buf[FILENAME_MAX];
+ char *myargs[1];
+ int error, status;
+ pid_t pid, waitres;
+
+ snprintf(buf, sizeof(buf), "%s/spawnp_enoexec.sh",
+ atf_tc_get_config_var(tc, "srcdir"));
+ myargs[0] = NULL;
+ error = posix_spawnp(&pid, buf, NULL, NULL, myargs, myenv);
+ ATF_REQUIRE(error == 0);
+ waitres = waitpid(pid, &status, 0);
+ ATF_REQUIRE(waitres == pid);
+ ATF_REQUIRE(WIFEXITED(status) && WEXITSTATUS(status) == 42);
+}
+
ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, posix_spawn_simple_test);
ATF_TP_ADD_TC(tp, posix_spawn_no_such_command_negative_test);
+ ATF_TP_ADD_TC(tp, posix_spawnp_enoexec_fallback);
+ ATF_TP_ADD_TC(tp, posix_spawnp_enoexec_fallback_null_argv0);
return (atf_no_error());
}
diff --git a/lib/libc/tests/gen/spawnp_enoexec.sh b/lib/libc/tests/gen/spawnp_enoexec.sh
new file mode 100644
index 000000000000..02941633e108
--- /dev/null
+++ b/lib/libc/tests/gen/spawnp_enoexec.sh
@@ -0,0 +1,4 @@
+# $FreeBSD$
+# Intentionally no interpreter
+
+exit 42