Adding upstream version 1.9.15p5.upstream/1.9.15p5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 595 insertions, 0 deletions

diff --git a/src/sudo_intercept.c b/src/sudo_intercept.c
new file mode 100644
index 0000000..4eeb71c
--- /dev/null
+++ b/src/sudo_intercept.c
@@ -0,0 +1,595 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2021-2022 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+#include <string.h>
+#include <signal.h>
+#ifdef HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+# include <compat/stdbool.h>
+#endif /* HAVE_STDBOOL_H */
+#if defined(HAVE_SHL_LOAD)
+# include <dl.h>
+#elif defined(HAVE_DLOPEN)
+# include <dlfcn.h>
+#endif
+#ifdef HAVE_CRT_EXTERNS_H
+# include <crt_externs.h>
+#endif
+
+#include <sudo_compat.h>
+#include <sudo_debug.h>
+#include <sudo_util.h>
+#include <pathnames.h>
+
+/* execl flavors */
+#define SUDO_EXECL	0x0
+#define SUDO_EXECLE	0x1
+#define SUDO_EXECLP	0x2
+
+#ifdef HAVE__NSGETENVIRON
+# define environ (*_NSGetEnviron())
+#else
+extern char **environ;
+#endif
+
+extern bool command_allowed(const char *cmnd, char * const argv[], char * const envp[], char **ncmnd, char ***nargv, char ***nenvp);
+
+typedef int (*sudo_fn_execve_t)(const char *, char *const *, char *const *);
+
+static void
+free_vector(char **vec)
+{
+    char **cur;
+    debug_decl(free_vector, SUDO_DEBUG_EXEC);
+
+    if (vec != NULL) {
+	for (cur = vec; *cur != NULL; cur++) {
+	    sudo_mmap_free(*cur);
+	}
+	sudo_mmap_free(vec);
+    }
+
+    debug_return;
+}
+
+static char **
+copy_vector(char * const *src)
+{
+    char **copy;
+    size_t i, len = 0;
+    debug_decl(copy_vector, SUDO_DEBUG_EXEC);
+
+    if (src != NULL) {
+	while (src[len] != NULL)
+	    len++;
+    }
+    copy = sudo_mmap_allocarray(len + 1, sizeof(char *));
+    if (copy == NULL) {
+	debug_return_ptr(NULL);
+    }
+    for (i = 0; i < len; i++) {
+	copy[i] = sudo_mmap_strdup(src[i]);
+	if (copy[i] == NULL) {
+	    free_vector(copy);
+	    debug_return_ptr(NULL);
+	}
+    }
+    copy[i] = NULL;
+
+    debug_return_ptr(copy);
+}
+
+/*
+ * We do PATH resolution here rather than in the policy because we
+ * want to use the PATH in the current environment.
+ */
+static bool
+resolve_path(const char *cmnd, char *out_cmnd, size_t out_size)
+{
+    struct stat sb;
+    int errval = ENOENT;
+    char path[PATH_MAX];
+    char **p, *cp, *endp;
+    int dirlen, len;
+    debug_decl(resolve_path, SUDO_DEBUG_EXEC);
+
+    for (p = environ; (cp = *p) != NULL; p++) {
+	if (strncmp(cp, "PATH=", sizeof("PATH=") - 1) == 0) {
+	    cp += sizeof("PATH=") - 1;
+	    break;
+	}
+    }
+    if (cp == NULL) {
+	errno = ENOENT;
+	debug_return_bool(false);
+    }
+
+    endp = cp + strlen(cp);
+    while (cp < endp) {
+	char *colon = strchr(cp, ':');
+	dirlen = colon ? (int)(colon - cp) : (int)(endp - cp);
+	if (dirlen == 0) {
+	    /* empty PATH component is the same as "." */
+	    len = snprintf(path, sizeof(path), "./%s", cmnd);
+	} else {
+	    len = snprintf(path, sizeof(path), "%.*s/%s", dirlen, cp, cmnd);
+	}
+	cp = colon ? colon + 1 : endp;
+	if (len >= ssizeof(path)) {
+	    /* skip too long path */
+	    errval = ENAMETOOLONG;
+	    continue;
+	}
+
+	if (stat(path, &sb) == 0) {
+	    if (!S_ISREG(sb.st_mode))
+		continue;
+	    if (strlcpy(out_cmnd, path, out_size) >= out_size) {
+		errval = ENAMETOOLONG;
+		break;
+	    }
+	    debug_return_bool(true);
+	}
+	switch (errno) {
+	case EACCES:
+	    errval = EACCES;
+	    break;
+	case ELOOP:
+	case ENOTDIR:
+	case ENOENT:
+	    break;
+	default:
+	    debug_return_bool(false);
+	}
+    }
+    errno = errval;
+    debug_return_bool(false);
+}
+
+static int
+exec_wrapper(const char *cmnd, char * const argv[], char * const envp[],
+    bool is_execvp)
+{
+    char *cmnd_copy = NULL, **argv_copy = NULL, **envp_copy = NULL;
+    char *ncmnd = NULL, **nargv = NULL, **nenvp = NULL;
+    char cmnd_buf[PATH_MAX];
+    void *fn = NULL;
+    debug_decl(exec_wrapper, SUDO_DEBUG_EXEC);
+
+    if (cmnd == NULL) {
+	errno = EINVAL;
+	debug_return_int(-1);
+    }
+
+    /* Only check PATH for the command for execlp/execvp/execvpe. */
+    if (strchr(cmnd, '/') == NULL) {
+	if (!is_execvp) {
+	    errno = ENOENT;
+	    goto bad;
+	}
+	if (!resolve_path(cmnd, cmnd_buf, sizeof(cmnd_buf))) {
+	    goto bad;
+	}
+	cmnd = cmnd_buf;
+    } else {
+	struct stat sb;
+
+	/* Absolute or relative path name. */
+	if (stat(cmnd, &sb) == -1) {
+	    /* Leave errno unchanged. */
+	    goto bad;
+	} else if (!S_ISREG(sb.st_mode)) {
+	    errno = EACCES;
+	    goto bad;
+	}
+    }
+
+    /*
+     * Make copies of cmnd, argv, and envp.
+     */
+    cmnd_copy = sudo_mmap_strdup(cmnd);
+    if (cmnd_copy == NULL) {
+	debug_return_int(-1);
+    }
+    sudo_mmap_protect(cmnd_copy);
+    cmnd = cmnd_copy;
+
+    argv_copy = copy_vector(argv);
+    if (argv_copy == NULL) {
+	goto bad;
+    }
+    sudo_mmap_protect(argv_copy);
+    argv = argv_copy;
+
+    envp_copy = copy_vector(envp);
+    if (envp_copy == NULL) {
+	goto bad;
+    }
+    sudo_mmap_protect(envp_copy);
+    envp = envp_copy;
+
+# if defined(HAVE___INTERPOSE)
+    fn = execve;
+# elif defined(HAVE_DLOPEN)
+    fn = dlsym(RTLD_NEXT, "execve");
+# elif defined(HAVE_SHL_LOAD)
+    fn = sudo_shl_get_next("execve", TYPE_PROCEDURE);
+# endif
+    if (fn == NULL) {
+        errno = EACCES;
+	goto bad;
+    }
+
+    if (command_allowed(cmnd, argv, envp, &ncmnd, &nargv, &nenvp)) {
+	/* Execute the command using the "real" execve() function. */
+	((sudo_fn_execve_t)fn)(ncmnd, nargv, nenvp);
+
+	/* Fall back to exec via shell for execvp and friends. */
+	if (errno == ENOEXEC && is_execvp) {
+	    int argc;
+	    const char **shargv;
+
+	    for (argc = 0; argv[argc] != NULL; argc++)
+		continue;
+	    shargv = sudo_mmap_allocarray((size_t)argc + 2, sizeof(char *));
+	    if (shargv == NULL)
+		goto bad;
+	    shargv[0] = "sh";
+	    shargv[1] = ncmnd;
+	    memcpy(shargv + 2, nargv + 1, (size_t)argc * sizeof(char *));
+	    ((sudo_fn_execve_t)fn)(_PATH_SUDO_BSHELL, (char **)shargv, nenvp);
+	    sudo_mmap_free(shargv);
+	}
+    } else {
+	errno = EACCES;
+    }
+
+bad:
+    sudo_mmap_free(cmnd_copy);
+    if (ncmnd != cmnd_copy)
+	sudo_mmap_free(ncmnd);
+    free_vector(argv_copy);
+    if (nargv != argv_copy)
+	free_vector(nargv);
+    free_vector(envp_copy);
+    /* Leaks allocated preload vars. */
+    if (nenvp != envp_copy)
+	sudo_mmap_free(nenvp);
+
+    debug_return_int(-1);
+}
+
+static int
+execl_wrapper(int type, const char *name, const char *arg, va_list ap)
+{
+    char * const *envp = environ;
+    char **argv;
+    int argc = 1;
+    va_list ap2;
+    debug_decl(execl_wrapper, SUDO_DEBUG_EXEC);
+
+    if (name == NULL || arg == NULL) {
+	errno = EINVAL;
+	debug_return_int(-1);
+    }
+
+    va_copy(ap2, ap);
+    while (va_arg(ap2, char *) != NULL)
+	argc++;
+    va_end(ap2);
+    argv = sudo_mmap_allocarray((size_t)argc + 1, sizeof(char *));
+    if (argv == NULL)
+	debug_return_int(-1);
+
+    argc = 0;
+    argv[argc++] = (char *)arg;
+    while ((argv[argc] = va_arg(ap, char *)) != NULL)
+	argc++;
+    if (type == SUDO_EXECLE)
+	envp = va_arg(ap, char **);
+
+    exec_wrapper(name, argv, envp, type == SUDO_EXECLP);
+    sudo_mmap_free(argv);
+
+    debug_return_int(-1);
+}
+
+static int
+system_wrapper(const char *cmnd)
+{
+    const char * const argv[] = { "sh", "-c", cmnd, NULL };
+    const char shell[] = _PATH_SUDO_BSHELL;
+    struct sigaction saveint, savequit, sa;
+    sigset_t mask, omask;
+    pid_t child;
+    int status;
+    debug_decl(system_wrapper, SUDO_DEBUG_EXEC);
+
+    /* Special case for NULL command, just check whether shell exists. */
+    if (cmnd == NULL)
+	debug_return_int(access(shell, X_OK) == 0);
+
+    /* First, block signals to avoid potential race conditions. */
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGCHLD);
+    sigaddset(&mask, SIGINT);
+    sigaddset(&mask, SIGQUIT);
+    if (sigprocmask(SIG_BLOCK, &mask, &omask) == -1)
+	debug_return_int(-1);
+
+    switch (child = fork()) {
+    case -1:
+	/* error */
+	(void)sigprocmask(SIG_SETMASK, &omask, NULL);
+	debug_return_int(-1);
+    case 0:
+	/* child */
+	if (sigprocmask(SIG_SETMASK, &omask, NULL) != -1)
+	    exec_wrapper(shell, (char **)argv, environ, false);
+	_exit(127);
+    default:
+	/* parent */
+	break;
+    }
+
+    /* We must ignore SIGINT and SIGQUIT until the command finishes. */
+    memset(&sa, 0, sizeof(sa));
+    sigemptyset(&sa.sa_mask);
+    sa.sa_handler = SIG_IGN;
+    (void)sigaction(SIGINT, &sa, &saveint);
+    (void)sigaction(SIGQUIT, &sa, &savequit);
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGINT);
+    sigaddset(&mask, SIGQUIT);
+    (void)sigprocmask(SIG_UNBLOCK, &mask, NULL);
+
+    for (;;) {
+	if (waitpid(child, &status, 0) == -1) {
+	    if (errno == EINTR)
+		continue;
+	    status = -1;
+	}
+	break;
+    }
+
+    /* Restore signal mask and handlers. */
+    (void)sigprocmask(SIG_SETMASK, &omask, NULL);
+    (void)sigaction(SIGINT, &saveint, NULL);
+    (void)sigaction(SIGQUIT, &savequit, NULL);
+
+    debug_return_int(status);
+}
+
+#ifdef HAVE___INTERPOSE
+/*
+ * Mac OS X 10.4 and above has support for library symbol interposition.
+ * There is a good explanation of this in the Mac OS X Internals book.
+ */
+typedef struct interpose_s {
+    void *new_func;
+    void *orig_func;
+} interpose_t;
+
+static int
+my_system(const char *cmnd)
+{
+    return system_wrapper(cmnd);
+}
+
+static int
+my_execve(const char *cmnd, char * const argv[], char * const envp[])
+{
+    return exec_wrapper(cmnd, argv, envp, false);
+}
+
+static int
+my_execv(const char *cmnd, char * const argv[])
+{
+    return exec_wrapper(cmnd, argv, environ, false);
+}
+
+#ifdef HAVE_EXECVPE
+static int
+my_execvpe(const char *cmnd, char * const argv[], char * const envp[])
+{
+    return exec_wrapper(cmnd, argv, envp, true);
+}
+#endif
+
+static int
+my_execvp(const char *cmnd, char * const argv[])
+{
+    return exec_wrapper(cmnd, argv, environ, true);
+}
+
+static int
+my_execl(const char *name, const char *arg, ...)
+{
+    va_list ap;
+
+    va_start(ap, arg);
+    execl_wrapper(SUDO_EXECL, name, arg, ap);
+    va_end(ap);
+
+    return -1;
+}
+
+static int
+my_execle(const char *name, const char *arg, ...)
+{
+    va_list ap;
+
+    va_start(ap, arg);
+    execl_wrapper(SUDO_EXECLE, name, arg, ap);
+    va_end(ap);
+
+    return -1;
+}
+
+static int
+my_execlp(const char *name, const char *arg, ...)
+{
+    va_list ap;
+
+    va_start(ap, arg);
+    execl_wrapper(SUDO_EXECLP, name, arg, ap);
+    va_end(ap);
+
+    return -1;
+}
+
+/* Magic to tell dyld to do symbol interposition. */
+__attribute__((__used__)) static const interpose_t interposers[]
+__attribute__((__section__("__DATA,__interpose"))) = {
+    { (void *)my_system, (void *)system },
+    { (void *)my_execl, (void *)execl },
+    { (void *)my_execle, (void *)execle },
+    { (void *)my_execlp, (void *)execlp },
+    { (void *)my_execv, (void *)execv },
+    { (void *)my_execve, (void *)execve },
+    { (void *)my_execvp, (void *)execvp },
+#ifdef HAVE_EXECVPE
+    { (void *)my_execvpe, (void *)execvpe }
+#endif
+};
+
+#else /* HAVE___INTERPOSE */
+
+# if defined(HAVE_SHL_LOAD)
+static void *
+sudo_shl_get_next(const char *symbol, short type)
+{
+    const char *name, *myname;
+    struct shl_descriptor *desc;
+    void *fn = NULL;
+    int idx = 0;
+    debug_decl(sudo_shl_get_next, SUDO_DEBUG_EXEC);
+
+    /* Search for symbol but skip this shared object. */
+    /* XXX - could be set to a different path in sudo.conf */
+    myname = sudo_basename(_PATH_SUDO_INTERCEPT);
+    while (shl_get(idx++, &desc) == 0) {
+        name = sudo_basename(desc->filename);
+        if (strcmp(name, myname) == 0)
+            continue;
+        if (shl_findsym(&desc->handle, symbol, type, &fn) == 0)
+            break;
+    }
+
+    debug_return_ptr(fn);
+}
+# endif /* HAVE_SHL_LOAD */
+
+sudo_dso_public int system(const char *cmnd);
+sudo_dso_public int execve(const char *cmnd, char * const argv[], char * const envp[]);
+sudo_dso_public int execv(const char *cmnd, char * const argv[]);
+#ifdef HAVE_EXECVPE
+sudo_dso_public int execvpe(const char *cmnd, char * const argv[], char * const envp[]);
+#endif
+sudo_dso_public int execvp(const char *cmnd, char * const argv[]);
+sudo_dso_public int execl(const char *name, const char *arg, ...);
+sudo_dso_public int execle(const char *name, const char *arg, ...);
+sudo_dso_public int execlp(const char *name, const char *arg, ...);
+
+int
+system(const char *cmnd)
+{
+    return system_wrapper(cmnd);
+}
+
+int
+execve(const char *cmnd, char * const argv[], char * const envp[])
+{
+    return exec_wrapper(cmnd, argv, envp, false);
+}
+
+int
+execv(const char *cmnd, char * const argv[])
+{
+    return execve(cmnd, argv, environ);
+}
+
+#ifdef HAVE_EXECVPE
+int
+execvpe(const char *cmnd, char * const argv[], char * const envp[])
+{
+    return exec_wrapper(cmnd, argv, envp, true);
+}
+#endif
+
+int
+execvp(const char *cmnd, char * const argv[])
+{
+    return exec_wrapper(cmnd, argv, environ, true);
+}
+
+int
+execl(const char *name, const char *arg, ...)
+{
+    va_list ap;
+
+    va_start(ap, arg);
+    execl_wrapper(SUDO_EXECL, name, arg, ap);
+    va_end(ap);
+
+    return -1;
+}
+
+int
+execle(const char *name, const char *arg, ...)
+{
+    va_list ap;
+
+    va_start(ap, arg);
+    execl_wrapper(SUDO_EXECLE, name, arg, ap);
+    va_end(ap);
+
+    return -1;
+}
+
+int
+execlp(const char *name, const char *arg, ...)
+{
+    va_list ap;
+
+    va_start(ap, arg);
+    execl_wrapper(SUDO_EXECLP, name, arg, ap);
+    va_end(ap);
+
+    return -1;
+}
+#endif /* HAVE___INTERPOSE) */