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-rw-r--r--src/exec_preload.c367
1 files changed, 367 insertions, 0 deletions
diff --git a/src/exec_preload.c b/src/exec_preload.c
new file mode 100644
index 0000000..f82de7e
--- /dev/null
+++ b/src/exec_preload.c
@@ -0,0 +1,367 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2009-2022 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 <fcntl.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "sudo.h"
+#include "sudo_exec.h"
+#include "sudo_util.h"
+
+#ifdef RTLD_PRELOAD_VAR
+typedef void * (*sudo_alloc_fn_t)(size_t, size_t);
+typedef void (*sudo_free_fn_t)(void *);
+
+static void *
+sudo_allocarray(size_t nmemb, size_t size)
+{
+ return reallocarray(NULL, nmemb, size);
+}
+
+/*
+ * Allocate space for the string described by fmt and return it,
+ * or NULL on error.
+ * Currently only supports %%, %c, %d, and %s escapes.
+ */
+static char *
+fmtstr(sudo_alloc_fn_t alloc_fn, sudo_free_fn_t free_fn, const char *ofmt, ...)
+{
+ char *cp, *cur, *newstr = NULL;
+ size_t len, size = 1;
+ const char *fmt;
+ va_list ap;
+ debug_decl(fmtstr, SUDO_DEBUG_UTIL);
+
+ /* Determine size. */
+ va_start(ap, ofmt);
+ for (fmt = ofmt; *fmt != '\0'; ) {
+ if (fmt[0] == '%') {
+ switch (fmt[1]) {
+ case 'c':
+ (void)va_arg(ap, int);
+ FALLTHROUGH;
+ case '%':
+ size++;
+ fmt += 2;
+ continue;
+ case 's':
+ cp = va_arg(ap, char *);
+ size += strlen(cp ? cp : "(NULL)");
+ fmt += 2;
+ continue;
+ case 'd': {
+ char numbuf[(((sizeof(int) * 8) + 2) / 3) + 2];
+ len = snprintf(numbuf, sizeof(numbuf), "%d", va_arg(ap, int));
+ if (len >= sizeof(numbuf)) {
+ goto oflow;
+ }
+ size += len;
+ fmt += 2;
+ continue;
+ }
+ default:
+ /* Treat as literal. */
+ break;
+ }
+ }
+ size++;
+ fmt++;
+ }
+ va_end(ap);
+
+ newstr = alloc_fn(1, size);
+ if (newstr == NULL)
+ debug_return_str(NULL);
+
+ /* Format/copy data. */
+ cur = newstr;
+ va_start(ap, ofmt);
+ for (fmt = ofmt; *fmt != '\0'; ) {
+ if (fmt[0] == '%') {
+ switch (fmt[1]) {
+ case '%':
+ if (size < 2) {
+ goto oflow;
+ }
+ *cur++ = '%';
+ size--;
+ fmt += 2;
+ continue;
+ case 'c':
+ if (size < 2) {
+ goto oflow;
+ }
+ *cur++ = va_arg(ap, int);
+ size--;
+ fmt += 2;
+ continue;
+ case 's':
+ cp = va_arg(ap, char *);
+ len = strlcpy(cur, cp ? cp : "(NULL)", size);
+ if (len >= size) {
+ goto oflow;
+ }
+ cur += len;
+ size -= len;
+ fmt += 2;
+ continue;
+ case 'd':
+ len = snprintf(cur, size, "%d", va_arg(ap, int));
+ if (len >= size) {
+ goto oflow;
+ }
+ cur += len;
+ size -= len;
+ fmt += 2;
+ continue;
+ default:
+ /* Treat as literal. */
+ break;
+ }
+ }
+ if (size < 2) {
+ goto oflow;
+ }
+ *cur++ = *fmt++;
+ size++;
+ }
+
+ if (size < 1) {
+ goto oflow;
+ }
+ *cur = '\0';
+ va_end(ap);
+
+ debug_return_str(newstr);
+
+oflow:
+ /* We pre-allocate enough space, so this should never happen. */
+ va_end(ap);
+ free_fn(newstr);
+ sudo_warnx(U_("internal error, %s overflow"), __func__);
+ debug_return_str(NULL);
+}
+
+/*
+ * Add a DSO file to LD_PRELOAD or the system equivalent.
+ */
+static char **
+sudo_preload_dso_alloc(char *const envp[], const char *dso_file,
+ int intercept_fd, sudo_alloc_fn_t alloc_fn, sudo_free_fn_t free_fn)
+{
+ char *preload = NULL;
+ char **nep, **nenvp = NULL;
+ char *const *ep;
+ char **preload_ptr = NULL;
+ char **intercept_ptr = NULL;
+ char *const empty[1] = { NULL };
+ bool fd_present = false;
+ bool dso_present = false;
+# ifdef RTLD_PRELOAD_ENABLE_VAR
+ bool dso_enabled = false;
+# else
+ const bool dso_enabled = true;
+# endif
+# ifdef _PATH_ASAN_LIB
+ char *dso_buf = NULL;
+# endif
+ size_t env_size;
+ debug_decl(sudo_preload_dso_alloc, SUDO_DEBUG_UTIL);
+
+# ifdef _PATH_ASAN_LIB
+ /*
+ * The address sanitizer DSO needs to be first in the list.
+ */
+ dso_buf = fmtstr(alloc_fn, free_fn, "%s%c%s", _PATH_ASAN_LIB,
+ RTLD_PRELOAD_DELIM, dso_file);
+ if (dso_buf == NULL) {
+ goto oom;
+ }
+ dso_file = dso_buf;
+# endif
+
+ /*
+ * Preload a DSO file. For a list of LD_PRELOAD-alikes, see
+ * http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html
+ * XXX - need to support 32-bit and 64-bit variants
+ */
+
+ /* Treat a NULL envp as empty, thanks Linux. */
+ if (envp == NULL)
+ envp = empty;
+
+ /* Determine max size for new envp. */
+ for (env_size = 0; envp[env_size] != NULL; env_size++)
+ continue;
+ if (!dso_enabled)
+ env_size++;
+ if (intercept_fd != -1)
+ env_size++;
+ env_size += 2; /* dso_file + terminating NULL */
+
+ /* Allocate new envp. */
+ nenvp = alloc_fn(env_size, sizeof(*nenvp));
+ if (nenvp == NULL)
+ goto oom;
+
+ /*
+ * Shallow copy envp, with special handling for RTLD_PRELOAD_VAR,
+ * RTLD_PRELOAD_ENABLE_VAR and SUDO_INTERCEPT_FD.
+ */
+ for (ep = envp, nep = nenvp; *ep != NULL; ep++) {
+ if (strncmp(*ep, RTLD_PRELOAD_VAR "=", sizeof(RTLD_PRELOAD_VAR)) == 0) {
+ const char *cp = *ep + sizeof(RTLD_PRELOAD_VAR);
+ const size_t dso_len = strlen(dso_file);
+
+ /* Skip duplicates. */
+ if (preload_ptr != NULL)
+ continue;
+
+ /*
+ * Check to see if dso_file is already first in the list.
+ * We don't bother checking for it later in the list.
+ */
+ if (strncmp(cp, dso_file, dso_len) == 0) {
+ if (cp[dso_len] == '\0' || cp[dso_len] == RTLD_PRELOAD_DELIM)
+ dso_present = true;
+ }
+
+ /* Save pointer to LD_PRELOAD variable. */
+ preload_ptr = nep;
+
+ goto copy;
+ }
+ if (intercept_fd != -1 && strncmp(*ep, "SUDO_INTERCEPT_FD=",
+ sizeof("SUDO_INTERCEPT_FD=") - 1) == 0) {
+ const char *cp = *ep + sizeof("SUDO_INTERCEPT_FD=") - 1;
+ const char *errstr;
+ int fd;
+
+ /* Skip duplicates. */
+ if (intercept_ptr != NULL)
+ continue;
+
+ fd = sudo_strtonum(cp, 0, INT_MAX, &errstr);
+ if (fd == intercept_fd && errstr == NULL)
+ fd_present = true;
+
+ /* Save pointer to SUDO_INTERCEPT_FD variable. */
+ intercept_ptr = nep;
+
+ goto copy;
+ }
+# ifdef RTLD_PRELOAD_ENABLE_VAR
+ if (strncmp(*ep, RTLD_PRELOAD_ENABLE_VAR "=",
+ sizeof(RTLD_PRELOAD_ENABLE_VAR)) == 0) {
+ dso_enabled = true;
+ }
+# endif
+copy:
+ *nep++ = *ep; /* shallow copy */
+ }
+
+ /* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
+ if (!dso_present) {
+ if (preload_ptr == NULL) {
+# ifdef RTLD_PRELOAD_DEFAULT
+ preload = fmtstr(alloc_fn, free_fn, "%s=%s%c%s", RTLD_PRELOAD_VAR,
+ dso_file, RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
+ if (preload == NULL) {
+ goto oom;
+ }
+# else
+ preload = fmtstr(alloc_fn, free_fn, "%s=%s", RTLD_PRELOAD_VAR,
+ dso_file);
+ if (preload == NULL) {
+ goto oom;
+ }
+# endif
+ *nep++ = preload;
+ } else {
+ const char *old_val = *preload_ptr + sizeof(RTLD_PRELOAD_VAR);
+ preload = fmtstr(alloc_fn, free_fn, "%s=%s%c%s", RTLD_PRELOAD_VAR,
+ dso_file, RTLD_PRELOAD_DELIM, old_val);
+ if (preload == NULL) {
+ goto oom;
+ }
+ *preload_ptr = preload;
+ }
+ }
+# ifdef RTLD_PRELOAD_ENABLE_VAR
+ if (!dso_enabled) {
+ *nenvp++ = RTLD_PRELOAD_ENABLE_VAR "=";
+ }
+# endif
+ if (!fd_present && intercept_fd != -1) {
+ char *fdstr = fmtstr(alloc_fn, free_fn, "SUDO_INTERCEPT_FD=%d",
+ intercept_fd);
+ if (fdstr == NULL) {
+ goto oom;
+ }
+ if (intercept_ptr != NULL) {
+ *intercept_ptr = fdstr;
+ } else {
+ *nep++ = fdstr;
+ }
+ }
+
+ /* NULL terminate nenvp at last. */
+ *nep = NULL;
+
+# ifdef _PATH_ASAN_LIB
+ free_fn(dso_buf);
+# endif
+
+ debug_return_ptr(nenvp);
+oom:
+ sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+# ifdef _PATH_ASAN_LIB
+ free_fn(dso_buf);
+# endif
+ free_fn(preload);
+ free_fn(nenvp);
+ debug_return_ptr(NULL);
+}
+
+char **
+sudo_preload_dso_mmap(char *const envp[], const char *dso_file,
+ int intercept_fd)
+{
+ return sudo_preload_dso_alloc(envp, dso_file, intercept_fd,
+ sudo_mmap_allocarray_v1, sudo_mmap_free_v1);
+}
+
+char **
+sudo_preload_dso(char *const envp[], const char *dso_file,
+ int intercept_fd)
+{
+ return sudo_preload_dso_alloc(envp, dso_file, intercept_fd,
+ sudo_allocarray, free);
+}
+#endif /* RTLD_PRELOAD_VAR */
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-18 01:44:04 +0000