1 files changed, 160 insertions, 0 deletions
diff --git a/lib/util/mmap_alloc.c b/lib/util/mmap_alloc.c
new file mode 100644
index 0000000..b587338
--- /dev/null
+++ b/lib/util/mmap_alloc.c
@@ -0,0 +1,160 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
+ * Copyright (c) 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/mman.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#if defined(HAVE_STDINT_H)
+# include <stdint.h>
+#elif defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#endif
+
+#include <sudo_compat.h>
+#include <sudo_util.h>
+
+#if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
+# define MAP_ANON MAP_ANONYMOUS
+#endif
+
+#ifndef MAP_FAILED
+# define MAP_FAILED ((void *)-1)
+#endif
+
+/*
+ * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
+ * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
+ */
+#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
+
+/*
+ * Allocate "size" bytes via mmap().
+ * Space is allocated to store the size for later unmapping.
+ */
+void *
+sudo_mmap_alloc_v1(size_t size)
+{
+    void *ptr;
+    unsigned long *ulp;
+#ifndef MAP_ANON
+    int fd;
+
+    /* SunOS-style mmap allocation using /dev/zero. */
+    if ((fd = open("/dev/zero", O_RDWR)) == -1)
+	return NULL;
+    size += sizeof(unsigned long);
+    ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+    close(fd);
+#else
+    size += sizeof(unsigned long);
+    ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+#endif
+    if (ptr == MAP_FAILED) {
+	errno = ENOMEM;
+	return NULL;
+    }
+
+    /* Store size before the actual data. */
+    ulp = (unsigned long *)ptr;
+    ulp[0] = size;
+    return (void *)&ulp[1];
+}
+
+/*
+ * Allocate "nmemb" elements of "size" bytes via mmap().
+ * If overflow would occur, errno is set to ENOMEM and
+ * NULL is returned.
+ */
+void *
+sudo_mmap_allocarray_v1(size_t nmemb, size_t size)
+{
+    if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
+	    nmemb > 0 && SIZE_MAX / nmemb < size) {
+	errno = ENOMEM;
+	return NULL;
+    }
+    return sudo_mmap_alloc_v1(nmemb * size);
+}
+
+/*
+ * Make a copy of "str" via mmap() and return it.
+ */
+char *
+sudo_mmap_strdup_v1(const char *str)
+{
+    size_t len = strlen(str);
+    char *newstr;
+
+    if (len == SIZE_MAX) {
+	errno = ENOMEM;
+	return NULL;
+    }
+    newstr = sudo_mmap_alloc_v1(len + 1);
+    if (newstr != NULL) {
+        memcpy(newstr, str, len);
+        newstr[len] = '\0';
+    }
+
+    return newstr;
+}
+
+/*
+ * Set the page permissions for the allocation represented by "ptr" to
+ * read-only.  Returns 0 on success, -1 on failure.
+ */
+int
+sudo_mmap_protect_v1(void *ptr)
+{
+    if (ptr != NULL) {
+	unsigned long *ulp = ptr;
+	const unsigned long size = ulp[-1];
+	return mprotect((void *)&ulp[-1], size, PROT_READ);
+    }
+
+    /* Can't protect NULL. */
+    errno = EINVAL;
+    return -1;
+}
+
+/*
+ * Free "ptr" allocated by sudo_mmap_alloc().
+ * The allocated size is stored (as unsigned long) in ptr[-1].
+ */
+void
+sudo_mmap_free_v1(void *ptr)
+{
+    if (ptr != NULL) {
+	unsigned long *ulp = (unsigned long *)ptr - 1;
+	const unsigned long size = ulp[0];
+	int saved_errno = errno;
+
+	(void)munmap((void *)ulp, size);
+	errno = saved_errno;
+    }
+}