diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/um/os-Linux/mem.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c new file mode 100644 index 000000000..8530b2e08 --- /dev/null +++ b/arch/um/os-Linux/mem.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include <stdio.h> +#include <stddef.h> +#include <stdlib.h> +#include <unistd.h> +#include <errno.h> +#include <fcntl.h> +#include <string.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <sys/vfs.h> +#include <linux/magic.h> +#include <init.h> +#include <os.h> + +/* + * kasan_map_memory - maps memory from @start with a size of @len. + * The allocated memory is filled with zeroes upon success. + * @start: the start address of the memory to be mapped + * @len: the length of the memory to be mapped + * + * This function is used to map shadow memory for KASAN in uml + */ +void kasan_map_memory(void *start, size_t len) +{ + if (mmap(start, + len, + PROT_READ|PROT_WRITE, + MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, + -1, + 0) == MAP_FAILED) { + os_info("Couldn't allocate shadow memory: %s\n.", + strerror(errno)); + exit(1); + } +} + +/* Set by make_tempfile() during early boot. */ +static char *tempdir = NULL; + +/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */ +static int __init check_tmpfs(const char *dir) +{ + struct statfs st; + + os_info("Checking if %s is on tmpfs...", dir); + if (statfs(dir, &st) < 0) { + os_info("%s\n", strerror(errno)); + } else if (st.f_type != TMPFS_MAGIC) { + os_info("no\n"); + } else { + os_info("OK\n"); + return 0; + } + return -1; +} + +/* + * Choose the tempdir to use. We want something on tmpfs so that our memory is + * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the + * environment, we use that even if it's not on tmpfs, but we warn the user. + * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found + * then we fall back to /tmp. + */ +static char * __init choose_tempdir(void) +{ + static const char * const vars[] = { + "TMPDIR", + "TMP", + "TEMP", + NULL + }; + static const char fallback_dir[] = "/tmp"; + static const char * const tmpfs_dirs[] = { + "/dev/shm", + fallback_dir, + NULL + }; + int i; + const char *dir; + + os_info("Checking environment variables for a tempdir..."); + for (i = 0; vars[i]; i++) { + dir = getenv(vars[i]); + if ((dir != NULL) && (*dir != '\0')) { + os_info("%s\n", dir); + if (check_tmpfs(dir) >= 0) + goto done; + else + goto warn; + } + } + os_info("none found\n"); + + for (i = 0; tmpfs_dirs[i]; i++) { + dir = tmpfs_dirs[i]; + if (check_tmpfs(dir) >= 0) + goto done; + } + + dir = fallback_dir; +warn: + os_warn("Warning: tempdir %s is not on tmpfs\n", dir); +done: + /* Make a copy since getenv results may not remain valid forever. */ + return strdup(dir); +} + +/* + * Create an unlinked tempfile in a suitable tempdir. template must be the + * basename part of the template with a leading '/'. + */ +static int __init make_tempfile(const char *template) +{ + char *tempname; + int fd; + + if (tempdir == NULL) { + tempdir = choose_tempdir(); + if (tempdir == NULL) { + os_warn("Failed to choose tempdir: %s\n", + strerror(errno)); + return -1; + } + } + +#ifdef O_TMPFILE + fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700); + /* + * If the running system does not support O_TMPFILE flag then retry + * without it. + */ + if (fd != -1 || (errno != EINVAL && errno != EISDIR && + errno != EOPNOTSUPP)) + return fd; +#endif + + tempname = malloc(strlen(tempdir) + strlen(template) + 1); + if (tempname == NULL) + return -1; + + strcpy(tempname, tempdir); + strcat(tempname, template); + fd = mkstemp(tempname); + if (fd < 0) { + os_warn("open - cannot create %s: %s\n", tempname, + strerror(errno)); + goto out; + } + if (unlink(tempname) < 0) { + perror("unlink"); + goto close; + } + free(tempname); + return fd; +close: + close(fd); +out: + free(tempname); + return -1; +} + +#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX" + +static int __init create_tmp_file(unsigned long long len) +{ + int fd, err; + char zero; + + fd = make_tempfile(TEMPNAME_TEMPLATE); + if (fd < 0) + exit(1); + + /* + * Seek to len - 1 because writing a character there will + * increase the file size by one byte, to the desired length. + */ + if (lseek64(fd, len - 1, SEEK_SET) < 0) { + perror("lseek64"); + exit(1); + } + + zero = 0; + + err = write(fd, &zero, 1); + if (err != 1) { + perror("write"); + exit(1); + } + + return fd; +} + +int __init create_mem_file(unsigned long long len) +{ + int err, fd; + + fd = create_tmp_file(len); + + err = os_set_exec_close(fd); + if (err < 0) { + errno = -err; + perror("exec_close"); + } + return fd; +} + +void __init check_tmpexec(void) +{ + void *addr; + int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE); + + addr = mmap(NULL, UM_KERN_PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0); + os_info("Checking PROT_EXEC mmap in %s...", tempdir); + if (addr == MAP_FAILED) { + err = errno; + os_warn("%s\n", strerror(err)); + close(fd); + if (err == EPERM) + os_warn("%s must be not mounted noexec\n", tempdir); + exit(1); + } + os_info("OK\n"); + munmap(addr, UM_KERN_PAGE_SIZE); + + close(fd); +} |