From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/um/os-Linux/umid.c | 408 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 408 insertions(+) create mode 100644 arch/um/os-Linux/umid.c (limited to 'arch/um/os-Linux/umid.c') diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c new file mode 100644 index 000000000..7a1abb829 --- /dev/null +++ b/arch/um/os-Linux/umid.c @@ -0,0 +1,408 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define UML_DIR "~/.uml/" + +#define UMID_LEN 64 + +/* Changed by set_umid, which is run early in boot */ +static char umid[UMID_LEN] = { 0 }; + +/* Changed by set_uml_dir and make_uml_dir, which are run early in boot */ +static char *uml_dir = UML_DIR; + +static int __init make_uml_dir(void) +{ + char dir[512] = { '\0' }; + int len, err; + + if (*uml_dir == '~') { + char *home = getenv("HOME"); + + err = -ENOENT; + if (home == NULL) { + printk(UM_KERN_ERR + "%s: no value in environment for $HOME\n", + __func__); + goto err; + } + strlcpy(dir, home, sizeof(dir)); + uml_dir++; + } + strlcat(dir, uml_dir, sizeof(dir)); + len = strlen(dir); + if (len > 0 && dir[len - 1] != '/') + strlcat(dir, "/", sizeof(dir)); + + err = -ENOMEM; + uml_dir = malloc(strlen(dir) + 1); + if (uml_dir == NULL) { + printk(UM_KERN_ERR "%s : malloc failed, errno = %d\n", + __func__, errno); + goto err; + } + strcpy(uml_dir, dir); + + if ((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)) { + printk(UM_KERN_ERR "Failed to mkdir '%s': %s\n", + uml_dir, strerror(errno)); + err = -errno; + goto err_free; + } + return 0; + +err_free: + free(uml_dir); +err: + uml_dir = NULL; + return err; +} + +/* + * Unlinks the files contained in @dir and then removes @dir. + * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We + * ignore ENOENT errors for anything (they happen, strangely enough - possibly + * due to races between multiple dying UML threads). + */ +static int remove_files_and_dir(char *dir) +{ + DIR *directory; + struct dirent *ent; + int len; + char file[256]; + int ret; + + directory = opendir(dir); + if (directory == NULL) { + if (errno != ENOENT) + return -errno; + else + return 0; + } + + while ((ent = readdir(directory)) != NULL) { + if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, "..")) + continue; + len = strlen(dir) + strlen("/") + strlen(ent->d_name) + 1; + if (len > sizeof(file)) { + ret = -E2BIG; + goto out; + } + + sprintf(file, "%s/%s", dir, ent->d_name); + if (unlink(file) < 0 && errno != ENOENT) { + ret = -errno; + goto out; + } + } + + if (rmdir(dir) < 0 && errno != ENOENT) { + ret = -errno; + goto out; + } + + ret = 0; +out: + closedir(directory); + return ret; +} + +/* + * This says that there isn't already a user of the specified directory even if + * there are errors during the checking. This is because if these errors + * happen, the directory is unusable by the pre-existing UML, so we might as + * well take it over. This could happen either by + * the existing UML somehow corrupting its umid directory + * something other than UML sticking stuff in the directory + * this boot racing with a shutdown of the other UML + * In any of these cases, the directory isn't useful for anything else. + * + * Boolean return: 1 if in use, 0 otherwise. + */ +static inline int is_umdir_used(char *dir) +{ + char pid[sizeof("nnnnnnnnn")], *end, *file; + int fd, p, n, err; + size_t filelen = strlen(dir) + sizeof("/pid") + 1; + + file = malloc(filelen); + if (!file) + return -ENOMEM; + + snprintf(file, filelen, "%s/pid", dir); + + fd = open(file, O_RDONLY); + if (fd < 0) { + fd = -errno; + if (fd != -ENOENT) { + printk(UM_KERN_ERR "is_umdir_used : couldn't open pid " + "file '%s', err = %d\n", file, -fd); + } + goto out; + } + + err = 0; + n = read(fd, pid, sizeof(pid)); + if (n < 0) { + printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file " + "'%s', err = %d\n", file, errno); + goto out_close; + } else if (n == 0) { + printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file " + "'%s', 0-byte read\n", file); + goto out_close; + } + + p = strtoul(pid, &end, 0); + if (end == pid) { + printk(UM_KERN_ERR "is_umdir_used : couldn't parse pid file " + "'%s', errno = %d\n", file, errno); + goto out_close; + } + + if ((kill(p, 0) == 0) || (errno != ESRCH)) { + printk(UM_KERN_ERR "umid \"%s\" is already in use by pid %d\n", + umid, p); + return 1; + } + +out_close: + close(fd); +out: + free(file); + return 0; +} + +/* + * Try to remove the directory @dir unless it's in use. + * Precondition: @dir exists. + * Returns 0 for success, < 0 for failure in removal or if the directory is in + * use. + */ +static int umdir_take_if_dead(char *dir) +{ + int ret; + if (is_umdir_used(dir)) + return -EEXIST; + + ret = remove_files_and_dir(dir); + if (ret) { + printk(UM_KERN_ERR "is_umdir_used - remove_files_and_dir " + "failed with err = %d\n", ret); + } + return ret; +} + +static void __init create_pid_file(void) +{ + char pid[sizeof("nnnnnnnnn")], *file; + int fd, n; + + n = strlen(uml_dir) + UMID_LEN + sizeof("/pid"); + file = malloc(n); + if (!file) + return; + + if (umid_file_name("pid", file, n)) + goto out; + + fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644); + if (fd < 0) { + printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: " + "%s\n", file, strerror(errno)); + goto out; + } + + snprintf(pid, sizeof(pid), "%d\n", getpid()); + n = write(fd, pid, strlen(pid)); + if (n != strlen(pid)) + printk(UM_KERN_ERR "Write of pid file failed - err = %d\n", + errno); + + close(fd); +out: + free(file); +} + +int __init set_umid(char *name) +{ + if (strlen(name) > UMID_LEN - 1) + return -E2BIG; + + strlcpy(umid, name, sizeof(umid)); + + return 0; +} + +/* Changed in make_umid, which is called during early boot */ +static int umid_setup = 0; + +static int __init make_umid(void) +{ + int fd, err; + char tmp[256]; + + if (umid_setup) + return 0; + + make_uml_dir(); + + if (*umid == '\0') { + strlcpy(tmp, uml_dir, sizeof(tmp)); + strlcat(tmp, "XXXXXX", sizeof(tmp)); + fd = mkstemp(tmp); + if (fd < 0) { + printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: " + "%s\n", tmp, strerror(errno)); + err = -errno; + goto err; + } + + close(fd); + + set_umid(&tmp[strlen(uml_dir)]); + + /* + * There's a nice tiny little race between this unlink and + * the mkdir below. It'd be nice if there were a mkstemp + * for directories. + */ + if (unlink(tmp)) { + err = -errno; + goto err; + } + } + + snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid); + err = mkdir(tmp, 0777); + if (err < 0) { + err = -errno; + if (err != -EEXIST) + goto err; + + if (umdir_take_if_dead(tmp) < 0) + goto err; + + err = mkdir(tmp, 0777); + } + if (err) { + err = -errno; + printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid, + errno); + goto err; + } + + umid_setup = 1; + + create_pid_file(); + + err = 0; + err: + return err; +} + +static int __init make_umid_init(void) +{ + if (!make_umid()) + return 0; + + /* + * If initializing with the given umid failed, then try again with + * a random one. + */ + printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a " + "random umid\n", umid); + *umid = '\0'; + make_umid(); + + return 0; +} + +__initcall(make_umid_init); + +int __init umid_file_name(char *name, char *buf, int len) +{ + int n, err; + + err = make_umid(); + if (err) + return err; + + n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name); + if (n >= len) { + printk(UM_KERN_ERR "umid_file_name : buffer too short\n"); + return -E2BIG; + } + + return 0; +} + +char *get_umid(void) +{ + return umid; +} + +static int __init set_uml_dir(char *name, int *add) +{ + if (*name == '\0') { + os_warn("uml_dir can't be an empty string\n"); + return 0; + } + + if (name[strlen(name) - 1] == '/') { + uml_dir = name; + return 0; + } + + uml_dir = malloc(strlen(name) + 2); + if (uml_dir == NULL) { + os_warn("Failed to malloc uml_dir - error = %d\n", errno); + + /* + * Return 0 here because do_initcalls doesn't look at + * the return value. + */ + return 0; + } + sprintf(uml_dir, "%s/", name); + + return 0; +} + +__uml_setup("uml_dir=", set_uml_dir, +"uml_dir=\n" +" The location to place the pid and umid files.\n\n" +); + +static void remove_umid_dir(void) +{ + char *dir, err; + + dir = malloc(strlen(uml_dir) + UMID_LEN + 1); + if (!dir) + return; + + sprintf(dir, "%s%s", uml_dir, umid); + err = remove_files_and_dir(dir); + if (err) + os_warn("%s - remove_files_and_dir failed with err = %d\n", + __func__, err); + + free(dir); +} + +__uml_exitcall(remove_umid_dir); -- cgit v1.2.3