blob: 3752931cf8f8c193dd6ee42f655cc46669bd261f [file] [log] [blame]
/*
* fs.c filesystem APIs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: David Ahern <dsa@cumulusnetworks.com>
*
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/mount.h>
#include <ctype.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include "utils.h"
#ifndef HAVE_HANDLE_AT
# include <sys/syscall.h>
#endif
#define CGROUP2_FS_NAME "cgroup2"
/* if not already mounted cgroup2 is mounted here for iproute2's use */
#define MNT_CGRP2_PATH "/var/run/cgroup2"
#ifndef HAVE_HANDLE_AT
struct file_handle {
unsigned handle_bytes;
int handle_type;
unsigned char f_handle[];
};
static int name_to_handle_at(int dirfd, const char *pathname,
struct file_handle *handle, int *mount_id, int flags)
{
return syscall(__NR_name_to_handle_at, dirfd, pathname, handle,
mount_id, flags);
}
static int open_by_handle_at(int mount_fd, struct file_handle *handle, int flags)
{
return syscall(__NR_open_by_handle_at, mount_fd, handle, flags);
}
#endif
/* return mount path of first occurrence of given fstype */
static char *find_fs_mount(const char *fs_to_find)
{
char path[4096];
char fstype[128]; /* max length of any filesystem name */
char *mnt = NULL;
FILE *fp;
fp = fopen("/proc/mounts", "r");
if (!fp) {
fprintf(stderr,
"Failed to open mounts file: %s\n", strerror(errno));
return NULL;
}
while (fscanf(fp, "%*s %4095s %127s %*s %*d %*d\n",
path, fstype) == 2) {
if (strcmp(fstype, fs_to_find) == 0) {
mnt = strdup(path);
break;
}
}
fclose(fp);
return mnt;
}
/* caller needs to free string returned */
char *find_cgroup2_mount(bool do_mount)
{
char *mnt = find_fs_mount(CGROUP2_FS_NAME);
if (mnt)
return mnt;
if (!do_mount) {
fprintf(stderr, "Failed to find cgroup2 mount\n");
return NULL;
}
mnt = strdup(MNT_CGRP2_PATH);
if (!mnt) {
fprintf(stderr, "Failed to allocate memory for cgroup2 path\n");
return NULL;
}
if (make_path(mnt, 0755)) {
fprintf(stderr, "Failed to setup cgroup2 directory\n");
free(mnt);
return NULL;
}
if (mount("none", mnt, CGROUP2_FS_NAME, 0, NULL)) {
/* EBUSY means already mounted */
if (errno == EBUSY)
goto out;
if (errno == ENODEV) {
fprintf(stderr,
"Failed to mount cgroup2. Are CGROUPS enabled in your kernel?\n");
} else {
fprintf(stderr,
"Failed to mount cgroup2: %s\n",
strerror(errno));
}
free(mnt);
return NULL;
}
out:
return mnt;
}
__u64 get_cgroup2_id(const char *path)
{
char fh_buf[sizeof(struct file_handle) + sizeof(__u64)] = { 0 };
struct file_handle *fhp = (struct file_handle *)fh_buf;
union {
__u64 id;
unsigned char bytes[sizeof(__u64)];
} cg_id = { .id = 0 };
char *mnt = NULL;
int mnt_fd = -1;
int mnt_id;
if (!path) {
fprintf(stderr, "Invalid cgroup2 path\n");
return 0;
}
fhp->handle_bytes = sizeof(__u64);
if (name_to_handle_at(AT_FDCWD, path, fhp, &mnt_id, 0) < 0) {
/* try at cgroup2 mount */
while (*path == '/')
path++;
if (*path == '\0') {
fprintf(stderr, "Invalid cgroup2 path\n");
goto out;
}
mnt = find_cgroup2_mount(false);
if (!mnt)
goto out;
mnt_fd = open(mnt, O_RDONLY);
if (mnt_fd < 0) {
fprintf(stderr, "Failed to open cgroup2 mount\n");
goto out;
}
fhp->handle_bytes = sizeof(__u64);
if (name_to_handle_at(mnt_fd, path, fhp, &mnt_id, 0) < 0) {
fprintf(stderr, "Failed to get cgroup2 ID: %s\n",
strerror(errno));
goto out;
}
}
if (fhp->handle_bytes != sizeof(__u64)) {
fprintf(stderr, "Invalid size of cgroup2 ID\n");
goto out;
}
memcpy(cg_id.bytes, fhp->f_handle, sizeof(__u64));
out:
if (mnt_fd >= 0)
close(mnt_fd);
free(mnt);
return cg_id.id;
}
#define FILEID_INO32_GEN 1
/* caller needs to free string returned */
char *get_cgroup2_path(__u64 id, bool full)
{
char fh_buf[sizeof(struct file_handle) + sizeof(__u64)] = { 0 };
struct file_handle *fhp = (struct file_handle *)fh_buf;
union {
__u64 id;
unsigned char bytes[sizeof(__u64)];
} cg_id = { .id = id };
int mnt_fd = -1, fd = -1;
char link_buf[PATH_MAX];
char *path = NULL;
char fd_path[64];
int link_len;
char *mnt = NULL;
if (!id) {
fprintf(stderr, "Invalid cgroup2 ID\n");
goto out;
}
mnt = find_cgroup2_mount(false);
if (!mnt)
goto out;
mnt_fd = open(mnt, O_RDONLY);
if (mnt_fd < 0) {
fprintf(stderr, "Failed to open cgroup2 mount\n");
goto out;
}
fhp->handle_bytes = sizeof(__u64);
fhp->handle_type = FILEID_INO32_GEN;
memcpy(fhp->f_handle, cg_id.bytes, sizeof(__u64));
fd = open_by_handle_at(mnt_fd, fhp, 0);
if (fd < 0) {
fprintf(stderr, "Failed to open cgroup2 by ID\n");
goto out;
}
snprintf(fd_path, sizeof(fd_path), "/proc/self/fd/%d", fd);
link_len = readlink(fd_path, link_buf, sizeof(link_buf) - 1);
if (link_len < 0) {
fprintf(stderr,
"Failed to read value of symbolic link %s\n",
fd_path);
goto out;
}
link_buf[link_len] = '\0';
if (full)
path = strdup(link_buf);
else
path = strdup(link_buf + strlen(mnt));
if (!path)
fprintf(stderr,
"Failed to allocate memory for cgroup2 path\n");
out:
if (fd >= 0)
close(fd);
if (mnt_fd >= 0)
close(mnt_fd);
free(mnt);
return path;
}
int make_path(const char *path, mode_t mode)
{
char *dir, *delim;
int rc = -1;
delim = dir = strdup(path);
if (dir == NULL) {
fprintf(stderr, "strdup failed copying path");
return -1;
}
/* skip '/' -- it had better exist */
if (*delim == '/')
delim++;
while (1) {
delim = strchr(delim, '/');
if (delim)
*delim = '\0';
rc = mkdir(dir, mode);
if (rc && errno != EEXIST) {
fprintf(stderr, "mkdir failed for %s: %s\n",
dir, strerror(errno));
goto out;
}
if (delim == NULL)
break;
*delim = '/';
delim++;
if (*delim == '\0')
break;
}
rc = 0;
out:
free(dir);
return rc;
}
int get_command_name(const char *pid, char *comm, size_t len)
{
char path[PATH_MAX];
char line[128];
FILE *fp;
if (snprintf(path, sizeof(path),
"/proc/%s/status", pid) >= sizeof(path)) {
return -1;
}
fp = fopen(path, "r");
if (!fp)
return -1;
comm[0] = '\0';
while (fgets(line, sizeof(line), fp)) {
char *nl, *name;
name = strstr(line, "Name:");
if (!name)
continue;
name += 5;
while (isspace(*name))
name++;
nl = strchr(name, '\n');
if (nl)
*nl = '\0';
strlcpy(comm, name, len);
break;
}
fclose(fp);
return 0;
}
int get_task_name(pid_t pid, char *name, size_t len)
{
char path[PATH_MAX];
FILE *f;
if (!pid)
return -1;
if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
return -1;
f = fopen(path, "r");
if (!f)
return -1;
if (!fgets(name, len, f))
return -1;
/* comm ends in \n, get rid of it */
name[strcspn(name, "\n")] = '\0';
fclose(f);
return 0;
}