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如何通過 mount() 掛載 cgroup 控制器

[英]How can i mount cgroup controller by mount()

 原文  2022-06-15 09:37:41  9   1    c/ linux/ linux-kernel/ mount/ mount-point

問題描述

我想用 c 語言通過 mount() 掛載 cgroup 控制器。

像這樣的代碼，mount_path已經給了777權限並由root運行（主機不是容器，具有完整功能），但程序返回“mount failed：Operation not allowed”，我嘗試使用mount命令運行良好，但代碼不

我的代碼中有錯誤嗎？

mount("none", mount_path, "cgroup", 0, "none,name=memory")

只想要像mount -t cgroup -o memory cgroup /tmp一樣的效果

我找到了 stackoverflow 和 github，但找不到答案。

謝謝

代碼很簡單，像這樣

// if(mount("none", mount_path, "cgroup", 0, "none,name=memory")){
if(mount("cgroup", "/tmp/b", "cgroup", 0, "memory")){
        perror("mount failed");
    }

strace 掛載結果strace -o trace.txt mount -t cgroup -o memory cgroup /tmp

execve("/usr/bin/mount", ["mount", "-t", "cgroup", "-o", "memory", "cgroup", "/tmp/a/"], 0xffffd37390c0 /* 50 vars */) = 0
brk(NULL)                               = 0xaaab1a331000
faccessat(AT_FDCWD, "/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=69312, ...}) = 0
mmap(NULL, 69312, PROT_READ, MAP_PRIVATE, 3, 0) = 0xffff9d7aa000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libmount.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\340\263\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=383480, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff9d7e7000
mmap(NULL, 447832, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d73c000
mprotect(0xffff9d797000, 65536, PROT_NONE) = 0
mmap(0xffff9d7a7000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x5b000) = 0xffff9d7a7000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0`\17\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1450832, ...}) = 0
mmap(NULL, 1519552, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d5c9000
mprotect(0xffff9d724000, 61440, PROT_NONE) = 0
mmap(0xffff9d733000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15a000) = 0xffff9d733000
mmap(0xffff9d739000, 12224, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff9d739000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libblkid.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\360\236\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=355240, ...}) = 0
mmap(NULL, 419600, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d562000
mprotect(0xffff9d5b3000, 65536, PROT_NONE) = 0
mmap(0xffff9d5c3000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x51000) = 0xffff9d5c3000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libselinux.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0 e\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=154872, ...}) = 0
mmap(NULL, 227800, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d52a000
mprotect(0xffff9d54f000, 61440, PROT_NONE) = 0
mmap(0xffff9d55e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x24000) = 0xffff9d55e000
mmap(0xffff9d560000, 6616, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff9d560000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0\0\"\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=514504, ...}) = 0
mmap(NULL, 578176, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d49c000
mprotect(0xffff9d518000, 65536, PROT_NONE) = 0
mmap(0xffff9d528000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x7c000) = 0xffff9d528000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0P\17\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=14560, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff9d7e5000
mmap(NULL, 78080, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d488000
mprotect(0xffff9d48b000, 61440, PROT_NONE) = 0
mmap(0xffff9d49a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0xffff9d49a000
close(3)                                = 0
openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0\267\0\1\0\0\0Ha\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=164304, ...}) = 0
mmap(NULL, 197624, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xffff9d457000
mprotect(0xffff9d473000, 61440, PROT_NONE) = 0
mmap(0xffff9d482000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b000) = 0xffff9d482000
mmap(0xffff9d484000, 13304, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xffff9d484000
close(3)                                = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff9d7e3000
mprotect(0xffff9d733000, 16384, PROT_READ) = 0
mprotect(0xffff9d482000, 4096, PROT_READ) = 0
mprotect(0xffff9d49a000, 4096, PROT_READ) = 0
mprotect(0xffff9d528000, 4096, PROT_READ) = 0
mprotect(0xffff9d55e000, 4096, PROT_READ) = 0
mprotect(0xffff9d5c3000, 20480, PROT_READ) = 0
mprotect(0xffff9d7a7000, 8192, PROT_READ) = 0
mprotect(0xaaaae690a000, 4096, PROT_READ) = 0
mprotect(0xffff9d7ec000, 4096, PROT_READ) = 0
munmap(0xffff9d7aa000, 69312)           = 0
set_tid_address(0xffff9d7e30e0)         = 16344
set_robust_list(0xffff9d7e30f0, 24)     = 0
rt_sigaction(SIGRTMIN, {sa_handler=0xffff9d45cbd0, sa_mask=[], sa_flags=SA_SIGINFO}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {sa_handler=0xffff9d45cc90, sa_mask=[], sa_flags=SA_RESTART|SA_SIGINFO}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
statfs("/sys/fs/selinux", 0xffffff7f4740) = -1 ENOENT (No such file or directory)
statfs("/selinux", 0xffffff7f4740)      = -1 ENOENT (No such file or directory)
brk(NULL)                               = 0xaaab1a331000
brk(0xaaab1a352000)                     = 0xaaab1a352000
openat(AT_FDCWD, "/proc/filesystems", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
read(3, "nodev\tsysfs\nnodev\ttmpfs\nnodev\tbd"..., 1024) = 413
read(3, "", 1024)                       = 0
close(3)                                = 0
faccessat(AT_FDCWD, "/etc/selinux/config", F_OK) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=3035952, ...}) = 0
mmap(NULL, 3035952, PROT_READ, MAP_PRIVATE, 3, 0) = 0xffff9d171000
close(3)                                = 0
getuid()                                = 0
geteuid()                               = 0
faccessat(AT_FDCWD, "/sys/fs/smackfs", F_OK) = -1 ENOENT (No such file or directory)
newfstatat(AT_FDCWD, "/tmp", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
newfstatat(AT_FDCWD, "/tmp/a", {st_mode=S_IFDIR|0755, st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
newfstatat(AT_FDCWD, "/sbin/mount.cgroup", 0xffffff7f2418, 0) = -1 ENOENT (No such file or directory)
newfstatat(AT_FDCWD, "/sbin/fs.d/mount.cgroup", 0xffffff7f2418, 0) = -1 ENOENT (No such file or directory)
newfstatat(AT_FDCWD, "/sbin/fs/mount.cgroup", 0xffffff7f2418, 0) = -1 ENOENT (No such file or directory)
getuid()                                = 0
geteuid()                               = 0
getgid()                                = 0
getegid()                               = 0
prctl(PR_GET_DUMPABLE)                  = 1 (SUID_DUMP_USER)
newfstatat(AT_FDCWD, "/run", {st_mode=S_IFDIR|0755, st_size=1000, ...}, 0) = 0
newfstatat(AT_FDCWD, "/run/mount/utab", {st_mode=S_IFREG|0644, st_size=500, ...}, AT_SYMLINK_NOFOLLOW) = 0
newfstatat(AT_FDCWD, "/run/mount/utab", {st_mode=S_IFREG|0644, st_size=500, ...}, 0) = 0
geteuid()                               = 0
getegid()                               = 0
getuid()                                = 0
getgid()                                = 0
faccessat(AT_FDCWD, "/run/mount/utab", R_OK|W_OK) = 0
mount("cgroup", "/tmp/a", "cgroup", 0, "memory") = 0
close(1)                                = 0
close(2)                                = 0
exit_group(0)                           = ?
+++ exited with 0 +++

編輯mount("none", mount_path, "cgroup", 0, "none,name=memory")到mount("cgroup", "/tmp/b", "cgroup", 0, "memory") mount()返回 0，但掛載路徑中沒有文件

1 個解決方案

解決方案1
 1 已采納  2022-06-15 11:34:46

如果我從以下代碼構建可執行文件：

#include <stdio.h>
#include <sys/mount.h>

int main() {
    if(mount("cgroup", "/tmp/b", "cgroup", 0, "memory")){
        perror("mount failed");
    }
}

並以非root用戶身份運行它，我得到：

$ ./mounttest
mount failed: Operation not permitted

如果我在使用 cgroupsv2 的系統上以root身份運行它，我會看到：

$ sudo ./mounttest
mount failed: Device or resource busy

我們可以通過運行mount -t cgroup2 。 如果我們看到一個坐騎...

cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,seclabel,nsdelegate,memory_recursiveprot)

...然后我們使用 cgroupsv2 並且我們無法使用-o memory選項。

在使用 cgroupsv1 的系統上，它按預期工作：

$ sudo ./mounttest
$ ls /tmp/b
cgroup.clone_children           memory.kmem.tcp.failcnt             memory.soft_limit_in_bytes
cgroup.event_control            memory.kmem.tcp.limit_in_bytes      memory.stat
cgroup.procs                    memory.kmem.tcp.max_usage_in_bytes  memory.swappiness
cgroup.sane_behavior            memory.kmem.tcp.usage_in_bytes      memory.usage_in_bytes
init.scope                      memory.kmem.usage_in_bytes          memory.use_hierarchy
memory.failcnt                  memory.limit_in_bytes               notify_on_release
memory.force_empty              memory.max_usage_in_bytes           release_agent
memory.kmem.failcnt             memory.move_charge_at_immigrate     system.slice
memory.kmem.limit_in_bytes      memory.numa_stat                    tasks
memory.kmem.max_usage_in_bytes  memory.oom_control                  user.slice
memory.kmem.slabinfo            memory.pressure_level

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