5

cap_setgid、cap_setuid、を設定しようとしていcap_setpcapます。

#include <sys/types.h>
#include <sys/capability.h>

int main()
{
    cap_t caps;
    caps = cap_get_proc();
    cap_value_t cap_list[2];

    cap_list[0] = CAP_SETUID;
    cap_list[1] = CAP_SETGID;

    cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_list, CAP_SET);
    cap_set_flag(caps, CAP_INHERITABLE, 2, cap_list, CAP_SET);
    cap_set_proc(caps);
    cap_free(caps);
    setgid(65534);
    setuid(65534);

    cap_get_proc();
    setgid(0);
    setuid(0);

    return 0;
}

実行は root ユーザーで行っています。プログラムをトレースすると、これが示されます

capget({_LINUX_CAPABILITY_VERSION_3, 0}, NULL) = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, {CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, 0}) = 0
capset({_LINUX_CAPABILITY_VERSION_3, 0}, {CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, CAP_SETGID|CAP_SETUID|CAP_SETPCAP}) = 0
setgid(65534)                           = 0
setuid(65534)                           = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, NULL) = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, {0, 0, CAP_SETGID|CAP_SETUID|CAP_SETPCAP}) = 0
setgid(0)                               = -1 EPERM (Operation not permitted)
setuid(0)                               = -1 EPERM (Operation not permitted)
exit_group(0)                           = ?
+++ exited with 0 +++

権限は設定されていますが、機能しません。この問題を解決する方法はありますか?

更新:prctlコードに追加

21a22
> prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
24a26
> cap_set_flag(caps, CAP_EFFECTIVE, 3, cap_list, CAP_SET);

だから今は

prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
setgid(65534);
setuid(65534);
cap_set_flag(caps, CAP_EFFECTIVE, 3, cap_list, CAP_SET);

キャップは の後に継承されsetuid、手動で設定されたキャップはまだ存在しますが、問題は解決しませんでした

setgid(65534)                           = 0
setuid(65534)                           = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, NULL) = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, {0, CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, CAP_SETGID|CAP_SETUID|CAP_SETPCAP}) = 0
setgid(0)                               = -1 EPERM (Operation not permitted)
setuid(0)                               = -1 EPERM (Operation not permitted)
exit_group(0)                           = ?
+++ exited with 0 +++

UPDATE2: 理解できません。setuidキャップを確認するために、1st の後に 2strs を追加しました。

printf("cape set %d\n", cap_set_flag(caps, CAP_EFFECTIVE, 3, cap_list, CAP_SET));
printf("%s\n", cap_to_text(cap_get_proc(), NULL));

それは戻った

catp set 0
=p cap_setgid,cap_setuid,cap_setpcap+i

有効なフラグは設定されていませんが、cap_set_flag は 0 を返しました

4

2 に答える 2

12

デフォルトでは、機能セットは UID 遷移で失われます。使用する

prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);

許可された機能を保持する( cap_set_flag(caps, CAP_PERMITTED, ...))。有効な機能セットはリセットされますが、再確立できることに注意してください。

以下は私にとってはうまくいきます。

#include <sys/capability.h>
#include <sys/prctl.h>
#include <unistd.h>

int main(int argc, char **argv) {
    cap_value_t cap_values[] = {CAP_SETUID, CAP_SETGID};
    cap_t caps;

    caps = cap_get_proc();
    cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET);
    cap_set_proc(caps);
    prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
    cap_free(caps);

    setgid(65534);
    setuid(65534);

    caps = cap_get_proc();
    cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET);
    cap_set_proc(caps);
    cap_free(caps);

    setgid(0);
    setuid(0);

    return 0;
}

$ sudo strace ./a.out
...
capget({_LINUX_CAPABILITY_VERSION_3, 0}, {CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT |CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP,CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE| CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, 0}) = 0
capset({_LINUX_CAPABILITY_VERSION_3, 0}, {CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT |CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP,CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE| CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, 0}) = 0
prctl(PR_SET_KEEPCAPS, 1) = 0
setgid(65534) = 0
setuid(65534) = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, NULL) = 0
capget({_LINUX_CAPABILITY_VERSION_3, 0}, {0, CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT|CAP_SYS_PTRACE |CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, 0}) = 0
capset({_LINUX_CAPABILITY_VERSION_3, 0}, {CAP_SETGID|CAP_SETUID, CAP_CHOWN|CAP_DAC_OVERRIDE|CAP_DAC_READ_SEARCH|CAP_FOWNER|CAP_FSETID|CAP_KILL|CAP_SETGID|CAP_SETUID|CAP_SETPCAP|CAP_LINUX_IMMUTABLE|CAP_NET_BIND_SERVICE|CAP_NET_BROADCAST|CAP_NET_ADMIN|CAP_NET_RAW|CAP_IPC_LOCK|CAP_IPC_OWNER|CAP_SYS_MODULE|CAP_SYS_RAWIO|CAP_SYS_CHROOT |CAP_SYS_PTRACE|CAP_SYS_PACCT|CAP_SYS_ADMIN|CAP_SYS_BOOT|CAP_SYS_NICE|CAP_SYS_RESOURCE|CAP_SYS_TIME|CAP_SYS_TTY_CONFIG|CAP_MKNOD|CAP_LEASE|CAP_AUDIT_WRITE|CAP_AUDIT_CONTROL|CAP_SETFCAP, 0}) = 0
setgid(0) = 0
セットイド (0) = 0
...
于 2012-08-28T06:33:01.383 に答える