[lxc-devel] Question: Some confusion about lxc-test-apparmor #2206

Hongzhi, Song hongzhi.song at windriver.com
Wed Mar 7 09:00:57 UTC 2018


Dose it mean that I should unenable the files listed in files_to_deny[], 
when using lxc-test-apparmor ?


On 2018年03月07日 16:57, Hongzhi, Song wrote:
>
> I have some confusion about source code of lxc-test-apparmor defined 
> in 'lxc/src/tests/aa.c'.
>
>   * The output of||
>   * |lxc-test-apparmor|
>
> |passed with /sys/kernel/uevent_helper passed with /proc/sys/fs/file-nr 
> failed - opened /sys/kernel/mm/ksm/pages_to_scan |
>
>   * |ls -l /sys/kernel/uevent_helper|
>   * |ls -l /sys/kernel/mm/ksm/pages_to_scan|
>
> |root at intel-x86-64:# ls -l /sys/kernel/uevent_helper ls: cannot access 
> '/sys/kernel/uevent_helper': No such file or directory 
> root at intel-x86-64:# ls -l /sys/kernel/mm/ksm/pages_to_scan -rw-r--r-- 
> 1 root root 4096 Mar 6 19:17 /sys/kernel/mm/ksm/pages_to_scan |
>
>
>         Issue description
>
> As shown above, /sys/kernel/mm/ksm/pages_to_scan is exist, and can be 
> opened. But error message prompts that fail to open it.
> I refer to source code lxc/src/tests/aa.c, branch master.
>
> |108 char *files_to_deny[] = { 109 "/sys/kernel/uevent_helper", 110 
> "/proc/sys/fs/file-nr", 111 "/sys/kernel/mm/ksm/pages_to_scan", 112 
> "/proc/sys/kernel/sysrq", 113 NULL }; |
> |115 static bool test_aa_policy(struct lxc_container *c) 116 { 117 int 
> i, ret; 118 119 for (i = 0; files_to_deny[i]; i++) { 120 ret = 
> do_test_file_open(c, files_to_deny[i]); 121 if (ret < 0) { 122 
> fprintf(stderr, "attach failed; skipping test\n"); 123 return true; 
> 124 } 125 if (ret > 0) { 126 fprintf(stderr, "failed - opened %s\n", 
> 127 files_to_deny[i]); 128 return false; 129 } 130 fprintf(stderr, 
> "passed with %s\n", files_to_deny[i]); 131 } ...... |
> |63 static int do_test_file_open(struct lxc_container *c, char *fnam) 
> 64 { 65 int fret = -1; 66 int ret; 67 pid_t pid; 68 int pipefd[2]; 69 
> char result[1024]; 70 lxc_attach_options_t attach_options = 
> LXC_ATTACH_OPTIONS_DEFAULT; 71 72 ret = pipe(pipefd); 73 if (ret < 0) 
> { 74 fprintf(stderr, "pipe failed %d\n", ret); 75 return fret; 76 } 77 
> attach_options.stdout_fd = pipefd[1]; 78 attach_options.attach_flags 
> &= ~(LXC_ATTACH_LSM_EXEC|LXC_ATTACH_DROP_CAPABILITIES); 79 
> attach_options.attach_flags |= LXC_ATTACH_LSM_NOW; 80 ret = 
> c->attach(c, test_attach_write_file, fnam, &attach_options, &pid); 
> ...... 85 86 ret = read(pipefd[0], result, sizeof(result)-1); 87 if 
> (ret < 0) { 88 fprintf(stderr, "read failed %d\n", ret); 89 goto err2; 
> 90 } 91 92 fret = 1; 93 if (strncmp(result, "no", 2) == 0) 94 fret = 
> 0; ...... 101 return fret; 102 } |
> |41 static int test_attach_write_file(void* payload) 42 { 43 char *fnam 
> = payload; 44 FILE *f; 45 46 f = fopen(fnam, "w"); 47 if (f) { 48 
> printf("yes\n"); 49 fclose(f); 50 fflush(NULL); 51 return 1; 52 } 53 
> printf("no\n"); 54 fflush(NULL); 55 return 0; 56 } |
>
> Line46-48: If open interfaces successfully listed in files_to_deny[], 
> Line108, printf 'yes' into pipe[1].
> Line86: And then pipe[0] reads out 'yes'.
> Line92-101: If result is 'yes', do_test_file_open() will return 1.
> Line125-128: If the return of do_test_file_open() is 1, then fprintf( 
> failed open).
> So can anyone tell me why files listed in files_to_deny[] exit but 
> print fail.
>
> Thanks.
>
>
> ||

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linuxcontainers.org/pipermail/lxc-devel/attachments/20180307/cbc5a86e/attachment.html>


More information about the lxc-devel mailing list