Re: [LTP] [PATCH v4 3/3] mlock/mlock02.c: add EPERM and ENOMEM errno tests

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Zeng Linggang" <zenglg.jy@cn.fujitsu.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: "ltp-list" <ltp-list@lists.sourceforge.net>
> Sent: Monday, 3 March, 2014 8:51:19 AM
> Subject: [PATCH v4 3/3] mlock/mlock02.c: add EPERM and ENOMEM errno tests
> 
> Add EPERM and ENOMEM errno tests for mlock(2).
> 
> Signed-off-by: Zeng Linggang <zenglg.jy@cn.fujitsu.com>
> ---
>  testcases/kernel/syscalls/mlock/mlock02.c | 82
>  ++++++++++++++++++++++++++++++-
>  1 file changed, 80 insertions(+), 2 deletions(-)
> 
> diff --git a/testcases/kernel/syscalls/mlock/mlock02.c
> b/testcases/kernel/syscalls/mlock/mlock02.c
> index a6f99e6..b7579ac 100644
> --- a/testcases/kernel/syscalls/mlock/mlock02.c
> +++ b/testcases/kernel/syscalls/mlock/mlock02.c
> @@ -23,11 +23,20 @@
>   *   1. mlock() fails with -1 return value and sets errno to ENOMEM,
>   *      if some of the specified address range does not correspond to
>   *      mapped pages in the address space of the process.
> + *   2. mlock() fails with -1 return value and sets errno to ENOMEM,
> + *      if (Linux  2.6.9  and  later)  the caller had a non-zero
> RLIMIT_MEMLOCK
> + *      soft resource limit, but tried to lock more memory than the limit
> + *      permitted.  This limit is not enforced if the process is privileged
> + *      (CAP_IPC_LOCK).
> + *   3. mlock() fails with -1 return value and sets errno to EPERM,
> + *      if (Linux 2.6.9 and later) the caller was not privileged
> (CAP_IPC_LOCK)
> + *      and its RLIMIT_MEMLOCK soft resource limit was 0.
>   */
>  
>  #include <errno.h>
>  #include <unistd.h>
>  #include <sys/mman.h>
> +#include <pwd.h>
>  
>  #include "test.h"
>  #include "usctest.h"
> @@ -40,14 +49,18 @@ char *TCID = "mlock02";
>  static void setup(void);
>  static void cleanup(void);
>  static void test_enomem1(void);
> +static void test_enomem2(void);
> +static void test_eperm(void);
>  static void mlock_verify(const void *, const size_t, const int);
>  
>  static size_t len;
> +static struct rlimit original;
> +static struct passwd *ltpuser;
>  
> -static void (*test_func[])(void) = { test_enomem1 };
> +static void (*test_func[])(void) = { test_enomem1, test_enomem2, test_eperm
> };
>  
>  int TST_TOTAL = ARRAY_SIZE(test_func);
> -static int exp_enos[] = { ENOMEM, 0 };
> +static int exp_enos[] = { ENOMEM, EPERM, 0 };
>  
>  int main(int ac, char **av)
>  {
> @@ -73,11 +86,17 @@ int main(int ac, char **av)
>  
>  static void setup(void)
>  {
> +	tst_require_root(NULL);
> +
>  	tst_sig(NOFORK, DEF_HANDLER, cleanup);
>  
>  	TEST_PAUSE;
>  
> +	ltpuser = SAFE_GETPWNAM(cleanup, "nobody");
> +
>  	len = getpagesize();
> +
> +	SAFE_GETRLIMIT(cleanup, RLIMIT_MEMLOCK, &original);
>  }
>  
>  static void test_enomem1(void)
> @@ -111,6 +130,65 @@ static void test_enomem1(void)
>  	mlock_verify(addr, len, ENOMEM);
>  }
>  
> +static void test_enomem2(void)
> +{
> +	void *addr;
> +	struct rlimit rl;
> +
> +	if ((tst_kvercmp(2, 6, 9)) < 0) {
> +		tst_resm(TCONF,
> +			 "ENOMEM error value test for this condition needs "
> +			 "kernel 2.6.9 or higher");
> +		return;
> +	}
> +

Hi,



> +	rl.rlim_max = len;
> +	rl.rlim_cur = len;

"tried to  lock  more  memory than the limit permitted."
You currently allow as much as you try to mlock.

I'd suggest:
-       rl.rlim_max = len;
-       rl.rlim_cur = len;
+       rl.rlim_max = len - 1;
+       rl.rlim_cur = len - 1;


> +	SAFE_SETRLIMIT(cleanup, RLIMIT_MEMLOCK, &rl);
> +
> +	addr = SAFE_MMAP(cleanup, NULL, len, PROT_NONE,

Trying to mlock PROT_NONE will give you ENOMEM no matter how big the limit is.
I suggest PROT_READ here.

> +			 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
> +
> +	SAFE_SETEUID(cleanup, ltpuser->pw_uid);
> +
> +	mlock_verify(&addr, len, ENOMEM);

This is trying to mlock memory location of "addr" variable,
not the area that was just allocated with mmap.

Notice the address passed to mlock() in this strace output:
  mmap(NULL, 4096, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0) = 0x7fe39bfbc000
  setresuid(-1, 99, -1)                   = 0
  mlock(0x7fff721089a8, 4096)             = -1 ENOMEM (Cannot allocate memory)

-       mlock_verify(&addr, len, ENOMEM);
+       mlock_verify(addr, len, ENOMEM);

> +
> +	SAFE_SETEUID(cleanup, 0);
> +
> +	SAFE_MUNMAP(cleanup, addr, len);
> +
> +	SAFE_SETRLIMIT(cleanup, RLIMIT_MEMLOCK, &original);
> +}
> +
> +static void test_eperm(void)
> +{
> +	void *addr;
> +	struct rlimit rl;
> +
> +	if ((tst_kvercmp(2, 6, 9)) < 0) {
> +		tst_resm(TCONF,
> +			 "EPERM error value test needs kernel 2.6.9 or higher");
> +		return;
> +	}
> +
> +	rl.rlim_max = 0;
> +	rl.rlim_cur = 0;
> +	SAFE_SETRLIMIT(cleanup, RLIMIT_MEMLOCK, &rl);
> +
> +	addr = SAFE_MMAP(cleanup, NULL, len, PROT_NONE,
> +			 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
> +
> +	SAFE_SETEUID(cleanup, ltpuser->pw_uid);
> +
> +	mlock_verify(&addr, len, EPERM);

Same as in test_enomem2():
-       mlock_verify(&addr, len, EPERM);
+       mlock_verify(addr, len, EPERM);

Regards,
Jan

> +
> +	SAFE_SETEUID(cleanup, 0);
> +
> +	SAFE_MUNMAP(cleanup, addr, len);
> +
> +	SAFE_SETRLIMIT(cleanup, RLIMIT_MEMLOCK, &original);
> +}
> +
>  static void mlock_verify(const void *addr, const size_t len, const int
>  error)
>  {
>  	TEST(mlock(addr, len));
> --
> 1.8.4.2
> 
> 
> 
> 

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