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      1 /*
      2  * Copyright (c) International Business Machines  Corp., 2001
      3  * Copyright (c) 2013 Cyril Hrubis <chrubis (at) suse.cz>
      4  *
      5  * This program is free software;  you can redistribute it and/or modify
      6  * it under the terms of the GNU General Public License as published by
      7  * the Free Software Foundation; either version 2 of the License, or
      8  * (at your option) any later version.
      9  *
     10  * This program is distributed in the hope that it will be useful,
     11  * but WITHOUT ANY WARRANTY;  without even the implied warranty of
     12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
     13  * the GNU General Public License for more details.
     14  *
     15  * You should have received a copy of the GNU General Public License
     16  * along with this program;  if not, write to the Free Software
     17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     18  */
     19 
     20 /*
     21  * Test Name : readlink04
     22  *
     23  * Test Description :
     24  *  Verify that, readlink call will succeed to read the contents of the
     25  *  symbolic link if invoked by non-root user who is not the owner of the
     26  *  symbolic link.
     27  *
     28  * Expected Result:
     29  *  readlink() should return the contents of symbolic link path in the
     30  *  specified buffer on success.
     31  */
     32 
     33 #include <stdlib.h>
     34 #include <pwd.h>
     35 #include <sys/types.h>
     36 #include <sys/stat.h>
     37 #include <fcntl.h>
     38 #include <sys/wait.h>
     39 #include <errno.h>
     40 #include <string.h>
     41 #include "test.h"
     42 #include "safe_macros.h"
     43 
     44 char *TCID = "readlink04";
     45 int TST_TOTAL = 1;
     46 
     47 static char *TESTFILE = "./testfile";
     48 static char *SYMFILE = "slink_file";
     49 
     50 #define MAX_SIZE	256
     51 
     52 static int exp_val;
     53 static char buffer[MAX_SIZE];
     54 
     55 static void setup(void);
     56 static void cleanup(void);
     57 
     58 int main(int ac, char **av)
     59 {
     60 	int lc;
     61 
     62 	tst_parse_opts(ac, av, NULL, NULL);
     63 
     64 	setup();
     65 
     66 	for (lc = 0; TEST_LOOPING(lc); lc++) {
     67 
     68 		tst_count = 0;
     69 
     70 		/*
     71 		 * Call readlink(2) to read the contents of
     72 		 * symlink into a buffer.
     73 		 */
     74 		TEST(readlink(SYMFILE, buffer, sizeof(buffer)));
     75 
     76 		if (TEST_RETURN == -1) {
     77 			tst_resm(TFAIL | TTERRNO, "readlink() on %s failed",
     78 			         SYMFILE);
     79 			continue;
     80 		}
     81 
     82 		if (TEST_RETURN == exp_val) {
     83 			/* Check for the contents of buffer */
     84 			if (memcmp(buffer, TESTFILE, exp_val) != 0) {
     85 				tst_brkm(TFAIL, cleanup, "TESTFILE %s "
     86 					 "and buffer contents %s "
     87 					 "differ", TESTFILE, buffer);
     88 			} else {
     89 				tst_resm(TPASS, "readlink() "
     90 					 "functionality on '%s' is "
     91 					 "correct", SYMFILE);
     92 			}
     93 		} else {
     94 			tst_resm(TFAIL, "readlink() return value %ld "
     95 				 "doesn't match, Expected %d",
     96 				 TEST_RETURN, exp_val);
     97 		}
     98 	}
     99 
    100 	cleanup();
    101 	tst_exit();
    102 }
    103 
    104 #define FILE_MODE  S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH
    105 
    106 static void setup(void)
    107 {
    108 	int fd;
    109 	char *tmp_dir = NULL;
    110 	struct passwd *pwent;
    111 
    112 	tst_require_root();
    113 
    114 	TEST_PAUSE;
    115 
    116 	tst_tmpdir();
    117 
    118 	/* get the name of the temporary directory */
    119 	if ((tmp_dir = getcwd(tmp_dir, 0)) == NULL)
    120 		tst_brkm(TBROK, NULL, "getcwd failed");
    121 
    122 	if ((pwent = getpwnam("bin")) == NULL)
    123 		tst_brkm(TBROK, cleanup, "getpwname() failed");
    124 
    125 	/* make the tmp directory belong to bin */
    126 	SAFE_CHOWN(cleanup, tmp_dir, pwent->pw_uid, pwent->pw_gid);
    127 
    128 	if (chmod(tmp_dir, 0711) != 0)
    129 		tst_brkm(TBROK|TERRNO, cleanup, "chmod(%s) failed", tmp_dir);
    130 
    131 	/* create test file and symlink */
    132 	if ((fd = open(TESTFILE, O_RDWR | O_CREAT, FILE_MODE)) == -1)
    133 		tst_brkm(TBROK|TERRNO, cleanup, "open(%s) failed", TESTFILE);
    134 
    135 	if (close(fd))
    136 		tst_brkm(TBROK|TERRNO, cleanup, "close(%s) failed", TESTFILE);
    137 
    138 	SAFE_SYMLINK(cleanup, TESTFILE, SYMFILE);
    139 
    140 	/* set up the expected return value from the readlink() call */
    141 	exp_val = strlen(TESTFILE);
    142 
    143 	/* fill the buffer with a known value */
    144 	memset(buffer, 0, MAX_SIZE);
    145 
    146 	/* finally, change the id of the parent process to "nobody" */
    147 	if ((pwent = getpwnam("nobody")) == NULL)
    148 		tst_brkm(TBROK, cleanup, "getpwname() failed for nobody");
    149 
    150 	SAFE_SETEUID(cleanup, pwent->pw_uid);
    151 }
    152 
    153 static void cleanup(void)
    154 {
    155 	SAFE_SETEUID(NULL, 0);
    156 
    157 	tst_rmdir();
    158 }
    159