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libapparmor: Strip a trailing newline character in aa_splitcon(3)
Adjust the internal splitcon() function to strip a single trailing newline character when the bool strip_newline argument is true. aa_getprocattr_raw(2) needs to set strip_newline to true since the kernel appends a newline character to the end of the AppArmor contexts read from /proc/>PID>/attr/current. aa_splitcon(3) also sets strip_newline to true since it is unknown whether the context is originated from a location that appends a newline or not. aa_getpeercon_raw(2) does not set strip_newline to true since it is unexpected for the kernel to append a newline to the the buffer returned from getsockopt(2). This patch also creates tests specifically for splitcon() and updates the aa_splitcon(3) man page. Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Acked-by: Seth Arnold <seth.arnold@canonical.com>
This commit is contained in:
Tyler Hicks
parent
8fffe4c721
commit
c6e395c08f
3 changed files with 168 additions and 54 deletions
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@ -40,6 +40,11 @@ terminated. The enforcement mode is also NUL terminated and the parenthesis
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surrounding the mode are removed. If @mode is non-NULL, it will point to the
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first character in the enforcement mode string on success.
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The Linux kernel's /proc/<PID>/attr/current interface appends a trailing
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newline character to AppArmor contexts that are read from that file. If @con
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contains a single trailing newline character, it will be stripped by
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aa_splitcon() prior to all other processing.
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=head1 RETURN VALUE
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Returns a pointer to the first character in the label string. NULL is returned
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@ -50,7 +55,9 @@ on error.
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Context Label Mode
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----------------------------- ------------------ -------
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unconfined unconfined NULL
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unconfined\n unconfined NULL
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/bin/ping (enforce) /bin/ping enforce
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/bin/ping (enforce)\n /bin/ping enforce
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/usr/sbin/rsyslogd (complain) /usr/sbin/rsyslogd complain
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=head1 BUGS
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@ -171,19 +171,31 @@ static bool parse_unconfined(char *con, int size)
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* splitcon - split the confinement context into a label and mode
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* @con: the confinement context
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* @size: size of the confinement context (not including the NUL terminator)
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* @strip_newline: true if a trailing newline character should be stripped
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* @mode: if non-NULL and a mode is present, will point to mode string in @con
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* on success
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*
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* Modifies the @con string to split it into separate label and mode strings.
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* The @mode argument is optional. If @mode is NULL, @con will still be split
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* between the label and mode (if present) but @mode will not be set.
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* If @strip_newline is true and @con contains a single trailing newline, it
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* will be stripped on success (it will not be stripped on error). The @mode
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* argument is optional. If @mode is NULL, @con will still be split between the
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* label and mode (if present) but @mode will not be set.
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*
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* Returns: a pointer to the label string or NULL on error
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*/
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static char *splitcon(char *con, int size, char **mode)
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static char *splitcon(char *con, int size, bool strip_newline, char **mode)
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{
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char *label = NULL;
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char *mode_str = NULL;
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char *newline = NULL;
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if (size == 0)
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goto out;
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if (strip_newline && con[size - 1] == '\n') {
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newline = &con[size - 1];
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size--;
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}
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if (parse_unconfined(con, size)) {
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label = con;
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@ -203,6 +215,8 @@ static char *splitcon(char *con, int size, char **mode)
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}
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}
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out:
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if (label && strip_newline && newline)
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*newline = 0; /* overwrite '\n', if requested, on success */
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if (mode)
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*mode = mode_str;
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return label;
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@ -214,15 +228,16 @@ out:
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* @mode: if non-NULL and a mode is present, will point to mode string in @con
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* on success
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*
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* Modifies the @con string to split it into separate label and mode strings.
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* The @mode argument is optional. If @mode is NULL, @con will still be split
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* Modifies the @con string to split it into separate label and mode strings. A
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* single trailing newline character will be stripped from @con, if found. The
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* @mode argument is optional. If @mode is NULL, @con will still be split
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* between the label and mode (if present) but @mode will not be set.
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*
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* Returns: a pointer to the label string or NULL on error
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*/
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char *aa_splitcon(char *con, char **mode)
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{
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return splitcon(con, strlen(con), mode);
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return splitcon(con, strlen(con), true, mode);
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}
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/**
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@ -282,21 +297,18 @@ int aa_getprocattr_raw(pid_t tid, const char *attr, char *buf, int len,
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errno = saved;
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goto out;
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} else if (size > 0 && buf[size - 1] != 0) {
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char *nul;
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/* check for null termination */
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if (buf[size - 1] == '\n') {
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nul = &buf[size - 1];
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} else if (len == 0) {
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errno = ERANGE;
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goto out2;
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} else {
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nul = &buf[size];
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size++;
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if (buf[size - 1] != '\n') {
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if (len == 0) {
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errno = ERANGE;
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goto out2;
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} else {
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buf[size] = 0;
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size++;
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}
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}
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*nul = 0;
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if (splitcon(buf, nul - buf, mode) != buf) {
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if (splitcon(buf, size, true, mode) != buf) {
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errno = EINVAL;
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goto out2;
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}
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@ -663,7 +675,7 @@ int aa_getpeercon_raw(int fd, char *buf, int *len, char **mode)
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}
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}
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if (splitcon(buf, optlen - 1, mode) != buf) {
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if (splitcon(buf, optlen - 1, false, mode) != buf) {
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rc = -1;
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errno = EINVAL;
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goto out;
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@ -19,7 +19,7 @@
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#include <stdio.h>
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#include <string.h>
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#include "features.c"
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#include "kernel.c"
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static int nullcmp_and_strcmp(const void *s1, const void *s2)
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{
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@ -30,6 +30,30 @@ static int nullcmp_and_strcmp(const void *s1, const void *s2)
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return strcmp(s1, s2);
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}
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static int do_test_splitcon(char *con, int size, bool strip_nl, char **mode,
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const char *expected_label,
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const char *expected_mode, const char *error)
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{
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char *label;
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int rc = 0;
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label = splitcon(con, size, strip_nl, mode);
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if (nullcmp_and_strcmp(label, expected_label)) {
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fprintf(stderr, "FAIL: %s: label \"%s\" != \"%s\"\n",
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error, label, expected_label);
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rc = 1;
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}
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if (mode && nullcmp_and_strcmp(*mode, expected_mode)) {
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fprintf(stderr, "FAIL: %s: mode \"%s\" != \"%s\"\n",
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error, *mode, expected_mode);
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rc = 1;
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}
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return rc;
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}
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static int do_test_aa_splitcon(char *con, char **mode,
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const char *expected_label,
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const char *expected_mode, const char *error)
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@ -54,69 +78,136 @@ static int do_test_aa_splitcon(char *con, char **mode,
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return rc;
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}
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#define TEST_SPLITCON(con, expected_label, expected_mode, error) \
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#define TEST_SPLITCON(con, size, strip_nl, expected_label, \
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expected_mode, error) \
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do { \
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char c1[] = con; \
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char c2[] = con; \
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size_t sz = size < 0 ? strlen(con) : size; \
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char *mode; \
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\
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if (do_test_aa_splitcon(c1, &mode, expected_label, \
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expected_mode, error)) { \
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if (do_test_splitcon(c1, sz, strip_nl, &mode, \
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expected_label, expected_mode, \
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"splitcon: " error)) { \
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rc = 1; \
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} else if (do_test_aa_splitcon(c2, NULL, expected_label,\
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NULL, \
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error " (NULL mode)")) { \
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} else if (do_test_splitcon(c2, sz, strip_nl, NULL, \
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expected_label, NULL, \
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"splitcon: " error " (NULL mode)")) { \
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rc = 1; \
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} \
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} while (0)
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#define TEST_AA_SPLITCON(con, expected_label, expected_mode, error) \
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do { \
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char c1[] = con; \
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char c2[] = con; \
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char c3[] = con "\n"; \
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char *mode; \
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\
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if (do_test_aa_splitcon(c1, &mode, expected_label, \
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expected_mode, "aa_splitcon: " error)) {\
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rc = 1; \
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} else if (do_test_aa_splitcon(c2, NULL, expected_label,\
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NULL, \
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"aa_splitcon: " error " (NULL mode)")) {\
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rc = 1; \
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} else if (do_test_aa_splitcon(c3, &mode, \
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expected_label, expected_mode, \
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"aa_splitcon: " error " (newline)")) { \
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rc = 1; \
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} \
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} while (0)
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static int test_splitcon(void)
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{
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int rc = 0;
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/**
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* NOTE: the TEST_SPLITCON() macro automatically generates
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* corresponding tests with a NULL mode pointer.
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*/
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TEST_SPLITCON("", 0, true, NULL, NULL, "empty string test #1");
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TEST_SPLITCON("", 0, false, NULL, NULL, "empty string test #2");
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TEST_SPLITCON("unconfined", -1, true, "unconfined", NULL,
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"unconfined #1");
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TEST_SPLITCON("unconfined", -1, false, "unconfined", NULL,
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"unconfined #2");
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TEST_SPLITCON("unconfined\n", -1, true, "unconfined", NULL,
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"unconfined #3");
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TEST_SPLITCON("unconfined\n", -1, false, NULL, NULL,
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"unconfined #4");
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TEST_SPLITCON("label (mode)", -1, true, "label", "mode",
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"basic split #1");
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TEST_SPLITCON("label (mode)", -1, false, "label", "mode",
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"basic split #2");
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TEST_SPLITCON("label (mode)\n", -1, true, "label", "mode",
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"basic split #3");
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TEST_SPLITCON("label (mode)\n", -1, false, NULL, NULL,
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"basic split #4");
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TEST_SPLITCON("/a/b/c (enforce)", -1, true, "/a/b/c", "enforce",
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"path enforce split #1");
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TEST_SPLITCON("/a/b/c (enforce)", -1, false, "/a/b/c", "enforce",
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"path enforce split #2");
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TEST_SPLITCON("/a/b/c (enforce)\n", -1, true, "/a/b/c", "enforce",
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"path enforce split #3");
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TEST_SPLITCON("/a/b/c (enforce)\n", -1, false, NULL, NULL,
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"path enforce split #4");
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return rc;
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}
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static int test_aa_splitcon(void)
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{
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int rc = 0;
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TEST_SPLITCON("label (mode)", "label", "mode", "basic split");
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/**
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* NOTE: the TEST_AA_SPLITCON() macro automatically generates
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* corresponding tests with a NULL mode pointer and contexts with
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* trailing newline characters.
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*/
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TEST_SPLITCON("/a/b/c (enforce)", "/a/b/c", "enforce",
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"path enforce split");
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TEST_AA_SPLITCON("label (mode)", "label", "mode", "basic split");
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TEST_SPLITCON("/a/b/c (complain)", "/a/b/c", "complain",
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"path complain split");
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TEST_AA_SPLITCON("/a/b/c (enforce)", "/a/b/c", "enforce",
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"path enforce split");
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TEST_SPLITCON("profile_name (enforce)", "profile_name", "enforce",
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"name enforce split");
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TEST_AA_SPLITCON("/a/b/c (complain)", "/a/b/c", "complain",
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"path complain split");
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TEST_SPLITCON("profile_name (complain)", "profile_name", "complain",
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"name complain split");
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TEST_AA_SPLITCON("profile_name (enforce)", "profile_name", "enforce",
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"name enforce split");
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TEST_SPLITCON("unconfined", "unconfined", NULL, "unconfined");
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TEST_AA_SPLITCON("profile_name (complain)", "profile_name", "complain",
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"name complain split");
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TEST_SPLITCON("(odd) (enforce)", "(odd)", "enforce",
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"parenthesized label #1");
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TEST_AA_SPLITCON("unconfined", "unconfined", NULL, "unconfined");
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TEST_SPLITCON("(odd) (enforce) (enforce)", "(odd) (enforce)", "enforce",
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"parenthesized label #2");
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TEST_AA_SPLITCON("(odd) (enforce)", "(odd)", "enforce",
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"parenthesized label #1");
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TEST_SPLITCON("/usr/bin/😺 (enforce)", "/usr/bin/😺", "enforce",
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"non-ASCII path");
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TEST_AA_SPLITCON("(odd) (enforce) (enforce)", "(odd) (enforce)",
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"enforce", "parenthesized label #2");
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TEST_SPLITCON("👍 (enforce)", "👍", "enforce", "non-ASCII profile name");
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TEST_AA_SPLITCON("/usr/bin/😺 (enforce)", "/usr/bin/😺", "enforce",
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"non-ASCII path");
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TEST_AA_SPLITCON("👍 (enforce)", "👍", "enforce",
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"non-ASCII profile name");
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/* Negative tests */
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TEST_SPLITCON("", NULL, NULL, "empty string test");
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TEST_AA_SPLITCON("", NULL, NULL, "empty string test");
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TEST_SPLITCON("/a/b/c (complain)\n", NULL, NULL,
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"path split w/ invalid trailing newline");
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TEST_AA_SPLITCON("profile\t(enforce)", NULL, NULL,
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"invalid tab separator");
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TEST_SPLITCON("unconfined\n", NULL, NULL,
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"unconfined w/ invalid trailing newline");
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TEST_SPLITCON("profile\t(enforce)", NULL, NULL,
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"invalid tab separator");
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TEST_SPLITCON("profile(enforce)", NULL, NULL,
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"invalid missing separator");
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TEST_AA_SPLITCON("profile(enforce)", NULL, NULL,
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"invalid missing separator");
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return rc;
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}
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@ -125,6 +216,10 @@ int main(void)
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{
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int retval, rc = 0;
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retval = test_splitcon();
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if (retval)
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rc = retval;
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retval = test_aa_splitcon();
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if (retval)
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rc = retval;
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