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Merge pull request #6113 from keszybz/shell-quoting 

Use "dollar-single-quotes" to escape shell-sensitive strings
This commit is contained in:
Lennart Poettering 2017-06-20 20:17:03 +02:00 committed by GitHub
parent b1e98c643c 804ee07c13
commit 6c223c6719
8 changed files with 134 additions and 33 deletions
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25
man/systemctl.xml
View File

@ -1495,11 +1495,26 @@ Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output err
<term><command>show-environment</command></term>
<listitem>
<para>Dump the systemd manager environment block. The
environment block will be dumped in straight-forward form
suitable for sourcing into a shell script. This environment
block will be passed to all processes the manager
spawns.</para>
<para>Dump the systemd manager environment block. This is the environment
block that is passed to all processes the manager spawns. The environment
block will be dumped in straight-forward form suitable for sourcing into
most shells. If no special characters or whitespace is present in the variable
values, no escaping is performed, and the assignments have the form
<literal>VARIABLE=value</literal>. If whitespace or characters which have
special meaning to the shell are present, dollar-single-quote escaping is
used, and assignments have the form <literal>VARIABLE=$'value'</literal>.
This syntax is known to be supported by
<citerefentry project='die-net'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>zsh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>ksh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
and
<citerefentry project='die-net'><refentrytitle>busybox</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<citerefentry project='die-net'><refentrytitle>ash</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
but not
<citerefentry project='die-net'><refentrytitle>dash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
or
<citerefentry project='die-net'><refentrytitle>fish</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>

38
src/basic/escape.c
View File

@ -441,10 +441,16 @@ char *octescape(const char *s, size_t len) {
}
static char *strcpy_backslash_escaped(char *t, const char *s, const char *bad) {
static char *strcpy_backslash_escaped(char *t, const char *s, const char *bad, bool escape_tab_nl) {
assert(bad);
for (; *s; s++) {
if (escape_tab_nl && IN_SET(*s, '\n', '\t')) {
*(t++) = '\\';
*(t++) = *s == '\n' ? 'n' : 't';
continue;
}
if (*s == '\\' || strchr(bad, *s))
*(t++) = '\\';
@ -461,20 +467,21 @@ char *shell_escape(const char *s, const char *bad) {
if (!r)
return NULL;
t = strcpy_backslash_escaped(r, s, bad);
t = strcpy_backslash_escaped(r, s, bad, false);
*t = 0;
return r;
}
char *shell_maybe_quote(const char *s) {
char* shell_maybe_quote(const char *s, EscapeStyle style) {
const char *p;
char *r, *t;
assert(s);
/* Encloses a string in double quotes if necessary to make it
* OK as shell string. */
/* Encloses a string in quotes if necessary to make it OK as a shell
* string. Note that we treat benign UTF-8 characters as needing
* escaping too, but that should be OK. */
for (p = s; *p; p++)
if (*p <= ' ' ||
@ -485,17 +492,30 @@ char *shell_maybe_quote(const char *s) {
if (!*p)
return strdup(s);
r = new(char, 1+strlen(s)*2+1+1);
r = new(char, (style == ESCAPE_POSIX) + 1 + strlen(s)*2 + 1 + 1);
if (!r)
return NULL;
t = r;
*(t++) = '"';
if (style == ESCAPE_BACKSLASH)
*(t++) = '"';
else if (style == ESCAPE_POSIX) {
*(t++) = '$';
*(t++) = '\'';
} else
assert_not_reached("Bad EscapeStyle");
t = mempcpy(t, s, p - s);
t = strcpy_backslash_escaped(t, p, SHELL_NEED_ESCAPE);
if (style == ESCAPE_BACKSLASH)
t = strcpy_backslash_escaped(t, p, SHELL_NEED_ESCAPE, false);
else
t = strcpy_backslash_escaped(t, p, SHELL_NEED_ESCAPE_POSIX, true);
*(t++)= '"';
if (style == ESCAPE_BACKSLASH)
*(t++) = '"';
else
*(t++) = '\'';
*t = 0;
return r;

23
src/basic/escape.h
View File

@ -31,13 +31,30 @@
/* What characters are special in the shell? */
/* must be escaped outside and inside double-quotes */
#define SHELL_NEED_ESCAPE "\"\\`$"
/* can be escaped or double-quoted */
#define SHELL_NEED_QUOTES SHELL_NEED_ESCAPE GLOB_CHARS "'()<>|&;"
/* Those that can be escaped or double-quoted.
*
* Stricly speaking, ! does not need to be escaped, except in interactive
* mode, but let's be extra nice to the user and quote ! in case this
* output is ever used in interactive mode. */
#define SHELL_NEED_QUOTES SHELL_NEED_ESCAPE GLOB_CHARS "'()<>|&;!"
/* Note that we assume control characters would need to be escaped too in
* addition to the "special" characters listed here, if they appear in the
* string. Current users disallow control characters. Also '"' shall not
* be escaped.
*/
#define SHELL_NEED_ESCAPE_POSIX "\\\'"
typedef enum UnescapeFlags {
UNESCAPE_RELAX = 1,
} UnescapeFlags;
typedef enum EscapeStyle {
ESCAPE_BACKSLASH = 1,
ESCAPE_POSIX = 2,
} EscapeStyle;
char *cescape(const char *s);
char *cescape_length(const char *s, size_t n);
size_t cescape_char(char c, char *buf);
@ -51,4 +68,4 @@ char *xescape(const char *s, const char *bad);
char *octescape(const char *s, size_t len);
char *shell_escape(const char *s, const char *bad);
char *shell_maybe_quote(const char *s);
char* shell_maybe_quote(const char *s, EscapeStyle style);

2
src/core/job.c
View File

@ -741,7 +741,7 @@ static void job_print_status_message(Unit *u, JobType t, JobResult result) {
if (t == JOB_START && result == JOB_FAILED) {
_cleanup_free_ char *quoted;
quoted = shell_maybe_quote(u->id);
quoted = shell_maybe_quote(u->id, ESCAPE_BACKSLASH);
manager_status_printf(u->manager, STATUS_TYPE_NORMAL, NULL, "See 'systemctl status %s' for details.", strna(quoted));
}
}

2
src/environment-d-generator/environment-d-generator.c
View File

@ -78,7 +78,7 @@ static int load_and_print(void) {
t = strchr(*i, '=');
assert(t);
q = shell_maybe_quote(t + 1);
q = shell_maybe_quote(t + 1, ESCAPE_BACKSLASH);
if (!q)
return log_oom();

2
src/shared/bus-unit-util.c
View File

@ -860,7 +860,7 @@ static void log_job_error_with_service_result(const char* service, const char *r
assert(service);
service_shell_quoted = shell_maybe_quote(service);
service_shell_quoted = shell_maybe_quote(service, ESCAPE_BACKSLASH);
if (extra_args) {
_cleanup_free_ char *t;

26
src/systemctl/systemctl.c
View File

@ -47,6 +47,7 @@
#include "dropin.h"
#include "efivars.h"
#include "env-util.h"
#include "escape.h"
#include "exit-status.h"
#include "fd-util.h"
#include "fileio.h"
@ -5573,6 +5574,24 @@ static int reset_failed(int argc, char *argv[], void *userdata) {
return r;
}
static int print_variable(const char *s) {
const char *sep;
_cleanup_free_ char *esc = NULL;
sep = strchr(s, '=');
if (!sep) {
log_error("Invalid environment block");
return -EUCLEAN;
}
esc = shell_maybe_quote(sep + 1, ESCAPE_POSIX);
if (!esc)
return log_oom();
printf("%.*s=%s\n", (int)(sep-s), s, esc);
return 0;
}
static int show_environment(int argc, char *argv[], void *userdata) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
@ -5602,8 +5621,11 @@ static int show_environment(int argc, char *argv[], void *userdata) {
if (r < 0)
return bus_log_parse_error(r);
while ((r = sd_bus_message_read_basic(reply, SD_BUS_TYPE_STRING, &text)) > 0)
puts(text);
while ((r = sd_bus_message_read_basic(reply, SD_BUS_TYPE_STRING, &text)) > 0) {
r = print_variable(text);
if (r < 0)
return r;
}
if (r < 0)
return bus_log_parse_error(r);

49
src/test/test-escape.c
View File

@ -86,25 +86,52 @@ static void test_shell_escape(void) {
test_shell_escape_one("foo:bar,baz", ",:", "foo\\:bar\\,baz");
}
static void test_shell_maybe_quote_one(const char *s, const char *expected) {
_cleanup_free_ char *r;
static void test_shell_maybe_quote_one(const char *s,
EscapeStyle style,
const char *expected) {
_cleanup_free_ char *ret = NULL;
assert_se(r = shell_maybe_quote(s));
assert_se(streq(r, expected));
assert_se(ret = shell_maybe_quote(s, style));
log_debug("[%s] → [%s] (%s)", s, ret, expected);
assert_se(streq(ret, expected));
}
static void test_shell_maybe_quote(void) {
test_shell_maybe_quote_one("", "");
test_shell_maybe_quote_one("\\", "\"\\\\\"");
test_shell_maybe_quote_one("\"", "\"\\\"\"");
test_shell_maybe_quote_one("foobar", "foobar");
test_shell_maybe_quote_one("foo bar", "\"foo bar\"");
test_shell_maybe_quote_one("foo \"bar\" waldo", "\"foo \\\"bar\\\" waldo\"");
test_shell_maybe_quote_one("foo$bar", "\"foo\\$bar\"");
test_shell_maybe_quote_one("", ESCAPE_BACKSLASH, "");
test_shell_maybe_quote_one("", ESCAPE_POSIX, "");
test_shell_maybe_quote_one("\\", ESCAPE_BACKSLASH, "\"\\\\\"");
test_shell_maybe_quote_one("\\", ESCAPE_POSIX, "$'\\\\'");
test_shell_maybe_quote_one("\"", ESCAPE_BACKSLASH, "\"\\\"\"");
test_shell_maybe_quote_one("\"", ESCAPE_POSIX, "$'\"'");
test_shell_maybe_quote_one("foobar", ESCAPE_BACKSLASH, "foobar");
test_shell_maybe_quote_one("foobar", ESCAPE_POSIX, "foobar");
test_shell_maybe_quote_one("foo bar", ESCAPE_BACKSLASH, "\"foo bar\"");
test_shell_maybe_quote_one("foo bar", ESCAPE_POSIX, "$'foo bar'");
test_shell_maybe_quote_one("foo\tbar", ESCAPE_BACKSLASH, "\"foo\tbar\"");
test_shell_maybe_quote_one("foo\tbar", ESCAPE_POSIX, "$'foo\\tbar'");
test_shell_maybe_quote_one("foo\nbar", ESCAPE_BACKSLASH, "\"foo\nbar\"");
test_shell_maybe_quote_one("foo\nbar", ESCAPE_POSIX, "$'foo\\nbar'");
test_shell_maybe_quote_one("foo \"bar\" waldo", ESCAPE_BACKSLASH, "\"foo \\\"bar\\\" waldo\"");
test_shell_maybe_quote_one("foo \"bar\" waldo", ESCAPE_POSIX, "$'foo \"bar\" waldo'");
test_shell_maybe_quote_one("foo$bar", ESCAPE_BACKSLASH, "\"foo\\$bar\"");
test_shell_maybe_quote_one("foo$bar", ESCAPE_POSIX, "$'foo$bar'");
/* Note that current users disallow control characters, so this "test"
* is here merely to establish current behaviour. If control characters
* were allowed, they should be quoted, i.e. \001 should become \\001. */
test_shell_maybe_quote_one("a\nb\001", ESCAPE_BACKSLASH, "\"a\nb\001\"");
test_shell_maybe_quote_one("a\nb\001", ESCAPE_POSIX, "$'a\\nb\001'");
test_shell_maybe_quote_one("foo!bar", ESCAPE_BACKSLASH, "\"foo!bar\"");
test_shell_maybe_quote_one("foo!bar", ESCAPE_POSIX, "$'foo!bar'");
}
int main(int argc, char *argv[]) {
log_set_max_level(LOG_DEBUG);
log_parse_environment();
log_open();
test_cescape();
test_cunescape();
test_shell_escape();