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Commit | Line | Data |
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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
1968a360 | 2 | |
a8fbdf54 | 3 | #include <errno.h> |
a8fbdf54 TA |
4 | #include <stddef.h> |
5 | #include <stdint.h> | |
6 | #include <stdio.h> | |
1968a360 | 7 | #include <stdlib.h> |
1968a360 | 8 | #include <sys/prctl.h> |
07630cea | 9 | #include <unistd.h> |
1968a360 | 10 | |
0a42426d ZJS |
11 | #include "sd-login.h" |
12 | ||
07630cea | 13 | #include "copy.h" |
612ebf6c | 14 | #include "env-util.h" |
3ffd4af2 | 15 | #include "fd-util.h" |
6432da6a ZJS |
16 | #include "fileio.h" |
17 | #include "io-util.h" | |
8752c575 | 18 | #include "locale-util.h" |
a8fbdf54 | 19 | #include "log.h" |
1968a360 | 20 | #include "macro.h" |
3ffd4af2 | 21 | #include "pager.h" |
07630cea | 22 | #include "process-util.h" |
595225af | 23 | #include "rlimit-util.h" |
ce30c8dc | 24 | #include "signal-util.h" |
07630cea | 25 | #include "string-util.h" |
57c9e047 | 26 | #include "strv.h" |
07630cea | 27 | #include "terminal-util.h" |
ca78ad1d | 28 | #include "util.h" |
1968a360 LP |
29 | |
30 | static pid_t pager_pid = 0; | |
31 | ||
3f603952 LP |
32 | static int stored_stdout = -1; |
33 | static int stored_stderr = -1; | |
34 | static bool stdout_redirected = false; | |
35 | static bool stderr_redirected = false; | |
36 | ||
848e863a | 37 | _noreturn_ static void pager_fallback(void) { |
6a7c676c | 38 | int r; |
46e65dcc | 39 | |
f5fbe71d | 40 | r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, UINT64_MAX, 0); |
6a7c676c LP |
41 | if (r < 0) { |
42 | log_error_errno(r, "Internal pager failed: %m"); | |
4a8e40eb MS |
43 | _exit(EXIT_FAILURE); |
44 | } | |
46e65dcc | 45 | |
4a8e40eb MS |
46 | _exit(EXIT_SUCCESS); |
47 | } | |
48 | ||
6432da6a ZJS |
49 | static int no_quit_on_interrupt(int exe_name_fd, const char *less_opts) { |
50 | _cleanup_fclose_ FILE *file = NULL; | |
51 | _cleanup_free_ char *line = NULL; | |
52 | int r; | |
53 | ||
54 | assert(exe_name_fd >= 0); | |
55 | assert(less_opts); | |
56 | ||
57 | /* This takes ownership of exe_name_fd */ | |
58 | file = fdopen(exe_name_fd, "r"); | |
59 | if (!file) { | |
60 | safe_close(exe_name_fd); | |
1d788908 | 61 | return log_error_errno(errno, "Failed to create FILE object: %m"); |
6432da6a ZJS |
62 | } |
63 | ||
64 | /* Find the last line */ | |
65 | for (;;) { | |
66 | _cleanup_free_ char *t = NULL; | |
67 | ||
68 | r = read_line(file, LONG_LINE_MAX, &t); | |
69 | if (r < 0) | |
1d788908 | 70 | return log_error_errno(r, "Failed to read from socket: %m"); |
6432da6a ZJS |
71 | if (r == 0) |
72 | break; | |
73 | ||
74 | free_and_replace(line, t); | |
75 | } | |
76 | ||
77 | /* We only treat "less" specially. | |
78 | * Return true whenever option K is *not* set. */ | |
79 | r = streq_ptr(line, "less") && !strchr(less_opts, 'K'); | |
80 | ||
81 | log_debug("Pager executable is \"%s\", options \"%s\", quit_on_interrupt: %s", | |
82 | strnull(line), less_opts, yes_no(!r)); | |
83 | return r; | |
84 | } | |
85 | ||
0221d68a | 86 | int pager_open(PagerFlags flags) { |
6432da6a | 87 | _cleanup_close_pair_ int fd[2] = { -1, -1 }, exe_name_pipe[2] = { -1, -1 }; |
43942e80 | 88 | _cleanup_strv_free_ char **pager_args = NULL; |
6432da6a | 89 | const char *pager, *less_opts; |
4c253ed1 | 90 | int r; |
1968a360 | 91 | |
0221d68a | 92 | if (flags & PAGER_DISABLE) |
ea4b98e6 AK |
93 | return 0; |
94 | ||
1968a360 | 95 | if (pager_pid > 0) |
f89a3b6f | 96 | return 1; |
1968a360 | 97 | |
ac96418b | 98 | if (terminal_is_dumb()) |
f89a3b6f | 99 | return 0; |
729e3769 | 100 | |
85afeae8 | 101 | if (!is_main_thread()) |
1d788908 | 102 | return log_error_errno(SYNTHETIC_ERRNO(EPERM), "Pager invoked from wrong thread."); |
85afeae8 | 103 | |
bcbd61db LP |
104 | pager = getenv("SYSTEMD_PAGER"); |
105 | if (!pager) | |
106 | pager = getenv("PAGER"); | |
107 | ||
43942e80 YW |
108 | if (pager) { |
109 | pager_args = strv_split(pager, WHITESPACE); | |
110 | if (!pager_args) | |
1d788908 | 111 | return log_oom(); |
43942e80 YW |
112 | |
113 | /* If the pager is explicitly turned off, honour it */ | |
114 | if (strv_isempty(pager_args) || strv_equal(pager_args, STRV_MAKE("cat"))) | |
115 | return 0; | |
116 | } | |
bcbd61db | 117 | |
d13b5227 LP |
118 | /* Determine and cache number of columns/lines before we spawn the pager so that we get the value from the |
119 | * actual tty */ | |
bcbd61db | 120 | (void) columns(); |
d13b5227 | 121 | (void) lines(); |
1968a360 | 122 | |
d262e99e | 123 | if (pipe2(fd, O_CLOEXEC) < 0) |
4a62c710 | 124 | return log_error_errno(errno, "Failed to create pager pipe: %m"); |
1968a360 | 125 | |
6432da6a ZJS |
126 | /* This is a pipe to feed the name of the executed pager binary into the parent */ |
127 | if (pipe2(exe_name_pipe, O_CLOEXEC) < 0) | |
128 | return log_error_errno(errno, "Failed to create exe_name pipe: %m"); | |
129 | ||
130 | /* Initialize a good set of less options */ | |
131 | less_opts = getenv("SYSTEMD_LESS"); | |
132 | if (!less_opts) | |
133 | less_opts = "FRSXMK"; | |
134 | if (flags & PAGER_JUMP_TO_END) | |
135 | less_opts = strjoina(less_opts, " +G"); | |
136 | ||
97033ba4 LP |
137 | /* We set SIGINT as PR_DEATHSIG signal here, to match the "K" parameter we set in $LESS, which enables SIGINT behaviour. */ |
138 | r = safe_fork("(pager)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGINT|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pager_pid); | |
4c253ed1 | 139 | if (r < 0) |
b6e1fff1 | 140 | return r; |
4c253ed1 | 141 | if (r == 0) { |
6432da6a | 142 | const char *less_charset, *exe; |
1968a360 | 143 | |
4c253ed1 | 144 | /* In the child start the pager */ |
ce30c8dc | 145 | |
1d788908 LP |
146 | if (dup2(fd[0], STDIN_FILENO) < 0) { |
147 | log_error_errno(errno, "Failed to duplicate file descriptor to STDIN: %m"); | |
148 | _exit(EXIT_FAILURE); | |
149 | } | |
150 | ||
3d94f76c | 151 | safe_close_pair(fd); |
1968a360 | 152 | |
1d788908 LP |
153 | if (setenv("LESS", less_opts, 1) < 0) { |
154 | log_error_errno(errno, "Failed to set environment variable LESS: %m"); | |
0357fa0d | 155 | _exit(EXIT_FAILURE); |
1d788908 | 156 | } |
1968a360 | 157 | |
612ebf6c | 158 | /* Initialize a good charset for less. This is particularly important if we output UTF-8 |
a1b4e6e9 LP |
159 | * characters. */ |
160 | less_charset = getenv("SYSTEMD_LESSCHARSET"); | |
161 | if (!less_charset && is_locale_utf8()) | |
162 | less_charset = "utf-8"; | |
0357fa0d | 163 | if (less_charset && |
1d788908 LP |
164 | setenv("LESSCHARSET", less_charset, 1) < 0) { |
165 | log_error_errno(errno, "Failed to set environment variable LESSCHARSET: %m"); | |
0357fa0d | 166 | _exit(EXIT_FAILURE); |
1d788908 | 167 | } |
a1b4e6e9 | 168 | |
612ebf6c | 169 | /* People might invoke us from sudo, don't needlessly allow less to be a way to shell out |
0a42426d ZJS |
170 | * privileged stuff. If the user set $SYSTEMD_PAGERSECURE, trust their configuration of the |
171 | * pager. If they didn't, use secure mode when under euid is changed. If $SYSTEMD_PAGERSECURE | |
172 | * wasn't explicitly set, and we autodetect the need for secure mode, only use the pager we | |
173 | * know to be good. */ | |
b8f736b3 | 174 | int use_secure_mode = getenv_bool_secure("SYSTEMD_PAGERSECURE"); |
0a42426d ZJS |
175 | bool trust_pager = use_secure_mode >= 0; |
176 | if (use_secure_mode == -ENXIO) { | |
177 | uid_t uid; | |
178 | ||
179 | r = sd_pid_get_owner_uid(0, &uid); | |
612ebf6c | 180 | if (r < 0) |
0a42426d | 181 | log_debug_errno(r, "sd_pid_get_owner_uid() failed, enabling pager secure mode: %m"); |
612ebf6c | 182 | |
0a42426d ZJS |
183 | use_secure_mode = r < 0 || uid != geteuid(); |
184 | ||
185 | } else if (use_secure_mode < 0) { | |
186 | log_warning_errno(use_secure_mode, "Unable to parse $SYSTEMD_PAGERSECURE, assuming true: %m"); | |
187 | use_secure_mode = true; | |
612ebf6c LP |
188 | } |
189 | ||
0a42426d ZJS |
190 | /* We generally always set variables used by less, even if we end up using a different pager. |
191 | * They shouldn't hurt in any case, and ideally other pagers would look at them too. */ | |
063f9f0d | 192 | r = set_unset_env("LESSSECURE", use_secure_mode ? "1" : NULL, true); |
0a42426d | 193 | if (r < 0) { |
063f9f0d | 194 | log_error_errno(r, "Failed to adjust environment variable LESSSECURE: %m"); |
0a42426d ZJS |
195 | _exit(EXIT_FAILURE); |
196 | } | |
197 | ||
198 | if (trust_pager && pager_args) { /* The pager config might be set globally, and we cannot | |
199 | * know if the user adjusted it to be appropriate for the | |
200 | * secure mode. Thus, start the pager specified through | |
201 | * envvars only when $SYSTEMD_PAGERSECURE was explicitly set | |
202 | * as well. */ | |
1d788908 LP |
203 | r = loop_write(exe_name_pipe[1], pager_args[0], strlen(pager_args[0]) + 1, false); |
204 | if (r < 0) { | |
205 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 206 | _exit(EXIT_FAILURE); |
1d788908 | 207 | } |
6432da6a | 208 | |
43942e80 | 209 | execvp(pager_args[0], pager_args); |
1d788908 | 210 | log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
118dccc9 | 211 | "Failed to execute '%s', using fallback pagers: %m", pager_args[0]); |
6432da6a | 212 | } |
1968a360 | 213 | |
0a42426d ZJS |
214 | /* Debian's alternatives command for pagers is called 'pager'. Note that we do not call |
215 | * sensible-pagers here, since that is just a shell script that implements a logic that is | |
216 | * similar to this one anyway, but is Debian-specific. */ | |
6432da6a | 217 | FOREACH_STRING(exe, "pager", "less", "more") { |
0a42426d ZJS |
218 | /* Only less implements secure mode right now. */ |
219 | if (use_secure_mode && !streq(exe, "less")) | |
220 | continue; | |
221 | ||
1d788908 LP |
222 | r = loop_write(exe_name_pipe[1], exe, strlen(exe) + 1, false); |
223 | if (r < 0) { | |
224 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 225 | _exit(EXIT_FAILURE); |
1d788908 | 226 | } |
6432da6a | 227 | execlp(exe, exe, NULL); |
1d788908 | 228 | log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
118dccc9 | 229 | "Failed to execute '%s', using next fallback pager: %m", exe); |
6432da6a | 230 | } |
1968a360 | 231 | |
0a42426d | 232 | /* Our builtin is also very secure. */ |
d8f8b18c | 233 | r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in)") + 1, false); |
1d788908 LP |
234 | if (r < 0) { |
235 | log_error_errno(r, "Failed to write pager name to socket: %m"); | |
6432da6a | 236 | _exit(EXIT_FAILURE); |
1d788908 | 237 | } |
d8f8b18c FR |
238 | /* Close pipe to signal the parent to start sending data */ |
239 | safe_close_pair(exe_name_pipe); | |
4a8e40eb MS |
240 | pager_fallback(); |
241 | /* not reached */ | |
1968a360 LP |
242 | } |
243 | ||
244 | /* Return in the parent */ | |
a45e7bb4 MS |
245 | stored_stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 3); |
246 | if (dup2(fd[1], STDOUT_FILENO) < 0) { | |
247 | stored_stdout = safe_close(stored_stdout); | |
4a62c710 | 248 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); |
a45e7bb4 MS |
249 | } |
250 | stdout_redirected = true; | |
251 | ||
252 | stored_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3); | |
253 | if (dup2(fd[1], STDERR_FILENO) < 0) { | |
254 | stored_stderr = safe_close(stored_stderr); | |
8b5264aa | 255 | return log_error_errno(errno, "Failed to duplicate pager pipe: %m"); |
a45e7bb4 MS |
256 | } |
257 | stderr_redirected = true; | |
1968a360 | 258 | |
6432da6a ZJS |
259 | exe_name_pipe[1] = safe_close(exe_name_pipe[1]); |
260 | ||
261 | r = no_quit_on_interrupt(TAKE_FD(exe_name_pipe[0]), less_opts); | |
262 | if (r < 0) | |
263 | return r; | |
264 | if (r > 0) | |
9c274488 | 265 | (void) ignore_signals(SIGINT); |
6432da6a | 266 | |
f89a3b6f | 267 | return 1; |
1968a360 LP |
268 | } |
269 | ||
270 | void pager_close(void) { | |
271 | ||
272 | if (pager_pid <= 0) | |
273 | return; | |
274 | ||
275 | /* Inform pager that we are done */ | |
a45e7bb4 | 276 | (void) fflush(stdout); |
77018a8c MS |
277 | if (stdout_redirected) |
278 | if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0) | |
279 | (void) close(STDOUT_FILENO); | |
a45e7bb4 MS |
280 | stored_stdout = safe_close(stored_stdout); |
281 | (void) fflush(stderr); | |
77018a8c MS |
282 | if (stderr_redirected) |
283 | if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0) | |
284 | (void) close(STDERR_FILENO); | |
a45e7bb4 MS |
285 | stored_stderr = safe_close(stored_stderr); |
286 | stdout_redirected = stderr_redirected = false; | |
8b5264aa | 287 | |
74ca738f | 288 | (void) kill(pager_pid, SIGCONT); |
c73d180d | 289 | (void) wait_for_terminate(pager_pid, NULL); |
1968a360 LP |
290 | pager_pid = 0; |
291 | } | |
f89a3b6f LP |
292 | |
293 | bool pager_have(void) { | |
294 | return pager_pid > 0; | |
295 | } | |
78002a67 ZJS |
296 | |
297 | int show_man_page(const char *desc, bool null_stdio) { | |
298 | const char *args[4] = { "man", NULL, NULL, NULL }; | |
299 | char *e = NULL; | |
300 | pid_t pid; | |
301 | size_t k; | |
302 | int r; | |
78002a67 ZJS |
303 | |
304 | k = strlen(desc); | |
305 | ||
306 | if (desc[k-1] == ')') | |
307 | e = strrchr(desc, '('); | |
308 | ||
309 | if (e) { | |
310 | char *page = NULL, *section = NULL; | |
311 | ||
312 | page = strndupa(desc, e - desc); | |
313 | section = strndupa(e + 1, desc + k - e - 2); | |
314 | ||
315 | args[1] = section; | |
316 | args[2] = page; | |
317 | } else | |
318 | args[1] = desc; | |
319 | ||
0672e2c6 | 320 | r = safe_fork("(man)", FORK_RESET_SIGNALS|FORK_DEATHSIG|(null_stdio ? FORK_NULL_STDIO : 0)|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid); |
4c253ed1 | 321 | if (r < 0) |
b6e1fff1 | 322 | return r; |
4c253ed1 | 323 | if (r == 0) { |
78002a67 | 324 | /* Child */ |
78002a67 | 325 | execvp(args[0], (char**) args); |
56f64d95 | 326 | log_error_errno(errno, "Failed to execute man: %m"); |
78002a67 ZJS |
327 | _exit(EXIT_FAILURE); |
328 | } | |
329 | ||
2e87a1fd | 330 | return wait_for_terminate_and_check(NULL, pid, 0); |
78002a67 | 331 | } |