14554080340

Committed 19 Apr 2025 11:46AM UTC coverage: 72.101% (-0.03%) from 72.13%

Build # 14554080340

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Commit Message

Add two new paragraphs to coding style about header files (#37188)

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83.69

/src/basic/pidfd-util.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <sys/ioctl.h>
#include <threads.h>
#include <unistd.h>

#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "log.h"
#include "macro.h"
#include "memory-util.h"
#include "missing_fs.h"
#include "missing_magic.h"
#include "mountpoint-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "pidfd-util.h"
#include "process-util.h"
#include "stat-util.h"
#include "string-util.h"

static int have_pidfs = -1;

static int pidfd_check_pidfs(int pid_fd) {

        /* NB: the passed fd *must* be acquired via pidfd_open(), i.e. must be a true pidfd! */

        if (have_pidfs >= 0)
                return have_pidfs;

        return (have_pidfs = fd_is_fs_type(pid_fd, PID_FS_MAGIC));
}

int pidfd_get_namespace(int fd, unsigned long ns_type_cmd) {
        static bool cached_supported = true;

        /* Obtain the namespace fd from pidfd directly through ioctl(PIDFD_GET_*_NAMESPACE).
         *
         * Returns -EOPNOTSUPP if ioctl on pidfds are not supported, -ENOPKG if the requested namespace
         * is disabled in kernel. (The errno used are different from what kernel returns via ioctl(),
         * see below) */

        assert(fd >= 0);

        /* If we know ahead of time that pidfs is unavailable, shortcut things. But otherwise we don't
         * call pidfd_check_pidfs() here, which is kinda extraneous and our own cache is required
         * anyways (pidfs is introduced in kernel 6.9 while ioctl support there is added in 6.11). */
        if (have_pidfs == 0 || !cached_supported)
                return -EOPNOTSUPP;

        int nsfd = ioctl(fd, ns_type_cmd);
        if (nsfd < 0) {
                /* Kernel returns EOPNOTSUPP if the ns type in question is disabled. Hence we need to look
                 * at precise errno instead of generic ERRNO_IS_(IOCTL_)NOT_SUPPORTED. */
                if (IN_SET(errno, ENOTTY, EINVAL)) {
                        cached_supported = false;
                        return -EOPNOTSUPP;
                }
                if (errno == EOPNOTSUPP) /* Translate to something more recognizable */
                        return -ENOPKG;

                return -errno;
        }

        return nsfd;
}

static int pidfd_get_info(int fd, struct pidfd_info *info) {
        static bool cached_supported = true;

        assert(fd >= 0);
        assert(info);

        if (have_pidfs == 0 || !cached_supported)
                return -EOPNOTSUPP;

        if (ioctl(fd, PIDFD_GET_INFO, info) < 0) {
                if (ERRNO_IS_IOCTL_NOT_SUPPORTED(errno)) {
                        cached_supported = false;
                        return -EOPNOTSUPP;
                }

                return -errno;
        }

        return 0;
}

static int pidfd_get_pid_fdinfo(int fd, pid_t *ret) {
        char path[STRLEN("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)];
        _cleanup_free_ char *fdinfo = NULL;
        int r;

        assert(fd >= 0);

        xsprintf(path, "/proc/self/fdinfo/%i", fd);

        r = read_full_virtual_file(path, &fdinfo, NULL);
        if (r == -ENOENT)
                return proc_fd_enoent_errno();
        if (r < 0)
                return r;

        char *p = find_line_startswith(fdinfo, "Pid:");
        if (!p)
                return -ENOTTY; /* not a pidfd? */

        p = skip_leading_chars(p, /* bad = */ NULL);
        p[strcspn(p, WHITESPACE)] = 0;

        if (streq(p, "0"))
                return -EREMOTE; /* PID is in foreign PID namespace? */
        if (streq(p, "-1"))
                return -ESRCH;   /* refers to reaped process? */

        return parse_pid(p, ret);
}

static int pidfd_get_pid_ioctl(int fd, pid_t *ret) {
        struct pidfd_info info = { .mask = PIDFD_INFO_PID };
        int r;

        assert(fd >= 0);

        r = pidfd_get_info(fd, &info);
        if (r < 0)
                return r;

        assert(FLAGS_SET(info.mask, PIDFD_INFO_PID));

        if (ret)
                *ret = info.pid;
        return 0;
}

int pidfd_get_pid(int fd, pid_t *ret) {
        int r;

        /* Converts a pidfd into a pid. We try ioctl(PIDFD_GET_INFO) (kernel 6.13+) first,
         * /proc/self/fdinfo/ as fallback. Well known errors:
         *
         *    -EBADF   → fd invalid
         *    -ESRCH   → fd valid, but process is already reaped
         *
         * pidfd_get_pid_fdinfo() might additionally fail for other reasons:
         *
         *    -ENOSYS  → /proc/ not mounted
         *    -ENOTTY  → fd valid, but not a pidfd
         *    -EREMOTE → fd valid, but pid is in another namespace we cannot translate to the local one
         *               (when using PIDFD_GET_INFO this is indistinguishable from -ESRCH)
         */

        assert(fd >= 0);

        r = pidfd_get_pid_ioctl(fd, ret);
        if (r != -EOPNOTSUPP)
                return r;

        return pidfd_get_pid_fdinfo(fd, ret);
}

int pidfd_verify_pid(int pidfd, pid_t pid) {
        pid_t current_pid;
        int r;

        assert(pidfd >= 0);
        assert(pid > 0);

        r = pidfd_get_pid(pidfd, &current_pid);
        if (r < 0)
                return r;

        return current_pid != pid ? -ESRCH : 0;
}

int pidfd_get_ppid(int fd, pid_t *ret) {
        struct pidfd_info info = { .mask = PIDFD_INFO_PID };
        int r;

        assert(fd >= 0);

        r = pidfd_get_info(fd, &info);
        if (r < 0)
                return r;

        assert(FLAGS_SET(info.mask, PIDFD_INFO_PID));

        if (info.ppid == 0) /* See comments in pid_get_ppid() */
                return -EADDRNOTAVAIL;

        if (ret)
                *ret = info.ppid;
        return 0;
}

int pidfd_get_uid(int fd, uid_t *ret) {
        struct pidfd_info info = { .mask = PIDFD_INFO_CREDS };
        int r;

        assert(fd >= 0);

        r = pidfd_get_info(fd, &info);
        if (r < 0)
                return r;

        assert(FLAGS_SET(info.mask, PIDFD_INFO_CREDS));

        if (ret)
                *ret = info.ruid;
        return 0;
}

int pidfd_get_cgroupid(int fd, uint64_t *ret) {
        struct pidfd_info info = { .mask = PIDFD_INFO_CGROUPID };
        int r;

        assert(fd >= 0);

        r = pidfd_get_info(fd, &info);
        if (r < 0)
                return r;

        assert(FLAGS_SET(info.mask, PIDFD_INFO_CGROUPID));

        if (ret)
                *ret = info.cgroupid;
        return 0;
}

int pidfd_get_inode_id(int fd, uint64_t *ret) {
        static bool file_handle_supported = true;
        int r;

        assert(fd >= 0);

        r = pidfd_check_pidfs(fd);
        if (r < 0)
                return r;
        if (r == 0)
                return -EOPNOTSUPP;

        if (file_handle_supported) {
                union {
                        struct file_handle file_handle;
                        uint8_t space[offsetof(struct file_handle, f_handle) + sizeof(uint64_t)];
                } fh = {
                        .file_handle.handle_bytes = sizeof(uint64_t),
                        .file_handle.handle_type = FILEID_KERNFS,
                };
                int mnt_id;

                r = RET_NERRNO(name_to_handle_at(fd, "", &fh.file_handle, &mnt_id, AT_EMPTY_PATH));
                if (r >= 0) {
                        if (ret)
                                *ret = *(uint64_t*) fh.file_handle.f_handle;
                        return 0;
                }
                assert(r != -EOVERFLOW);
                if (is_name_to_handle_at_fatal_error(r))
                        return r;

                file_handle_supported = false;
        }

#if SIZEOF_INO_T == 8
        struct stat st;
        if (fstat(fd, &st) < 0)
                return -errno;

        if (ret)
                *ret = (uint64_t) st.st_ino;
        return 0;

#elif SIZEOF_INO_T == 4
        /* On 32-bit systems (where sizeof(ino_t) == 4), the inode id returned by fstat() cannot be used to
         * reliably identify the process, nor can we communicate the origin of the id with the clients.
         * Hence let's just refuse to acquire pidfdid through fstat() here. All clients shall also insist on
         * the 64-bit id from name_to_handle_at(). */
        return -EOPNOTSUPP;
#else
#  error Unsupported ino_t size
#endif
}

int pidfd_get_inode_id_self_cached(uint64_t *ret) {
        static thread_local uint64_t cached = 0;
        static thread_local pid_t initialized = 0; /* < 0: cached error; == 0: invalid; > 0: valid and pid that was current */
        int r;

        assert(ret);

        if (initialized == getpid_cached()) {
                *ret = cached;
                return 0;
        }
        if (initialized < 0)
                return initialized;

        _cleanup_close_ int fd = pidfd_open(getpid_cached(), 0);
        if (fd < 0)
                return -errno;

        r = pidfd_get_inode_id(fd, &cached);
        if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
                return (initialized = -EOPNOTSUPP);
        if (r < 0)
                return r;

        *ret = cached;
        initialized = getpid_cached();
        return 0;
}

1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3	#include <sys/ioctl.h>
4	#include <threads.h>
5	#include <unistd.h>
6
7	#include "errno-util.h"
8	#include "fd-util.h"
9	#include "fileio.h"
10	#include "log.h"
11	#include "macro.h"
12	#include "memory-util.h"
13	#include "missing_fs.h"
14	#include "missing_magic.h"
15	#include "mountpoint-util.h"
16	#include "parse-util.h"
17	#include "path-util.h"
18	#include "pidfd-util.h"
19	#include "process-util.h"
20	#include "stat-util.h"
21	#include "string-util.h"
22
23	static int have_pidfs = -1;
24
25	static int pidfd_check_pidfs(int pid_fd) {	39,462✔
26
27	/* NB: the passed fd must be acquired via pidfd_open(), i.e. must be a true pidfd! */
28
29	if (have_pidfs >= 0)	39,462✔
30	return have_pidfs;
31
32	return (have_pidfs = fd_is_fs_type(pid_fd, PID_FS_MAGIC));	18,519✔
33	}
34
35	int pidfd_get_namespace(int fd, unsigned long ns_type_cmd) {	8,157✔
36	static bool cached_supported = true;	8,157✔
37
38	/* Obtain the namespace fd from pidfd directly through ioctl(PIDFD_GET_*_NAMESPACE).
39	*
40	* Returns -EOPNOTSUPP if ioctl on pidfds are not supported, -ENOPKG if the requested namespace
41	* is disabled in kernel. (The errno used are different from what kernel returns via ioctl(),
42	* see below) */
43
44	assert(fd >= 0);	8,157✔
45
46	/* If we know ahead of time that pidfs is unavailable, shortcut things. But otherwise we don't
47	* call pidfd_check_pidfs() here, which is kinda extraneous and our own cache is required
48	* anyways (pidfs is introduced in kernel 6.9 while ioctl support there is added in 6.11). */
49	if (have_pidfs == 0 \|\| !cached_supported)	8,157✔
50	return -EOPNOTSUPP;
51
52	int nsfd = ioctl(fd, ns_type_cmd);	7,009✔
53	if (nsfd < 0) {	7,009✔
54	/* Kernel returns EOPNOTSUPP if the ns type in question is disabled. Hence we need to look
55	* at precise errno instead of generic ERRNO_IS_(IOCTL_)NOT_SUPPORTED. */
56	if (IN_SET(errno, ENOTTY, EINVAL)) {	795✔
57	cached_supported = false;	795✔
58	return -EOPNOTSUPP;	795✔
59	}
60	if (errno == EOPNOTSUPP) /* Translate to something more recognizable */	×
61	return -ENOPKG;
62
63	return -errno;	×
64	}
65
66	return nsfd;
67	}
68
69	static int pidfd_get_info(int fd, struct pidfd_info *info) {	52,266✔
70	static bool cached_supported = true;	52,266✔
71
72	assert(fd >= 0);	52,266✔
73	assert(info);	52,266✔
74
75	if (have_pidfs == 0 \|\| !cached_supported)	52,266✔
76	return -EOPNOTSUPP;
77
78	if (ioctl(fd, PIDFD_GET_INFO, info) < 0) {	35,243✔
79	if (ERRNO_IS_IOCTL_NOT_SUPPORTED(errno)) {	1,513✔
80	cached_supported = false;	960✔
81	return -EOPNOTSUPP;	960✔
82	}
83
84	return -errno;	553✔
85	}
86
87	return 0;
88	}
89
90	static int pidfd_get_pid_fdinfo(int fd, pid_t *ret) {	16,620✔
91	char path[STRLEN("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)];	16,620✔
92	_cleanup_free_ char *fdinfo = NULL;	16,620✔
93	int r;	16,620✔
94
95	assert(fd >= 0);	16,620✔
96
97	xsprintf(path, "/proc/self/fdinfo/%i", fd);	16,620✔
98
99	r = read_full_virtual_file(path, &fdinfo, NULL);	16,620✔
100	if (r == -ENOENT)	16,620✔
101	return proc_fd_enoent_errno();	×
102	if (r < 0)	16,620✔
103	return r;
104
105	char *p = find_line_startswith(fdinfo, "Pid:");	16,620✔
106	if (!p)	16,620✔
107	return -ENOTTY; /* not a pidfd? */
108
109	p = skip_leading_chars(p, /* bad = */ NULL);	16,620✔
110	p[strcspn(p, WHITESPACE)] = 0;	16,620✔
111
112	if (streq(p, "0"))	16,620✔
113	return -EREMOTE; /* PID is in foreign PID namespace? */
114	if (streq(p, "-1"))	16,620✔
115	return -ESRCH; /* refers to reaped process? */
116
117	return parse_pid(p, ret);	15,307✔
118	}
119
120	static int pidfd_get_pid_ioctl(int fd, pid_t *ret) {	49,846✔
121	struct pidfd_info info = { .mask = PIDFD_INFO_PID };	49,846✔
122	int r;	49,846✔
123
124	assert(fd >= 0);	49,846✔
125
126	r = pidfd_get_info(fd, &info);	49,846✔
127	if (r < 0)	49,846✔
128	return r;	49,846✔
129
130	assert(FLAGS_SET(info.mask, PIDFD_INFO_PID));	32,673✔
131
132	if (ret)	32,673✔
133	*ret = info.pid;	32,673✔
134	return 0;
135	}
136
137	int pidfd_get_pid(int fd, pid_t *ret) {	49,846✔
138	int r;	49,846✔
139
140	/* Converts a pidfd into a pid. We try ioctl(PIDFD_GET_INFO) (kernel 6.13+) first,
141	* /proc/self/fdinfo/ as fallback. Well known errors:
142	*
143	* -EBADF → fd invalid
144	* -ESRCH → fd valid, but process is already reaped
145	*
146	* pidfd_get_pid_fdinfo() might additionally fail for other reasons:
147	*
148	* -ENOSYS → /proc/ not mounted
149	* -ENOTTY → fd valid, but not a pidfd
150	* -EREMOTE → fd valid, but pid is in another namespace we cannot translate to the local one
151	* (when using PIDFD_GET_INFO this is indistinguishable from -ESRCH)
152	*/
153
154	assert(fd >= 0);	49,846✔
155
156	r = pidfd_get_pid_ioctl(fd, ret);	49,846✔
157	if (r != -EOPNOTSUPP)	49,846✔
158	return r;
159
160	return pidfd_get_pid_fdinfo(fd, ret);	16,620✔
161	}
162
163	int pidfd_verify_pid(int pidfd, pid_t pid) {	33,438✔
164	pid_t current_pid;	33,438✔
165	int r;	33,438✔
166
167	assert(pidfd >= 0);	33,438✔
168	assert(pid > 0);	33,438✔
169
170	r = pidfd_get_pid(pidfd, &current_pid);	33,438✔
171	if (r < 0)	33,438✔
172	return r;	33,438✔
173
174	return current_pid != pid ? -ESRCH : 0;	31,572✔
175	}
176
177	int pidfd_get_ppid(int fd, pid_t *ret) {	2,366✔
178	struct pidfd_info info = { .mask = PIDFD_INFO_PID };	2,366✔
179	int r;	2,366✔
180
181	assert(fd >= 0);	2,366✔
182
183	r = pidfd_get_info(fd, &info);	2,366✔
184	if (r < 0)	2,366✔
185	return r;	2,366✔
186
187	assert(FLAGS_SET(info.mask, PIDFD_INFO_PID));	1,012✔
188
189	if (info.ppid == 0) /* See comments in pid_get_ppid() */	1,012✔
190	return -EADDRNOTAVAIL;
191
192	if (ret)	1,012✔
193	*ret = info.ppid;	1,012✔
194	return 0;
195	}
196
197	int pidfd_get_uid(int fd, uid_t *ret) {	54✔
198	struct pidfd_info info = { .mask = PIDFD_INFO_CREDS };	54✔
199	int r;	54✔
200
201	assert(fd >= 0);	54✔
202
203	r = pidfd_get_info(fd, &info);	54✔
204	if (r < 0)	54✔
205	return r;	54✔
206
207	assert(FLAGS_SET(info.mask, PIDFD_INFO_CREDS));	45✔
208
209	if (ret)	45✔
210	*ret = info.ruid;	45✔
211	return 0;
212	}
213
214	int pidfd_get_cgroupid(int fd, uint64_t *ret) {	×
215	struct pidfd_info info = { .mask = PIDFD_INFO_CGROUPID };	×
216	int r;	×
217
218	assert(fd >= 0);	×
219
220	r = pidfd_get_info(fd, &info);	×
221	if (r < 0)	×
222	return r;	×
223
224	assert(FLAGS_SET(info.mask, PIDFD_INFO_CGROUPID));	×
225
226	if (ret)	×
227	*ret = info.cgroupid;	×
228	return 0;
229	}
230
231	int pidfd_get_inode_id(int fd, uint64_t *ret) {	39,462✔
232	static bool file_handle_supported = true;	39,462✔
233	int r;	39,462✔
234
235	assert(fd >= 0);	39,462✔
236
237	r = pidfd_check_pidfs(fd);	39,462✔
238	if (r < 0)	39,462✔
239	return r;	39,462✔
240	if (r == 0)	39,462✔
241	return -EOPNOTSUPP;
242
243	if (file_handle_supported) {	33,656✔
244	union {	33,656✔
245	struct file_handle file_handle;
246	uint8_t space[offsetof(struct file_handle, f_handle) + sizeof(uint64_t)];
247	} fh = {	33,656✔
248	.file_handle.handle_bytes = sizeof(uint64_t),
249	.file_handle.handle_type = FILEID_KERNFS,
250	};
251	int mnt_id;	33,656✔
252
253	r = RET_NERRNO(name_to_handle_at(fd, "", &fh.file_handle, &mnt_id, AT_EMPTY_PATH));	33,656✔
254	if (r >= 0) {	×
255	if (ret)	33,656✔
256	ret = (uint64_t*) fh.file_handle.f_handle;	33,656✔
257	return 0;	33,656✔
258	}
259	assert(r != -EOVERFLOW);	×
260	if (is_name_to_handle_at_fatal_error(r))	×
261	return r;
262
263	file_handle_supported = false;	×
264	}
265
266	#if SIZEOF_INO_T == 8
267	struct stat st;	×
268	if (fstat(fd, &st) < 0)	×
269	return -errno;	×
270
271	if (ret)	×
272	*ret = (uint64_t) st.st_ino;	×
273	return 0;
274
275	#elif SIZEOF_INO_T == 4
276	/* On 32-bit systems (where sizeof(ino_t) == 4), the inode id returned by fstat() cannot be used to
277	* reliably identify the process, nor can we communicate the origin of the id with the clients.
278	* Hence let's just refuse to acquire pidfdid through fstat() here. All clients shall also insist on
279	* the 64-bit id from name_to_handle_at(). */
280	return -EOPNOTSUPP;
281	#else
282	# error Unsupported ino_t size
283	#endif
284	}
285
286	int pidfd_get_inode_id_self_cached(uint64_t *ret) {	38,701✔
287	static thread_local uint64_t cached = 0;	38,701✔
288	static thread_local pid_t initialized = 0; /* < 0: cached error; == 0: invalid; > 0: valid and pid that was current */	38,701✔
289	int r;	38,701✔
290
291	assert(ret);	38,701✔
292
293	if (initialized == getpid_cached()) {	38,701✔
294	*ret = cached;	4,203✔
295	return 0;	4,203✔
296	}
297	if (initialized < 0)	34,498✔
298	return initialized;
299
300	_cleanup_close_ int fd = pidfd_open(getpid_cached(), 0);	72,747✔
301	if (fd < 0)	34,046✔
302	return -errno;	×
303
304	r = pidfd_get_inode_id(fd, &cached);	34,046✔
305	if (ERRNO_IS_NEG_NOT_SUPPORTED(r))	34,046✔
306	return (initialized = -EOPNOTSUPP);	3,505✔
307	if (r < 0)	30,541✔
308	return r;
309
310	*ret = cached;	30,541✔
311	initialized = getpid_cached();	30,541✔
312	return 0;	30,541✔
313	}

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