12877533250

Committed 20 Jan 2025 11:16PM UTC coverage: 0.117%. Remained the same

Build # 12877533250

Build Type

push

github

Committed by

web-flow

Commit Message

pidfd: cache our own pidfd inode id, and use it at various places (#36060)

This is split out of and preparation for #35224, but makes a ton of
sense on its own

Coverage Stats

0 of 95 new or added lines in 10 files covered. (0.0%)

4667 existing lines in 34 files now uncovered.

478 of 408040 relevant lines covered (0.12%)

1.45 hits per line

Source File
Press 'n' to go to next uncovered line, 'b' for previous

0.0

/src/basic/random-util.c

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

#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/random.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/auxv.h>
#include <sys/ioctl.h>
#include <sys/time.h>

#include "alloc-util.h"
#include "env-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "io-util.h"
#include "iovec-util.h"
#include "missing_random.h"
#include "missing_syscall.h"
#include "missing_threads.h"
#include "parse-util.h"
#include "pidfd-util.h"
#include "process-util.h"
#include "random-util.h"
#include "sha256.h"
#include "time-util.h"

/* This is a "best effort" kind of thing, but has no real security value. So, this should only be used by
 * random_bytes(), which is not meant for crypto. This could be made better, but we're *not* trying to roll a
 * userspace prng here, or even have forward secrecy, but rather just do the shortest thing that is at least
 * better than libc rand(). */
static void fallback_random_bytes(void *p, size_t n) {
        static thread_local uint64_t fallback_counter = 0;
        struct {
                char label[32];
                uint64_t call_id, block_id;
                usec_t stamp_mono, stamp_real;
                pid_t pid, tid;
                uint64_t pidfdid;
                uint8_t auxval[16];
        } state = {
                /* Arbitrary domain separation to prevent other usage of AT_RANDOM from clashing. */
                .call_id = fallback_counter++,
                .stamp_mono = now(CLOCK_MONOTONIC),
                .stamp_real = now(CLOCK_REALTIME),
                .pid = getpid_cached(),
                .tid = gettid(),
        };

        memcpy(state.label, "systemd fallback random bytes v1", sizeof(state.label));
        memcpy(state.auxval, ULONG_TO_PTR(getauxval(AT_RANDOM)), sizeof(state.auxval));
        (void) pidfd_get_inode_id_self_cached(&state.pidfdid);

        while (n > 0) {
                struct sha256_ctx ctx;

                sha256_init_ctx(&ctx);
                sha256_process_bytes(&state, sizeof(state), &ctx);
                if (n < SHA256_DIGEST_SIZE) {
                        uint8_t partial[SHA256_DIGEST_SIZE];
                        sha256_finish_ctx(&ctx, partial);
                        memcpy(p, partial, n);
                        break;
                }
                sha256_finish_ctx(&ctx, p);
                p = (uint8_t *) p + SHA256_DIGEST_SIZE;
                n -= SHA256_DIGEST_SIZE;
                ++state.block_id;
        }
}

void random_bytes(void *p, size_t n) {
        static bool have_grndinsecure = true;

        assert(p || n == 0);

        if (n == 0)
                return;

        for (;;) {
                ssize_t l;

                l = getrandom(p, n, have_grndinsecure ? GRND_INSECURE : GRND_NONBLOCK);
                if (l < 0 && errno == EINVAL && have_grndinsecure) {
                        /* No GRND_INSECURE; fallback to GRND_NONBLOCK. */
                        have_grndinsecure = false;
                        continue;
                }
                if (l <= 0)
                        break; /* Will block (with GRND_NONBLOCK), or unexpected error. Give up and fallback
                                  to /dev/urandom. */

                if ((size_t) l == n)
                        return; /* Done reading, success. */

                p = (uint8_t *) p + l;
                n -= l;
                /* Interrupted by a signal; keep going. */
        }

        _cleanup_close_ int fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
        if (fd >= 0 && loop_read_exact(fd, p, n, false) >= 0)
                return;

        /* This is a terrible fallback. Oh well. */
        fallback_random_bytes(p, n);
}

int crypto_random_bytes(void *p, size_t n) {
        assert(p || n == 0);

        if (n == 0)
                return 0;

        for (;;) {
                ssize_t l;

                l = getrandom(p, n, 0);
                if (l < 0)
                        return -errno;
                if (l == 0)
                        return -EIO; /* Weird, should never happen. */

                if ((size_t) l == n)
                        return 0; /* Done reading, success. */

                p = (uint8_t *) p + l;
                n -= l;
                /* Interrupted by a signal; keep going. */
        }
}

int crypto_random_bytes_allocate_iovec(size_t n, struct iovec *ret) {
        _cleanup_free_ void *p = NULL;
        int r;

        assert(ret);

        p = malloc(MAX(n, 1U));
        if (!p)
                return -ENOMEM;

        r = crypto_random_bytes(p, n);
        if (r < 0)
                return r;

        *ret = IOVEC_MAKE(TAKE_PTR(p), n);
        return 0;
}

size_t random_pool_size(void) {
        _cleanup_free_ char *s = NULL;
        int r;

        /* Read pool size, if possible */
        r = read_one_line_file("/proc/sys/kernel/random/poolsize", &s);
        if (r < 0)
                log_debug_errno(r, "Failed to read pool size from kernel: %m");
        else {
                unsigned sz;

                r = safe_atou(s, &sz);
                if (r < 0)
                        log_debug_errno(r, "Failed to parse pool size: %s", s);
                else
                        /* poolsize is in bits on 2.6, but we want bytes */
                        return CLAMP(sz / 8, RANDOM_POOL_SIZE_MIN, RANDOM_POOL_SIZE_MAX);
        }

        /* Use the minimum as default, if we can't retrieve the correct value */
        return RANDOM_POOL_SIZE_MIN;
}

int random_write_entropy(int fd, const void *seed, size_t size, bool credit) {
        _cleanup_close_ int opened_fd = -EBADF;
        int r;

        assert(seed || size == 0);

        if (size == 0)
                return 0;

        if (fd < 0) {
                opened_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY);
                if (opened_fd < 0)
                        return -errno;

                fd = opened_fd;
        }

        if (credit) {
                _cleanup_free_ struct rand_pool_info *info = NULL;

                /* The kernel API only accepts "int" as entropy count (which is in bits), let's avoid any
                 * chance for confusion here. */
                if (size > INT_MAX / 8)
                        return -EOVERFLOW;

                info = malloc(offsetof(struct rand_pool_info, buf) + size);
                if (!info)
                        return -ENOMEM;

                info->entropy_count = size * 8;
                info->buf_size = size;
                memcpy(info->buf, seed, size);

                if (ioctl(fd, RNDADDENTROPY, info) < 0)
                        return -errno;
        } else {
                r = loop_write(fd, seed, size);
                if (r < 0)
                        return r;
        }

        return 1;
}

uint64_t random_u64_range(uint64_t m) {
        uint64_t x, remainder;

        /* Generates a random number in the range 0…m-1, unbiased. (Java's algorithm) */

        if (m == 0) /* Let's take m == 0 as special case to return an integer from the full range */
                return random_u64();
        if (m == 1)
                return 0;

        remainder = UINT64_MAX % m;

        do {
                x = random_u64();
        } while (x >= UINT64_MAX - remainder);

        return x % m;
}

1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3	#include <elf.h>
4	#include <errno.h>
5	#include <fcntl.h>
6	#include <linux/random.h>
7	#include <stdbool.h>
8	#include <stdint.h>
9	#include <stdlib.h>
10	#include <string.h>
11	#include <sys/auxv.h>
12	#include <sys/ioctl.h>
13	#include <sys/time.h>
14
15	#include "alloc-util.h"
16	#include "env-util.h"
17	#include "errno-util.h"
18	#include "fd-util.h"
19	#include "fileio.h"
20	#include "io-util.h"
21	#include "iovec-util.h"
22	#include "missing_random.h"
23	#include "missing_syscall.h"
24	#include "missing_threads.h"
25	#include "parse-util.h"
26	#include "pidfd-util.h"
27	#include "process-util.h"
28	#include "random-util.h"
29	#include "sha256.h"
30	#include "time-util.h"
31
32	/* This is a "best effort" kind of thing, but has no real security value. So, this should only be used by
33	* random_bytes(), which is not meant for crypto. This could be made better, but we're not trying to roll a
34	* userspace prng here, or even have forward secrecy, but rather just do the shortest thing that is at least
35	* better than libc rand(). */
36	static void fallback_random_bytes(void *p, size_t n) {	×
37	static thread_local uint64_t fallback_counter = 0;	×
38	struct {	×
39	char label[32];
40	uint64_t call_id, block_id;
41	usec_t stamp_mono, stamp_real;
42	pid_t pid, tid;
43	uint64_t pidfdid;
44	uint8_t auxval[16];
45	} state = {	×
46	/* Arbitrary domain separation to prevent other usage of AT_RANDOM from clashing. */
47	.call_id = fallback_counter++,	×
48	.stamp_mono = now(CLOCK_MONOTONIC),	×
49	.stamp_real = now(CLOCK_REALTIME),	×
50	.pid = getpid_cached(),	×
51	.tid = gettid(),	×
52	};
53
54	memcpy(state.label, "systemd fallback random bytes v1", sizeof(state.label));	×
55	memcpy(state.auxval, ULONG_TO_PTR(getauxval(AT_RANDOM)), sizeof(state.auxval));	×
NEW 56	(void) pidfd_get_inode_id_self_cached(&state.pidfdid);	×
57
58	while (n > 0) {	×
59	struct sha256_ctx ctx;	×
60
61	sha256_init_ctx(&ctx);	×
62	sha256_process_bytes(&state, sizeof(state), &ctx);	×
63	if (n < SHA256_DIGEST_SIZE) {	×
64	uint8_t partial[SHA256_DIGEST_SIZE];	×
65	sha256_finish_ctx(&ctx, partial);	×
66	memcpy(p, partial, n);	×
67	break;	×
68	}
69	sha256_finish_ctx(&ctx, p);	×
70	p = (uint8_t *) p + SHA256_DIGEST_SIZE;	×
71	n -= SHA256_DIGEST_SIZE;	×
72	++state.block_id;	×
73	}
74	}	×
75
76	void random_bytes(void *p, size_t n) {	×
77	static bool have_grndinsecure = true;	×
78
79	assert(p \|\| n == 0);	×
80
81	if (n == 0)	×
82	return;
83
84	for (;;) {	×
85	ssize_t l;	×
86
87	l = getrandom(p, n, have_grndinsecure ? GRND_INSECURE : GRND_NONBLOCK);	×
88	if (l < 0 && errno == EINVAL && have_grndinsecure) {	×
89	/* No GRND_INSECURE; fallback to GRND_NONBLOCK. */
90	have_grndinsecure = false;	×
91	continue;	×
92	}
93	if (l <= 0)	×
94	break; /* Will block (with GRND_NONBLOCK), or unexpected error. Give up and fallback
95	to /dev/urandom. */
96
97	if ((size_t) l == n)	×
98	return; /* Done reading, success. */
99
100	p = (uint8_t *) p + l;	×
101	n -= l;	×
102	/* Interrupted by a signal; keep going. */
103	}
104
105	_cleanup_close_ int fd = open("/dev/urandom", O_RDONLY\|O_CLOEXEC\|O_NOCTTY);	×
106	if (fd >= 0 && loop_read_exact(fd, p, n, false) >= 0)	×
107	return;	×
108
109	/* This is a terrible fallback. Oh well. */
110	fallback_random_bytes(p, n);	×
111	}
112
113	int crypto_random_bytes(void *p, size_t n) {	×
114	assert(p \|\| n == 0);	×
115
116	if (n == 0)	×
117	return 0;
118
119	for (;;) {	×
120	ssize_t l;	×
121
122	l = getrandom(p, n, 0);	×
123	if (l < 0)	×
124	return -errno;	×
125	if (l == 0)	×
126	return -EIO; /* Weird, should never happen. */
127
128	if ((size_t) l == n)	×
129	return 0; /* Done reading, success. */
130
131	p = (uint8_t *) p + l;	×
132	n -= l;	×
133	/* Interrupted by a signal; keep going. */
134	}
135	}
136
137	int crypto_random_bytes_allocate_iovec(size_t n, struct iovec *ret) {	×
138	_cleanup_free_ void *p = NULL;	×
139	int r;	×
140
141	assert(ret);	×
142
143	p = malloc(MAX(n, 1U));	×
144	if (!p)	×
145	return -ENOMEM;
146
147	r = crypto_random_bytes(p, n);	×
148	if (r < 0)	×
149	return r;
150
151	*ret = IOVEC_MAKE(TAKE_PTR(p), n);	×
152	return 0;	×
153	}
154
155	size_t random_pool_size(void) {	×
156	_cleanup_free_ char *s = NULL;	×
157	int r;	×
158
159	/* Read pool size, if possible */
160	r = read_one_line_file("/proc/sys/kernel/random/poolsize", &s);	×
161	if (r < 0)	×
162	log_debug_errno(r, "Failed to read pool size from kernel: %m");	×
163	else {
164	unsigned sz;	×
165
166	r = safe_atou(s, &sz);	×
167	if (r < 0)	×
168	log_debug_errno(r, "Failed to parse pool size: %s", s);	×
169	else
170	/* poolsize is in bits on 2.6, but we want bytes */
171	return CLAMP(sz / 8, RANDOM_POOL_SIZE_MIN, RANDOM_POOL_SIZE_MAX);	×
172	}
173
174	/* Use the minimum as default, if we can't retrieve the correct value */
175	return RANDOM_POOL_SIZE_MIN;
176	}
177
178	int random_write_entropy(int fd, const void *seed, size_t size, bool credit) {	×
179	_cleanup_close_ int opened_fd = -EBADF;	×
180	int r;	×
181
182	assert(seed \|\| size == 0);	×
183
184	if (size == 0)	×
185	return 0;
186
187	if (fd < 0) {	×
188	opened_fd = open("/dev/urandom", O_WRONLY\|O_CLOEXEC\|O_NOCTTY);	×
189	if (opened_fd < 0)	×
190	return -errno;	×
191
192	fd = opened_fd;
193	}
194
195	if (credit) {	×
196	_cleanup_free_ struct rand_pool_info *info = NULL;	×
197
198	/* The kernel API only accepts "int" as entropy count (which is in bits), let's avoid any
199	* chance for confusion here. */
200	if (size > INT_MAX / 8)	×
201	return -EOVERFLOW;
202
203	info = malloc(offsetof(struct rand_pool_info, buf) + size);	×
204	if (!info)	×
205	return -ENOMEM;
206
207	info->entropy_count = size * 8;	×
208	info->buf_size = size;	×
209	memcpy(info->buf, seed, size);	×
210
211	if (ioctl(fd, RNDADDENTROPY, info) < 0)	×
212	return -errno;	×
213	} else {
214	r = loop_write(fd, seed, size);	×
215	if (r < 0)	×
216	return r;	×
217	}
218
219	return 1;
220	}
221
222	uint64_t random_u64_range(uint64_t m) {	×
223	uint64_t x, remainder;	×
224
225	/* Generates a random number in the range 0…m-1, unbiased. (Java's algorithm) */
226
227	if (m == 0) /* Let's take m == 0 as special case to return an integer from the full range */	×
228	return random_u64();	×
229	if (m == 1)	×
230	return 0;
231
232	remainder = UINT64_MAX % m;	×
233
234	do {	×
235	x = random_u64();	×
236	} while (x >= UINT64_MAX - remainder);	×
237
238	return x % m;	×
239	}

systemd / systemd / 12877533250

Source File Press 'n' to go to next uncovered line, 'b' for previous

Source File
Press 'n' to go to next uncovered line, 'b' for previous