diff options
Diffstat (limited to 'src/shared/memfd.c')
| -rw-r--r-- | src/shared/memfd.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/src/shared/memfd.c b/src/shared/memfd.c new file mode 100644 index 0000000000..4dd70a2473 --- /dev/null +++ b/src/shared/memfd.c @@ -0,0 +1,308 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2013 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <stdio.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <sys/mman.h> +#include <sys/prctl.h> + +#include "util.h" +#include "bus-label.h" +#include "missing.h" +#include "memfd.h" + +#include "sd-bus.h" + +struct sd_memfd { + int fd; + FILE *f; +}; + +int sd_memfd_new(sd_memfd **m, const char *name) { + + _cleanup_close_ int kdbus = -1; + _cleanup_free_ char *g = NULL; + sd_memfd *n; + + assert_return(m, -EINVAL); + + kdbus = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC); + if (kdbus < 0) + return -errno; + + if (name) { + /* The kernel side is pretty picky about the character + * set here, let's do the usual bus escaping to deal + * with that. */ + + g = bus_label_escape(name); + if (!g) + return -ENOMEM; + + name = g; + + } else { + char pr[17] = {}; + + /* If no name is specified we generate one. We include + * a hint indicating our library implementation, and + * add the thread name to it */ + + assert_se(prctl(PR_GET_NAME, (unsigned long) pr) >= 0); + + if (isempty(pr)) + name = "sd"; + else { + _cleanup_free_ char *e = NULL; + + e = bus_label_escape(pr); + if (!e) + return -ENOMEM; + + g = strappend("sd-", e); + if (!g) + return -ENOMEM; + + name = g; + } + } + + n = new0(struct sd_memfd, 1); + if (!n) + return -ENOMEM; + + n->fd = memfd_create(name, 0, MFD_ALLOW_SEALING); + if (n->fd < 0) { + free(n); + return -errno; + } + + *m = n; + return 0; +} + +int sd_memfd_new_from_fd(sd_memfd **m, int fd) { + sd_memfd *n; + + assert_return(m, -EINVAL); + assert_return(fd >= 0, -EINVAL); + + /* Check if this is a sealable fd */ + if (fcntl(fd, F_GET_SEALS) < 0) + return -ENOTTY; + + n = new0(struct sd_memfd, 1); + if (!n) + return -ENOMEM; + + n->fd = fd; + *m = n; + + return 0; +} + +void sd_memfd_free(sd_memfd *m) { + if (!m) + return; + + if (m->f) + fclose(m->f); + else + safe_close(m->fd); + + free(m); +} + +int sd_memfd_get_fd(sd_memfd *m) { + assert_return(m, -EINVAL); + + return m->fd; +} + +int sd_memfd_get_file(sd_memfd *m, FILE **f) { + assert_return(m, -EINVAL); + assert_return(f, -EINVAL); + + if (!m->f) { + m->f = fdopen(m->fd, "r+"); + if (!m->f) + return -errno; + } + + *f = m->f; + return 0; +} + +int sd_memfd_dup_fd(sd_memfd *m) { + int fd; + + assert_return(m, -EINVAL); + + fd = fcntl(m->fd, F_DUPFD_CLOEXEC, 3); + if (fd < 0) + return -errno; + + return fd; +} + +int sd_memfd_map(sd_memfd *m, uint64_t offset, size_t size, void **p) { + void *q; + int sealed; + + assert_return(m, -EINVAL); + assert_return(size > 0, -EINVAL); + assert_return(p, -EINVAL); + + sealed = sd_memfd_get_sealed(m); + if (sealed < 0) + return sealed; + + q = mmap(NULL, size, sealed ? PROT_READ : PROT_READ|PROT_WRITE, MAP_PRIVATE, m->fd, offset); + if (q == MAP_FAILED) + return -errno; + + *p = q; + return 0; +} + +int sd_memfd_set_sealed(sd_memfd *m) { + int r; + + assert_return(m, -EINVAL); + + r = fcntl(m->fd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE); + if (r < 0) + return -errno; + + return 0; +} + +int sd_memfd_get_sealed(sd_memfd *m) { + int r; + + assert_return(m, -EINVAL); + + r = fcntl(m->fd, F_GET_SEALS); + if (r < 0) + return -errno; + + return (r & (F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE)) == + (F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE); +} + +int sd_memfd_get_size(sd_memfd *m, uint64_t *sz) { + int r; + struct stat stat; + + assert_return(m, -EINVAL); + assert_return(sz, -EINVAL); + + r = fstat(m->fd, &stat); + if (r < 0) + return -errno; + + *sz = stat.st_size; + return r; +} + +int sd_memfd_set_size(sd_memfd *m, uint64_t sz) { + int r; + + assert_return(m, -EINVAL); + + r = ftruncate(m->fd, sz); + if (r < 0) + return -errno; + + return r; +} + +int sd_memfd_new_and_map(sd_memfd **m, const char *name, size_t sz, void **p) { + sd_memfd *n; + int r; + + r = sd_memfd_new(&n, name); + if (r < 0) + return r; + + r = sd_memfd_set_size(n, sz); + if (r < 0) { + sd_memfd_free(n); + return r; + } + + r = sd_memfd_map(n, 0, sz, p); + if (r < 0) { + sd_memfd_free(n); + return r; + } + + *m = n; + return 0; +} + +int sd_memfd_get_name(sd_memfd *m, char **name) { + char path[sizeof("/proc/self/fd/") + DECIMAL_STR_MAX(int)], buf[FILENAME_MAX+1], *e; + const char *delim, *end; + _cleanup_free_ char *n = NULL; + ssize_t k; + + assert_return(m, -EINVAL); + assert_return(name, -EINVAL); + + sprintf(path, "/proc/self/fd/%i", m->fd); + + k = readlink(path, buf, sizeof(buf)); + if (k < 0) + return -errno; + + if ((size_t) k >= sizeof(buf)) + return -E2BIG; + + buf[k] = 0; + + delim = strstr(buf, ":["); + if (!delim) + return -EIO; + + delim = strchr(delim + 2, ':'); + if (!delim) + return -EIO; + + delim++; + + end = strchr(delim, ']'); + if (!end) + return -EIO; + + n = strndup(delim, end - delim); + if (!n) + return -ENOMEM; + + e = bus_label_unescape(n); + if (!e) + return -ENOMEM; + + *name = e; + + return 0; +} |