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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
commit | b750101eb236130cf056c675997decbac904cc49 (patch) | |
tree | a5df1a06754bdd014cb975c051c83b01c9a97532 /src/basic/audit-util.c | |
parent | Initial commit. (diff) | |
download | systemd-upstream.tar.xz systemd-upstream.zip |
Adding upstream version 252.22.upstream/252.22upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/basic/audit-util.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/src/basic/audit-util.c b/src/basic/audit-util.c new file mode 100644 index 0000000..f2dce20 --- /dev/null +++ b/src/basic/audit-util.c @@ -0,0 +1,148 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> +#include <linux/audit.h> +#include <linux/netlink.h> +#include <stdio.h> +#include <sys/socket.h> + +#include "alloc-util.h" +#include "audit-util.h" +#include "fd-util.h" +#include "fileio.h" +#include "macro.h" +#include "parse-util.h" +#include "process-util.h" +#include "socket-util.h" +#include "user-util.h" + +int audit_session_from_pid(pid_t pid, uint32_t *id) { + _cleanup_free_ char *s = NULL; + const char *p; + uint32_t u; + int r; + + assert(id); + + /* We don't convert ENOENT to ESRCH here, since we can't + * really distinguish between "audit is not available in the + * kernel" and "the process does not exist", both which will + * result in ENOENT. */ + + p = procfs_file_alloca(pid, "sessionid"); + + r = read_one_line_file(p, &s); + if (r < 0) + return r; + + r = safe_atou32(s, &u); + if (r < 0) + return r; + + if (!audit_session_is_valid(u)) + return -ENODATA; + + *id = u; + return 0; +} + +int audit_loginuid_from_pid(pid_t pid, uid_t *uid) { + _cleanup_free_ char *s = NULL; + const char *p; + uid_t u; + int r; + + assert(uid); + + p = procfs_file_alloca(pid, "loginuid"); + + r = read_one_line_file(p, &s); + if (r < 0) + return r; + + r = parse_uid(s, &u); + if (r == -ENXIO) /* the UID was -1 */ + return -ENODATA; + if (r < 0) + return r; + + *uid = u; + return 0; +} + +static int try_audit_request(int fd) { + struct iovec iov; + struct msghdr mh; + ssize_t n; + + assert(fd >= 0); + + struct { + struct nlmsghdr hdr; + struct nlmsgerr err; + } _packed_ msg = { + .hdr.nlmsg_len = NLMSG_LENGTH(0), + .hdr.nlmsg_type = AUDIT_GET_FEATURE, + .hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK, + }; + iov = (struct iovec) { + .iov_base = &msg, + .iov_len = msg.hdr.nlmsg_len, + }; + mh = (struct msghdr) { + .msg_iov = &iov, + .msg_iovlen = 1, + }; + + if (sendmsg(fd, &mh, MSG_NOSIGNAL) < 0) + return -errno; + + iov.iov_len = sizeof(msg); + + n = recvmsg_safe(fd, &mh, 0); + if (n < 0) + return -errno; + if (n != NLMSG_LENGTH(sizeof(struct nlmsgerr))) + return -EIO; + + if (msg.hdr.nlmsg_type != NLMSG_ERROR) + return -EINVAL; + + return msg.err.error; +} + +bool use_audit(void) { + static int cached_use = -1; + int r; + + if (cached_use < 0) { + int fd; + + fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_AUDIT); + if (fd < 0) { + cached_use = !IN_SET(errno, EAFNOSUPPORT, EPROTONOSUPPORT, EPERM); + if (!cached_use) + log_debug_errno(errno, "Won't talk to audit: %m"); + } else { + /* If we try and use the audit fd but get -ECONNREFUSED, it is because + * we are not in the initial user namespace, and the kernel does not + * have support for audit outside of the initial user namespace + * (see https://elixir.bootlin.com/linux/latest/C/ident/audit_netlink_ok). + * + * If we receive any other error, do not disable audit because we are not + * sure that the error indicates that audit will not work in general. */ + r = try_audit_request(fd); + if (r < 0) { + cached_use = r != -ECONNREFUSED; + log_debug_errno(r, cached_use ? + "Failed to make request on audit fd, ignoring: %m" : + "Won't talk to audit: %m"); + } else + cached_use = true; + + safe_close(fd); + } + } + + return cached_use; +} |