passt/linux_dep.h
David Gibson 14dd70e2b3 linux_dep: Fix CLOSE_RANGE_UNSHARE availability handling
If CLOSE_RANGE_UNSHARE isn't defined, we define a fallback version of
close_range() which is a (successful) no-op.  This is broken in several
ways:
 * It doesn't actually fix compile if using old kernel headers, because
   the caller of close_range() still directly uses CLOSE_RANGE_UNSHARE
   unprotected by ifdefs
 * Even if it did fix the compile, it means inconsistent behaviour between
   a compile time failure to find the value (we silently don't close files)
   and a runtime failure (we die with an error from close_range())
 * Silently not closing the files we intend to close for security reasons
   is probably not a good idea in any case

We don't want to simply error if close_range() or CLOSE_RANGE_UNSHARE isn't
available, because that would require running on kernel >= 5.9.  On the
other hand there's not really any other way to flush all possible fds
leaked by the parent (close() in a loop takes over a minute).  So in this
case print a warning and carry on.

As bonus this fixes a cppcheck error I see with some different options I'm
looking to apply in future.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2024-11-08 08:26:17 +01:00

144 lines
4.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright Red Hat
*
* Declarations for Linux specific dependencies
*/
#ifndef LINUX_DEP_H
#define LINUX_DEP_H
/* struct tcp_info_linux - Information from Linux TCP_INFO getsockopt()
*
* Largely derived from include/linux/tcp.h in the Linux kernel
*
* Some fields returned by TCP_INFO have been there for ages and are shared with
* BSD. struct tcp_info from netinet/tcp.h has only those fields. There are
* also a many Linux specific extensions to the structure, which are only found
* in the linux/tcp.h version of struct tcp_info.
*
* We want to use some of those extension fields, when available. We can test
* for availability in the runtime kernel using the length returned from
* getsockopt(). However, we won't necessarily be compiled against the same
* kernel headers as we'll run with, so compiling directly against linux/tcp.h
* means wrapping every field access in an #ifdef whose #else does the same
* thing as when the field is missing at runtime. This rapidly gets messy.
*
* Instead we define here struct tcp_info_linux which includes all the Linux
* extensions that we want to use. This is taken from v6.11 of the kernel.
*/
struct tcp_info_linux {
uint8_t tcpi_state;
uint8_t tcpi_ca_state;
uint8_t tcpi_retransmits;
uint8_t tcpi_probes;
uint8_t tcpi_backoff;
uint8_t tcpi_options;
uint8_t tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
uint8_t tcpi_delivery_rate_app_limited:1, tcpi_fastopen_client_fail:2;
uint32_t tcpi_rto;
uint32_t tcpi_ato;
uint32_t tcpi_snd_mss;
uint32_t tcpi_rcv_mss;
uint32_t tcpi_unacked;
uint32_t tcpi_sacked;
uint32_t tcpi_lost;
uint32_t tcpi_retrans;
uint32_t tcpi_fackets;
/* Times. */
uint32_t tcpi_last_data_sent;
uint32_t tcpi_last_ack_sent;
uint32_t tcpi_last_data_recv;
uint32_t tcpi_last_ack_recv;
/* Metrics. */
uint32_t tcpi_pmtu;
uint32_t tcpi_rcv_ssthresh;
uint32_t tcpi_rtt;
uint32_t tcpi_rttvar;
uint32_t tcpi_snd_ssthresh;
uint32_t tcpi_snd_cwnd;
uint32_t tcpi_advmss;
uint32_t tcpi_reordering;
uint32_t tcpi_rcv_rtt;
uint32_t tcpi_rcv_space;
uint32_t tcpi_total_retrans;
/* Linux extensions */
uint64_t tcpi_pacing_rate;
uint64_t tcpi_max_pacing_rate;
uint64_t tcpi_bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked */
uint64_t tcpi_bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived */
uint32_t tcpi_segs_out; /* RFC4898 tcpEStatsPerfSegsOut */
uint32_t tcpi_segs_in; /* RFC4898 tcpEStatsPerfSegsIn */
uint32_t tcpi_notsent_bytes;
uint32_t tcpi_min_rtt;
uint32_t tcpi_data_segs_in; /* RFC4898 tcpEStatsDataSegsIn */
uint32_t tcpi_data_segs_out; /* RFC4898 tcpEStatsDataSegsOut */
uint64_t tcpi_delivery_rate;
uint64_t tcpi_busy_time; /* Time (usec) busy sending data */
uint64_t tcpi_rwnd_limited; /* Time (usec) limited by receive window */
uint64_t tcpi_sndbuf_limited; /* Time (usec) limited by send buffer */
uint32_t tcpi_delivered;
uint32_t tcpi_delivered_ce;
uint64_t tcpi_bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut */
uint64_t tcpi_bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans */
uint32_t tcpi_dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups */
uint32_t tcpi_reord_seen; /* reordering events seen */
uint32_t tcpi_rcv_ooopack; /* Out-of-order packets received */
uint32_t tcpi_snd_wnd; /* peer's advertised receive window after
* scaling (bytes)
*/
uint32_t tcpi_rcv_wnd; /* local advertised receive window after
* scaling (bytes)
*/
uint32_t tcpi_rehash; /* PLB or timeout triggered rehash attempts */
uint16_t tcpi_total_rto; /* Total number of RTO timeouts, including
* SYN/SYN-ACK and recurring timeouts.
*/
uint16_t tcpi_total_rto_recoveries; /* Total number of RTO
* recoveries, including any
* unfinished recovery.
*/
uint32_t tcpi_total_rto_time; /* Total time spent in RTO recoveries
* in milliseconds, including any
* unfinished recovery.
*/
};
#include <linux/falloc.h>
#ifndef FALLOC_FL_COLLAPSE_RANGE
#define FALLOC_FL_COLLAPSE_RANGE 0x08
#endif
#include <linux/close_range.h>
/* glibc < 2.34 and musl as of 1.2.5 need these */
#ifndef SYS_close_range
#define SYS_close_range 436
#endif
#ifndef CLOSE_RANGE_UNSHARE /* Linux kernel < 5.9 */
#define CLOSE_RANGE_UNSHARE (1U << 1)
#endif
__attribute__ ((weak))
/* cppcheck-suppress funcArgNamesDifferent */
int close_range(unsigned int first, unsigned int last, int flags) {
return syscall(SYS_close_range, first, last, flags);
}
#endif /* LINUX_DEP_H */