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bef3efbeb8
Each read from a file in efivarfs results in two calls to EFI (one to get the file size, another to get the actual data). On X86 these EFI calls result in broadcast system management interrupts (SMI) which affect performance of the whole system. A malicious user can loop performing reads from efivarfs bringing the system to its knees. Linus suggested per-user rate limit to solve this. So we add a ratelimit structure to "user_struct" and initialize it for the root user for no limit. When allocating user_struct for other users we set the limit to 100 per second. This could be used for other places that want to limit the rate of some detrimental user action. In efivarfs if the limit is exceeded when reading, we take an interruptible nap for 50ms and check the rate limit again. Signed-off-by: Tony Luck <tony.luck@intel.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
67 lines
1.8 KiB
C
67 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SCHED_USER_H
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#define _LINUX_SCHED_USER_H
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#include <linux/uidgid.h>
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#include <linux/atomic.h>
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#include <linux/ratelimit.h>
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struct key;
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/*
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* Some day this will be a full-fledged user tracking system..
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*/
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struct user_struct {
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atomic_t __count; /* reference count */
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atomic_t processes; /* How many processes does this user have? */
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atomic_t sigpending; /* How many pending signals does this user have? */
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#ifdef CONFIG_FANOTIFY
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atomic_t fanotify_listeners;
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#endif
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#ifdef CONFIG_EPOLL
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atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
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#endif
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#ifdef CONFIG_POSIX_MQUEUE
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/* protected by mq_lock */
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unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */
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#endif
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unsigned long locked_shm; /* How many pages of mlocked shm ? */
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unsigned long unix_inflight; /* How many files in flight in unix sockets */
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atomic_long_t pipe_bufs; /* how many pages are allocated in pipe buffers */
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#ifdef CONFIG_KEYS
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struct key *uid_keyring; /* UID specific keyring */
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struct key *session_keyring; /* UID's default session keyring */
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#endif
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/* Hash table maintenance information */
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struct hlist_node uidhash_node;
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kuid_t uid;
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#if defined(CONFIG_PERF_EVENTS) || defined(CONFIG_BPF_SYSCALL) || \
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defined(CONFIG_NET)
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atomic_long_t locked_vm;
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#endif
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/* Miscellaneous per-user rate limit */
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struct ratelimit_state ratelimit;
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};
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extern int uids_sysfs_init(void);
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extern struct user_struct *find_user(kuid_t);
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extern struct user_struct root_user;
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#define INIT_USER (&root_user)
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/* per-UID process charging. */
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extern struct user_struct * alloc_uid(kuid_t);
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static inline struct user_struct *get_uid(struct user_struct *u)
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{
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atomic_inc(&u->__count);
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return u;
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}
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extern void free_uid(struct user_struct *);
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#endif /* _LINUX_SCHED_USER_H */
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