mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 17:16:41 +07:00
cdc4e47da8
Lots of places in the kernel use memcpy(buf, comm, TASK_COMM_LEN); but
the result is typically passed to print("%s", buf) and extra bytes
after zero don't cause any harm.
In bpf the result of bpf_get_current_comm() is used as the part of
map key and was causing spurious hash map mismatches.
Use strlcpy() to guarantee zero-terminated string.
bpf verifier checks that output buffer is zero-initialized,
so even for short task names the output buffer don't have junk bytes.
Note it's not a security concern, since kprobe+bpf is root only.
Fixes: ffeedafbf0
("bpf: introduce current->pid, tgid, uid, gid, comm accessors")
Reported-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
180 lines
4.8 KiB
C
180 lines
4.8 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/bpf.h>
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#include <linux/rcupdate.h>
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#include <linux/random.h>
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#include <linux/smp.h>
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#include <linux/ktime.h>
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#include <linux/sched.h>
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#include <linux/uidgid.h>
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/* If kernel subsystem is allowing eBPF programs to call this function,
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* inside its own verifier_ops->get_func_proto() callback it should return
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* bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
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*
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* Different map implementations will rely on rcu in map methods
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* lookup/update/delete, therefore eBPF programs must run under rcu lock
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* if program is allowed to access maps, so check rcu_read_lock_held in
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* all three functions.
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*/
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static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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/* verifier checked that R1 contains a valid pointer to bpf_map
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* and R2 points to a program stack and map->key_size bytes were
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* initialized
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*/
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struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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void *key = (void *) (unsigned long) r2;
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void *value;
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WARN_ON_ONCE(!rcu_read_lock_held());
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value = map->ops->map_lookup_elem(map, key);
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/* lookup() returns either pointer to element value or NULL
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* which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type
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*/
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return (unsigned long) value;
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}
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const struct bpf_func_proto bpf_map_lookup_elem_proto = {
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.func = bpf_map_lookup_elem,
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.gpl_only = false,
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.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_MAP_KEY,
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};
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static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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void *key = (void *) (unsigned long) r2;
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void *value = (void *) (unsigned long) r3;
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WARN_ON_ONCE(!rcu_read_lock_held());
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return map->ops->map_update_elem(map, key, value, r4);
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}
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const struct bpf_func_proto bpf_map_update_elem_proto = {
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.func = bpf_map_update_elem,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_MAP_KEY,
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.arg3_type = ARG_PTR_TO_MAP_VALUE,
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.arg4_type = ARG_ANYTHING,
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};
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static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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void *key = (void *) (unsigned long) r2;
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WARN_ON_ONCE(!rcu_read_lock_held());
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return map->ops->map_delete_elem(map, key);
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}
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const struct bpf_func_proto bpf_map_delete_elem_proto = {
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.func = bpf_map_delete_elem,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_MAP_KEY,
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};
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const struct bpf_func_proto bpf_get_prandom_u32_proto = {
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.func = bpf_user_rnd_u32,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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};
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static u64 bpf_get_smp_processor_id(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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return raw_smp_processor_id();
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}
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const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
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.func = bpf_get_smp_processor_id,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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};
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static u64 bpf_ktime_get_ns(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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/* NMI safe access to clock monotonic */
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return ktime_get_mono_fast_ns();
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}
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const struct bpf_func_proto bpf_ktime_get_ns_proto = {
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.func = bpf_ktime_get_ns,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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};
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static u64 bpf_get_current_pid_tgid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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struct task_struct *task = current;
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if (!task)
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return -EINVAL;
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return (u64) task->tgid << 32 | task->pid;
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}
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const struct bpf_func_proto bpf_get_current_pid_tgid_proto = {
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.func = bpf_get_current_pid_tgid,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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};
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static u64 bpf_get_current_uid_gid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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struct task_struct *task = current;
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kuid_t uid;
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kgid_t gid;
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if (!task)
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return -EINVAL;
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current_uid_gid(&uid, &gid);
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return (u64) from_kgid(&init_user_ns, gid) << 32 |
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from_kuid(&init_user_ns, uid);
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}
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const struct bpf_func_proto bpf_get_current_uid_gid_proto = {
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.func = bpf_get_current_uid_gid,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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};
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static u64 bpf_get_current_comm(u64 r1, u64 size, u64 r3, u64 r4, u64 r5)
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{
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struct task_struct *task = current;
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char *buf = (char *) (long) r1;
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if (!task)
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return -EINVAL;
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strlcpy(buf, task->comm, min_t(size_t, size, sizeof(task->comm)));
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return 0;
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}
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const struct bpf_func_proto bpf_get_current_comm_proto = {
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.func = bpf_get_current_comm,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_STACK,
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.arg2_type = ARG_CONST_STACK_SIZE,
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};
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