801a01a441
sites and installing a hook at the kernel's trap handler. The fasttrap code
will emulate the overwritten instruction in some common cases, but otherwise
copies it out into some scratch space in the traced process' address space
and ensures that it's executed after returning from the trap.
In Solaris and illumos, this (per-thread) scratch space comes from some
reserved space in TLS, accessible via the fs segment register. This
approach is somewhat unappealing on FreeBSD since it would require some
modifications to rtld and jemalloc (for static TLS) to ensure that TLS is
executable, and would thus introduce dependencies on their implementation
details. I think it would also be impossible to safely trace static binaries
compiled without these modifications.
This change implements the functionality in a different way, by having
fasttrap map pages into the target process' address space on demand. Each
page is divided into 64-byte chunks for use by individual threads, and
fasttrap's process descriptor struct has been extended to keep track of
any scratch space allocated for the corresponding process.
With this change it's possible to trace all libc functions in a program,
e.g. with
pid$target:libc.so.*::entry {@[probefunc] = count();}
Previously this would generally cause the victim process to crash, as
tracing memcpy on amd64 requires the functionality described above.
Tested by: Prashanth Kumar <pra_udupi@yahoo.co.in> (earlier version)
MFC after: 6 weeks
168 lines
5.3 KiB
C
168 lines
5.3 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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* $FreeBSD$
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*
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*/
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#ifndef _DTRACE_CDDL_H_
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#define _DTRACE_CDDL_H_
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#include <sys/proc.h>
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#define LOCK_LEVEL 10
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/*
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* Kernel DTrace extension to 'struct proc' for FreeBSD.
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*/
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typedef struct kdtrace_proc {
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int p_dtrace_probes; /* Are there probes for this proc? */
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u_int64_t p_dtrace_count; /* Number of DTrace tracepoints */
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void *p_dtrace_helpers; /* DTrace helpers, if any */
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int p_dtrace_model;
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} kdtrace_proc_t;
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/*
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* Kernel DTrace extension to 'struct thread' for FreeBSD.
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*/
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typedef struct kdtrace_thread {
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u_int8_t td_dtrace_stop; /* Indicates a DTrace-desired stop */
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u_int8_t td_dtrace_sig; /* Signal sent via DTrace's raise() */
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u_int td_predcache; /* DTrace predicate cache */
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u_int64_t td_dtrace_vtime; /* DTrace virtual time */
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u_int64_t td_dtrace_start; /* DTrace slice start time */
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union __tdu {
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struct __tds {
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u_int8_t _td_dtrace_on;
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/* Hit a fasttrap tracepoint. */
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u_int8_t _td_dtrace_step;
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/* About to return to kernel. */
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u_int8_t _td_dtrace_ret;
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/* Handling a return probe. */
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u_int8_t _td_dtrace_ast;
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/* Saved ast flag. */
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#ifdef __amd64__
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u_int8_t _td_dtrace_reg;
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#endif
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} _tds;
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u_long _td_dtrace_ft; /* Bitwise or of these flags. */
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} _tdu;
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#define td_dtrace_ft _tdu._td_dtrace_ft
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#define td_dtrace_on _tdu._tds._td_dtrace_on
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#define td_dtrace_step _tdu._tds._td_dtrace_step
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#define td_dtrace_ret _tdu._tds._td_dtrace_ret
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#define td_dtrace_ast _tdu._tds._td_dtrace_ast
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#define td_dtrace_reg _tdu._tds._td_dtrace_reg
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uintptr_t td_dtrace_pc; /* DTrace saved pc from fasttrap. */
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uintptr_t td_dtrace_npc; /* DTrace next pc from fasttrap. */
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uintptr_t td_dtrace_scrpc;
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/* DTrace per-thread scratch location. */
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uintptr_t td_dtrace_astpc;
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/* DTrace return sequence location. */
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#ifdef __amd64__
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uintptr_t td_dtrace_regv;
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#endif
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u_int64_t td_hrtime; /* Last time on cpu. */
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int td_errno; /* Syscall return value. */
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void *td_dtrace_sscr; /* Saved scratch space location. */
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} kdtrace_thread_t;
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/*
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* Definitions to reference fields in the FreeBSD DTrace structures defined
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* above using the names of fields in similar structures in Solaris. Note
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* that the separation on FreeBSD is a licensing constraint designed to
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* keep the GENERIC kernel BSD licensed.
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*/
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#define t_dtrace_vtime td_dtrace->td_dtrace_vtime
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#define t_dtrace_start td_dtrace->td_dtrace_start
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#define t_dtrace_stop td_dtrace->td_dtrace_stop
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#define t_dtrace_sig td_dtrace->td_dtrace_sig
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#define t_predcache td_dtrace->td_predcache
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#define t_dtrace_ft td_dtrace->td_dtrace_ft
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#define t_dtrace_on td_dtrace->td_dtrace_on
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#define t_dtrace_step td_dtrace->td_dtrace_step
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#define t_dtrace_ret td_dtrace->td_dtrace_ret
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#define t_dtrace_ast td_dtrace->td_dtrace_ast
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#define t_dtrace_reg td_dtrace->td_dtrace_reg
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#define t_dtrace_pc td_dtrace->td_dtrace_pc
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#define t_dtrace_npc td_dtrace->td_dtrace_npc
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#define t_dtrace_scrpc td_dtrace->td_dtrace_scrpc
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#define t_dtrace_astpc td_dtrace->td_dtrace_astpc
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#define t_dtrace_regv td_dtrace->td_dtrace_regv
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#define t_dtrace_sscr td_dtrace->td_dtrace_sscr
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#define p_dtrace_helpers p_dtrace->p_dtrace_helpers
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#define p_dtrace_count p_dtrace->p_dtrace_count
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#define p_dtrace_probes p_dtrace->p_dtrace_probes
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#define p_model p_dtrace->p_dtrace_model
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#define DATAMODEL_NATIVE 0
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#ifdef __amd64__
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#define DATAMODEL_LP64 0
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#define DATAMODEL_ILP32 1
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#else
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#define DATAMODEL_LP64 1
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#define DATAMODEL_ILP32 0
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#endif
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/*
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* Definitions for fields in struct proc which are named differently in FreeBSD.
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*/
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#define p_cred p_ucred
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#define p_parent p_pptr
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/*
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* Definitions for fields in struct thread which are named differently in FreeBSD.
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*/
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#define t_procp td_proc
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#define t_tid td_tid
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#define t_did td_tid
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int priv_policy(const cred_t *, int, boolean_t, int, const char *);
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boolean_t priv_policy_only(const cred_t *, int, boolean_t);
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boolean_t priv_policy_choice(const cred_t *, int, boolean_t);
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/*
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* Test privilege. Audit success or failure, allow privilege debugging.
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* Returns 0 for success, err for failure.
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*/
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#define PRIV_POLICY(cred, priv, all, err, reason) \
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priv_policy((cred), (priv), (all), (err), (reason))
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/*
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* Test privilege. Audit success only, no privilege debugging.
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* Returns 1 for success, and 0 for failure.
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*/
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#define PRIV_POLICY_CHOICE(cred, priv, all) \
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priv_policy_choice((cred), (priv), (all))
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/*
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* Test privilege. No priv_debugging, no auditing.
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* Returns 1 for success, and 0 for failure.
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*/
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#define PRIV_POLICY_ONLY(cred, priv, all) \
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priv_policy_only((cred), (priv), (all))
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#endif /* !_DTRACE_CDDL_H_ */
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