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Handle renameat2 on RHEL 8 and systems with glibc < 2.28 #147

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Jul 16, 2024
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Handle renameat2 on RHEL 8 and systems with glibc < 2.28 #147

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3741afc
First attempt at intercepting syscall for renameat2
reidsunderland Jun 11, 2024
95ab888
better implementation for renameat2 with syscall
reidsunderland Jul 15, 2024
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2 changes: 2 additions & 0 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@ LIBCLOCATION=$(shell ldd /bin/sh | awk '/libc\.so\./ { print; }' | cut -d' ' -f3
# also remove -ljson-c from EXT_LIB declaration.
# to work with sr3, change SR_APPNAME=\"sr3\" ... otherwise will be managed by version 2.
# on Power9, -fstack-check causes coredumps, so removed for now.
# On RHEL8, add -DINTERCEPT_SYSCALL to handle cases where mv calls syscall directly, instead of calling renameat2.
# See sarrac issue #145 for more information about syscall/renameat2.

CFLAGS = -DHAVE_JSONC -DSR_APPNAME=\"sr3\" -DFORCE_LIBC_REGEX=\"$(LIBCLOCATION)\" -fPIC -ftest-coverage -std=gnu99 -Wall -g -D_GNU_SOURCE $(RABBIT_INCDIR)

Expand Down
82 changes: 79 additions & 3 deletions libsr3shim.c
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Expand Up @@ -19,6 +19,14 @@

#include "sr_post.h"

/*
See https://github.com/MetPX/sarrac/issues/145.
glibc < 2.28 doesn't provide renameat2.
*/
#if !__GLIBC_PREREQ(2,28)
#define INTERCEPT_SYSCALL
#endif

/*
libsrshim - intercepts calls to libc and kernel to post files for broker.

Expand Down Expand Up @@ -48,6 +56,8 @@ SR_SHIM_CONFIG -- environment variable to set configuration file name
void exit_cleanup_posts();
int exit_cleanup_posts_setup = 0;

void syscall_init();

int mypid = 0;
int pid_seconds_wallclock = 0;
int srshim_debug_level = -1;
Expand Down Expand Up @@ -855,10 +865,16 @@ static int renameat_init_done = 0;
typedef int (*renameat_fn)(int, const char *, int, const char *);
static renameat_fn renameat_fn_ptr = NULL;


static int renameat2_init_done = 0;
typedef int (*renameat2_fn)(int, const char *, int, const char *, unsigned int);
static renameat2_fn renameat2_fn_ptr = NULL;

static int syscall_init_done = 0;
typedef long int (*syscall_fn)(long int, ...);
static syscall_fn syscall_fn_ptr = NULL;


int renameorlink(int olddirfd, const char *oldpath, int newdirfd,
const char *newpath, int flags, int link)
/*
Expand All @@ -879,6 +895,7 @@ int renameorlink(int olddirfd, const char *oldpath, int newdirfd,
renameat2_fn_ptr = (renameat2_fn) dlsym(RTLD_NEXT, "renameat2");
renameat2_init_done = 1;
}

if (!renameat_init_done) {
renameat_fn_ptr = (renameat_fn) dlsym(RTLD_NEXT, "renameat");
renameat_init_done = 1;
Expand All @@ -894,6 +911,10 @@ int renameorlink(int olddirfd, const char *oldpath, int newdirfd,
linkat_init_done = 1;
}

if (!syscall_init_done) {
syscall_init();
}

if (link) {
if (linkat_fn_ptr)
status = linkat_fn_ptr(olddirfd, oldpath, newdirfd, newpath, flags);
Expand All @@ -904,11 +925,15 @@ int renameorlink(int olddirfd, const char *oldpath, int newdirfd,
" renameorlink could not identify real entry point for link\n");
}
} else {
if (renameat2_fn_ptr)
if (renameat2_fn_ptr) {
sr_shimdebug_msg(1, " renameorlink using renameat2\n");
status = renameat2_fn_ptr(olddirfd, oldpath, newdirfd, newpath, flags);
else if (renameat_fn_ptr && !flags)
} else if (renameat_fn_ptr && !flags) {
status = renameat_fn_ptr(olddirfd, oldpath, newdirfd, newpath);
else {
} else if (syscall_fn_ptr) {
sr_shimdebug_msg(1, " renameorlink using renameat2 via syscall(316, ...)\n");
status = syscall_fn_ptr(316, olddirfd, oldpath, newdirfd, newpath, flags);
} else {
sr_log_msg(logctxptr,LOG_ERROR,
" renameorlink could not identify real entry point for renameat\n");
return (-1);
Expand Down Expand Up @@ -1362,6 +1387,57 @@ int renameat2(int olddirfd, const char *oldpath, int newdirfd,
return (renameorlink(olddirfd, oldpath, newdirfd, newpath, flags, 0));
}

void syscall_init()
{
if (!syscall_init_done) {
setup_exit();
syscall_fn_ptr = (syscall_fn) dlsym(RTLD_NEXT, "syscall");
syscall_init_done = 1;
}
}

#ifdef INTERCEPT_SYSCALL
long int syscall(long int __sysno, ...)
{
va_list args;
int status = -1;

int olddirfd = -1;
char *oldpath = NULL;
int newdirfd = -1;
char *newpath = NULL;
int flags = -1;

sr_shimdebug_msg(1, "syscall %ld\n", __sysno);

if (!syscall_init_done) {
syscall_init();
}

// renameat2 is 316
if (__sysno == 316) {
sr_shimdebug_msg(1, "syscall %ld\n --> renameat2, will call renameorlink", __sysno);

va_start(args, __sysno);
olddirfd = va_arg(args, int);
oldpath = va_arg(args, char*);
newdirfd = va_arg(args, int);
newpath = va_arg(args, char*);
flags = va_arg(args, int);
va_end(args);

sr_shimdebug_msg(1, "%d, %s, %d, %s, %d", olddirfd, oldpath, newdirfd, newpath, flags);
status = renameorlink(olddirfd, oldpath, newdirfd, newpath, flags, 0);
}
else {
sr_shimdebug_msg(1, "syscall %ld NOT IMPLEMENTED\n", __sysno);
sr_log_msg(logctxptr,LOG_ERROR, "non-renameat2 syscall (%ld) not implemented\n", __sysno);
status = -1;
}
return status;
}
#endif

static int sendfile_init_done = 0;
typedef ssize_t(*sendfile_fn) (int, int, off_t *, size_t);
static sendfile_fn sendfile_fn_ptr = NULL;
Expand Down
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