Date: Tue, 11 May 2021 10:31:05 GMT From: Alex Richardson <arichardson@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 46c255b6325d - stable/13 - truss: improved support for decoding compat32 arguments Message-ID: <202105111031.14BAV5e7084733@gitrepo.freebsd.org>
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The branch stable/13 has been updated by arichardson: URL: https://cgit.FreeBSD.org/src/commit/?id=46c255b6325d4a84ca22a663cfbedb762ac12b02 commit 46c255b6325d4a84ca22a663cfbedb762ac12b02 Author: Alex Richardson <arichardson@FreeBSD.org> AuthorDate: 2021-03-25 11:12:17 +0000 Commit: Alex Richardson <arichardson@FreeBSD.org> CommitDate: 2021-05-11 08:39:24 +0000 truss: improved support for decoding compat32 arguments Currently running `truss -a -e` does not decode any argument values for freebsd32_* syscalls (open/readlink/etc.) This change checks whether a syscall starts with freebsd{32,64}_ and if so strips that prefix when looking up the syscall information. To ensure that the truss logs include the real syscall name we create a copy of the syscall information struct with the updated. The other problem is that when reading string array values, truss naively iterates over an array of char* and fetches the pointer value. This will result in arguments not being loaded if the pointer is not aligned to sizeof(void*), which can happens in the compat32 case. If it happens to be aligned, we would end up printing every other value. To fix this problem, this changes adds a pointer_size member to the procabi struct and uses that to correctly read indirect arguments as 64/32 bit addresses in the the compat32 case (and also compat64 on CheriBSD). The motivating use-case for this change is using truss for 64-bit programs on a CHERI system, but most of the diff also applies to 32-bit compat on a 64-bit system, so I'm upstreaming this instead of keeping it as a local CheriBSD patch. Output of `truss -aef ldd32 /usr/bin/ldd32` before: 39113: freebsd32_mmap(0x0,0x1000,0x3,0x1002,0xffffffff,0x0,0x0) = 543440896 (0x20644000) 39113: freebsd32_ioctl(0x1,0x402c7413,0xffffd2a0) = 0 (0x0) /usr/bin/ldd32: 39113: write(1,"/usr/bin/ldd32:\n",16) = 16 (0x10) 39113: fork() = 39114 (0x98ca) 39114: <new process> 39114: freebsd32_execve(0xffffd97e,0xffffd680,0x20634000) EJUSTRETURN 39114: freebsd32_mmap(0x0,0x20000,0x3,0x1002,0xffffffff,0x0,0x0) = 541237248 (0x2042a000) 39114: freebsd32_mprotect(0x20427000,0x1000,0x1) = 0 (0x0) 39114: issetugid() = 0 (0x0) 39114: openat(AT_FDCWD,"/etc/libmap32.conf",O_RDONLY|O_CLOEXEC,00) ERR#2 'No such file or directory' 39114: openat(AT_FDCWD,"/var/run/ld-elf32.so.hints",O_RDONLY|O_CLOEXEC,00) = 3 (0x3) 39114: read(3,"Ehnt\^A\0\0\0\M^@\0\0\0#\0\0\0\0"...,128) = 128 (0x80) 39114: freebsd32_fstat(0x3,0xffffbd98) = 0 (0x0) 39114: freebsd32_pread(0x3,0x2042f000,0x23,0x80,0x0) = 35 (0x23) 39114: close(3) = 0 (0x0) 39114: openat(AT_FDCWD,"/usr/lib32/libc.so.7",O_RDONLY|O_CLOEXEC|O_VERIFY,00) = 3 (0x3) 39114: freebsd32_fstat(0x3,0xffffc7d0) = 0 (0x0) 39114: freebsd32_mmap(0x0,0x1000,0x1,0x40002,0x3,0x0,0x0) = 541368320 (0x2044a000) After: 783: freebsd32_mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON|MAP_ALIGNED(12),-1,0x0) = 543543296 (0x2065d000) 783: freebsd32_ioctl(1,TIOCGETA,0xffffd7b0) = 0 (0x0) /usr/bin/ldd32: 783: write(1,"/usr/bin/ldd32:\n",16) = 16 (0x10) 784: <new process> 783: fork() = 784 (0x310) 784: freebsd32_execve("/usr/bin/ldd32",[ "(null)" ],[ "LD_32_TRACE_LOADED_OBJECTS_PROGNAME=/usr/bin/ldd32", "LD_TRACE_LOADED_OBJECTS_PROGNAME=/usr/bin/ldd32", "LD_32_TRACE_LOADED_OBJECTS=yes", "LD_TRACE_LOADED_OBJECTS=yes", "USER=root", "LOGNAME=root", "HOME=/root", "SHELL=/bin/csh", "BLOCKSIZE=K", "MAIL=/var/mail/root", "MM_CHARSET=UTF-8", "LANG=C.UTF-8", "PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/root/bin", "TERM=vt100", "HOSTTYPE=FreeBSD", "VENDOR=amd", "OSTYPE=FreeBSD", "MACHTYPE=x86_64", "SHLVL=1", "PWD=/root", "GROUP=wheel", "HOST=freebsd-amd64", "EDITOR=vi", "PAGER=less" ]) EJUSTRETURN 784: freebsd32_mmap(0x0,135168,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 541212672 (0x20424000) 784: freebsd32_mprotect(0x20421000,4096,PROT_READ) = 0 (0x0) 784: issetugid() = 0 (0x0) 784: sigfastblock(0x1,0x204234fc) = 0 (0x0) 784: open("/etc/libmap32.conf",O_RDONLY|O_CLOEXEC,00) ERR#2 'No such file or directory' 784: open("/var/run/ld-elf32.so.hints",O_RDONLY|O_CLOEXEC,00) = 3 (0x3) 784: read(3,"Ehnt\^A\0\0\0\M^@\0\0\0\v\0\0\0"...,128) = 128 (0x80) 784: freebsd32_fstat(3,{ mode=-r--r--r-- ,inode=18680,size=32768,blksize=0 }) = 0 (0x0) 784: freebsd32_pread(3,"/usr/lib32\0",11,0x80) = 11 (0xb) Reviewed By: jhb Differential Revision: https://reviews.freebsd.org/D27625 (cherry picked from commit 7daca4e2043fa8d88658eb8c2fc195128cb5c3da) --- usr.bin/truss/setup.c | 71 ++++++++++++++++++++++++++++-------------------- usr.bin/truss/syscalls.c | 59 +++++++++++++++++++++++++++++----------- usr.bin/truss/truss.h | 2 ++ 3 files changed, 87 insertions(+), 45 deletions(-) diff --git a/usr.bin/truss/setup.c b/usr.bin/truss/setup.c index 2ea1bce8919b..31c20d656b6a 100644 --- a/usr.bin/truss/setup.c +++ b/usr.bin/truss/setup.c @@ -74,59 +74,72 @@ static void new_proc(struct trussinfo *, pid_t, lwpid_t); static struct procabi cloudabi32 = { - "CloudABI32", - SYSDECODE_ABI_CLOUDABI32, - STAILQ_HEAD_INITIALIZER(cloudabi32.extra_syscalls), - { NULL } + .type = "CloudABI32", + .abi = SYSDECODE_ABI_CLOUDABI32, + .pointer_size = sizeof(uint32_t), + .extra_syscalls = STAILQ_HEAD_INITIALIZER(cloudabi32.extra_syscalls), + .syscalls = { NULL } }; static struct procabi cloudabi64 = { - "CloudABI64", - SYSDECODE_ABI_CLOUDABI64, - STAILQ_HEAD_INITIALIZER(cloudabi64.extra_syscalls), - { NULL } + .type = "CloudABI64", + .abi = SYSDECODE_ABI_CLOUDABI64, + .pointer_size = sizeof(uint64_t), + .extra_syscalls = STAILQ_HEAD_INITIALIZER(cloudabi64.extra_syscalls), + .syscalls = { NULL } }; static struct procabi freebsd = { - "FreeBSD", - SYSDECODE_ABI_FREEBSD, - STAILQ_HEAD_INITIALIZER(freebsd.extra_syscalls), - { NULL } + .type = "FreeBSD", + .abi = SYSDECODE_ABI_FREEBSD, + .pointer_size = sizeof(void *), + .extra_syscalls = STAILQ_HEAD_INITIALIZER(freebsd.extra_syscalls), + .syscalls = { NULL } }; -#ifdef __LP64__ +#if !defined(__SIZEOF_POINTER__) +#error "Use a modern compiler." +#endif + +#if __SIZEOF_POINTER__ > 4 static struct procabi freebsd32 = { - "FreeBSD32", - SYSDECODE_ABI_FREEBSD32, - STAILQ_HEAD_INITIALIZER(freebsd32.extra_syscalls), - { NULL } + .type = "FreeBSD32", + .abi = SYSDECODE_ABI_FREEBSD32, + .pointer_size = sizeof(uint32_t), + .compat_prefix = "freebsd32", + .extra_syscalls = STAILQ_HEAD_INITIALIZER(freebsd32.extra_syscalls), + .syscalls = { NULL } }; #endif static struct procabi linux = { - "Linux", - SYSDECODE_ABI_LINUX, - STAILQ_HEAD_INITIALIZER(linux.extra_syscalls), - { NULL } + .type = "Linux", + .abi = SYSDECODE_ABI_LINUX, + .pointer_size = sizeof(void *), + .extra_syscalls = STAILQ_HEAD_INITIALIZER(linux.extra_syscalls), + .syscalls = { NULL } }; -#ifdef __LP64__ +#if __SIZEOF_POINTER__ > 4 static struct procabi linux32 = { - "Linux32", - SYSDECODE_ABI_LINUX32, - STAILQ_HEAD_INITIALIZER(linux32.extra_syscalls), - { NULL } + .type = "Linux32", + .abi = SYSDECODE_ABI_LINUX32, + .pointer_size = sizeof(uint32_t), + .extra_syscalls = STAILQ_HEAD_INITIALIZER(linux32.extra_syscalls), + .syscalls = { NULL } }; #endif static struct procabi_table abis[] = { { "CloudABI ELF32", &cloudabi32 }, { "CloudABI ELF64", &cloudabi64 }, -#ifdef __LP64__ +#if __SIZEOF_POINTER__ == 4 + { "FreeBSD ELF32", &freebsd }, +#elif __SIZEOF_POINTER__ == 8 { "FreeBSD ELF64", &freebsd }, { "FreeBSD ELF32", &freebsd32 }, #else - { "FreeBSD ELF32", &freebsd }, +#error "Unsupported pointer size" #endif #if defined(__powerpc64__) { "FreeBSD ELF64 V2", &freebsd }, @@ -137,7 +150,7 @@ static struct procabi_table abis[] = { #if defined(__i386__) { "FreeBSD a.out", &freebsd }, #endif -#ifdef __LP64__ +#if __SIZEOF_POINTER__ >= 8 { "Linux ELF64", &linux }, { "Linux ELF32", &linux32 }, #else diff --git a/usr.bin/truss/syscalls.c b/usr.bin/truss/syscalls.c index 91ddc65e457f..eaea3ad96765 100644 --- a/usr.bin/truss/syscalls.c +++ b/usr.bin/truss/syscalls.c @@ -963,7 +963,6 @@ print_mask_arg32(bool (*decoder)(FILE *, uint32_t, uint32_t *), FILE *fp, fprintf(fp, "|0x%x", rem); } -#ifndef __LP64__ /* * Add argument padding to subsequent system calls after Quad * syscall arguments as needed. This used to be done by hand in the @@ -1008,7 +1007,6 @@ quad_fixup(struct syscall_decode *sc) } } } -#endif static struct syscall * find_syscall(struct procabi *abi, u_int number) @@ -1029,10 +1027,13 @@ add_syscall(struct procabi *abi, u_int number, struct syscall *sc) { struct extra_syscall *es; -#ifndef __LP64__ - /* FIXME: should be based on syscall ABI not truss ABI */ - quad_fixup(&sc->decode); -#endif + /* + * quad_fixup() is currently needed for all 32-bit ABIs. + * TODO: This should probably be a function pointer inside struct + * procabi instead. + */ + if (abi->pointer_size == 4) + quad_fixup(&sc->decode); if (number < nitems(abi->syscalls)) { assert(abi->syscalls[number] == NULL); @@ -1055,16 +1056,19 @@ struct syscall * get_syscall(struct threadinfo *t, u_int number, u_int nargs) { struct syscall *sc; + struct procabi *procabi; const char *sysdecode_name; + const char *lookup_name; const char *name; u_int i; - sc = find_syscall(t->proc->abi, number); + procabi = t->proc->abi; + sc = find_syscall(procabi, number); if (sc != NULL) return (sc); /* Memory is not explicitly deallocated, it's released on exit(). */ - sysdecode_name = sysdecode_syscallname(t->proc->abi->abi, number); + sysdecode_name = sysdecode_syscallname(procabi->abi, number); if (sysdecode_name == NULL) asprintf(__DECONST(char **, &name), "#%d", number); else @@ -1073,8 +1077,14 @@ get_syscall(struct threadinfo *t, u_int number, u_int nargs) sc = calloc(1, sizeof(*sc)); sc->name = name; + /* Also decode compat syscalls arguments by stripping the prefix. */ + lookup_name = name; + if (procabi->compat_prefix != NULL && strncmp(procabi->compat_prefix, + name, strlen(procabi->compat_prefix)) == 0) + lookup_name += strlen(procabi->compat_prefix); + for (i = 0; i < nitems(decoded_syscalls); i++) { - if (strcmp(name, decoded_syscalls[i].name) == 0) { + if (strcmp(lookup_name, decoded_syscalls[i].name) == 0) { sc->decode = decoded_syscalls[i]; add_syscall(t->proc->abi, number, sc); return (sc); @@ -1817,12 +1827,15 @@ print_arg(struct syscall_arg *sc, unsigned long *args, register_t *retval, case StringArray: { uintptr_t addr; union { - char *strarray[0]; + int32_t strarray32[PAGE_SIZE / sizeof(int32_t)]; + int64_t strarray64[PAGE_SIZE / sizeof(int64_t)]; char buf[PAGE_SIZE]; } u; char *string; size_t len; u_int first, i; + size_t pointer_size = + trussinfo->curthread->proc->abi->pointer_size; /* * Only parse argv[] and environment arrays from exec calls @@ -1842,7 +1855,7 @@ print_arg(struct syscall_arg *sc, unsigned long *args, register_t *retval, * a partial page. */ addr = args[sc->offset]; - if (addr % sizeof(char *) != 0) { + if (addr % pointer_size != 0) { print_pointer(fp, args[sc->offset]); break; } @@ -1852,22 +1865,36 @@ print_arg(struct syscall_arg *sc, unsigned long *args, register_t *retval, print_pointer(fp, args[sc->offset]); break; } + assert(len > 0); fputc('[', fp); first = 1; i = 0; - while (u.strarray[i] != NULL) { - string = get_string(pid, (uintptr_t)u.strarray[i], 0); + for (;;) { + uintptr_t straddr; + if (pointer_size == 4) { + if (u.strarray32[i] == 0) + break; + /* sign-extend 32-bit pointers */ + straddr = (intptr_t)u.strarray32[i]; + } else if (pointer_size == 8) { + if (u.strarray64[i] == 0) + break; + straddr = (intptr_t)u.strarray64[i]; + } else { + errx(1, "Unsupported pointer size: %zu", + pointer_size); + } + string = get_string(pid, straddr, 0); fprintf(fp, "%s \"%s\"", first ? "" : ",", string); free(string); first = 0; i++; - if (i == len / sizeof(char *)) { + if (i == len / pointer_size) { addr += len; len = PAGE_SIZE; - if (get_struct(pid, addr, u.buf, len) == - -1) { + if (get_struct(pid, addr, u.buf, len) == -1) { fprintf(fp, ", <inval>"); break; } diff --git a/usr.bin/truss/truss.h b/usr.bin/truss/truss.h index 5154515848bf..a3ce8f27d953 100644 --- a/usr.bin/truss/truss.h +++ b/usr.bin/truss/truss.h @@ -58,6 +58,8 @@ struct extra_syscall { struct procabi { const char *type; enum sysdecode_abi abi; + size_t pointer_size; + const char *compat_prefix; STAILQ_HEAD(, extra_syscall) extra_syscalls; struct syscall *syscalls[SYSCALL_NORMAL_COUNT]; };
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