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binfmt_flat: Remove shared library support

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In a recent discussion[1] it was reported that the binfmt_flat library
support was only ever used on m68k and even on m68k has not been used
in a very long time.

The structure of binfmt_flat is different from all of the other binfmt
implementations because of this shared library support and it made
life and code review more effort when I refactored the code in fs/exec.c.

Since in practice the code is dead remove the binfmt_flat shared library
support and make maintenance of the code easier.

[1] https://lkml.kernel.org/r/81788b56-5b15-7308-38c7-c7f2502c4e15@linux-m68k.org

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARM
Tested-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/87levzzts4.fsf_-_@email.froward.int.ebiederm.org
This commit is contained in:
Eric W. Biederman 2022-04-20 09:58:03 -05:00 • committed by Kees Cook
parent 8d005269c5
commit 70578ff336
9 changed files with 40 additions and 163 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
arch/arm/configs/lpc18xx_defconfig
View file

@ -30,7 +30,6 @@ CONFIG_ARM_APPENDED_DTB=y
# CONFIG_BLK_DEV_BSG is not set
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_ZFLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
# CONFIG_COREDUMP is not set
CONFIG_NET=y
CONFIG_PACKET=y

1
arch/arm/configs/mps2_defconfig
View file

@ -23,7 +23,6 @@ CONFIG_PREEMPT_VOLUNTARY=y
CONFIG_ZBOOT_ROM_TEXT=0x0
CONFIG_ZBOOT_ROM_BSS=0x0
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
# CONFIG_COREDUMP is not set
# CONFIG_SUSPEND is not set
CONFIG_NET=y

1
arch/arm/configs/stm32_defconfig
View file

@ -28,7 +28,6 @@ CONFIG_ZBOOT_ROM_BSS=0x0
CONFIG_XIP_KERNEL=y
CONFIG_XIP_PHYS_ADDR=0x08008000
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
# CONFIG_COREDUMP is not set
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y

1
arch/arm/configs/vf610m4_defconfig
View file

@ -18,7 +18,6 @@ CONFIG_XIP_KERNEL=y
CONFIG_XIP_PHYS_ADDR=0x0f000080
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_ZFLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
# CONFIG_SUSPEND is not set
# CONFIG_UEVENT_HELPER is not set
# CONFIG_STANDALONE is not set

1
arch/sh/configs/rsk7201_defconfig
View file

@ -25,7 +25,6 @@ CONFIG_CMDLINE_OVERWRITE=y
CONFIG_CMDLINE="console=ttySC0,115200 earlyprintk=serial ignore_loglevel"
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_ZFLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
CONFIG_PM=y
CONFIG_CPU_IDLE=y
# CONFIG_STANDALONE is not set

1
arch/sh/configs/rsk7203_defconfig
View file

@ -30,7 +30,6 @@ CONFIG_CMDLINE_OVERWRITE=y
CONFIG_CMDLINE="console=ttySC0,115200 earlyprintk=serial ignore_loglevel"
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_ZFLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
CONFIG_PM=y
CONFIG_CPU_IDLE=y
CONFIG_NET=y

1
arch/sh/configs/se7206_defconfig
View file

@ -40,7 +40,6 @@ CONFIG_CMDLINE_OVERWRITE=y
CONFIG_CMDLINE="console=ttySC3,115200 ignore_loglevel earlyprintk=serial"
CONFIG_BINFMT_FLAT=y
CONFIG_BINFMT_ZFLAT=y
CONFIG_BINFMT_SHARED_FLAT=y
CONFIG_BINFMT_MISC=y
CONFIG_NET=y
CONFIG_PACKET=y

6
fs/Kconfig.binfmt
View file

@ -142,12 +142,6 @@ config BINFMT_ZFLAT
help
Support FLAT format compressed binaries
config BINFMT_SHARED_FLAT
bool "Enable shared FLAT support"
depends on BINFMT_FLAT
help
Support FLAT shared libraries
config HAVE_AOUT
def_bool n

190
fs/binfmt_flat.c
View file

@ -68,11 +68,7 @@
#define RELOC_FAILED 0xff00ff01 /* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff /* Placeholder for unused library */
#ifdef CONFIG_BINFMT_SHARED_FLAT
#define MAX_SHARED_LIBS (4)
#else
#define MAX_SHARED_LIBS (1)
#endif
#define MAX_SHARED_LIBS (1)
#ifdef CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
#define DATA_START_OFFSET_WORDS (0)
@ -92,10 +88,6 @@ struct lib_info {
} lib_list[MAX_SHARED_LIBS];
};
#ifdef CONFIG_BINFMT_SHARED_FLAT
static int load_flat_shared_library(int id, struct lib_info *p);
#endif
static int load_flat_binary(struct linux_binprm *);
static struct linux_binfmt flat_format = {
@ -307,51 +299,18 @@ out_free:
/****************************************************************************/
static unsigned long
calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
calc_reloc(unsigned long r, struct lib_info *p)
{
unsigned long addr;
int id;
unsigned long start_brk;
unsigned long start_data;
unsigned long text_len;
unsigned long start_code;
#ifdef CONFIG_BINFMT_SHARED_FLAT
if (r == 0)
id = curid; /* Relocs of 0 are always self referring */
else {
id = (r >> 24) & 0xff; /* Find ID for this reloc */
r &= 0x00ffffff; /* Trim ID off here */
}
if (id >= MAX_SHARED_LIBS) {
pr_err("reference 0x%lx to shared library %d", r, id);
goto failed;
}
if (curid != id) {
if (internalp) {
pr_err("reloc address 0x%lx not in same module "
"(%d != %d)", r, curid, id);
goto failed;
} else if (!p->lib_list[id].loaded &&
load_flat_shared_library(id, p) < 0) {
pr_err("failed to load library %d", id);
goto failed;
}
/* Check versioning information (i.e. time stamps) */
if (p->lib_list[id].build_date && p->lib_list[curid].build_date &&
p->lib_list[curid].build_date < p->lib_list[id].build_date) {
pr_err("library %d is younger than %d", id, curid);
goto failed;
}
}
#else
id = 0;
#endif
start_brk = p->lib_list[id].start_brk;
start_data = p->lib_list[id].start_data;
start_code = p->lib_list[id].start_code;
text_len = p->lib_list[id].text_len;
start_brk = p->lib_list[0].start_brk;
start_data = p->lib_list[0].start_data;
start_code = p->lib_list[0].start_code;
text_len = p->lib_list[0].text_len;
if (r > start_brk - start_data + text_len) {
pr_err("reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
@ -443,7 +402,7 @@ static inline u32 __user *skip_got_header(u32 __user *rp)
}
static int load_flat_file(struct linux_binprm *bprm,
struct lib_info *libinfo, int id, unsigned long *extra_stack)
struct lib_info *libinfo, unsigned long *extra_stack)
{
struct flat_hdr *hdr;
unsigned long textpos, datapos, realdatastart;
@ -495,14 +454,6 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}
/* Don't allow old format executables to use shared libraries */
if (rev == OLD_FLAT_VERSION && id != 0) {
pr_err("shared libraries are not available before rev 0x%lx\n",
FLAT_VERSION);
ret = -ENOEXEC;
goto err;
}
/*
* fix up the flags for the older format, there were all kinds
* of endian hacks, this only works for the simple cases
@ -553,15 +504,13 @@ static int load_flat_file(struct linux_binprm *bprm,
}
/* Flush all traces of the currently running executable */
if (id == 0) {
ret = begin_new_exec(bprm);
if (ret)
goto err;
ret = begin_new_exec(bprm);
if (ret)
goto err;
/* OK, This is the point of no return */
set_personality(PER_LINUX_32BIT);
setup_new_exec(bprm);
}
/* OK, This is the point of no return */
set_personality(PER_LINUX_32BIT);
setup_new_exec(bprm);
/*
* calculate the extra space we need to map in
@ -741,42 +690,40 @@ static int load_flat_file(struct linux_binprm *bprm,
text_len -= sizeof(struct flat_hdr); /* the real code len */
/* The main program needs a little extra setup in the task structure */
if (id == 0) {
current->mm->start_code = start_code;
current->mm->end_code = end_code;
current->mm->start_data = datapos;
current->mm->end_data = datapos + data_len;
/*
* set up the brk stuff, uses any slack left in data/bss/stack
* allocation. We put the brk after the bss (between the bss
* and stack) like other platforms.
* Userspace code relies on the stack pointer starting out at
* an address right at the end of a page.
*/
current->mm->start_brk = datapos + data_len + bss_len;
current->mm->brk = (current->mm->start_brk + 3) & ~3;
current->mm->start_code = start_code;
current->mm->end_code = end_code;
current->mm->start_data = datapos;
current->mm->end_data = datapos + data_len;
/*
* set up the brk stuff, uses any slack left in data/bss/stack
* allocation. We put the brk after the bss (between the bss
* and stack) like other platforms.
* Userspace code relies on the stack pointer starting out at
* an address right at the end of a page.
*/
current->mm->start_brk = datapos + data_len + bss_len;
current->mm->brk = (current->mm->start_brk + 3) & ~3;
#ifndef CONFIG_MMU
current->mm->context.end_brk = memp + memp_size - stack_len;
current->mm->context.end_brk = memp + memp_size - stack_len;
#endif
}
if (flags & FLAT_FLAG_KTRACE) {
pr_info("Mapping is %lx, Entry point is %x, data_start is %x\n",
textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
pr_info("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
id ? "Lib" : "Load", bprm->filename,
"Load", bprm->filename,
start_code, end_code, datapos, datapos + data_len,
datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
}
/* Store the current module values into the global library structure */
libinfo->lib_list[id].start_code = start_code;
libinfo->lib_list[id].start_data = datapos;
libinfo->lib_list[id].start_brk = datapos + data_len + bss_len;
libinfo->lib_list[id].text_len = text_len;
libinfo->lib_list[id].loaded = 1;
libinfo->lib_list[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
libinfo->lib_list[id].build_date = ntohl(hdr->build_date);
libinfo->lib_list[0].start_code = start_code;
libinfo->lib_list[0].start_data = datapos;
libinfo->lib_list[0].start_brk = datapos + data_len + bss_len;
libinfo->lib_list[0].text_len = text_len;
libinfo->lib_list[0].loaded = 1;
libinfo->lib_list[0].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
libinfo->lib_list[0].build_date = ntohl(hdr->build_date);
/*
* We just load the allocations into some temporary memory to
@ -799,7 +746,7 @@ static int load_flat_file(struct linux_binprm *bprm,
if (rp_val == 0xffffffff)
break;
if (rp_val) {
addr = calc_reloc(rp_val, libinfo, id, 0);
addr = calc_reloc(rp_val, libinfo);
if (addr == RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
@ -835,7 +782,7 @@ static int load_flat_file(struct linux_binprm *bprm,
return -EFAULT;
relval = ntohl(tmp);
addr = flat_get_relocate_addr(relval);
rp = (u32 __user *)calc_reloc(addr, libinfo, id, 1);
rp = (u32 __user *)calc_reloc(addr, libinfo);
if (rp == (u32 __user *)RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
@ -858,7 +805,7 @@ static int load_flat_file(struct linux_binprm *bprm,
*/
addr = ntohl((__force __be32)addr);
}
addr = calc_reloc(addr, libinfo, id, 0);
addr = calc_reloc(addr, libinfo);
if (addr == RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
@ -886,7 +833,7 @@ static int load_flat_file(struct linux_binprm *bprm,
/* zero the BSS, BRK and stack areas */
if (clear_user((void __user *)(datapos + data_len), bss_len +
(memp + memp_size - stack_len - /* end brk */
libinfo->lib_list[id].start_brk) + /* start brk */
libinfo->lib_list[0].start_brk) + /* start brk */
stack_len))
return -EFAULT;
@ -896,49 +843,6 @@ err:
}
/****************************************************************************/
#ifdef CONFIG_BINFMT_SHARED_FLAT
/*
* Load a shared library into memory. The library gets its own data
* segment (including bss) but not argv/argc/environ.
*/
static int load_flat_shared_library(int id, struct lib_info *libs)
{
/*
* This is a fake bprm struct; only the members "buf", "file" and
* "filename" are actually used.
*/
struct linux_binprm bprm;
int res;
char buf[16];
loff_t pos = 0;
memset(&bprm, 0, sizeof(bprm));
/* Create the file name */
sprintf(buf, "/lib/lib%d.so", id);
/* Open the file up */
bprm.filename = buf;
bprm.file = open_exec(bprm.filename);
res = PTR_ERR(bprm.file);
if (IS_ERR(bprm.file))
return res;
res = kernel_read(bprm.file, bprm.buf, BINPRM_BUF_SIZE, &pos);
if (res >= 0)
res = load_flat_file(&bprm, libs, id, NULL);
allow_write_access(bprm.file);
fput(bprm.file);
return res;
}
#endif /* CONFIG_BINFMT_SHARED_FLAT */
/****************************************************************************/
/*
@ -971,7 +875,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);
res = load_flat_file(bprm, &libinfo, 0, &stack_len);
res = load_flat_file(bprm, &libinfo, &stack_len);
if (res < 0)
return res;
@ -1016,20 +920,6 @@ static int load_flat_binary(struct linux_binprm *bprm)
*/
start_addr = libinfo.lib_list[0].entry;
#ifdef CONFIG_BINFMT_SHARED_FLAT
for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
if (libinfo.lib_list[i].loaded) {
/* Push previos first to call address */
unsigned long __user *sp;
current->mm->start_stack -= sizeof(unsigned long);
sp = (unsigned long __user *)current->mm->start_stack;
if (put_user(start_addr, sp))
return -EFAULT;
start_addr = libinfo.lib_list[i].entry;
}
}
#endif
#ifdef FLAT_PLAT_INIT
FLAT_PLAT_INIT(regs);
#endif