execve updates for v5.19-rc1

- Fix binfmt_flat GOT handling for riscv (Niklas Cassel)
 
 - Remove unused/broken shared library and coredump code (Eric W. Biederman)
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Merge tag 'execve-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Fix binfmt_flat GOT handling for riscv (Niklas Cassel)

 - Remove unused/broken binfmt_flat shared library and coredump code
   (Eric W. Biederman)

* tag 'execve-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt_flat: Remove shared library support
  binfmt_flat: Drop vestiges of coredump support
  binfmt_flat: do not stop relocating GOT entries prematurely on riscv

arch/arm/configs/lpc18xx_defconfig

@@ -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

arch/arm/configs/mps2_defconfig

@@ -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

arch/arm/configs/stm32_defconfig

@@ -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

arch/arm/configs/vf610m4_defconfig

@@ -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

arch/sh/configs/rsk7201_defconfig

@@ -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

arch/sh/configs/rsk7203_defconfig

@@ -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

arch/sh/configs/se7206_defconfig

@@ -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

fs/Kconfig.binfmt

@@ -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
 

fs/binfmt_flat.c

@@ -37,7 +37,6 @@
 #include <linux/flat.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
-#include <linux/coredump.h>
 
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
@@ -69,11 +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			(1)
-#define	MAX_SHARED_LIBS			(4)
-#else
-#define	MAX_SHARED_LIBS			(1)
-#endif
 
 #ifdef CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
 #define DATA_START_OFFSET_WORDS		(0)
@@ -93,38 +88,13 @@ 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 *);
-#ifdef CONFIG_COREDUMP
-static int flat_core_dump(struct coredump_params *cprm);
-#endif
 
 static struct linux_binfmt flat_format = {
 	.module		= THIS_MODULE,
 	.load_binary	= load_flat_binary,
-#ifdef CONFIG_COREDUMP
-	.core_dump	= flat_core_dump,
-	.min_coredump	= PAGE_SIZE
-#endif
 };
 
-/****************************************************************************/
-/*
- * Routine writes a core dump image in the current directory.
- * Currently only a stub-function.
- */
-
-#ifdef CONFIG_COREDUMP
-static int flat_core_dump(struct coredump_params *cprm)
-{
-	pr_warn("Process %s:%d received signr %d and should have core dumped\n",
-		current->comm, current->pid, cprm->siginfo->si_signo);
-	return 1;
-}
-#endif
 
 /****************************************************************************/
 /*
@@ -329,51 +299,18 @@ static int decompress_exec(struct linux_binprm *bprm, loff_t fpos, char *dst,
 /****************************************************************************/
 
 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
+	start_brk = p->lib_list[0].start_brk;
-	if (r == 0)
+	start_data = p->lib_list[0].start_data;
-		id = curid;	/* Relocs of 0 are always self referring */
+	start_code = p->lib_list[0].start_code;
-	else {
+	text_len = p->lib_list[0].text_len;
-		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;
 
 	if (r > start_brk - start_data + text_len) {
 		pr_err("reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
@@ -440,8 +377,32 @@ static void old_reloc(unsigned long rl)
 
 /****************************************************************************/
 
+static inline u32 __user *skip_got_header(u32 __user *rp)
+{
+	if (IS_ENABLED(CONFIG_RISCV)) {
+		/*
+		 * RISC-V has a 16 byte GOT PLT header for elf64-riscv
+		 * and 8 byte GOT PLT header for elf32-riscv.
+		 * Skip the whole GOT PLT header, since it is reserved
+		 * for the dynamic linker (ld.so).
+		 */
+		u32 rp_val0, rp_val1;
+
+		if (get_user(rp_val0, rp))
+			return rp;
+		if (get_user(rp_val1, rp + 1))
+			return rp;
+
+		if (rp_val0 == 0xffffffff && rp_val1 == 0xffffffff)
+			rp += 4;
+		else if (rp_val0 == 0xffffffff)
+			rp += 2;
+	}
+	return 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;
@@ -493,14 +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
@@ -551,15 +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);
-		ret = begin_new_exec(bprm);
+	if (ret)
-		if (ret)
+		goto err;
-			goto err;
 
-		/* OK, This is the point of no return */
+	/* OK, This is the point of no return */
-		set_personality(PER_LINUX_32BIT);
+	set_personality(PER_LINUX_32BIT);
-		setup_new_exec(bprm);
+	setup_new_exec(bprm);
-	}
 
 	/*
 	 * calculate the extra space we need to map in
@@ -739,42 +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->start_code = start_code;
+	current->mm->end_code = end_code;
-		current->mm->end_code = end_code;
+	current->mm->start_data = datapos;
-		current->mm->start_data = datapos;
+	current->mm->end_data = datapos + data_len;
-		current->mm->end_data = datapos + data_len;
+	/*
-		/*
+	 * set up the brk stuff, uses any slack left in data/bss/stack
-		 * set up the brk stuff, uses any slack left in data/bss/stack
+	 * allocation.  We put the brk after the bss (between the bss
-		 * allocation.  We put the brk after the bss (between the bss
+	 * and stack) like other platforms.
-		 * and stack) like other platforms.
+	 * Userspace code relies on the stack pointer starting out at
-		 * Userspace code relies on the stack pointer starting out at
+	 * an address right at the end of a page.
-		 * an address right at the end of a page.
+	 */
-		 */
+	current->mm->start_brk = datapos + data_len + bss_len;
-		current->mm->start_brk = datapos + data_len + bss_len;
+	current->mm->brk = (current->mm->start_brk + 3) & ~3;
-		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[0].start_code = start_code;
-	libinfo->lib_list[id].start_data = datapos;
+	libinfo->lib_list[0].start_data = datapos;
-	libinfo->lib_list[id].start_brk = datapos + data_len + bss_len;
+	libinfo->lib_list[0].start_brk = datapos + data_len + bss_len;
-	libinfo->lib_list[id].text_len = text_len;
+	libinfo->lib_list[0].text_len = text_len;
-	libinfo->lib_list[id].loaded = 1;
+	libinfo->lib_list[0].loaded = 1;
-	libinfo->lib_list[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
+	libinfo->lib_list[0].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
-	libinfo->lib_list[id].build_date = ntohl(hdr->build_date);
+	libinfo->lib_list[0].build_date = ntohl(hdr->build_date);
 
 	/*
 	 * We just load the allocations into some temporary memory to
@@ -789,14 +738,15 @@ static int load_flat_file(struct linux_binprm *bprm,
 	 * image.
 	 */
 	if (flags & FLAT_FLAG_GOTPIC) {
-		for (rp = (u32 __user *)datapos; ; rp++) {
+		rp = skip_got_header((u32 __user *) datapos);
+		for (; ; rp++) {
 			u32 addr, rp_val;
 			if (get_user(rp_val, rp))
 				return -EFAULT;
 			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;
@@ -832,7 +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;
@@ -855,7 +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;
@@ -883,7 +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;
 
@@ -893,49 +843,6 @@ static int load_flat_file(struct linux_binprm *bprm,
 }
 
 
-/****************************************************************************/
-#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 */
 /****************************************************************************/
 
 /*
@@ -968,7 +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;
 
@@ -1013,20 +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