1 files changed, 176 insertions, 62 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 3a6175fe10c0..02b16910f4c9 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -386,6 +386,127 @@ static unsigned long total_mapping_size(struct elf_phdr *cmds, int nr)
 				ELF_PAGESTART(cmds[first_idx].p_vaddr);
 }
 
+/**
+ * load_elf_phdrs() - load ELF program headers
+ * @elf_ex:   ELF header of the binary whose program headers should be loaded
+ * @elf_file: the opened ELF binary file
+ *
+ * Loads ELF program headers from the binary file elf_file, which has the ELF
+ * header pointed to by elf_ex, into a newly allocated array. The caller is
+ * responsible for freeing the allocated data. Returns an ERR_PTR upon failure.
+ */
+static struct elf_phdr *load_elf_phdrs(struct elfhdr *elf_ex,
+				       struct file *elf_file)
+{
+	struct elf_phdr *elf_phdata = NULL;
+	int retval, size, err = -1;
+
+	/*
+	 * If the size of this structure has changed, then punt, since
+	 * we will be doing the wrong thing.
+	 */
+	if (elf_ex->e_phentsize != sizeof(struct elf_phdr))
+		goto out;
+
+	/* Sanity check the number of program headers... */
+	if (elf_ex->e_phnum < 1 ||
+		elf_ex->e_phnum > 65536U / sizeof(struct elf_phdr))
+		goto out;
+
+	/* ...and their total size. */
+	size = sizeof(struct elf_phdr) * elf_ex->e_phnum;
+	if (size > ELF_MIN_ALIGN)
+		goto out;
+
+	elf_phdata = kmalloc(size, GFP_KERNEL);
+	if (!elf_phdata)
+		goto out;
+
+	/* Read in the program headers */
+	retval = kernel_read(elf_file, elf_ex->e_phoff,
+			     (char *)elf_phdata, size);
+	if (retval != size) {
+		err = (retval < 0) ? retval : -EIO;
+		goto out;
+	}
+
+	/* Success! */
+	err = 0;
+out:
+	if (err) {
+		kfree(elf_phdata);
+		elf_phdata = NULL;
+	}
+	return elf_phdata;
+}
+
+#ifndef CONFIG_ARCH_BINFMT_ELF_STATE
+
+/**
+ * struct arch_elf_state - arch-specific ELF loading state
+ *
+ * This structure is used to preserve architecture specific data during
+ * the loading of an ELF file, throughout the checking of architecture
+ * specific ELF headers & through to the point where the ELF load is
+ * known to be proceeding (ie. SET_PERSONALITY).
+ *
+ * This implementation is a dummy for architectures which require no
+ * specific state.
+ */
+struct arch_elf_state {
+};
+
+#define INIT_ARCH_ELF_STATE {}
+
+/**
+ * arch_elf_pt_proc() - check a PT_LOPROC..PT_HIPROC ELF program header
+ * @ehdr:	The main ELF header
+ * @phdr:	The program header to check
+ * @elf:	The open ELF file
+ * @is_interp:	True if the phdr is from the interpreter of the ELF being
+ *		loaded, else false.
+ * @state:	Architecture-specific state preserved throughout the process
+ *		of loading the ELF.
+ *
+ * Inspects the program header phdr to validate its correctness and/or
+ * suitability for the system. Called once per ELF program header in the
+ * range PT_LOPROC to PT_HIPROC, for both the ELF being loaded and its
+ * interpreter.
+ *
+ * Return: Zero to proceed with the ELF load, non-zero to fail the ELF load
+ *         with that return code.
+ */
+static inline int arch_elf_pt_proc(struct elfhdr *ehdr,
+				   struct elf_phdr *phdr,
+				   struct file *elf, bool is_interp,
+				   struct arch_elf_state *state)
+{
+	/* Dummy implementation, always proceed */
+	return 0;
+}
+
+/**
+ * arch_check_elf() - check a PT_LOPROC..PT_HIPROC ELF program header
+ * @ehdr:	The main ELF header
+ * @has_interp:	True if the ELF has an interpreter, else false.
+ * @state:	Architecture-specific state preserved throughout the process
+ *		of loading the ELF.
+ *
+ * Provides a final opportunity for architecture code to reject the loading
+ * of the ELF & cause an exec syscall to return an error. This is called after
+ * all program headers to be checked by arch_elf_pt_proc have been.
+ *
+ * Return: Zero to proceed with the ELF load, non-zero to fail the ELF load
+ *         with that return code.
+ */
+static inline int arch_check_elf(struct elfhdr *ehdr, bool has_interp,
+				 struct arch_elf_state *state)
+{
+	/* Dummy implementation, always proceed */
+	return 0;
+}
+
+#endif /* !CONFIG_ARCH_BINFMT_ELF_STATE */
 
 /* This is much more generalized than the library routine read function,
    so we keep this separate.  Technically the library read function
@@ -394,16 +515,15 @@ static unsigned long total_mapping_size(struct elf_phdr *cmds, int nr)
 
 static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 		struct file *interpreter, unsigned long *interp_map_addr,
-		unsigned long no_base)
+		unsigned long no_base, struct elf_phdr *interp_elf_phdata)
 {
-	struct elf_phdr *elf_phdata;
 	struct elf_phdr *eppnt;
 	unsigned long load_addr = 0;
 	int load_addr_set = 0;
 	unsigned long last_bss = 0, elf_bss = 0;
 	unsigned long error = ~0UL;
 	unsigned long total_size;
-	int retval, i, size;
+	int i;
 
 	/* First of all, some simple consistency checks */
 	if (interp_elf_ex->e_type != ET_EXEC &&
@@ -414,40 +534,14 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 	if (!interpreter->f_op->mmap)
 		goto out;
 
-	/*
-	 * If the size of this structure has changed, then punt, since
-	 * we will be doing the wrong thing.
-	 */
-	if (interp_elf_ex->e_phentsize != sizeof(struct elf_phdr))
-		goto out;
-	if (interp_elf_ex->e_phnum < 1 ||
-		interp_elf_ex->e_phnum > 65536U / sizeof(struct elf_phdr))
-		goto out;
-
-	/* Now read in all of the header information */
-	size = sizeof(struct elf_phdr) * interp_elf_ex->e_phnum;
-	if (size > ELF_MIN_ALIGN)
-		goto out;
-	elf_phdata = kmalloc(size, GFP_KERNEL);
-	if (!elf_phdata)
-		goto out;
-
-	retval = kernel_read(interpreter, interp_elf_ex->e_phoff,
-			     (char *)elf_phdata, size);
-	error = -EIO;
-	if (retval != size) {
-		if (retval < 0)
-			error = retval;	
-		goto out_close;
-	}
-
-	total_size = total_mapping_size(elf_phdata, interp_elf_ex->e_phnum);
+	total_size = total_mapping_size(interp_elf_phdata,
+					interp_elf_ex->e_phnum);
 	if (!total_size) {
 		error = -EINVAL;
-		goto out_close;
+		goto out;
 	}
 
-	eppnt = elf_phdata;
+	eppnt = interp_elf_phdata;
 	for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) {
 		if (eppnt->p_type == PT_LOAD) {
 			int elf_type = MAP_PRIVATE | MAP_DENYWRITE;
@@ -474,7 +568,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 				*interp_map_addr = map_addr;
 			error = map_addr;
 			if (BAD_ADDR(map_addr))
-				goto out_close;
+				goto out;
 
 			if (!load_addr_set &&
 			    interp_elf_ex->e_type == ET_DYN) {
@@ -493,7 +587,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 			    eppnt->p_memsz > TASK_SIZE ||
 			    TASK_SIZE - eppnt->p_memsz < k) {
 				error = -ENOMEM;
-				goto out_close;
+				goto out;
 			}
 
 			/*
@@ -523,7 +617,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 		 */
 		if (padzero(elf_bss)) {
 			error = -EFAULT;
-			goto out_close;
+			goto out;
 		}
 
 		/* What we have mapped so far */
@@ -532,13 +626,10 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
 		/* Map the last of the bss segment */
 		error = vm_brk(elf_bss, last_bss - elf_bss);
 		if (BAD_ADDR(error))
-			goto out_close;
+			goto out;
 	}
 
 	error = load_addr;
-
-out_close:
-	kfree(elf_phdata);
 out:
 	return error;
 }
@@ -575,10 +666,9 @@ static int load_elf_binary(struct linux_binprm *bprm)
 	int load_addr_set = 0;
 	char * elf_interpreter = NULL;
 	unsigned long error;
-	struct elf_phdr *elf_ppnt, *elf_phdata;
+	struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL;
 	unsigned long elf_bss, elf_brk;
 	int retval, i;
-	unsigned int size;
 	unsigned long elf_entry;
 	unsigned long interp_load_addr = 0;
 	unsigned long start_code, end_code, start_data, end_data;
@@ -589,6 +679,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
 		struct elfhdr elf_ex;
 		struct elfhdr interp_elf_ex;
 	} *loc;
+	struct arch_elf_state arch_state = INIT_ARCH_ELF_STATE;
 
 	loc = kmalloc(sizeof(*loc), GFP_KERNEL);
 	if (!loc) {
@@ -611,26 +702,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
 	if (!bprm->file->f_op->mmap)
 		goto out;
 
-	/* Now read in all of the header information */
-	if (loc->elf_ex.e_phentsize != sizeof(struct elf_phdr))
-		goto out;
-	if (loc->elf_ex.e_phnum < 1 ||
-	 	loc->elf_ex.e_phnum > 65536U / sizeof(struct elf_phdr))
-		goto out;
-	size = loc->elf_ex.e_phnum * sizeof(struct elf_phdr);
-	retval = -ENOMEM;
-	elf_phdata = kmalloc(size, GFP_KERNEL);
+	elf_phdata = load_elf_phdrs(&loc->elf_ex, bprm->file);
 	if (!elf_phdata)
 		goto out;
 
-	retval = kernel_read(bprm->file, loc->elf_ex.e_phoff,
-			     (char *)elf_phdata, size);
-	if (retval != size) {
-		if (retval >= 0)
-			retval = -EIO;
-		goto out_free_ph;
-	}
-
 	elf_ppnt = elf_phdata;
 	elf_bss = 0;
 	elf_brk = 0;
@@ -699,12 +774,21 @@ static int load_elf_binary(struct linux_binprm *bprm)
 
 	elf_ppnt = elf_phdata;
 	for (i = 0; i < loc->elf_ex.e_phnum; i++, elf_ppnt++)
-		if (elf_ppnt->p_type == PT_GNU_STACK) {
+		switch (elf_ppnt->p_type) {
+		case PT_GNU_STACK:
 			if (elf_ppnt->p_flags & PF_X)
 				executable_stack = EXSTACK_ENABLE_X;
 			else
 				executable_stack = EXSTACK_DISABLE_X;
 			break;
+
+		case PT_LOPROC ... PT_HIPROC:
+			retval = arch_elf_pt_proc(&loc->elf_ex, elf_ppnt,
+						  bprm->file, false,
+						  &arch_state);
+			if (retval)
+				goto out_free_dentry;
+			break;
 		}
 
 	/* Some simple consistency checks for the interpreter */
@@ -716,8 +800,36 @@ static int load_elf_binary(struct linux_binprm *bprm)
 		/* Verify the interpreter has a valid arch */
 		if (!elf_check_arch(&loc->interp_elf_ex))
 			goto out_free_dentry;
+
+		/* Load the interpreter program headers */
+		interp_elf_phdata = load_elf_phdrs(&loc->interp_elf_ex,
+						   interpreter);
+		if (!interp_elf_phdata)
+			goto out_free_dentry;
+
+		/* Pass PT_LOPROC..PT_HIPROC headers to arch code */
+		elf_ppnt = interp_elf_phdata;
+		for (i = 0; i < loc->interp_elf_ex.e_phnum; i++, elf_ppnt++)
+			switch (elf_ppnt->p_type) {
+			case PT_LOPROC ... PT_HIPROC:
+				retval = arch_elf_pt_proc(&loc->interp_elf_ex,
+							  elf_ppnt, interpreter,
+							  true, &arch_state);
+				if (retval)
+					goto out_free_dentry;
+				break;
+			}
 	}
 
+	/*
+	 * Allow arch code to reject the ELF at this point, whilst it's
+	 * still possible to return an error to the code that invoked
+	 * the exec syscall.
+	 */
+	retval = arch_check_elf(&loc->elf_ex, !!interpreter, &arch_state);
+	if (retval)
+		goto out_free_dentry;
+
 	/* Flush all traces of the currently running executable */
 	retval = flush_old_exec(bprm);
 	if (retval)
@@ -725,7 +837,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
 
 	/* Do this immediately, since STACK_TOP as used in setup_arg_pages
 	   may depend on the personality.  */
-	SET_PERSONALITY(loc->elf_ex);
+	SET_PERSONALITY2(loc->elf_ex, &arch_state);
 	if (elf_read_implies_exec(loc->elf_ex, executable_stack))
 		current->personality |= READ_IMPLIES_EXEC;
 
@@ -890,7 +1002,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
 		elf_entry = load_elf_interp(&loc->interp_elf_ex,
 					    interpreter,
 					    &interp_map_addr,
-					    load_bias);
+					    load_bias, interp_elf_phdata);
 		if (!IS_ERR((void *)elf_entry)) {
 			/*
 			 * load_elf_interp() returns relocation
@@ -917,6 +1029,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
 		}
 	}
 
+	kfree(interp_elf_phdata);
 	kfree(elf_phdata);
 
 	set_binfmt(&elf_format);
@@ -981,6 +1094,7 @@ out_ret:
 
 	/* error cleanup */
 out_free_dentry:
+	kfree(interp_elf_phdata);
 	allow_write_access(interpreter);
 	if (interpreter)
 		fput(interpreter);