[Devel] Re: [PATCH 17/38] groups: move code to kernel/groups.c

[Serge E. Hallyn]

Quoting Alexey Dobriyan (adobriyan at gmail.com):
> Move supplementary groups implementation to kernel/groups.c .
> kernel/sys.c already accumulated quite a few random stuff.
> 
> Do strictly copy/paste + add required headers to compile.
> Compile-tested on many configs and archs.
> 
> Signed-off-by: Alexey Dobriyan <adobriyan at gmail.com>

Agreed, I was thinking I'd do the same thing for groups c/r with Oren's set.

Acked-by: Serge Hallyn <serue at us.ibm.com>

> ---
>  kernel/Makefile |    1 +
>  kernel/groups.c |  288 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  kernel/sys.c    |  283 ------------------------------------------------------
>  3 files changed, 289 insertions(+), 283 deletions(-)
>  create mode 100644 kernel/groups.c
> 
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 4242366..705ad3d 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -11,6 +11,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o \
>  	    hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
>  	    notifier.o ksysfs.o pm_qos_params.o sched_clock.o cred.o \
>  	    async.o
> +obj-y += groups.o
>  
>  ifdef CONFIG_FUNCTION_TRACER
>  # Do not trace debug files and internal ftrace files
> diff --git a/kernel/groups.c b/kernel/groups.c
> new file mode 100644
> index 0000000..1b95b2f
> --- /dev/null
> +++ b/kernel/groups.c
> @@ -0,0 +1,288 @@
> +/*
> + * Supplementary group IDs
> + */
> +#include <linux/cred.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/security.h>
> +#include <linux/syscalls.h>
> +#include <asm/uaccess.h>
> +
> +/* init to 2 - one for init_task, one to ensure it is never freed */
> +struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
> +
> +struct group_info *groups_alloc(int gidsetsize)
> +{
> +	struct group_info *group_info;
> +	int nblocks;
> +	int i;
> +
> +	nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
> +	/* Make sure we always allocate at least one indirect block pointer */
> +	nblocks = nblocks ? : 1;
> +	group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
> +	if (!group_info)
> +		return NULL;
> +	group_info->ngroups = gidsetsize;
> +	group_info->nblocks = nblocks;
> +	atomic_set(&group_info->usage, 1);
> +
> +	if (gidsetsize <= NGROUPS_SMALL)
> +		group_info->blocks[0] = group_info->small_block;
> +	else {
> +		for (i = 0; i < nblocks; i++) {
> +			gid_t *b;
> +			b = (void *)__get_free_page(GFP_USER);
> +			if (!b)
> +				goto out_undo_partial_alloc;
> +			group_info->blocks[i] = b;
> +		}
> +	}
> +	return group_info;
> +
> +out_undo_partial_alloc:
> +	while (--i >= 0) {
> +		free_page((unsigned long)group_info->blocks[i]);
> +	}
> +	kfree(group_info);
> +	return NULL;
> +}
> +
> +EXPORT_SYMBOL(groups_alloc);
> +
> +void groups_free(struct group_info *group_info)
> +{
> +	if (group_info->blocks[0] != group_info->small_block) {
> +		int i;
> +		for (i = 0; i < group_info->nblocks; i++)
> +			free_page((unsigned long)group_info->blocks[i]);
> +	}
> +	kfree(group_info);
> +}
> +
> +EXPORT_SYMBOL(groups_free);
> +
> +/* export the group_info to a user-space array */
> +static int groups_to_user(gid_t __user *grouplist,
> +			  const struct group_info *group_info)
> +{
> +	int i;
> +	unsigned int count = group_info->ngroups;
> +
> +	for (i = 0; i < group_info->nblocks; i++) {
> +		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
> +		unsigned int len = cp_count * sizeof(*grouplist);
> +
> +		if (copy_to_user(grouplist, group_info->blocks[i], len))
> +			return -EFAULT;
> +
> +		grouplist += NGROUPS_PER_BLOCK;
> +		count -= cp_count;
> +	}
> +	return 0;
> +}
> +
> +/* fill a group_info from a user-space array - it must be allocated already */
> +static int groups_from_user(struct group_info *group_info,
> +    gid_t __user *grouplist)
> +{
> +	int i;
> +	unsigned int count = group_info->ngroups;
> +
> +	for (i = 0; i < group_info->nblocks; i++) {
> +		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
> +		unsigned int len = cp_count * sizeof(*grouplist);
> +
> +		if (copy_from_user(group_info->blocks[i], grouplist, len))
> +			return -EFAULT;
> +
> +		grouplist += NGROUPS_PER_BLOCK;
> +		count -= cp_count;
> +	}
> +	return 0;
> +}
> +
> +/* a simple Shell sort */
> +static void groups_sort(struct group_info *group_info)
> +{
> +	int base, max, stride;
> +	int gidsetsize = group_info->ngroups;
> +
> +	for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
> +		; /* nothing */
> +	stride /= 3;
> +
> +	while (stride) {
> +		max = gidsetsize - stride;
> +		for (base = 0; base < max; base++) {
> +			int left = base;
> +			int right = left + stride;
> +			gid_t tmp = GROUP_AT(group_info, right);
> +
> +			while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
> +				GROUP_AT(group_info, right) =
> +				    GROUP_AT(group_info, left);
> +				right = left;
> +				left -= stride;
> +			}
> +			GROUP_AT(group_info, right) = tmp;
> +		}
> +		stride /= 3;
> +	}
> +}
> +
> +/* a simple bsearch */
> +int groups_search(const struct group_info *group_info, gid_t grp)
> +{
> +	unsigned int left, right;
> +
> +	if (!group_info)
> +		return 0;
> +
> +	left = 0;
> +	right = group_info->ngroups;
> +	while (left < right) {
> +		unsigned int mid = (left+right)/2;
> +		int cmp = grp - GROUP_AT(group_info, mid);
> +		if (cmp > 0)
> +			left = mid + 1;
> +		else if (cmp < 0)
> +			right = mid;
> +		else
> +			return 1;
> +	}
> +	return 0;
> +}
> +
> +/**
> + * set_groups - Change a group subscription in a set of credentials
> + * @new: The newly prepared set of credentials to alter
> + * @group_info: The group list to install
> + *
> + * Validate a group subscription and, if valid, insert it into a set
> + * of credentials.
> + */
> +int set_groups(struct cred *new, struct group_info *group_info)
> +{
> +	int retval;
> +
> +	retval = security_task_setgroups(group_info);
> +	if (retval)
> +		return retval;
> +
> +	put_group_info(new->group_info);
> +	groups_sort(group_info);
> +	get_group_info(group_info);
> +	new->group_info = group_info;
> +	return 0;
> +}
> +
> +EXPORT_SYMBOL(set_groups);
> +
> +/**
> + * set_current_groups - Change current's group subscription
> + * @group_info: The group list to impose
> + *
> + * Validate a group subscription and, if valid, impose it upon current's task
> + * security record.
> + */
> +int set_current_groups(struct group_info *group_info)
> +{
> +	struct cred *new;
> +	int ret;
> +
> +	new = prepare_creds();
> +	if (!new)
> +		return -ENOMEM;
> +
> +	ret = set_groups(new, group_info);
> +	if (ret < 0) {
> +		abort_creds(new);
> +		return ret;
> +	}
> +
> +	return commit_creds(new);
> +}
> +
> +EXPORT_SYMBOL(set_current_groups);
> +
> +SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
> +{
> +	const struct cred *cred = current_cred();
> +	int i;
> +
> +	if (gidsetsize < 0)
> +		return -EINVAL;
> +
> +	/* no need to grab task_lock here; it cannot change */
> +	i = cred->group_info->ngroups;
> +	if (gidsetsize) {
> +		if (i > gidsetsize) {
> +			i = -EINVAL;
> +			goto out;
> +		}
> +		if (groups_to_user(grouplist, cred->group_info)) {
> +			i = -EFAULT;
> +			goto out;
> +		}
> +	}
> +out:
> +	return i;
> +}
> +
> +/*
> + *	SMP: Our groups are copy-on-write. We can set them safely
> + *	without another task interfering.
> + */
> + 
> +SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
> +{
> +	struct group_info *group_info;
> +	int retval;
> +
> +	if (!capable(CAP_SETGID))
> +		return -EPERM;
> +	if ((unsigned)gidsetsize > NGROUPS_MAX)
> +		return -EINVAL;
> +
> +	group_info = groups_alloc(gidsetsize);
> +	if (!group_info)
> +		return -ENOMEM;
> +	retval = groups_from_user(group_info, grouplist);
> +	if (retval) {
> +		put_group_info(group_info);
> +		return retval;
> +	}
> +
> +	retval = set_current_groups(group_info);
> +	put_group_info(group_info);
> +
> +	return retval;
> +}
> +
> +/*
> + * Check whether we're fsgid/egid or in the supplemental group..
> + */
> +int in_group_p(gid_t grp)
> +{
> +	const struct cred *cred = current_cred();
> +	int retval = 1;
> +
> +	if (grp != cred->fsgid)
> +		retval = groups_search(cred->group_info, grp);
> +	return retval;
> +}
> +
> +EXPORT_SYMBOL(in_group_p);
> +
> +int in_egroup_p(gid_t grp)
> +{
> +	const struct cred *cred = current_cred();
> +	int retval = 1;
> +
> +	if (grp != cred->egid)
> +		retval = groups_search(cred->group_info, grp);
> +	return retval;
> +}
> +
> +EXPORT_SYMBOL(in_egroup_p);
> diff --git a/kernel/sys.c b/kernel/sys.c
> index e7998cf..4edcf51 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1112,289 +1112,6 @@ out:
>  	return err;
>  }
>  
> -/*
> - * Supplementary group IDs
> - */
> -
> -/* init to 2 - one for init_task, one to ensure it is never freed */
> -struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
> -
> -struct group_info *groups_alloc(int gidsetsize)
> -{
> -	struct group_info *group_info;
> -	int nblocks;
> -	int i;
> -
> -	nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
> -	/* Make sure we always allocate at least one indirect block pointer */
> -	nblocks = nblocks ? : 1;
> -	group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
> -	if (!group_info)
> -		return NULL;
> -	group_info->ngroups = gidsetsize;
> -	group_info->nblocks = nblocks;
> -	atomic_set(&group_info->usage, 1);
> -
> -	if (gidsetsize <= NGROUPS_SMALL)
> -		group_info->blocks[0] = group_info->small_block;
> -	else {
> -		for (i = 0; i < nblocks; i++) {
> -			gid_t *b;
> -			b = (void *)__get_free_page(GFP_USER);
> -			if (!b)
> -				goto out_undo_partial_alloc;
> -			group_info->blocks[i] = b;
> -		}
> -	}
> -	return group_info;
> -
> -out_undo_partial_alloc:
> -	while (--i >= 0) {
> -		free_page((unsigned long)group_info->blocks[i]);
> -	}
> -	kfree(group_info);
> -	return NULL;
> -}
> -
> -EXPORT_SYMBOL(groups_alloc);
> -
> -void groups_free(struct group_info *group_info)
> -{
> -	if (group_info->blocks[0] != group_info->small_block) {
> -		int i;
> -		for (i = 0; i < group_info->nblocks; i++)
> -			free_page((unsigned long)group_info->blocks[i]);
> -	}
> -	kfree(group_info);
> -}
> -
> -EXPORT_SYMBOL(groups_free);
> -
> -/* export the group_info to a user-space array */
> -static int groups_to_user(gid_t __user *grouplist,
> -			  const struct group_info *group_info)
> -{
> -	int i;
> -	unsigned int count = group_info->ngroups;
> -
> -	for (i = 0; i < group_info->nblocks; i++) {
> -		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
> -		unsigned int len = cp_count * sizeof(*grouplist);
> -
> -		if (copy_to_user(grouplist, group_info->blocks[i], len))
> -			return -EFAULT;
> -
> -		grouplist += NGROUPS_PER_BLOCK;
> -		count -= cp_count;
> -	}
> -	return 0;
> -}
> -
> -/* fill a group_info from a user-space array - it must be allocated already */
> -static int groups_from_user(struct group_info *group_info,
> -    gid_t __user *grouplist)
> -{
> -	int i;
> -	unsigned int count = group_info->ngroups;
> -
> -	for (i = 0; i < group_info->nblocks; i++) {
> -		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
> -		unsigned int len = cp_count * sizeof(*grouplist);
> -
> -		if (copy_from_user(group_info->blocks[i], grouplist, len))
> -			return -EFAULT;
> -
> -		grouplist += NGROUPS_PER_BLOCK;
> -		count -= cp_count;
> -	}
> -	return 0;
> -}
> -
> -/* a simple Shell sort */
> -static void groups_sort(struct group_info *group_info)
> -{
> -	int base, max, stride;
> -	int gidsetsize = group_info->ngroups;
> -
> -	for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
> -		; /* nothing */
> -	stride /= 3;
> -
> -	while (stride) {
> -		max = gidsetsize - stride;
> -		for (base = 0; base < max; base++) {
> -			int left = base;
> -			int right = left + stride;
> -			gid_t tmp = GROUP_AT(group_info, right);
> -
> -			while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
> -				GROUP_AT(group_info, right) =
> -				    GROUP_AT(group_info, left);
> -				right = left;
> -				left -= stride;
> -			}
> -			GROUP_AT(group_info, right) = tmp;
> -		}
> -		stride /= 3;
> -	}
> -}
> -
> -/* a simple bsearch */
> -int groups_search(const struct group_info *group_info, gid_t grp)
> -{
> -	unsigned int left, right;
> -
> -	if (!group_info)
> -		return 0;
> -
> -	left = 0;
> -	right = group_info->ngroups;
> -	while (left < right) {
> -		unsigned int mid = (left+right)/2;
> -		int cmp = grp - GROUP_AT(group_info, mid);
> -		if (cmp > 0)
> -			left = mid + 1;
> -		else if (cmp < 0)
> -			right = mid;
> -		else
> -			return 1;
> -	}
> -	return 0;
> -}
> -
> -/**
> - * set_groups - Change a group subscription in a set of credentials
> - * @new: The newly prepared set of credentials to alter
> - * @group_info: The group list to install
> - *
> - * Validate a group subscription and, if valid, insert it into a set
> - * of credentials.
> - */
> -int set_groups(struct cred *new, struct group_info *group_info)
> -{
> -	int retval;
> -
> -	retval = security_task_setgroups(group_info);
> -	if (retval)
> -		return retval;
> -
> -	put_group_info(new->group_info);
> -	groups_sort(group_info);
> -	get_group_info(group_info);
> -	new->group_info = group_info;
> -	return 0;
> -}
> -
> -EXPORT_SYMBOL(set_groups);
> -
> -/**
> - * set_current_groups - Change current's group subscription
> - * @group_info: The group list to impose
> - *
> - * Validate a group subscription and, if valid, impose it upon current's task
> - * security record.
> - */
> -int set_current_groups(struct group_info *group_info)
> -{
> -	struct cred *new;
> -	int ret;
> -
> -	new = prepare_creds();
> -	if (!new)
> -		return -ENOMEM;
> -
> -	ret = set_groups(new, group_info);
> -	if (ret < 0) {
> -		abort_creds(new);
> -		return ret;
> -	}
> -
> -	return commit_creds(new);
> -}
> -
> -EXPORT_SYMBOL(set_current_groups);
> -
> -SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
> -{
> -	const struct cred *cred = current_cred();
> -	int i;
> -
> -	if (gidsetsize < 0)
> -		return -EINVAL;
> -
> -	/* no need to grab task_lock here; it cannot change */
> -	i = cred->group_info->ngroups;
> -	if (gidsetsize) {
> -		if (i > gidsetsize) {
> -			i = -EINVAL;
> -			goto out;
> -		}
> -		if (groups_to_user(grouplist, cred->group_info)) {
> -			i = -EFAULT;
> -			goto out;
> -		}
> -	}
> -out:
> -	return i;
> -}
> -
> -/*
> - *	SMP: Our groups are copy-on-write. We can set them safely
> - *	without another task interfering.
> - */
> - 
> -SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
> -{
> -	struct group_info *group_info;
> -	int retval;
> -
> -	if (!capable(CAP_SETGID))
> -		return -EPERM;
> -	if ((unsigned)gidsetsize > NGROUPS_MAX)
> -		return -EINVAL;
> -
> -	group_info = groups_alloc(gidsetsize);
> -	if (!group_info)
> -		return -ENOMEM;
> -	retval = groups_from_user(group_info, grouplist);
> -	if (retval) {
> -		put_group_info(group_info);
> -		return retval;
> -	}
> -
> -	retval = set_current_groups(group_info);
> -	put_group_info(group_info);
> -
> -	return retval;
> -}
> -
> -/*
> - * Check whether we're fsgid/egid or in the supplemental group..
> - */
> -int in_group_p(gid_t grp)
> -{
> -	const struct cred *cred = current_cred();
> -	int retval = 1;
> -
> -	if (grp != cred->fsgid)
> -		retval = groups_search(cred->group_info, grp);
> -	return retval;
> -}
> -
> -EXPORT_SYMBOL(in_group_p);
> -
> -int in_egroup_p(gid_t grp)
> -{
> -	const struct cred *cred = current_cred();
> -	int retval = 1;
> -
> -	if (grp != cred->egid)
> -		retval = groups_search(cred->group_info, grp);
> -	return retval;
> -}
> -
> -EXPORT_SYMBOL(in_egroup_p);
> -
>  DECLARE_RWSEM(uts_sem);
>  
>  SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
> -- 
> 1.5.6.5
> 
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