Re: [PATCH] filesystems: use has_capability_noaudit interface for reserved blocks checks

Mingming Cao
2008-11-13T00:19:22Z

在 2008-11-11二的 14:12 -0500，Eric Paris写道：
> ext[2,3,4], ufs, and ubifs all check for CAP_SYS_RESOURCE to determine
> if they should allow reserved blocks to be used. A process not having
> this capability is not failing some security decision and should not be
> audited. Thus move to using has_capability_noaudit.
>
Looks fine to me.

Eric Sandeen has mentioned earlier about the security audit issue with
ext4. We fixed it in ext4, with this it is even better.

Reviewed-by: Mingming Cao <cmm@us.ibm.com>
> Signed-off-by: Eric Paris <eparis@redhat.com>
> ---
>
> I would like to push this patch through the security tree (since that's
> the only place the new cap_noaudit interface exists), but I'd like to
> get an ACK from each subsystem maintainer.
>
> fs/ext2/balloc.c | 2 +-
> fs/ext3/balloc.c | 2 +-
> fs/ext4/balloc.c | 2 +-
> fs/ubifs/budget.c | 3 ++-
> fs/ufs/balloc.c | 2 +-
> security/commoncap.c | 1 +
> security/security.c | 1 +
> 7 files changed, 8 insertions(+), 5 deletions(-)
>
>
> diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
> index 6dac7ba..e06d96d 100644
> --- a/fs/ext2/balloc.c
> +++ b/fs/ext2/balloc.c
> @@ -1192,7 +1192,7 @@ static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
>
> free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
> root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
> - if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
> + if (free_blocks < root_blocks + 1 && !has_capability_noaudit(current, CAP_SYS_RESOURCE) &&
> sbi->s_resuid != current->fsuid &&
> (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
> return 0;
> diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
> index f5b57a2..f224ee4 100644
> --- a/fs/ext3/balloc.c
> +++ b/fs/ext3/balloc.c
> @@ -1421,7 +1421,7 @@ static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
>
> free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
> root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
> - if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
> + if (free_blocks < root_blocks + 1 && !has_capability_noaudit(current, CAP_SYS_RESOURCE) &&
> sbi->s_resuid != current->fsuid &&
> (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
> return 0;
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index d2003cd..a7c7c52 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -626,7 +626,7 @@ int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
> /* Hm, nope. Are (enough) root reserved blocks available? */
> if (sbi->s_resuid == current->fsuid ||
> ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
> - capable(CAP_SYS_RESOURCE)) {
> + has_capability_noaudit(current, CAP_SYS_RESOURCE)) {
> if (free_blocks >= (nblocks + dirty_blocks))
> return 1;
> }
> diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
> index 1a4973e..d17b8b4 100644
> --- a/fs/ubifs/budget.c
> +++ b/fs/ubifs/budget.c
> @@ -32,6 +32,7 @@
>
> #include "ubifs.h"
> #include <linux/writeback.h>
> +#include <linux/capability.h>
> #include <asm/div64.h>
>
> /*
> @@ -363,7 +364,7 @@ long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs)
> */
> static int can_use_rp(struct ubifs_info *c)
> {
> - if (current->fsuid == c->rp_uid || capable(CAP_SYS_RESOURCE) ||
> + if (current->fsuid == c->rp_uid || has_capability_noaudit(current, CAP_SYS_RESOURCE) ||
> (c->rp_gid != 0 && in_group_p(c->rp_gid)))
> return 1;
> return 0;
> diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
> index 0d9ada1..ad4398b 100644
> --- a/fs/ufs/balloc.c
> +++ b/fs/ufs/balloc.c
> @@ -411,7 +411,7 @@ u64 ufs_new_fragments(struct inode *inode, void *p, u64 fragment,
> /*
> * There is not enough space for user on the device
> */
> - if (!capable(CAP_SYS_RESOURCE) && ufs_freespace(uspi, UFS_MINFREE) <= 0) {
> + if (!has_capability_noaudit(current, CAP_SYS_RESOURCE) && ufs_freespace(uspi, UFS_MINFREE) <= 0) {
> unlock_super (sb);
> UFSD("EXIT (FAILED)\n");
> return 0;
> diff --git a/security/commoncap.c b/security/commoncap.c
> index 73999f6..5401e77 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -55,6 +55,7 @@ int cap_capable(struct task_struct *tsk, int cap, int audit)
> return 0;
> return -EPERM;
> }
> +EXPORT_SYMBOL(cap_capable);
>
> int cap_settime(struct timespec *ts, struct timezone *tz)
> {
> diff --git a/security/security.c b/security/security.c
> index 346f21e..d061eb1 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -170,6 +170,7 @@ int security_capable_noaudit(struct task_struct *tsk, int cap)
> {
> return security_ops->capable(tsk, cap, SECURITY_CAP_NOAUDIT);
> }
> +EXPORT_SYMBOL(security_capable_noaudit);
>
> int security_acct(struct file *file)
> {
>
>
> --
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