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Preserve errno across _PC_CHOWN_RESTRICTED call on XFS 

Fix BZ #15305.

On kernel versions earlier than 2.6.29, the Linux kernel exported a
sysctl called restrict_chown for xfs, which could be used to allow
chown to users other than the owner.  2.6.29 removed this support,
causing the open_not_cancel_2 to fail and thus modify errno.  The fix
is to save and restore errno so that the caller sees it as unmodified.

Additionally, since the code to check the sysctl is not useful on
newer kernels, we add an ifdef so that in future the code block gets
rmeoved completely.
This commit is contained in:
Siddhesh Poyarekar 2013-04-03 10:56:45 +05:30
parent 52ce486045
commit d755bba40f
4 changed files with 25 additions and 1 deletions
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10
ChangeLog
View File

@ -1,3 +1,13 @@
2013-04-03 Siddhesh Poyarekar <siddhesh@redhat.com>
[BZ #15305]
* sysdeps/unix/sysv/linux/kernel-features.h
[__LINUX_KERNEL_VERSION >= 0x02061d]: Define
__ASSUME_XFS_RESTRICTED_CHOWN.
* sysdeps/unix/sysv/linux/pathconf.c
(__statfs_chown_restricted) [!__ASSUME_XFS_RESTRICTED_CHOWN]:
Save and restore errno.
2013-04-02 Joseph Myers <joseph@codesourcery.com>
[BZ #15327]

3
NEWS
View File

@ -12,7 +12,8 @@ Version 2.18
10357, 11120, 11561, 12723, 13550, 13889, 13951, 14142, 14176, 14200,
14317, 14327, 14496, 14812, 14920, 14964, 14981, 14982, 14985, 14994,
14996, 15003, 15006, 15020, 15023, 15036, 15054, 15055, 15062, 15078,
15160, 15214, 15232, 15234, 15283, 15285, 15287, 15304, 15307, 15327.
15160, 15214, 15232, 15234, 15283, 15285, 15287, 15304, 15305, 15307,
15327.
* Add support for calling C++11 thread_local object destructors on thread
and program exit. This needs compiler support for offloading C++11

6
sysdeps/unix/sysv/linux/kernel-features.h
View File

@ -221,3 +221,9 @@
#if defined __x86_64__ && __LINUX_KERNEL_VERSION >= 0x030100
# define __ASSUME_GETCPU_SYSCALL 1
#endif
/* 2.6.29 removed the XFS restricted_chown sysctl, so it is pointless looking
for it in newer kernels. */
#if __LINUX_KERNEL_VERSION >= 0x02061d
# define __ASSUME_XFS_RESTRICTED_CHOWN 1
#endif

7
sysdeps/unix/sysv/linux/pathconf.c
View File

@ -289,11 +289,16 @@ __statfs_chown_restricted (int result, const struct statfs *fsbuf)
return -1;
}
#if __ASSUME_XFS_RESTRICTED_CHOWN
return 1;
#else
int fd;
int save_errno;
long int retval = 1;
switch (fsbuf->f_type)
{
case XFS_SUPER_MAGIC:
save_errno = errno;
/* Read the value from /proc/sys/fs/xfs/restrict_chown. If we cannot
read it default to assume the restriction is in place. */
fd = open_not_cancel_2 ("/proc/sys/fs/xfs/restrict_chown", O_RDONLY);
@ -306,6 +311,7 @@ __statfs_chown_restricted (int result, const struct statfs *fsbuf)
close_not_cancel_no_status (fd);
}
__set_errno (save_errno);
break;
default:
@ -313,4 +319,5 @@ __statfs_chown_restricted (int result, const struct statfs *fsbuf)
}
return retval;
#endif
}